Influence of electron beam irradiation on the mechanical properties of PBAT/PLA polymeric blend / Influência da irradiação do feixe de elétron nas propriedades mecânicas da mistura polimérica PBAT/PLA (original) (raw)
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Journal of Applied Polymer Science, 2002
Dynamic mechanical properties of nonirradiated and irradiated blends of polyethylene (PE) and ethylene vinylacetate (EVA) copolymer have been determined. Effect of addition of EVA and radiational crosslinking on loss and storage modulus, tan ␦, and transition temperatures were determined. Increase in transition temperatures on exposure to radiation and decrease in transition temperatures with addition of EVA is observed. Peak broadening is observed on exposure to radiation. Values of the storage modulus increase while that of loss modulus and tan ␦ decrease on crosslinking.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
The effect of incorporation of polyethylene in the polypropylene matrix, on the radiation sensitivity of polypropylene, has been investigated. The changes in the properties such as tensile strength, elongation at break, Shore D hardness, density and melt flow index were monitored as function of polyethylene content and electron beam radiation dose. A correlation between the mechanical properties and morphology of the irradiated polymeric blends has been observed, which has been explained on the basis of Fourier-transform infrared spectroscopy, scanning electron microscope and X-ray diffraction studies. Improvement in the mechanical properties of the polypropylene, irradiated to an optimum electron beam dose, could be achieved by blending it with polyethylene >20%. The optimum radiation dose was found to be dependent on blend composition and morphology, however, an absorbed dose of 250 kGy found to be effective enough to ensure good mechanical properties of the polypropylene/polyethylene blends.
2009
Amidst the pollutants, plastics and especially the “PET bottles” packaging type, which comprise of poly(ethylene terephthalate) (PET), polypropylene (PP), polyethylene (PE) and poly[ethylene-co-(vinyl acetate)] (EVA) have been causing big damage to the environment. In this work, the polymeric blend PET/PP/PE/EVA was obtained by mechanical recycling “PET bottles” after consumption, with the objective of finding a solution for this environmental problem. It was also studied the different ionizing radiation dose effects (25, 50, 75, 100, 150, 200, 300, 400 and 500 kGy) on the blend properties using an electron beam accelerator. The morphologic properties of the non-irradiated and irradiated polymeric blend were evaluated by the Light Microscopy (LM) and Scanning Electron Microscopy (SEM). The analysis of the results appeared to be a not mixing and compatible blend. The use of the ionizing radiation improved the homogeneity of the blend. These modifications have been randomized and irre...
WAXD and FTIR studies of electron beam irradiated biodegradable polymers
Poly(L-lactic acid) (PLLA) and poly(ε-caprolactone) (PCL) have been receiving much attention lately due to their biodegradability in human body as well as in the soil, biocompatibility, environmentally friendly characteristics and non-toxicity. Morphology of biodegradable polymers affects the rate of their biodegradation. A polymer that has high degree of crystallinity will degrade at a slower rate due to the inherent increased stability. PCL homopolymer cross-linking degree increases with increasing doses of high energy radiation. On the other hand, the irradiation of PLLA homopolymer promotes mainly chain-scissions at doses below 250 kGy. In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50:50 (w:w) blend were electron beam irradiated using electron beam accelerator Dynamitron (E = 1.5 MeV) from Radiation Dynamics, Inc. at doses in the range of 50 to 1000 kGy in order to evaluate the effect of electron beam radiation on the homopolymers and blend. Wide-angle X-ray diffraction (WAXD) patterns of non irradiated and irradiated samples were obtained using a diffractometer Rigaku Denki Co. Ltd., Multiflex model; and FTIR spectra was obtained using a NICOLET 4700, ATR technique, ZnSe crystal at 45°. By WAXD patterns of as extruded non irradiated and irradiated PLLA it was observed broad diffusion peaks corresponding to amorphous polymer. There was a slight increase of the mean crystallite size of PCL homopolymer with increasing radiation dose. PCL crystalline index (CI) was 68% and decreased with radiation dose above 500 kGy. On the other hand. PLLA CI was 10% and increased with radiation dose above 750 kGy. On the other hand, PLLA presence on the 50:50 blend did not interfere on the observed mean crystallite size increase up to 250 kGy. From 500 kGy to 1 MGy the crystallite size of PCL was a little bigger in the blend than the homopolymer. Also it could be observed that the PLLA peak increase at 14.2° was affected by PCL presence on the blend above 750 kGy. In contrast, FTIR results have shown that this technique was not sensitive enough to observe the degradation promoted by ionizing radiation of the studied homopolymers and blends, and neither on the miscibility of the blends.
Journal of Applied Polymer Science, 2006
Waste polyethylene (WPE) was segregated from the municipality solid waste, cleaned, dried, and chopped into pieces, then processed in a Brabender Plasticorder using the melt mixing technique. Blends of WPE and virgin polyethylene were prepared in various proportions under optimized process conditions. Of the various blend proportions studied, 70/30 blend of WPE/low density polyethylene (LDPE) and 50/50 blend of WPE/high density polyethylene showed better mechanical properties and hence selected for further modification involving electron beam irradiation. Aforementioned blends were exposed to various doses of electron beam irradiation and the effect of irradiation on physicomechanical properties such as tensile strength, flexural modulus, hardness, and impact resistance were studied. Thermogravimetric analysis, X-ray diffraction studies, Fourier transform infrared spectroscopy, scanning electron microscopy, and gel content were considered to characterize the blends. Physicomechanical properties improved to an appreciable extent on irradiation but the elongation at break reduced drastically. Blow molding of the 70/30 WPE/LDPE blend could be done successfully to make bottles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 715–726, 2006
Journal of Vinyl and Additive Technology, 2012
Linear low-density polyethylene was blended with soya powder, and the blends were compatibilized with epoxidized natural rubber having 50 mol% of epoxidation. The content of soya powder was varied from 0 to 40 wt%. The blends were irradiated at 30 kGy with an electron beam. Degradation of the irradiated blends was evaluated by exposing the samples to an outdoor environment according to ISO 877.2. The degradation was monitored by changes in the tensile, morphological, and thermal properties, as well as the molecular structure and weight loss. The tensile strength and elongation at break (Eb) of the exposed samples decreased as a function of exposure period. The irradiated blends exhibited higher retention of tensile strength and Eb than nonirradiated blends after 1 year of exposure. The crystallinity of the irradiated blends increased upon exposure, though the nonirradiated blends showed higher crystallinity indicating higher degradability. Weight loss of the irradiated blends showed less change after 6 months of outdoor exposure, but significant change was observed after 1-year exposure. The molecular weight changes of the irradiated blends exhibited the same trend as weight loss. All the results confirmed that the degradability of the irradiated blends was comparable to that of the nonirradiated blends upon long-term outdoor exposure.
In this work, the effect of electron beam radiation of linear low-density polyethylene (LLDPE)/ poly (vinyl alcohol) (PVA) blends are presented. The blends were prepared by melt mixing at 150 ºC at 60/40 (php/php), of LLDPE and PVA. Gel extraction, infrared spectroscopy diffraction scanning calorimetry, thermogravimetric, tensile properties and scanning electron microcopy had been used to investigate the effect of electron beam radiation on the properties of LLDPE/PVA blends. The exposure of these blends to 200 kGy dose of electron beam radiation increased the gel content, tensile properties (tensile strength and Young's modulus) and thermal stability due to the crosslinking formation, while, the melting temperature of LLDPE and PVA decreased as the PVA content was increased. The crosslink formation between LLDPE and PVA in the irradiated blends was demonstrated by the embedded PVA in LLDPE matrix as observed in optical images.
In current investigation, the linear low-density polyethylene (LLDPE)/soya powder blends were compatibilised by polyethylene grafted maleic anhydride (PE-g-MA). The blends were prepared using internal mixer at a rotor speed of 50 rpm and temperature 150°C. The effect of LLDPE/soya powder composition and irradiation dose on the tensile properties of the blends was investigated. The results showed that an increase in soya powder content in the blends reduced the tensile strength and elongation at break. However, the tensile strength of LLDPE/soya powder blends was enhanced with the addition of the PEg -MA and further improved after irradiated with electron beam (EB) irradiation. The tensile strength of the blends increased with increasing irradiation dose, but the elongation at break decreased. From the morphological study done with scanning electron microscopy (SEM), the LLDPE formed continuous matrix after irradiation.
Journal of Radiation Research and Applied Sciences, 2013
Poly(L-lactic acid)/ethylene vinyl acetate polymer blends (PLLA/EVA) with various blend ratios were prepared through melt blending process. The structural-property behavior of the polymer blends before and after they had been exposed to gamma irradiation was investigated. The hydrolytic degradation was investigated. The interfacial interaction between PLLA and EVA was visualized by Mechanical testing and FTIR. The crystallization behaviors of the blends were investigated by Differential scanning calorimetry (DSC), and the thermal stability was studied by thermogravimetric analysis (TGA). The results show that the hydrolytic degradation rate of PLLA/EVA blend can be widely controlled by exposing the PLLA/ EVA to gamma-irradiation and also by EVA content. In alkaline solution, the hydrolytic degradation rate of the blends exposed 100 kGy and whose EVA content is higher than 50 wt% was decelerated while the rate of the unirradiated blends whose EVA content is lower than 20 wt% was accelerated. The tensile strength and modulus of the PLLAeEVA blend were increased by increasing PLLA content in the polymer blends and irradiation dose. FTIR spectra showed that some modifications occurred, after they had been exposed to gamma irradiation. The crystallization behavior was studied with differential scanning calorimetry and the composition-dependent changed of degree of crystallinity (X c) of the PLLA phase indicated that PLLA and EVA were immiscible over the composition range investigated. However, there is a sharp decrease in the crystallinity with increasing EVA and irradiation dose. The TGA thermograms showed that the irradiated blends were less thermally stable than the unirradiated blends, at higher temperatures, the opposite situation was seen.