Search Results (2)

The inherent brittleness of poly(lactic acid) (PLA) limits its use in a wider range of applications that require plastic deformation at higher stress levels. To overcome this, a series of poly(l-lactic acid) (PLLA)/biodegradable thermoplastic polyester elastomer (TPE) blends and their ternary blends with an ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) copolymer as a compatibilizer were prepared via melt blending to improve the poor impact strength and low ductility of PLAs. The thermal behavior, crystallinity, and miscibility of the binary and ternary blends were analyzed by differential scanning calorimetry (DSC). Tensile tests revealed a brittle–ductile transition when the binary PLLA/20TPE blend was compatibilized by 8.6 wt. % EMA-GMA, and the elongation at break increased from 10.9% to 227%. The “super tough” behavior of the PLLA/30TPE/12.9EMA-GMA ternary blend with the incomplete break and notched impact strength of 89.2 kJ∙m⁻² was observed at an ambient temperature (23 °C). In addition, unnotched PLLA/40TPE samples showed a tremendous improvement in crack initiation resistance at sub-zero test conditions (−40 °C) with an impact strength of 178.1 kJ∙m⁻². Morphological observation by scanning electron microscopy (SEM) indicates that EMA-GMA is preferentially located at the PLLA/TPE interphase, where it is partially incorporated into the matrix and partially encapsulates the TPE. The excellent combination of good interfacial adhesion, debonding cavitation, and subsequent matrix shear yielding worked synergistically with the phase transition from sea–island to co-continuous morphology to form an interesting super-toughening mechanism. Full article

Thermoplastic elastomers (TPEs) have attracted increasing attention for a wide variety of industrial and biomedical applications owing to their unique properties compared to those of traditional rubbers. To develop high-performance engineering TPEs and reduce the environmental pollution caused by plastic waste, α,ω-hydroxyl-terminated polycaprolactone (PCL) polyols with molecular weights of 1000–4200 g mol⁻¹ and polydispersity index (Ð) of 1.30–1.88 are synthesized via the ring-opening polymerization of sustainable ε-caprolactone using a heterogeneous double metal cyanide catalyst. The resulting PCL polyols are employed as soft segments to produce thermoplastic poly(ester ester) elastomers and are compared to conventional thermoplastic poly(ether ester) elastomers prepared from polytetramethylene ether glycol (PTMEG). Notably, the PCL-based TPEs exhibit superior mechanical properties and biodegradability compared to PTMEG-based TPEs owing to their crystallinity and microphase separation behaviors. Accordingly, they have 39.7 MPa ultimate strength and 47.6% biodegradability, which are much higher than those of PTMEG-based TPEs (23.4 MPa ultimate strength and 24.3% biodegradability). The introduction of biodegradable PCLs demonstrates significant potential for producing biodegradable TPEs with better properties than polyether-derived elastomers. Full article