Thermal behaviors and characteristics of polylactide/poly(butylene succinate) blend films via reactive compatibilization and plasticization

Abstract

Polylactide (PLA)/poly(butylene succinate) (PBS) blend films modified with a compatibilizer and a plasticizer were hot‐melted through a twin screw extruder and prepared by hydraulic press. Toluene diisocyanate (TDI) and polylactide‐grafted‐maleic anhydride (PLA‐g‐MA) were used as compatibilizers, while triethyl citrate and tricresyl phosphate acted as plasticizers. The effects of the type and content of compatibilizer and plasticizer on the mechanical characteristics, thermal properties, crystallization behavior, and phase morphology of the PLA/PBS blend films were investigated. Reactive compatibilization at increasing levels of TDI improved the compatibility of the PLA and PBS, affecting the toughness of the films. As evidenced by scanning electron microscope, the addition of TDI enhanced the interfacial adhesion of the blends, leading to the appearance of many elongated fibrils at the fracture surface. Furthermore, PLA/PBS blending with both TDI and PLA‐g‐MA led to an acceleration of the cold crystallization rate and an increment of the degree of crystallinity ( χc). Toluene diisocyanate could be a more effective compatibilizer than PLA‐g‐MA for PLA/PBS blend films. The synergistic combination of compatibilizer and plasticizer brought a significant improvement in elongation at break and tensile‐impact toughness of the PLA/PBS blends, compared with neat PLA. Their failure mode changed from brittle to ductile due to the improved compatibility and molecular segment mobility of the PLA and PBS phases. Differential scanning calorimeter results revealed that the plasticizers triethyl citrate and tricresyl phosphate changed the thermal behavior of Tcc and Tm, affecting α′ and α crystal formations. However, these plasticizers only slightly improved the thermal stability of the films.

Super tough poly(lactic acid) blends: a comprehensive review

“…Considering the fact that the use of petroleum-based plastics to toughen PLA would partially sacrice the sustainability, the exible petroleum-based synthesis polymers or biobased polymers, such as PBAT, PBS, PCL, PHAs et al [214][215][216][217] have recently been employed to toughen PLA. The wide application of biodegradable materials provides a good approach to reduce plastic pollution caused by non-biodegradable materials.…”

Toughening modification of PLLA with PCL in the presence of PCL‐b‐PLLA diblock copolymers as compatibilizer

“…Melt blending or compounding PLLA with different types of flexible polymers was one of the economic approaches to toughen PLLA . However, poly(ε‐caprolactone) (PCL) was a biodegradable aliphatic polyester with high flexibility and good biocompatibility and thermal stability, which had gained great attention as modifiers for PLLA, and the modifying results exhibited some improvements in the toughness of PLLA .…”

“…The Scanning electron microscope (SEM) micrographs of cryo-fractured surfaces of the blends. A, PLLA/PCL/19k-CL 67 LA 33 (80/20/5), B, 19k-CL 51 LA 49 (80/20/5), C, 19k-CL36 LA 64 (80/20/5), and D, 19k-CL19 LA 81 (80/20/5) rheological properties of PLLA/PCL/PCL-b-PLLA (80/20/10) ternary blends were displayed in Figures 5 and 6, respectively. The plots of the complex viscosity (η*) vs ω and Cole-Cole (η″ vs. η′) were applied to analyze the compatibility of melting blends.…”

“…Thus, we believed that the 19k-CL x LA y could partly be dispersed in the PLLA matrix and the PCL phases with increasing the content of 19k-CL x LA y in the PLA/PCL/19k-CL x LA y blends. In addition, with the compatibilizer partly dispersed into the matrix polymer as a modifier, its brittleness would decrease the elongation at break of the blends; this phenomena was explained by Guo et al15 When the content of compatibilizer poly (methyl methacrylate) (PMMA) was higher than 10 wt%, they found that PMMA partly dispersed into the PLLA phase as a modifier and decreased the elongation at break of the PLLA/poly (butylene adipate-co-butylene terephthalate) blends.Compared with 19k-CL19 LA 81 , the 19k-CL 51 LA 49 had better flexibility for the composition with 50 wt% CL units and 50 wt% LA units. When the content of added 19k-CL 51 LA 49 was increased above 5 phr, a part of 19k-CL 51 LA 49 dispersed into the PCL phases and the PLLA matrix, as a modifier for toughening the PLLA/PCL blend.…”

The effects of melt grafted maleated polybutylene succinate on the properties of poly(hydroxybutyrate‐co‐hydroxyhexanoate)/polybutylene succinate blends

“…In addition to the termination reactions, chain scission by either back‐biting or thermo‐hydrolysis may also occur. [ 33 ] Mani et al [ 28 ] also reported the occurrence of β‐scission of the polyester macroradical during the melt grafting reaction of maleated PBS, leading to the formation of radical chains and vinylidene chain ends, especially in the presence of an organic peroxide initiator. Since the grafting reaction was conducted at 160°C; which is above the ceiling temperature of MA (≥150°C), the poly(MA n ) was not present in the compatibilizer.…”