Thermal and mechanical properties of biodegradable star-shaped/linear polylactide stereocomplexes

The 6-arm star-shaped poly(l-lactide) (6pll)/linear poly(d-lactide) (1pdl) stereocomplex films were prepared by the solvent casting method. the influences of the 6pll/1pdl blend ratios (75/25,50/50,and 25/75 w/w) and 1pdl molecular weights (15,000,30,000,and 60,000 g/mol) on the thermal and mechanical properties of the stereocomplex films were investigated. the 6pll and 1pdls had a single melting temperature (tm) of homocrystallites at 174°c and 167°c,respectively. the 6pll/1pdl blends had two tms: a lower tm of homocrystallites (160-173°c) and a higher tm of stereocomplex crystallites (219-228°c). the stereocomplex crystallinity and mechanical properties of the 6pll/1pdl blend films were higher than those of 6pll and 1pdl and were the highest in the 50/50 (w/w) blend ratio. however,the stereocomplex crystallinity of the 50/50 (w/w) 6pll/1pdl blend films decreased and the mechanical properties increased as the molecular weight of 1pdl increased. © 2015 onanong cheerarot and yodthong baimark.