Effect of ethylene-co-vinyl acetate-glycidylmethacrylate and cellulose microfibers on the thermal, rheological and biodegradation properties of poly (lactic acid) based systems (original) (raw)
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International journal of biological macromolecules, 2018
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Disintegrability under composting conditions of plasticized PLA-PHB blends
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The disintegration under composting conditions of films based on poly(lactic acid)poly(hydroxybutyrate) (PLA-PHB) blends and intended for food packaging was studied. Two different plasticizers, poly(ethylene glycol) (PEG) and acetyl-tri-n-butyl citrate (ATBC), were used to limit the inherent brittleness of both biopolymers. Neat PLA, plasticized PLA and PLA-PHB films were processed by melt-blending and compression moulding and they were further treated under composting conditions in a laboratory-scale test at 58 ± 2 ºC. Disintegration levels were evaluated by monitoring their weight loss at different times: 0, 7, 14, 21 and 28 days. Morphological changes in all formulations were followed by optical and scanning electron microscopy (SEM). The influence of plasticizers on the disintegration of PLA and PLA-PHB blends was studied by evaluating their thermal and nanomechanical properties by thermogravimetric analysis (TGA) and the nanoindentation technique, respectively. Meanwhile, structural changes were followed by Fourier transformed infrared spectroscopy (FTIR). The ability of PHB to act as nucleating agent in PLA-PHB blends slowed down the PLA disintegration, while plasticizers speeded it up. The relationship between the mesolactide to lactide forms of PLA was calculated with a Pyrolysis-Gas Chromatography-Mass Spectrometry device (Py-GC/MS), revealing that the mesolactide form increased during composting.
Journal of Environmental Management, 2020
The current study evaluates aerobic biodegradation of melt extruded poly(lactic acid) PLA based blends under composting conditions. Samples of neat PLA (NPLA) and bio-based polyblend composites of PLA/LLDPE (linear low-density polyethylene) having different concentration of MCC (microcrystalline cellulose crystal) were analyzed to understand the biodegradation behavior of these blends under simulated composting conditions. Biodegradation kinetics revealed that higher content of MCC and PLA accelerated the biodegradation process of the polymeric blends. Increase in the spherulite growth size and decrease in the spherulite density of the biodegraded samples confirmed the decline in amorphous portion of the test samples due to microbial assimilation, leaving behind the crystalline portion. Surface morphological analysis revealed that the samples of PLA/LLDPE/ MCC blends underwent surface erosion prior to bulk biodegradation (50-80%) until the 90th day and the PLA formed fibril-like structures after degradation. This study would help in the design and preparation of biodegradable bio-based commercial blends in the future.
Journal of Polymers and the Environment, 2014
Biodegradable blends of poly(L-lactide) (PLL) and cellulose acetate butyrate (CAB) were prepared as 40-60 lm thick films cast from solution using chloroform as a solvent. Both poly(ethylene glycol) (PEG) and a polyester adipate (Paraplex G40) were used as plasticizers to decrease the PLL/CAB blends' glass transition temperature and make them more flexible. Ternary PLL/CAB/ PEG blends showed only partial compatibility due to phase separation of crystalline PLL-rich and CAB-rich domains. In contrast, when Paraplex G40 was used as the plasticizer, it produced PLL/CAB/Paraplex G40 blends with stable morphology over an extended period of time with much reduced phase separation. The PLL/CAB/plasticizer blend films all degraded in real composting conditions at PLL contents of over 50 wt%. Moreover, the PEG-plasticized ternary blend films showed complete degradability at PLL C 70 and CAB B 30 wt%. These results suggest that the CAB content and plasticizer type can be used to tune polymer blend compatibility and biodegradability. The most promising formulations were found to be PLL/CAB/ Paraplex G40 blends with compositions of PLL C 70, CAB B 30 and Paraplex G40 = 20 parts by weight, combining good polymer compatibility and biodegradability with a suitable balance of mechanical properties.
Thermal and composting degradation of EVA/Thermoplastic starch blends and their nanocomposites
Polymer Degradation and Stability
In this work, the thermal degradation and the disintegrability under composting conditions of meltprocessed blends based on ethylene-vinyl acetate and thermoplastic starch, EVA/TPS, as well as their nanocomposites, reinforced with natural bentonite, were studied. A special emphasis was first put on the influence of starch on the morphology, thermomechanical properties and hydrophilicity of these blends before composting analysis. In fact, the materials were characterized in terms of morphological, mechanical, thermal and structural properties as well as wettability performance, obtaining information about the immiscibility of the blends and their compatibilization when natural bentonite is used. The thermal stability of starch was increased according with the EVA content in the blend, while the compatibility between both polymeric phases was increased by adding the nanoclays. Consequently, the disintegration under composting condition at laboratory scale level of the obtained materials was conducted and the thermal and chemical-structural properties as well as the surface microstructural changes of recovered samples at different stages of disintegration were studied. Disintegration tests showed that EVA/TPS blends and their nanocomposites presented positive interactions, which delay the disintegration of TPS matrix in compost, thus improving TPS stability. Moreover, blending biodegradable polymers such as TPS with non-biodegradable polymers like EVA leads to the increase of compostable polymer percentage in partially-degradable materials giving a possible solution for the end-life of these materials after their use.
2018
Poly(lactic acid) (PLA) is arguably the most well-known biodegradable plastic. However, its degradation behavior is far from ideal. The goal of this work is to prepare PLA blends that exhibit accelerated biodegradation performance whilst retaining adequate mechanical properties. To accomplish this a copolymer consisting of poly(L-lactic acid) and poly(glycolic acid) (PGA) structural units was synthesized and subsequently melt blended with a commercially available PLA homopolymer. The anaerobic degradation behavior of the polymer blend was greatly enhanced as a result of the incorporation of 20 wt% of the copolymer. A moderate change in mechanical properties including a 20% reduction in stiffness and strength and an 80% increase in elongation to break was also observed.
Waste management (New York, N.Y.), 2018
Prediction studies of advanced (bio)degradable polymeric materials are crucial when their potential applications as compostable products with long shelf-life is considered for today's market. The aim of this study was to determine the effect of the polylactide (PLA) content in the blends of PLA and poly(butylene adipate-co-terephthalate) (PBAT); specifically how the material's thickness corresponded to changes that occurred in products during the degradation process. Additionally, the influence of talc on the degradation profile of all samples in all environments was investigated. It was found that, differences in the degradation rate of materials tested with a similar content of the PLA component could be caused by differences in their thickness, the presence of commercial additives used during processing or a combination of both. The obtained results indicated that the presence of talc may interfere with materials behavior towards water and consequently alter their degrada...
Degradation behaviors of linear low-density polyethylene and poly(L-lactic acid) blends
Journal of Applied Polymer Science, 2012
In this study, the degradability of linear low-density polyethylene (LLDPE) and poly(L-lactic acid) (PLLA) blend films under controlled composting conditions was investigated according to modified ASTM D 5338 (2003). Differential scanning calorimetry, X-ray diffraction, and Fourier transform infrared spectroscopy were used to determine the thermal and morphological properties of the plastic films. LLDPE 80 (80 wt % LLDPE and 20 wt % PLLA) degraded faster than grafted low-density polyethylene-maleic anhydride (M-g-L) 80/4 (80 wt % LLDPE, 20 wt % PLLA, and 4 phr compatibilizer) and pure LLDPE (LLDPE 100). The mechanical properties and weight changes were determined after composting. The tensile strength of LLDPE 100, LLDPE 80, and M-g-L 80/4 decreased by 20, 54, and 35%, respectively. The films, as a result of degradation, exhibited a decrease in their mass.