It could be seen from Fig. 3 that t

It could be seen from Fig. 3 that the solution optical rotation values of both raw agar and agar acetate were almost constant at high
temperature (higher than 70
◦
C) and low temperature (lower than
30
◦
C), and their variation trend on cooling were approximately
the same. This meant that the molecules of both raw agar and
agar acetate had not changed from single coil to double helix, and
were evenly dispersed in solution at high temperature (higher than
70
◦
C), but had turned into double helix and gathered completely
at low temperature (lower than 30
◦
C). As the agar acetate was prepared only by using acetyl group to replace the hydrogen atom
of hydroxyl group of agar molecule, the molecule of agar acetate