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Due to its favorable mechanical strength, transparency, and biocompatibility, polylactic acid (PLA) has considerable potential as a biodegradable material. Nevertheless, developing high‐performance PLA composites through environmentally friendly and cost‐effective methods remains a significant challenge. In this study, the composites comprising poly(L‐lactide) (PLLA), basalt fibers (BFs), and poly(D‐lactide) (PDLA) are prepared through facile melt blending. The in situ formed stereocomplex polylactide (SC‐PLA) crystals improve the crystallization ability and rheological behavior of PLLA/BF/PDLA composites. Upon adding 5 wt% PDLA, BFs are nicely dispersed in PLLA matrix because of increased shear intensity. The synergistic effect of BFs and SC‐PLA crystals enhances the mechanical, thermomechanical, and heat resistance properties of PLLA. In particular, PLLA/BF/10%PDLA composites exhibit a Vicat Softening Temperature (VST) of 155.5°C, increasing by approximately 100°C over neat PLLA. Annealing treatment increases the Young's modulus, thermomechanical properties, and VST of samples while reducing their tensile strength. Interestingly, the tensile strength of the annealed PLLA/BF/10%PDLA composites is 50.2 MPa, twice that of the annealed neat PLLA due to the introduction of SC‐PLA crystals. Simultaneously improving the rheological, mechanical, and heat resistance performance of PLLA opens possibilities for expanding its potential applications in the industrial field. [ABSTRACT FROM AUTHOR]

In order to overcome the drawback of poor mechanical and rheological properties and potentially extend the poly(butylene adipate-co-butylene terephthalate) (PBAT) application market, in this work, we developed PBAT blend with excellent comprehensive performance through blending with biodegradable poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA). Two-step melt blending and constant polylactide (PLA) content were devised to prepared PBAT blend. The effect of PDLA on the crystallization properties, rheological properties, miscibility, morphological structure, and mechanical properties of blend was investigated. According to torque-time curve and DSC results, PLA stereocomplex (SC-PLA) crystallites were formed in blend system. DMA results confirmed that the compatibility between PBAT and PLLA was not changed when PDLA was introduced. SEM results showed that the phase morphology of PBAT/20PLLA/0PDLA blend displayed typical sea-island structure and the particle size of dispersed phase decreased accompanying by agglomeration when PDLA was added. Rheological results showed that percolation SC-PLA network structure had formed and a much denser crystallite network could be formed with high PDLA content, which significantly enhanced rheological properties of blend. The mechanical results demonstrated that the addition of PDLA could significantly enhance mechanical properties. The blend with 6 wt% PDLA presented yield strength, elongation at break, and modulus about 13.3 MPa, 307%, and 221.2 MPa, respectively, the yield strength and modulus increased by 141.7% and 54.7% compared with the pure PBAT. [ABSTRACT FROM AUTHOR]

A ternary blend of poly(L-lactic acid) (PLA), poly(ε-caprolactone) (PCL) and poly(vinyl acetate) (PVAc) was melt compounded with an aim to obtain novel biodegradable blends with a balance of performance. We systematically studied the relationship between the microstructure and macroscopic properties of the ternary blends. PVAc was miscible with both PLA an PCL. It was interesting that PVAc was selectively located in the PLA matrix of PLA/PCL/PVAc ternary blends, which significantly affected the crystallization behavior, mechanical and rheological properties, and enzymatic hydrolysis rate of the blends. The inhibited crystallization of PLA was achieved, whereas the crystallization of PCL was not affected by incorporating PVAc. Unexpectedly, increases of 10%, 17% and 26% were achieved in the yield strength, breaking strength and modulus of the ternary blend with 20 wt% PVAc compared to PLA/PCL binary blend, while the elongation at break maintained above 300%. Moreover, the rheological properties was enhanced and enzymatic hydrolysis rate was decelerated by introduction of PVAc. The excellent stiffness − toughness balance coupled with the enhanced melt viscoelasticity of the blends will help to expand the property range and processing methods of biodegradable polymers. [ABSTRACT FROM AUTHOR]

• PLLA/EGA/PDLA ternary blends were prepared by melt blending. • Stereocomplex crystals were formed in-situ in PLLA/PDLA/EGA ternary blends. • SC-PLA crystal network improved the rheological properties of the blends. • SC-PLA crystals accelerated the crystallization rate of PLLA in ternary blends. • PLLA/EGA/PDLA ternary blends exhibited improved mechanical properties. Ternary blends comprising poly(L-lactide) (PLLA), ethylene-ethyl acrylate-glyceryl methacrylate terpolymer (EGA), and poly(D-lactide) (PDLA) were melt blended using low-temperature method to obtain blends with balanced properties. The formation of stereocomplex polylactide (SC-PLA) crystals was verified by torque changes and differential scanning calorimetry (DSC) results. The SC-PLA crystals formed a percolating network in the PLLA matrix at a concentration of 2 wt% PDLA, and blend melt presented solid-like rheological behavior. Attributing to the increased viscosity ratio between PLLA and EGA, the size of dispersed EGA phase increased. The crystallization of PLLA was significantly promoted because of the nucleation effect of SC-PLA crystals. The PLLA/EGA/2 %PDLA ternary blends with elongation at break of 138 % and impact strength of 72.3 kJ/m2 exhibited excellent toughness. These ternary blends demonstrated exceptional crystallization ability and tailored rheological and mechanical properties, opening a new path for developing high-performance PLLA-based materials in packaging industry. [ABSTRACT FROM AUTHOR]

• PLA/PHBH/PVAc ternary blends were prepared by simply melt mixing. • PVAc was electively located in PLA matrix and refined phase morphology. • Addition of PHBH and PVAc increased the flexibility and toughness of PLA. • Melt viscoelasticity of PLA was improved by incorporation of PHBH and PVAc. To toughen brittle poly(L-lactic acid) (PLA), poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBH) and poly(vinyl acetate) (PVAc) were introduced into PLA matrix to prepared PLA/PHBH/PVAc ternary blends. PVAc was electively located in PLA matrix and refined phase morphology owing to better miscibility of PVAc with PLA than with PHBH. Increase in PVAc content decreased the crystallization rate and the crystallinity of PLA due to the dilution effect. More importantly, prominent enhancement of flexibility and toughness of PLA was obtained by the addition of PHBH and PVAc. Elongation at the break and impact strength of ternary blend with 10 wt% PVAc were 277 % and 326 % higher than that of neat PLA. Melt viscoelasticity of PLA was improved by incorporation of PHBH and PVAc. The combination of increased toughness and high melt viscoelasticity established in PLA biodegradable blends represent properties required in a wider range of applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein, poly(L-lactide) (PLLA), poly(butylene adipate- co -terephthalate) (PBAT), and poly(D-lactide) (PDLA) were melt compounded by a low-temperature method to prepare ternary blends with balanced properties. Differential scanning calorimetry results and torque changes during melt blending confirmed that the stereocomplex polylactide (SC-PLA) crystallites were formed. Network structure composed of SC-PLA crystallites was formed when the PDLA content was 5 wt%, at which point the melts of the blend exhibited solid-like rheological behavior. The formation of SC-PLA crystallites increased the viscosity ratio between PLLA and PBAT melt, which led to an increase of the size of dispersed PBAT phase. Furthermore, the SC-PLA crystallites could greatly promote both nonisothermal and isothermal melt crystallization behaviors of PLLA/PBAT/PDLA ternary blends because of their effective heterogeneous nucleation effect. The ternary blend containing 2 wt% PDLA showed good toughness and had an elongation at break of 211% compared to the elongation at break of 3.5% for neat PLLA. These biodegradable blends showed excellent melt crystallization abilities as well as tailored rheological and mechanical properties, which could demonstrate their potential as traditional non-biodegradable plastic substitutes. [ABSTRACT FROM AUTHOR]