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101.
采用分子动力学方法模拟分析温度(375~550 K)对低密度聚乙烯(PE–LD)零剪切黏度的影响,通过Material Studio 8.0软件构建分子"位能模型",施加原子水平模拟研究凝聚态优化的分子力场(COMPASS)力场,经过几何优化、退火处理和动力学弛豫后,运行NPT系综的动力学模拟,进行数据处理。结果表明,PE–LD熔体的黏度随温度升高呈指数递减。从分子链自扩散和自由体积来分析其机理,结果显示,温度的升高,加剧了分子链之间的运动,减少了分子间的缠结,增大了熔体的自由体积,减少了分子间的内摩擦,从而导致黏度下降。 相似文献
102.
103.
In situ fibre‐reinforced composite films of poly(lactic acid)/low‐density polyethylene blends: effects of composition on morphology,transport and mechanical properties 下载免费PDF全文
This study aimed to investigate the effects of blend composition on packaging‐related properties of poly(lactic acid) (PLA) and low density polyethylene (LDPE) blown films. Blend films with PLA contents of 5–20 wt% were produced and compared. Scanning electron micrographs of cross‐sectional cryofractured surfaces of the blend films revealed that in situ fibre‐reinforced composites were obtained. Viscosity ratio of the polymer components of ca 1 confirmed that fibre formation was favourable for this blend system. PLA microdomains were dispersed throughout the film in forms of long fibres (length‐to‐diameter ratio > 100) and ribbons. The number of fibres and ribbons increased with an increase of PLA content. Critical content of PLA was found to be 20 wt% for effective improvement of both moduli and gas barrier properties. Incorporation of poly[ethylene‐co‐(methyl acrylate)] compatibilizer showed minimal effect on PLA structure. However, it did improve moduli and O2 barrier properties when sufficient amount (1.5 pph) was used in 10 wt% PLA/LDPE. In short, flow behaviour, ratio of polymer components and degree of compatibility together played intricate roles in the morphology and hence mechanical and transport properties of PLA/LDPE immiscible blends. © 2017 Society of Chemical Industry 相似文献
104.
《Measurement》2016
This study measured the effect of sugar beet pulp (SBP) and maleated polyethylene (MAPE) concentrations on the properties of low density polyethylene (LDPE) composites. SBP concentration has significantly increased density, thickness swelling (TSW), water absorption (WA), flexural strength (FS), tensile modulus (TM) and flexural modulus (FM) of composites while reducing tensile strength (TS), elongation at break (EatB) and impact strength (IS). Presence of MAPE has improved TSW, WA, TS, FS, TM and FM. However, EatB and IS were slightly worsened by MAPE use. Composites showed two main decomposition peaks; one coming from SBP (360–368 °C) and the second one from LDPE degradation (484–490 °C). SEM images showed improved dispersion of SBP. The composites has provided less than 2% weight loss and classified as ‘very durable material’ against white-rot and brown-rot fungi attack. Through this study, potential utilization of SBP in LDPE matrix was demonstrated. 相似文献
105.
106.
《Journal of Industrial and Engineering Chemistry》2014,20(4):1650-1655
The performance of a highly cross-linked polyethylene catalyst supported on alumina for low temperature selective catalytic reduction of NOx by unburned hydrocarbons (HCs) existing in an exhaust gas was examined at different engine conditions with the addition of exhaust-gas recirculation. The HXPE catalyst was shown to exhibit good NOx reduction activity at low temperatures (100–250 °C) where the only reductant was the unburned HC, which was already present in the exhaust flow. The maximum NOx reduction of approximately 52% was achieved at a temperature of 150 °C. HXPE demonstrated very good selectivity toward N2 in the majority of tested conditions (∼80%). 相似文献
107.
108.
Wande Zhang Pranav Soman Kyle Meggs Xin Qu Shaochen Chen 《Advanced functional materials》2013,23(25):3226-3232
Cells sense and respond to mechanical forces, regardless of whether the source is from a normal tissue matrix, an adjacent cell or a synthetic substrate. In recent years, cell response to surface rigidity has been extensively studied by modulating the elastic modulus of poly(ethylene glycol) (PEG)‐based hydrogels. In the context of biomaterials, Poisson's ratio, another fundamental material property parameter has not been explored, primarily because of challenges involved in tuning the Poisson's ratio in biological scaffolds. Two‐photon polymerization is used to fabricate suspended web structures that exhibit positive and negative Poisson's ratio (NPR), based on analytical models. NPR webs demonstrate biaxial expansion/compression behavior, as one or multiple cells apply local forces and move the structures. Unusual cell division on NPR structures is also demonstrated. This methodology can be used to tune the Poisson's ratio of several photocurable biomaterials and could have potential implications in the field of mechanobiology. 相似文献
109.
《国际聚合物材料杂志》2012,61(14):1091-1101
The melt flow behavior and thermal properties of low-density polyethylene (LDPE)/palm kernel shell (PKS) composites were studied. Polyethylene acrylic acid (PEAA) was used as a compatibilizer in the composites. The results showed that the increasing of PKS loading had decreased MFI values of LDPE/PKS composites. The presence of PEAA increased the MFI values of the LDPE/PKS composites. The apparent viscosity of the composites was found to exhibit a linear relationship with the reciprocal of the temperature. Thermal properties showed that higher filler loading tended to reduce the onset temperature as the PKS possessed lower degradation temperature compared to the LDPE. The presence of the PKS in the LDPE polymeric matrix improved the thermal stability of the composites. The addition of PEAA into the composites provided better interfacial bonding between the LDPE matrix and PKS filler, while higher onset temperature and lower total weight loss were observed of LDPE/PKS composites. The activation energy of the LDPE/PKS composites was increased with increasing filler loading. At similar filler loading, the presence of PEAA increased the activation energy of the LDPE/PKS composites. 相似文献
110.
《国际聚合物材料杂志》2012,61(2):173-184
Temperature variations of oriented polyethylene (PE) with a draw ratio of ~ 450% were measured in longitudinal adiabatic tension and compression (along the orientation axis) and transverse compression. Stress-strain curves (for tension and compression) were recorded. Linear thermal expansion coefficients in the longitudinal and transverse direction were measured. Thermoelastic characteristics and also thermal properties of oriented PE were quantitatively analyzed. It has been concluded that conformational dynamics has a dominating influence on these characteristics. 相似文献