Effects of graft polymer compatibilizers in blends of cellulose triacetate and poly(lactic acid)

Blends of cellulose triacetate (CTA) and poly(l-lactic acid) (PLLA) were prepared using graft polymer compatibilizers. The graft polymers were synthesized using a grafting-from approach via ring-opening polymerization of l- and d,l-lactide initiated from free hydroxyl groups along the CTA backbone. The blends incorporating either 1, 2.5 or 5% of each of the two graft polymer compatibilizers by weight in a 20:80 mixture of CTA:PLLA were solution-cast to yield films. Characterization of graft polymers included the use of H-1 NMR spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis. Mechanical properties of the compatibilized films were evaluated using tensile testing, and thermomechanical properties were analyzed using dynamic mechanical analysis (DMA). The compatibilized films exhibited greater tensile stress at yield than the uncompatibilized films for both types of compatibilizers, but no statistically significant changes were observed in modulus or strain at break, although modulus trended higher in compatibilized films. Stereochemical differences in tensile performance were statistically insignificant, though some differences in thermal behavior were observed. DMA and DSC revealed that crystallization of PLLA was altered by the addition of compatibilizer and CTA. (c) 2019 Society of Chemical Industry