The change in fine structure of rayon by graft polymerization under swollen state was already reported in our first paper
1). Refering the difference between dryeure and wet cross linking in the resin treatment
2),
3), it is probably possible to consider that the difference between graft polymerization under swollen state and unswollen state results in the difference in the coagulation of cellulose chains.
And also it has been well known that the graft polymerization to unswollen solid polymer is very difficult, therefore the difference of the change in fine structure according to the grafting method may be considered.
The sample grafted under swollen state (A) was prepared by reaction of rayon and methyl acrylate (MA) using ce
+4 as the initiator in aqueous solution, and the sample grafted under unswollen state (B) was prepared by pre-irradiation method using γ-ray from Co
60 followed by graft polymerization in solution containing MA, methanol and small amount of water.
A and B samples of various degree of grafting, following properties were measured; Transition, temperature
4), coagulation order, young's modulus, moisture regain and swelling in water. These properties are considered to be reflected by the structure of only cellulose in graft polymer, because PMA is insensitive to both ethanol and water sides its young's modulus and strength are very low compared with cellulose.
The experimental results obtained are followings:
(1) Lowering of transition temperature of A is more sharp than that of B.
(2) Coagulation distribution is not so largely shifted to lower side by B-method as in the Amethod.
(3) Lowering of the dry modulus of A is larger than that of B. About wet modulus the same result was obtained.
(4) Moisture regain is increased by A-method, but not changed by B-method.
(5) Degree of swelling as lowered by B-method.
Comparing the two samples of same degree of grafting-one is grafted when cellulose amorphouschains are swollen with water (A) the other is not swollen (B)-from above experimental results, followings are estimated,
(1) Coagulation state of cellulose is relatively preserved when B-method is employed. A-method destroys the hydrogen bonds and polymer grafted restricts the reformation of hydrogen bonds during the drying.
(2) A-method ever destroys the water inaccessible region, but B-method does not.
(3) Polymer grafted by B-method restricts the free swelling of cellulose chains but A-method does not
These considerations imply that the coagulation state of the back bone polymer during the graft polymerization has great effects on the resulted structure of back bone polymer and polymer grafted.
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