Peculiar crystallization kinetics of biodegradable poly(lactic acid)/poly(propylene carbonate) blends

Abstract

Binary blends of poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) were found to display a peculiar crystallization kinetics. The two biodegradable polymers were blended by melt mixing, to obtain binary blends at various compositions. Temperature‐modulated calorimetry and dynamic‐mechanical analysis indicated that the blend components are partially miscible, and display two separate glass transitions, at temperatures intermediate to those of the plain polymers. Electron microscopy analysis disclosed the morphology of PLA/PPC blends, made of PPC‐rich particles finely dispersed within the PLA‐rich matrix. The possible establishment of interactions between the functional groups of the two polymers upon melt mixing has been hypothesized as the reason for partial miscibility and compatibility of the two biodegradable polymers. The PLA/PPC blends display good mechanical properties, with enhanced performance at rupture compared with plain PLA. Most importantly, the addition of PPC affects also the crystallization kinetics of PLA, since the more mobile PPC chains favor diffusion of the stiffer PLA chain segments towards the growing crystals, which fastens the spherulite growth rate of PLA. Such positive influence of an amorphous polymer on crystal growth rate has been demonstrated here for the first time in blends that display phase‐separation in the melt. POLYM. ENG. SCI., 55:2698–2705, 2015. © 2015 Society of Plastics Engineers

Compatibilization of the poly(lactic acid)/poly(propylene carbonate) blends through in situ formation of poly(lactic acid)‐b‐poly(propylene carbonate) copolymer

“…Pure PPC had a far higher elongation at break of 608.1% than pure PLA and a tensile strength about 17.0 MPa. As has been reported in many literatures, PLA could be toughened by PPC in a certain extent, which is in agreement with our results that the elongation at break of PLA/PPC blends was much higher than that of pure PLA showed in Figure and Table .…”

Novel Biodegradable Cast Film from Carbon Dioxide Based Copolymer and Poly(Lactic Acid)

“…This could be caused by an accelerated influence of PPC on the crystallization rate of PLA in the blend system. It was also observed in another study that PPC induced faster growth rate of the PLA spherulites, leading to accelerated crystallization rate of PLA [13].…”

“…Additionally, PLA has similar chemical structure as PPC, which might help to obtain better compatibility in the blend [11]. In light of this, the PLA/PPC blend system has been investigated in some studies [3,[11][12][13]. However, results have shown that only partial miscibility exists between PLA and PPC, resulting in unfavorable properties.…”

A review on degradation mechanisms of polylactic acid: Hydrolytic, photodegradative, microbial, and enzymatic degradation

“…[58][59][60][61][62][63] It has numerous favorable properties including its strength, stiffness, biocompatibility, thermo-plasticity, monomer renewability and good processability. [64][65][66] Further, it is highly transparent and has the capability to be simply degraded. [67][68][69][70][71] Performance characteristics of PLA, such as stiffness, strength and gas permeability, have been determined to be comparable with conventional petrochemical-based plastics.…”