Dr. Patil et Gf. Fanta, SYNTHESIS AND PROCESSING OF GRAFT-COPOLYMERS FROM CORNSTARCH AND METHYL ACRYLATE - PHYSICAL AND MECHANICAL-PROPERTIES, Starke, 46(4), 1994, pp. 142-146
Starch-g-poly(methyl acrylate) (S-g-PMA), containing 40-65% PMA, was p
repared with ceric ammonium nitrate (CAN) initiation in a 2-gallon rea
ctor. CAN initiator was added either in one portion or portionwise. Gr
aft copolymers were characterized with respect to % acetone-extractabl
e polymer (largely PMA homopolymer), PMA content of the graft copolyme
r, and M(w) of PMA grafts. Normal cornstarch as well as waxy and high
amylose cornstarches were used in the grafting reaction. Conversions o
f monomer to polymer were nearly quantitative. Continuous plastic ribb
ons for tensile testing were prepared by extrusion processing. Tensile
properties varied with the method used for CAN addition (i. e., singl
e portion vs. portionwise) and depended upon the particular starch var
iety used in the graft polymerization reaction. Since water acts as a
plasticizer for starch, samples extruded at high moisture content exhi
bit higher % elongation (%E) values than the same polymers extruded at
low moisture. Values for %E also increase with higher percentages of
PMA in the graft copolymer.