Lightweight micro-cellular plastics from polylactide/polyolefin hybrids

Abstract

Semi-crystalline polylactide(PLA)/polyolefin multi-component blends were used as precursors for the generation of a new class of micro-cellular polymers. Either a polypropylene-based elastomer (PBE) or polypropylene (PP) homopolymer were utilized as dispersed phases at the 10 wt% level. An epoxy-functionalized terpolymer (PEGMMA) was introduced (1 wt%) as a reactive compatibilizer to reduce the dispersed phase droplet size and provide sufficient adhesion between the matrix and dispersed phase. In addition, a polyalkylene glycol liquid (PAG) was added to the blend (4 wt%) to serve as a PLA plasticizer and interfacial modifier. The multicomponent blends exhibited significant increases in strain at break as compared to neat PLA and were subjected to a range of uniaxial strains (10-90%) at room temperature. These cold drawn materials exhibited nearly constant cross-sectional area and fine micro-cellular structures, as revealed by scanning electron microscopy. Distinct different voiding mechanisms observed for the PBE-and PP-containing blends were ascribed to the differences in the dispersed phase elastic moduli and deformability. The material density of cold drawn blends was reduced by up to 34% when compared to the precursor blends without a noticeable change in cross-sectional area. The novel low-density microcellular PLA blends demonstrated outstanding mechanical properties such as high strength, high modulus, substantial ductility, and a 14-fold increase in impact resistance as compared to PLA homopolymer.

Investigating the degradability of polyethylene using starch, oxo‐material, and polylactic acid under the different environmental conditions

“…23 However, the tensile strength of the LPDE with starch increased because of the higher tensile strength of starch. 14, and (e) 22 after production LDPE films containing oxo-material with different contents were prepared, and their properties were monitored to evaluate the oxo-material influences on the degradability of LDPE. The result showed that the roughness of the film decline significantly from 119 (for LDPE) to below 50 for the LDPE films with starch.…”

“…6,7 Polyolefins such as polyethylene are used in several applications. [8][9][10][11][12][13][14] In the second strategy, the degradation of some petroleum-derived plastics by biological processes is considered. Several methods including recycling, landfilling, and incineration were investigated to decline the amount of polyolefins' wastes in the environment.…”

“…As a result, their waste piles up in the environment for many years without any change as they are resident to oxidation and biodegradation. [11][12][13][14] As starch is cheap, available year-round, and renewable, its blend with polyethylene is cost-effective. However, low quality of the recycled polymers, air pollution, and water reservoir contamination prevented these processes' applications in long-term view.…”

“…Biodegradable plastics have several other advantages including increased soil fertility, low accumulation of bulky plastic materials in the environment, and reduction in the cost of waste management. [8][9][10][11][12][13][14] In the second strategy, the degradation of some petroleum-derived plastics by biological processes is considered. For this aim, different additives such as starch and oxo-material and organic acids were added to the polyolefines to convert them into biodegradable in the environment.…”

“…For this aim, different additives such as starch and oxo-material and organic acids were added to the polyolefines to convert them into biodegradable in the environment. [11][12][13][14] As starch is cheap, available year-round, and renewable, its blend with polyethylene is cost-effective. The initial work on the production of biodegradable polyethylene (blended by starch) was performed in the United Kingdom to save the petroleum resources and reduce the polyethylene waste in the nature.…”