Structural, morphological and mechanical characteristics of polyethylene, poly(lactic acid) and poly(ethylene-co-glycidyl methacrylate) blends

Abstract

In this work, uncompatibilized and compatibilized blends of low density polyethylene (LDPE) and poly(lactic acid) (PLA) were subjected to several investigations: Fourier transform infrared (FTIR) spectroscopy, morphological analysis and mechanical testing (tensile, impact, microhardness). The copolymer (ethylene-coglycidyl methacrylate) (EGMA) was used as compatibilizer. The percentages of PLA in LDPE/PLA samples ranged from 0 to 100 wt% while the EGMA was added to the blend 60/40 (LDPE/PLA) at concentrations of 2, 5, 7, 10, 15 and 20 parts per hundred (phr). FTIR analysis showed the absence of any interaction between LDPE and PLA, but after addition of compatibilizer, reactions between epoxy groups of EGMA and carboxylic or hydroxyl groups of PLA were confirmed. Tensile and impact tests revealed a loss of ductility of LDPE with the incorporation of PLA, except for the composition 80/20 (LDPE/PLA). However, the addition of 15 phr of EGMA led to the maximum increase in the elongation-at-break (about three times the value of uncompatibilized blend) and in the impact strength, but a marginal improvement was observed for tensile strength. SEM micrographs confirmed that the enhancement of mechanical properties is due to the improvement of the interfacial adhesion between different phases owing to the presence of EGMA. The microhardness values of the different blends (uncompatibilized or compatibilized) were in good agreement with the macroscopic mechanical properties (tensile and impact strengths).

Effect of Blending Procedure on Tensile and Degradation Properties of Toughened Biodegradable Poly(lactic acid) Blend with Poly(trimethylene terephthalate) and Reactive Compatibilizer

“…After blending with PLA and PTT, the peak of the epoxy ring in PEGMA at 910 cm −1 disappeared for the PLA/PTT/PEGMA blends produced by both one‐step and two‐step blending with unreacted PLA and PTT removed. It was confirmed that the epoxy ring of PEGMA had already opened and reacted with other polymers . The spectrum of the blend produced by one‐step blending in Figure d shows the existence of PEGMA from the sharp peaks of CH stretching vibrations in CH 2 at 2917 and 2849 cm −1 .…”

“…PEGMA at the interface between the PLA matrix phase and PTT particles functioned as a compatibilizer by enhancing the interfacial adhesion between the two phases, which stabilized and reduced the size of the dispersed phase. [12,21] These features suggest that the improved mechanical properties of the PLA/PTT/PEGMA blend produced by two-step blending originated in the presence of PEGMA at the interface between the PLA and PTT phases.…”

“…It was confirmed that the epoxy ring of PEGMA had already opened and reacted with other polymers. [21,30,31] The spectrum of the blend produced by one-step blending in Figure 9d shows the existence of PEGMA from the sharp peaks of CH stretching vibrations in CH 2 at 2917 and 2849 cm −1 . A peak at 1757 cm −1 , attributed to the CO bond of PLA, was also observed, but the peak at 1715 cm −1 was not clearly observed.…”

“…Poly(ethylene-co-glycidyl methacrylate) (PEGMA) was used as a reactive compatibilizer for polymer blends including polyesters in many studies because the epoxy ring in PEGMA can react with both carboxyl and hydroxyl groups in a polyester. [18][19][20][21][22][23] PEGMA was expected to react with the end groups of both PLA and PTT and then act as a compatibilizer for a PLA/PTT blend.…”

Investigating effect of ferric stearate on stabilization efficiency of a phenolic antioxidant during thermal oxidation of polyethylene

“…With the constantly expanding use of polymers and ever-increasing attention being paid to environmental pollution, the use of degradable film forming polymers has become a crucial demand [5][6][7]. This problem could be solved by adding some pro-oxidant additives, which are usually organometallic compounds of transition metals that accelerate oxidation process under influence of heat and/or sunlight [8].…”