MULTIPHASE MATERIALS WITH LIGNIN .2. STARLIKE COPOLYMERS WITH CAPROLACTONE

Multiphase starlike copolymers have been prepared using polycaprolacto ne as hard, arm segments and hydroxypropyl lignin as the core of the s tar. Copolymer architecture differed in terms of the average number of arms per core, which ranged between 2 and 7; and in terms of hydroxyp ropyl lignin molecular size and T-g, which ranged between 2100 and 640 0 D and -7 and +85 degrees C, respectively. The copolymers, which had; nearly uniform but broad molecular weight distributions, were analyzed with regard to solution properties, thermal characteristics, and crys tallinity. The Mark-Houwink-Sakurada exponential factor remained virtu ally constant (i.e., ca. 0.66) for all copolymer types. The thermal ch aracteristics were all in support of multiphase morphology, and they d iffered with copolymer architecture. Copolymers having hydroxypropyl l ignin with T-g's greater than the T-m of caprolactone resulted in sign ificant T-m depression, whereas this could not be observed for copolym ers with low T-g cores. T-m increased with arm length as the degree of polymerization of the caprolactone rose to 50. Crystallinity was esta blished for all copolymers, even those with arms shorter than 10 capro lactone units in length.