Triblock Copolymer Compatibilizers for Enhancing the Mechanical Properties of a Renewable Bio-Polymer

Abstract

Poly(lactic acid) (PLA) is an emerging plastic that has insufficient properties (e.g., it is too brittle) for widespread commercial use. Previous research results have shown that the strength and toughness of basalt fiber reinforced PLA composites (PLA/BF) still need to be improved. To address this limitation, this study aimed to obtain an effective compatibilizer for PLA/BF. Melt-blending of poly(butylene adipate-co-terephthalate) (PBAT) with PLA in the presence of 4,4′-methylene diphenyl diisocyanate (MDI: 0.5 wt% of the total resin) afforded PLA/PBAT-MDI triblock copolymers. The triblock copolymers were melt-blended to improve the interfacial adhesion of PLA/BF and thus obtain excellent performance of the PLA-ternary polymers. This work presents the first investigation on the effects of PLA/PBAT-MDI triblock copolymers as compatibilizers for PLA/BF blends. The resultant mechanics, the morphology, interface, crystallinity, and thermal stability of the PLA-bio polymers were comprehensively examined via standard characterization techniques. The crystallinity of the PLA-ternary polymers was as high as 43.6%, 1.44× that of PLA/BF, and 163.5% higher than that of pure PLA. The stored energy of the PLA-ternary polymers reached 20,306.2 MPa, 5.5× than that of PLA/BF, and 18.6× of pure PLA. Moreover, the fatigue life of the PLA-ternary polymers was substantially improved, 5.85× than that of PLA/PBAT-MDI triblock copolymers. Thus, the PLA/PBAT-MDI triblock copolymers are compatibilizers that improve the mechanical properties of PLA/BF.

Influence of a Multiple Epoxy Chain Extender on the Rheological Behavior, Crystallization, and Mechanical Properties of Polyglycolic Acid

“…The most common method of tackling the poor stability and low melt strength resulting from the thermal degradation of polyester materials, such as poly(lactide) (PLA), poly(butanediol terephthalate) (PBT), and poly(butylene-adipate-co-terephthalate) (PBAT) during processing and molding is to modify these polyesters with chain extenders (CEs). CEs, such as polycarbodiimide (PCD) [15,16], multi-functional epoxides [17][18][19], diisocyanates [20,21], dianhydrides [22,23], and tris(nonyl-phenyl) phosphate (TNPP) [24,25], increase the molecular weight and melt strength of polyesters. They also serve as reactive compatibilizers in the blend through the introduction of chain extension/branching reactions to reconnect the cracked chains.…”

On the Production of Poly(Lactic Acid) (PLA) Compounds with Metallic Stearates Based on Zinc, Magnesium and Cobalt. Investigation of Torque Rheometry and Thermal Properties

“…20,21 From the point of view of technical characteristics, PLA has high tensile strength, high elastic modulus, good transparency, biocompatibility, and good processability, generating potential for applications in packaging and the biomedical area. [22][23][24] Thus, PLA is considered a bioplastic with all the characteristics to replace traditional plastic. 25 However, the main drawback of PLA is its low impact strength, which limits its application in parts that require high impact.…”

Synthesis and Characterization of Cellulose Diacetate-Graft-Polylactide via Solvent-Free Melt Ring-Opening Graft Copolymerization

“…Under certain conditions, stereocomplex (sc) crystals form between PLLA and PDLA molecular chains, and the resultant stereocomplex poly (lactic acid) (scPLA) can endow PLA-based materials with strong mechanical characteristics and heat resistance. [ 24 , 25 , 26 ]. It is a green thermoplastic polyester that combines biocompatibility with bioresorbability.…”