Regulation of polymorphic behavior of biodegradable poly(butylene adipate) by multi-walled carbon nanotubes

Biodegradable poly(butylene adipate) (PBA) may crystallize in the alpha-or beta-form under different conditions. Relative to the beta-form, the alpha-form crystals are thermodynamically more stable and show a faster biodegradation rate; however, they are formed during the nonisothermal melt crystallization at only a relatively low cooling rate. In the present work, carboxyl-functionalized multi-walled carbon nanotubes (f-MWCNTs) were incorporated into the PBA matrix at low f-MWCNTs loading to regulate the polymorphic behavior of PBA crystals. It is found that the formation of polymorphic crystals of PBA is affected not only by cooling rate during the crystallization process but also by the f-MWCNTs loading. The formation of alpha-form crystals can be induced by f-MWCNTs at a high cooling rate, providing an effective way of controlling the polymorphic crystal formation and biodegradation rate of PBA for its wider practical application.