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A polyurethane (PUR and PU) is poly
A polyurethane (PUR and PU) is polymer composed of a chain of organic units joined by carbamate (urethane) links.
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl groups are called triols, et cetera. In practice, polyols are distinguished from short chain or low-molecular weight glycol chain extenders and cross linkers such as ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), glycerine, and trimethylolpropane (TMP). Polyols are polymers in their own right. They are formed by base-catalyzed addition of propylene oxide (PO), ethylene oxide (EO) onto a hydroxyl or amine containing initiator, or by polyesterification of a di-acid, such as adipic acid, with glycols, such as ethylene glycol or dipropylene glycol (DPG). Polyols extended with PO or EO are polyether polyols. Polyols formed by polyesterification are polyester polyols. The choice of initiator, extender, and molecular weight of the polyol greatly affect its physical state, and the physical properties of the polyurethane polymer. Important characteristics of polyols are their molecular backbone, initiator, molecular weight, % primary hydroxyl groups, functionality, and viscosity.
PU reaction mechanism catalyzed by a tertiary amine
reaction meachanism
carbon dioxide gas formed by reacting water and isocyanate
water isocyanate reaction
The polymerization reaction is catalyzed by tertiary amines, such as dimethylcyclohexylamine, and organometallic compounds, such as dibutyltin dilaurate or bismuth octanoate. Furthermore, catalysts can be chosen based on whether they favor the urethane (gel) reaction, such as 1,4-diazabicyclo[2.2.2]octane (also called DABCO or TEDA), or the urea (blow) reaction, such as bis-(2-dimethylaminoethyl)ether, or specifically drive the isocyanate trimerization reaction, such as potassium octoate.
A polyurethane (PUR and PU) is polymer composed of a chain of organic units joined by carbamate (urethane) links.
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl gro
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl groups are called triols, et cetera. In practice, polyols are distinguished from short chain or low-molecular weight glycol chain extenders and cross linkers such as ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), glycerine, and trimethylolpropane (TMP). Polyols are polymers in their own right. They are formed by base-catalyzed addition of propylene oxide (PO), ethylene oxide (EO) onto a hydroxyl or amine containing initiator, or by polyesterification of a di-acid, such as adipic acid, with glycols, such as ethylene glycol or dipropylene glycol (DPG). Polyols extended with PO or EO are polyether polyols. Polyols formed by polyesterification are polyester polyols. The choice of initiator, extender, and molecular weight of the polyol greatly affect its physical state, and the physical properties of the polyurethane polymer. Important characteristics of polyols are their molecular backbone, initiator, molecular weight, % primary hydroxyl groups, functionality, and viscosity.
PU reaction mechanism catalyzed by a tertiary amine
reaction meachanism
carbon dioxide gas formed by reacting water and isocyanate
water isocyanate reaction
The polymerization reaction is catalyzed by tertiary amines, such as dimethylcyclohexylamine, and organometallic compounds, such as dibutyltin dilaurate or bismuth octanoate. Furthermore, catalysts can be chosen based on whether they favor the urethane (gel) reaction, such as 1,4-diazabicyclo[2.2.2]octane (also called DABCO or TEDA), or the urea (blow) reaction, such as bis-(2-dimethylaminoethyl)ether, or specifically drive the isocyanate trimerization reaction, such as potassium octoate.
A polyurethane (PUR and PU) is polymer composed of a chain of organic units joined by carbamate (urethane) links.
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl gro
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Poliuretan (PUR dan PU) adalah polimer terdiri dari rantai organik unit bergabung dengan carbamate (urethane) link.
polimer Polyurethane dibentuk dengan menggabungkan dua bi - atau lebih tinggi monomer fungsional. Berisi dua atau lebih kelompok fungsional isocyanate (dengan formula-N = C = O) dan yang lain berisi dua atau lebih kelompok hidroksil (dengan formula-OH). Alkohol dan kelompok isocyanate bergabung untuk membentuk hubungan urethane:
ROH R'NCO → ROC (O) N (H) R' (R dan R' adalah kelompok-kelompok alkil atau Aril)
proses menggabungkan ini, kadang-kadang disebut kondensasi, biasanya memerlukan kehadiran katalis. Monomer lebih rumit juga digunakan.
poliuretan digunakan dalam pembuatan busa yang fleksibel, high-ketahanan tempat duduk; Panel insulasi busa kaku; microcellular busa segel dan gasket; tahan lama elastomeric roda dan ban; Bushing otomotif suspensi; senyawa pot listrik; perekat kinerja tinggi; lapisan permukaan dan sealant permukaan; serat sintetis (misalnya, Spandex); lapisan bawah karpet; dan bagian-bagian plastik keras (misalnya, untuk alat elektronik).
Poliuretan juga digunakan untuk pembuatan selang dan skateboard roda karena menggabungkan properti terbaik kedua karet dan plastik.
poliuretan berada di kelas senyawa-senyawa yang disebut reaksi polimer, yang meliputi epoxies, tak jenuh polyesters dan phenolic.[5][6][7][8][9] hubungan urethane diproduksi oleh bereaksi grup isocyanate -N = C = O dengan kelompok hidroksil (alkohol), -OH. Poliuretan diproduksi oleh reaksi polyaddition polyisocyanate dengan polyalcohol (polyol) hadapan katalis dan aditif lainnya. Dalam kasus ini, polyisocyanate adalah molekul dengan dua atau lebih isocyanate fungsional kelompok, R-(N = C = O) n ≥ 2 dan polyol adalah molekul dengan dua atau lebih fungsional kelompok hidroksil, R'-≥ n (OH) 2. Produk reaksi adalah polimer yang mengandung urethane hubungan, - RNHCOOR'-. Isocyanates akan bereaksi dengan setiap molekul yang berisi hidrogen aktif. Penting, isocyanates bereaksi dengan air untuk membentuk hubungan urea dan gas karbon dioksida; mereka juga bereaksi dengan polyetheramines untuk bentuk polyureas. Secara komersial, poliuretan diproduksi oleh bereaksi isocyanate cair dengan campuran cair polyol, katalis dan aditif lainnya. Dua komponen ini disebut sebagai sistem poliuretan, atau hanya sebuah sistem. Isocyanate sering disebut di Amerika Utara sebagai 'Sisi-A' atau hanya 'iso'. Perpaduan polyol dan aditif lainnya sering disebut sebagai 'B' atau 'Poli'. Campuran ini mungkin juga disebut 'resin' atau 'resin campuran'. Di Eropa, artinya 'Sisi-A' dan 'B' dibalik. Resin campuran aditif dapat mencakup jaringan Extender, salib linkers, surfaktan, flame retardants, meniup agen, pigmen, dan pengisi.
Komponen penting pertama polimer poliuretan adalah isocyanate. Molekul yang berisi dua kelompok isocyanate disebut diisocyanates. Molekul-molekul ini juga disebut sebagai monomer atau unit monomer, karena mereka sendiri yang digunakan untuk menghasilkan isocyanates polimer yang mengandung tiga atau lebih kelompok-kelompok fungsional isocyanate. Isocyanates dapat digolongkan sebagai aromatik, seperti diphenylmethane diisocyanate (MDI) atau diisocyanate toluena (TDI); atau alifatik, seperti hexamethylene diisocyanate (IPM) atau isophorone diisocyanate (IPDI). Contoh polymeric isocyanate adalah Polimerik diphenylmethane diisocyanate, yang adalah campuran molekul dengan dua, tiga, empat atau lebih kelompok isocyanate, dengan rata-rata fungsi 2.7. Isocyanates dapat dimodifikasi lebih lanjut oleh sebagian bereaksi mereka dengan polyol untuk membentuk prepolymer. Kuasi-prepolymer ini terbentuk ketika rasio stoikiometri isocyanate untuk kelompok hidroksil lebih besar dari 2:1. Prepolymer benar terbentuk ketika rasio stoikiometri sama dengan 2:1. Prepolymers dapat digunakan sebagai kelembaban menyembuhkan poliuretan. Karakteristik penting isocyanates adalah tulang punggung molekuler, % NCO konten mereka, fungsionalitas, dan viskositas.
komponen penting kedua polimer poliuretan adalah polyol. Molekul yang berisi dua grup hidroksil disebut diols, mereka dengan tiga kelompok hidroksil disebut triols, dan sebagainya. Dalam prakteknya, polyol dibedakan dari rantai pendek atau berat molekul rendah glikol jaringan Extender dan lintas linkers seperti etilena glikol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), gliserin, dan trimethylolpropane (TMP). Polyol adalah polimer dalam hak mereka sendiri. Mereka dibentuk oleh basa-dikatalisasi penambahan propilena oksida (PO), etilen oksida (EO) ke hidroksil atau amina yang mengandung inisiator, atau polyesterification di-asam, seperti dietil, dengan glycols, seperti ethylene glycol atau glikol dipropilen (DPG). Polyol diperpanjang dengan PO atau EO adalah polyol polieter. Polyol dibentuk oleh polyesterification adalah poliester polyol. Pilihan pemrakarsa, extender, dan berat molekul dari polyol sangat mempengaruhi kondisi fisik, dan sifat-sifat fisik polimer poliuretan. Penting Karakteristik dari polyol mereka tulang punggung molekuler, inisiator, berat molekul, kelompok hidroksil utama %, fungsionalitas, dan viskositas.
PU mekanisme reaksi dikatalisis oleh amina tersier
reaksi meachanism
gas karbon dioksida dibentuk oleh air bereaksi dan isocyanate
air isocyanate reaksi
polimerisasi reaksi dikatalisis oleh amina tersier, seperti dimethylcyclohexylamine dan organologam, seperti dibutyltin dilaurate atau bismut octanoate. Selain itu, katalis dapat dipilih berdasarkan apakah mereka mendukung reaksi urethane (gel), seperti 1,4-diazabisiklo [2.2.2] oktana (juga disebut DABCO atau TEDA), atau reaksi urea (pukulan), seperti bis-(2-dimethylaminoethyl) eter, atau secara khusus drive isocyanate trimerization reaksi, seperti kalium octoate.
poliuretan (PUR dan PU) adalah polimer yang terdiri dari rantai organik unit bergabung dengan carbamate (urethane) link.
polimer Polyurethane dibentuk dengan menggabungkan dua bi - atau lebih tinggi monomer fungsional. Berisi dua atau lebih kelompok fungsional isocyanate (dengan formula-N = C = O) dan yang lain berisi dua atau lebih kelompok hidroksil (dengan formula-OH). Alkohol dan kelompok isocyanate bergabung untuk membentuk hubungan urethane:
ROH R'NCO → ROC (O) N (H) R' (R dan R' adalah kelompok-kelompok alkil atau Aril)
proses menggabungkan ini, kadang-kadang disebut kondensasi, biasanya memerlukan kehadiran katalis. Monomer lebih rumit juga digunakan.
poliuretan digunakan dalam pembuatan busa yang fleksibel, high-ketahanan tempat duduk; Panel insulasi busa kaku; microcellular busa segel dan gasket; tahan lama elastomeric roda dan ban; Bushing otomotif suspensi; senyawa pot listrik; perekat kinerja tinggi; lapisan permukaan dan sealant permukaan; serat sintetis (misalnya, Spandex); lapisan bawah karpet; dan bagian-bagian plastik keras (misalnya, untuk alat elektronik).
poliuretan juga digunakan untuk pembuatan selang dan skateboard roda karena menggabungkan properti terbaik kedua karet dan plastik.
poliuretan berada di kelas senyawa-senyawa yang disebut reaksi polimer, yang meliputi epoxies, tak jenuh polyesters dan phenolic.[5][6][7][8][9] hubungan urethane diproduksi oleh bereaksi grup isocyanate -N = C = O dengan kelompok hidroksil (alkohol), -OH. Poliuretan diproduksi oleh reaksi polyaddition polyisocyanate dengan polyalcohol (polyol) hadapan katalis dan aditif lainnya. Dalam kasus ini, polyisocyanate adalah molekul dengan dua atau lebih isocyanate kelompok fungsional, R-(N = C = O) n ≥ 2 dan polyol adalah molekul dengan dua atau lebih fungsional kelompok hidroksil, R'-≥ n (OH) 2. Produk reaksi adalah polimer yang mengandung urethane hubungan, - RNHCOOR'-. Isocyanates akan bereaksi dengan setiap molekul yang berisi hidrogen aktif. Penting, isocyanates bereaksi dengan air untuk membentuk hubungan urea dan gas karbon dioksida; mereka juga bereaksi dengan polyetheramines untuk bentuk polyureas. Secara komersial, poliuretan diproduksi oleh bereaksi isocyanate cair dengan campuran cair polyol, katalis dan aditif lainnya. Dua komponen ini disebut sebagai sistem poliuretan, atau hanya sebuah sistem. Isocyanate sering disebut di Amerika Utara sebagai 'Sisi-A' atau hanya 'iso'. Perpaduan polyol dan aditif lainnya sering disebut sebagai 'B' atau 'Poli'. Campuran ini mungkin juga disebut 'resin' atau 'resin campuran'. Di Eropa, artinya 'Sisi-A' dan 'B' dibalik. Resin campuran aditif dapat mencakup jaringan Extender, salib linkers, surfaktan, flame retardants, meniup agen, pigmen, dan pengisi.
Komponen penting pertama polimer poliuretan adalah isocyanate. Molekul yang berisi dua kelompok isocyanate disebut diisocyanates. Molekul-molekul ini juga disebut sebagai monomer atau unit monomer, karena mereka sendiri yang digunakan untuk menghasilkan isocyanates polimer yang mengandung tiga atau lebih kelompok-kelompok fungsional isocyanate. Isocyanates dapat digolongkan sebagai aromatik, seperti diphenylmethane diisocyanate (MDI) atau diisocyanate toluena (TDI); atau alifatik, seperti hexamethylene diisocyanate (IPM) atau isophorone diisocyanate (IPDI). Contoh polymeric isocyanate adalah Polimerik diphenylmethane diisocyanate, yang adalah campuran molekul dengan dua, tiga, empat atau lebih kelompok isocyanate, dengan rata-rata fungsi 2.7. Isocyanates dapat dimodifikasi lebih lanjut oleh sebagian bereaksi mereka dengan polyol untuk membentuk prepolymer. Kuasi-prepolymer ini terbentuk ketika rasio stoikiometri isocyanate untuk kelompok hidroksil lebih besar dari 2:1. Prepolymer benar terbentuk ketika rasio stoikiometri sama dengan 2:1. Prepolymers dapat digunakan sebagai kelembaban menyembuhkan poliuretan. Karakteristik penting isocyanates adalah tulang punggung molekuler, % NCO konten mereka, fungsionalitas, dan viskositas.
komponen penting kedua polimer poliuretan adalah polyol. Molekul yang berisi dua grup hidroksil disebut diols, mereka dengan tiga hidroksil gro
polimer Polyurethane dibentuk dengan menggabungkan dua bi - atau lebih tinggi monomer fungsional. Berisi dua atau lebih kelompok fungsional isocyanate (dengan formula-N = C = O) dan yang lain berisi dua atau lebih kelompok hidroksil (dengan formula-OH). Alkohol dan kelompok isocyanate bergabung untuk membentuk hubungan urethane:
ROH R'NCO → ROC (O) N (H) R' (R dan R' adalah kelompok-kelompok alkil atau Aril)
proses menggabungkan ini, kadang-kadang disebut kondensasi, biasanya memerlukan kehadiran katalis. Monomer lebih rumit juga digunakan.
poliuretan digunakan dalam pembuatan busa yang fleksibel, high-ketahanan tempat duduk; Panel insulasi busa kaku; microcellular busa segel dan gasket; tahan lama elastomeric roda dan ban; Bushing otomotif suspensi; senyawa pot listrik; perekat kinerja tinggi; lapisan permukaan dan sealant permukaan; serat sintetis (misalnya, Spandex); lapisan bawah karpet; dan bagian-bagian plastik keras (misalnya, untuk alat elektronik).
Poliuretan juga digunakan untuk pembuatan selang dan skateboard roda karena menggabungkan properti terbaik kedua karet dan plastik.
poliuretan berada di kelas senyawa-senyawa yang disebut reaksi polimer, yang meliputi epoxies, tak jenuh polyesters dan phenolic.[5][6][7][8][9] hubungan urethane diproduksi oleh bereaksi grup isocyanate -N = C = O dengan kelompok hidroksil (alkohol), -OH. Poliuretan diproduksi oleh reaksi polyaddition polyisocyanate dengan polyalcohol (polyol) hadapan katalis dan aditif lainnya. Dalam kasus ini, polyisocyanate adalah molekul dengan dua atau lebih isocyanate fungsional kelompok, R-(N = C = O) n ≥ 2 dan polyol adalah molekul dengan dua atau lebih fungsional kelompok hidroksil, R'-≥ n (OH) 2. Produk reaksi adalah polimer yang mengandung urethane hubungan, - RNHCOOR'-. Isocyanates akan bereaksi dengan setiap molekul yang berisi hidrogen aktif. Penting, isocyanates bereaksi dengan air untuk membentuk hubungan urea dan gas karbon dioksida; mereka juga bereaksi dengan polyetheramines untuk bentuk polyureas. Secara komersial, poliuretan diproduksi oleh bereaksi isocyanate cair dengan campuran cair polyol, katalis dan aditif lainnya. Dua komponen ini disebut sebagai sistem poliuretan, atau hanya sebuah sistem. Isocyanate sering disebut di Amerika Utara sebagai 'Sisi-A' atau hanya 'iso'. Perpaduan polyol dan aditif lainnya sering disebut sebagai 'B' atau 'Poli'. Campuran ini mungkin juga disebut 'resin' atau 'resin campuran'. Di Eropa, artinya 'Sisi-A' dan 'B' dibalik. Resin campuran aditif dapat mencakup jaringan Extender, salib linkers, surfaktan, flame retardants, meniup agen, pigmen, dan pengisi.
Komponen penting pertama polimer poliuretan adalah isocyanate. Molekul yang berisi dua kelompok isocyanate disebut diisocyanates. Molekul-molekul ini juga disebut sebagai monomer atau unit monomer, karena mereka sendiri yang digunakan untuk menghasilkan isocyanates polimer yang mengandung tiga atau lebih kelompok-kelompok fungsional isocyanate. Isocyanates dapat digolongkan sebagai aromatik, seperti diphenylmethane diisocyanate (MDI) atau diisocyanate toluena (TDI); atau alifatik, seperti hexamethylene diisocyanate (IPM) atau isophorone diisocyanate (IPDI). Contoh polymeric isocyanate adalah Polimerik diphenylmethane diisocyanate, yang adalah campuran molekul dengan dua, tiga, empat atau lebih kelompok isocyanate, dengan rata-rata fungsi 2.7. Isocyanates dapat dimodifikasi lebih lanjut oleh sebagian bereaksi mereka dengan polyol untuk membentuk prepolymer. Kuasi-prepolymer ini terbentuk ketika rasio stoikiometri isocyanate untuk kelompok hidroksil lebih besar dari 2:1. Prepolymer benar terbentuk ketika rasio stoikiometri sama dengan 2:1. Prepolymers dapat digunakan sebagai kelembaban menyembuhkan poliuretan. Karakteristik penting isocyanates adalah tulang punggung molekuler, % NCO konten mereka, fungsionalitas, dan viskositas.
komponen penting kedua polimer poliuretan adalah polyol. Molekul yang berisi dua grup hidroksil disebut diols, mereka dengan tiga kelompok hidroksil disebut triols, dan sebagainya. Dalam prakteknya, polyol dibedakan dari rantai pendek atau berat molekul rendah glikol jaringan Extender dan lintas linkers seperti etilena glikol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), gliserin, dan trimethylolpropane (TMP). Polyol adalah polimer dalam hak mereka sendiri. Mereka dibentuk oleh basa-dikatalisasi penambahan propilena oksida (PO), etilen oksida (EO) ke hidroksil atau amina yang mengandung inisiator, atau polyesterification di-asam, seperti dietil, dengan glycols, seperti ethylene glycol atau glikol dipropilen (DPG). Polyol diperpanjang dengan PO atau EO adalah polyol polieter. Polyol dibentuk oleh polyesterification adalah poliester polyol. Pilihan pemrakarsa, extender, dan berat molekul dari polyol sangat mempengaruhi kondisi fisik, dan sifat-sifat fisik polimer poliuretan. Penting Karakteristik dari polyol mereka tulang punggung molekuler, inisiator, berat molekul, kelompok hidroksil utama %, fungsionalitas, dan viskositas.
PU mekanisme reaksi dikatalisis oleh amina tersier
reaksi meachanism
gas karbon dioksida dibentuk oleh air bereaksi dan isocyanate
air isocyanate reaksi
polimerisasi reaksi dikatalisis oleh amina tersier, seperti dimethylcyclohexylamine dan organologam, seperti dibutyltin dilaurate atau bismut octanoate. Selain itu, katalis dapat dipilih berdasarkan apakah mereka mendukung reaksi urethane (gel), seperti 1,4-diazabisiklo [2.2.2] oktana (juga disebut DABCO atau TEDA), atau reaksi urea (pukulan), seperti bis-(2-dimethylaminoethyl) eter, atau secara khusus drive isocyanate trimerization reaksi, seperti kalium octoate.
poliuretan (PUR dan PU) adalah polimer yang terdiri dari rantai organik unit bergabung dengan carbamate (urethane) link.
polimer Polyurethane dibentuk dengan menggabungkan dua bi - atau lebih tinggi monomer fungsional. Berisi dua atau lebih kelompok fungsional isocyanate (dengan formula-N = C = O) dan yang lain berisi dua atau lebih kelompok hidroksil (dengan formula-OH). Alkohol dan kelompok isocyanate bergabung untuk membentuk hubungan urethane:
ROH R'NCO → ROC (O) N (H) R' (R dan R' adalah kelompok-kelompok alkil atau Aril)
proses menggabungkan ini, kadang-kadang disebut kondensasi, biasanya memerlukan kehadiran katalis. Monomer lebih rumit juga digunakan.
poliuretan digunakan dalam pembuatan busa yang fleksibel, high-ketahanan tempat duduk; Panel insulasi busa kaku; microcellular busa segel dan gasket; tahan lama elastomeric roda dan ban; Bushing otomotif suspensi; senyawa pot listrik; perekat kinerja tinggi; lapisan permukaan dan sealant permukaan; serat sintetis (misalnya, Spandex); lapisan bawah karpet; dan bagian-bagian plastik keras (misalnya, untuk alat elektronik).
poliuretan juga digunakan untuk pembuatan selang dan skateboard roda karena menggabungkan properti terbaik kedua karet dan plastik.
poliuretan berada di kelas senyawa-senyawa yang disebut reaksi polimer, yang meliputi epoxies, tak jenuh polyesters dan phenolic.[5][6][7][8][9] hubungan urethane diproduksi oleh bereaksi grup isocyanate -N = C = O dengan kelompok hidroksil (alkohol), -OH. Poliuretan diproduksi oleh reaksi polyaddition polyisocyanate dengan polyalcohol (polyol) hadapan katalis dan aditif lainnya. Dalam kasus ini, polyisocyanate adalah molekul dengan dua atau lebih isocyanate kelompok fungsional, R-(N = C = O) n ≥ 2 dan polyol adalah molekul dengan dua atau lebih fungsional kelompok hidroksil, R'-≥ n (OH) 2. Produk reaksi adalah polimer yang mengandung urethane hubungan, - RNHCOOR'-. Isocyanates akan bereaksi dengan setiap molekul yang berisi hidrogen aktif. Penting, isocyanates bereaksi dengan air untuk membentuk hubungan urea dan gas karbon dioksida; mereka juga bereaksi dengan polyetheramines untuk bentuk polyureas. Secara komersial, poliuretan diproduksi oleh bereaksi isocyanate cair dengan campuran cair polyol, katalis dan aditif lainnya. Dua komponen ini disebut sebagai sistem poliuretan, atau hanya sebuah sistem. Isocyanate sering disebut di Amerika Utara sebagai 'Sisi-A' atau hanya 'iso'. Perpaduan polyol dan aditif lainnya sering disebut sebagai 'B' atau 'Poli'. Campuran ini mungkin juga disebut 'resin' atau 'resin campuran'. Di Eropa, artinya 'Sisi-A' dan 'B' dibalik. Resin campuran aditif dapat mencakup jaringan Extender, salib linkers, surfaktan, flame retardants, meniup agen, pigmen, dan pengisi.
Komponen penting pertama polimer poliuretan adalah isocyanate. Molekul yang berisi dua kelompok isocyanate disebut diisocyanates. Molekul-molekul ini juga disebut sebagai monomer atau unit monomer, karena mereka sendiri yang digunakan untuk menghasilkan isocyanates polimer yang mengandung tiga atau lebih kelompok-kelompok fungsional isocyanate. Isocyanates dapat digolongkan sebagai aromatik, seperti diphenylmethane diisocyanate (MDI) atau diisocyanate toluena (TDI); atau alifatik, seperti hexamethylene diisocyanate (IPM) atau isophorone diisocyanate (IPDI). Contoh polymeric isocyanate adalah Polimerik diphenylmethane diisocyanate, yang adalah campuran molekul dengan dua, tiga, empat atau lebih kelompok isocyanate, dengan rata-rata fungsi 2.7. Isocyanates dapat dimodifikasi lebih lanjut oleh sebagian bereaksi mereka dengan polyol untuk membentuk prepolymer. Kuasi-prepolymer ini terbentuk ketika rasio stoikiometri isocyanate untuk kelompok hidroksil lebih besar dari 2:1. Prepolymer benar terbentuk ketika rasio stoikiometri sama dengan 2:1. Prepolymers dapat digunakan sebagai kelembaban menyembuhkan poliuretan. Karakteristik penting isocyanates adalah tulang punggung molekuler, % NCO konten mereka, fungsionalitas, dan viskositas.
komponen penting kedua polimer poliuretan adalah polyol. Molekul yang berisi dua grup hidroksil disebut diols, mereka dengan tiga hidroksil gro
Sedang diterjemahkan, harap tunggu..
A polyurethane (PUR and PU) is polymer composed of a chain of organic units joined by carbamate (urethane) links.
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl groups are called triols, et cetera. In practice, polyols are distinguished from short chain or low-molecular weight glycol chain extenders and cross linkers such as ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), glycerine, and trimethylolpropane (TMP). Polyols are polymers in their own right. They are formed by base-catalyzed addition of propylene oxide (PO), ethylene oxide (EO) onto a hydroxyl or amine containing initiator, or by polyesterification of a di-acid, such as adipic acid, with glycols, such as ethylene glycol or dipropylene glycol (DPG). Polyols extended with PO or EO are polyether polyols. Polyols formed by polyesterification are polyester polyols. The choice of initiator, extender, and molecular weight of the polyol greatly affect its physical state, and the physical properties of the polyurethane polymer. Important characteristics of polyols are their molecular backbone, initiator, molecular weight, % primary hydroxyl groups, functionality, and viscosity.
PU reaction mechanism catalyzed by a tertiary amine
reaction meachanism
carbon dioxide gas formed by reacting water and isocyanate
water isocyanate reaction
The polymerization reaction is catalyzed by tertiary amines, such as dimethylcyclohexylamine, and organometallic compounds, such as dibutyltin dilaurate or bismuth octanoate. Furthermore, catalysts can be chosen based on whether they favor the urethane (gel) reaction, such as 1,4-diazabicyclo[2.2.2]octane (also called DABCO or TEDA), or the urea (blow) reaction, such as bis-(2-dimethylaminoethyl)ether, or specifically drive the isocyanate trimerization reaction, such as potassium octoate.
A polyurethane (PUR and PU) is polymer composed of a chain of organic units joined by carbamate (urethane) links.
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl gro
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl groups are called triols, et cetera. In practice, polyols are distinguished from short chain or low-molecular weight glycol chain extenders and cross linkers such as ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), glycerine, and trimethylolpropane (TMP). Polyols are polymers in their own right. They are formed by base-catalyzed addition of propylene oxide (PO), ethylene oxide (EO) onto a hydroxyl or amine containing initiator, or by polyesterification of a di-acid, such as adipic acid, with glycols, such as ethylene glycol or dipropylene glycol (DPG). Polyols extended with PO or EO are polyether polyols. Polyols formed by polyesterification are polyester polyols. The choice of initiator, extender, and molecular weight of the polyol greatly affect its physical state, and the physical properties of the polyurethane polymer. Important characteristics of polyols are their molecular backbone, initiator, molecular weight, % primary hydroxyl groups, functionality, and viscosity.
PU reaction mechanism catalyzed by a tertiary amine
reaction meachanism
carbon dioxide gas formed by reacting water and isocyanate
water isocyanate reaction
The polymerization reaction is catalyzed by tertiary amines, such as dimethylcyclohexylamine, and organometallic compounds, such as dibutyltin dilaurate or bismuth octanoate. Furthermore, catalysts can be chosen based on whether they favor the urethane (gel) reaction, such as 1,4-diazabicyclo[2.2.2]octane (also called DABCO or TEDA), or the urea (blow) reaction, such as bis-(2-dimethylaminoethyl)ether, or specifically drive the isocyanate trimerization reaction, such as potassium octoate.
A polyurethane (PUR and PU) is polymer composed of a chain of organic units joined by carbamate (urethane) links.
Polyurethane polymers are formed by combining two bi- or higher functional monomers. One contains two or more isocyanate functional groups (with formula –N=C=O) and the other contains two or more hydroxyl groups (with formula –OH). The alcohol and the isocyanate groups combine to form a urethane linkage:
ROH + R’NCO → ROC(O)N(H)R’ (R and R’ are alkyl or aryl groups)
This combining process, sometimes called condensation, typically requires the presence of a catalyst. More complicated monomers are also used.
Polyurethanes are used in the manufacture of flexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires; automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex); carpet underlay; and hard-plastic parts (e.g., for electronic instruments).
Polyurethane is also used for the manufacture of hoses and skateboard wheels as it combines the best properties of both rubber and plastic.
Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics.[5][6][7][8][9] A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R’-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR’-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a urea linkage and carbon dioxide gas; they also react with polyetheramines to form polyureas. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, catalyst, and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the ‘A-side’ or just the ‘iso’. The blend of polyols and other additives is commonly referred to as the ‘B-side’ or as the ‘poly’. This mixture might also be called a ‘resin’ or ‘resin blend’. In Europe the meanings for ‘A-side’ and ‘B-side’ are reversed. Resin blend additives may include chain extenders, cross linkers, surfactants, flame retardants, blowing agents, pigments, and fillers.
The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as monomers or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as aromatic, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI); or aliphatic, such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a prepolymer. A quasi-prepolymer is formed when the stoichiometric ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Prepolymers can be used as moisture cure polyurethane. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and viscosity.
The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called diols, those with three hydroxyl gro
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- Selamat beraktivitas
- Why you always ingnore me
- With a great crown on her head full two
- Saatnya tidur semoga mimpi indah
- As he gazed upon her, "what a fine thing
- With
- Are mine
- Believe me
- Kalau memang tidak suka silakah hapus ko
- Goodbye city of lampung and to meet agai
- Nanti ya kapan2
- Semoga slalu dalam lindungan allah
- Bye bye city of lampung and to meet agai
- Aku tidak tahu dan biarkan waktu yang me
- Goodbye city of lampung and to meet agai
- L'esprit de ma cherie
- good night
- And on each side of her stood her guards
- Be reminded of my self in your soul
- Sifatmu bagai serigala berbulu domba
- disini
- The fisherman went up to her and said,"w
- I really love dear
- Apakah di sana kau rindukan aku
