Abstract
A series of different contents of glycidyl methacrylate (GMA)-grafted natural rubber (GNR) copolymers were fabricated via green bulk melt-grafting reactions, and super-tough bio-based poly (lactic acid) (PLA)/GNR thermoplastic vulcanizates (TPVs) were achieved by in-situ dynamic vulcanization. Increasing the graft yield, gel fraction, and crosslinking density of GNR vulcanizates effectively improved the ductility of the PLA/GNR TPVs, while prolonging the dynamic vulcanization time and increasing the GMA graft yield led to a notable enhancement in the impact toughness of the PLA/GNR TPVs. PLA/30 wt % GNR TPVs exhibited a significantly increased elongation (410%) and notched impact strength (73.2 kJ/m2), which were 40 and 15 times higher than those of the PLA/30 wt % NR TPVs, respectively. The new bio-based PLA/GNR TPVs offer promise as replacements for petroleum-based polymers in the automotive, 3D printing, and packaging fields.
Highlights
(lactic acid) (PLA) is a promising bio-material with excellent biodegradability, good processing, and high mechanical strength, which makes it a suitable alternative for petrochemical polymers to alleviate the problems of diminishing oil resources
We found that the microstructure of natural rubber (NR) graft-modified glycidyl methacrylate (GMA) and vulcanization conditions had an important effect on the structure and performances of PLA-based thermoplastic vulcanizates (TPVs)
These results demonstrate that the chemical interfacial adhesion became stronger with an increased GMA graft yield and vulcanization time, and a large proportion of micro–nanoscale grafted natural rubber (GNR) vulcanizates embedded in the PLA/GNR TPVs induced extensive plastic deformation and yielding of the PLA matrix, contributing to a greatly enhanced impact strength
Summary
(lactic acid) (PLA) is a promising bio-material with excellent biodegradability, good processing, and high mechanical strength, which makes it a suitable alternative for petrochemical polymers to alleviate the problems of diminishing oil resources. The disadvantages of PLA, including its brittleness and low heat distortion temperature, greatly limit its use [1,2,3,4] Many flexible polymers, both biodegradable and non-biodegradable, have been blended with PLA to improve its toughness, including poly (butylene succinate), poly (butylene adipate-co-terephthalate), poly(carbonate), etc. We focused on the effect of different contents of NR-GMA on the microstructure and toughness of PLA-based TPVs [27]. We found that the microstructure of NR graft-modified GMA (including graft yield, gel content, and crosslinking density) and vulcanization conditions had an important effect on the structure and performances of PLA-based thermoplastic vulcanizates (TPVs). TPVs has not previously been systematically discussed In this manuscript, three kinds of glycidyl methacrylate-grafted natural rubber (GNR) copolymers were synthesized, and the microstructure of these modified GNRs were characterized. The influence of the GNR microstructure and the vulcanizing conditions on the structure and properties of PLA TPVs were systematically investigated
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