Controlling orientation, polymorphism, and crystallinity in thin films of poly(lactic‐acid) homopolymer and stereocomplex aligned by high temperature rubbing

Abstract High temperature rubbing is a fast and low‐cost method that can align semi‐crystalline polymers such as poly(lactic acid) (PLA) by application of shear‐force via rotating cylinder covered with microfiber cloth on thin film maintained at high temperature. A multi technique approach uncovers the role thickness PLA structure. Both poly( l ‐lactic (PLLA) stereo‐complex (SC‐PLA) be readily aligned rubbing. The T R are key parameters control polymorphism, in‐plane orientation, crystallinity contact plane polymer crystals. Rubbing PLLA films in range 80–140°C affords different polymorphs (mesophase, α ′, ′ + mixtures pure phase) depending Pure form 53% obtained = 140°C whereas oriented crystalline SC‐PLA 200°C.