EVA含量与PP/EVA共混体系机械性能的研究

针对PP材料低温下机械强度比较差的特点,利用弹性体 EVA对PP进行增韧改性.叙述了在PP/EVA共混塑料合金加工过程中,不同的EVA含量对改性共混体系所产生的基本力学性能的影响,讨论了EVA含量与体系各主要机械性能,如拉伸强度、断裂伸长率、抗弯曲强度、冲击强度之间的关系.     

The effects of electron beam radiation on material properties and degradation of commercial PBAT/PLA blend

This work investigates the potential application of e-beam radiation for sterilization of food packaging made of commercial polyester blend of poly(butylene adipate-co-terephthalate) and polylactide known under the trade name Ecovio 23B1. Ecovio film was irradiated at doses of 5, 13, and 26 kGy and the effect of sterilization on the microorganism inactivation ability was performed. The influence of radiation doses on structural and packaging properties such as tensile strength, barrier, and migration properties was also studied. ¹H NMR and FTIR analysis revealed no significant changes in the polymer structure, however, the molar mass of irradiated samples decreased with increasing radiation dose. This result indicated the occurrence of degradation process during radiation, which was confirmed by the thermal analysis and accelerated enzymatic degradation. The packaging properties did not changed significantly and the overall migration for 10% ethanol, isooctane, and MPPO was below the limit for all of the studied samples. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48462.     

The effect of mercapto‐modified EVA on rheological and dynamic mechanical properties of NBR/EVA blends

The effect of mercapto‐modified ethylene vinyl acetate copolymer (EVALSH) on the rheological and dynamic mechanical properties of acrylonitrile butadiene rubber (NBR) and ethylene vinyl acetate copolymer (EVA) blends was evaluated at different blend compositions. The addition of 5 phr of EVALSH in the blends resulted in an increase of the melt viscosity and a substantial decrease of the extrudate swell ratio. These results can be attributed to the interactions occurring between the double bond of the NBR phase and the mercapto groups along the EVALSH backbone. The power–law index also presents a slight increase in the presence of EVALSH, indicating a decrease in the pseudoplastic nature of the compatibilized blends. The reactive compatibilization of NBR/EVA blends with EVALSH was also confirmed by the decrease of damping values and an increase of glass transition temperature, in dynamic mechanical analysis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2335–2344, 2002     

Radiation effects on HDPE/EVA blends

In this article, we discuss the radiation effects of high‐density polyethylene (HDPE)/ethylene–vinyl acetate (EVA) copolymer blends. In comparison with the low‐density polyethylene/EVA blends, the EVA content in the HDPE/EVA blends had a lower enhancement effect on radiation crosslinking by γ‐ray irradiation in air. The phenomenon is discussed with the compatibility, morphology, and thermal properties of HDPE/EVA blends. The HDPE/EVA blends were partly compatible in the amorphous region, and radiation crosslinking of the HDPE/EVA blend was less significant, although increasing the amorphous region's content of the HDPE/EVA blends and the vinyl acetate content of EVA were beneficial to radiation crosslinking. The good compatibility was a prerequisite for the enhancement effect of EVA on the radiation crosslinking of the polyethylene/EVA copolymer. The radiation crosslinking and the degradation mechanism of HDPE/EVA blends were examined quantitatively by a novel method, the step analysis process of irradiated HDPE/EVA blends with a thermal gravimetric analysis technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 553–558, 2002     

Radiation processing of ethylene‐propylene rubber

The effects of ionizing radiation on ethylene‐propylene copolymer were evaluated over the range of total γ doses up to 500 kGy. The influence of the irradiation dose was investigated by oxygen uptake and thermal analysis. Four testing temperatures (170, 180, 190, and 200°C) and two heating rates between 2.9 and 5.9 K/min were selected for oxygen uptake measurements and thermal analysis, respectively. The competition between crosslinking and scission was examined on the basis of kinetic parameters of postirradiation oxidation. The influence of the momentary concentration of hydrocarbon free radicals is discussed in regard to the contribution of the antagonistic processes of crosslinking and oxidative degradation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 298–303, 2000     

Radiation effects on methyl vinyl polysilicone foam

The effects on methyl vinyl polysilicone foam of ⁶⁰Co γ‐ray radiation at room temperature was studied in air, in vacuo, and in an inert gas atmosphere. The unirradiated and irradiated samples were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, pyrolysis gas chromatography/mass spectroscopy, and thermogravimetric analysis, and the gas products after radiation were analyzed by gas chromatography/mass spectroscopy. The changes of the gel fraction, compression properties, and the stress–relaxation ratio with dose for irradiated samples were observed. The results show that the second crosslinking reaction in the polysilicone after chemical crosslinking took place at a low dose (2 × 10⁵ Gy), but radiation degradation was predominant, with the dose increasing step by step. The mechanical properties of polysilicone foam gradually became low grade after it was irradiated by any dose in excess of 2 × 10⁵ Gy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3437–3441, 2003     

Radiation effects on LDPE/EVA blends

Radiation effects of low‐density polyethylene/ethylene‐vinyl acetate copolymer (LDPE/EVA) blends were discussed. EVA content in the LDPE/EVA blends was an enhancement effect on radiation crosslinking of LDPE/EVA blends, and the highest radiation crosslinking was obtained when the EVA content was reached at 30% when irradiated by γ‐ray in air. The phenomenon was discussed with the compatibility, morphology, and thermal properties of LDPE/EVA blends and found that the enhanced radiation crosslinking of the LDPE/EVA blends was proportional to the good compatibility, the increasing degree of the amorphous region's content of the LDPE/EVA blends, and the vinyl acetate content of EVA. We also found that the vinyl acetate of EVA in the blends is easily oxidized by γ‐ray irradiation in air. The possible radiation crosslinking and degradation mechanism of LDPE/EVA blends was discussed quantitatively with a novel method “step‐analysis” process of irradiated LDPE/EVA blends in the thermal gravimetric analysis (TGA) technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1296–1302, 2002     

Physical properties of ethylene vinyl acetate copolymer (EVA)/natural rubber (NR) blend based foam

In this study an attempt was made to improve the rebound resilience and to decrease the density of ethylene‐vinyl acetate copolymer (EVA) foam. For this purpose, EVA was blended with natural rubber (NR), and EVA/NR blends were foamed at 155°C, 160°C, and 165°C. To investigate the correlation between crosslinking behavior and physical properties of foams, crosslinking behavior of EVA/NR blends was monitored. The physical properties of the foams were then measured as a function of foaming temperatures and blend compositions: 165°C was found to be the optimal temperature for a crosslinking of EVA/NR foam. As a result, the density of EVA/NR blend foamed at 165°C was found to be the lowest. EVA/NR (90/10) blend, foamed at 165°C, showed lower density, better rebound resilience, and greater tear strength than EVA foam. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2212–2216, 2004     

Combustion Behavior and Thermal Oxidative Degradation of EVA Containing Intumescent Flame Retardant

Microencapsulated ammonium polyphosphate (VAPP) with poly(vinyl alcohol)- melamine-formaldehyde (VMF) shell was introduced in ethylene vinyl acetate copolymer (EVA) to improve its flame retardancy. Due to the presence of VMF shell, VAPP shows better compatibility, flame retardancy and water resistance compared with ammonium polyphosphate (APP) in EVA. The flammability of EVA and its flame-retarded composites was studied by LOI, UL-94 and cone calorimeter. The composite containing 40 wt% VAPP can pass V-0 in UL-94 test, and hot water treatment shows few effects on its LOI value and UL-94 rating. The cone results indicated that the use of VAPP in EVA can significantly decrease heat release rate and total heat release compared with APP. To understand the mechanism of action of VAPP, dynamic FTIR experiments were carried out on EVA and EVA/VAPP composites. Based on above studies, the flame retardant mechanism of VAPP in EVA composite is discussed.     

EVA交联机理的研究

研究了过氧化二异丙苯(DCP)对乙烯-醋酸乙烯共聚物(EVA)交联的影响,分析交联过程的反应机理.对交联的EVA样品进行紫外光辐照,分析在该过程中所发生的反应,并研究加入紫外线吸收剂2-羟基-4-正辛氧基-二苯甲酮(UV-531)后,对交联EVA样品在紫外光辐照下交联的影响.     

Effect of electron beam irradiation and vinyl acetate content on the physicochemical properties of LDPE/EVA blends

The radiation‐induced crosslinking, compatibility, and surface modification of low density polyethylene/ethylene vinyl acetate blends (LDPE/EVA) were investigated. The structural and physical properties were characterized in terms of gel content, hot set, mechanical properties, contact angle, and surface free energy. The highest crosslink density was obtained at 20 wt % of EVA. Gel content of LDPE/EVA blends was increased with increasing irradiation dose, vinyl acetate (VA), and EVA contents. The hot set results are consistent with the gel content data. Mechanical testing showed that the tensile strength of samples increased with increasing irradiation dose up to 180 kGy, whereas the elongation at break was decreased with increasing irradiation dose. Contact angle measurements showed that the surface hydrophillicity of LDPE blend was increased with increasing irradiation dose and contents of both VA and EVA. The surface free energy was greatly dependent on irradiation dose and content of both VA and EVA. The total surface free energies of different LDPE formulations were in the range 17.25–32.51 mN/m, in which the polar (^pσ) and disperse (^dσ_s) values were within the range 16.52–26.6 and 0.9–5.91 mN/m, respectively. In conclusion, electron beam irradiation and blending LDPE with EVA improved the wettability or adhesion properties of LDPE/EVA blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

EVA的应用与加工

EVA是一类重要的乙烯基共聚物。介绍了它的分类、性能、应用、各种加工技术及进展。     

Mechanical and thermal properties of EVA blended with biodegradable ethyl cellulose

In this study, biodegradable blend of Poly (Ethylene‐co‐Vinyl Acetate) (EVA) and Ethyl Cellulose (EC) were prepared. Ethylene vinyl alcohol (EVOH) copolymer was used as an interfacial compatibilizer to enhance adhesion between EVA and EC. The melt blended compatibilized biocomposites were examined for mechanical and thermal properties as per the ASTM standards. It has been found that the EC has a reinforcing effect on EVA leading to enhanced tensile strength and also impart biodegradability. Thus, a high loading of 50% EC could be added without compromising much on the mechanical properties. Analysis of the tensile data using predictive theories showed an enhanced interaction of the dispersed phase (EC) and the matrix (EVA). The compatibilizing effects of EVOH on these blends were confirmed by the significant improvement in the mechanical properties comparable with neat EVA as also observed by SEM microscopy. The TGA thermograms exhibits two‐stage degradation and as EC content increases, the onset temperature for thermal degradation reduces. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on the influence of electron beam irradiation on the thermal,mechanical, and rheological properties of ethylene‐octene copolymer with high comonomer content

Ethylene‐octene copolymer (EOC) was irradiated using electron beam irradiation at different dosages (30, 60, 90, and 120 kGy). Effect of irradiation dosage on thermal and mechanical properties was studied. When compared to low density polyethylene, EOC exhibited higher degree of crosslinking reflected in increased gel content, higher elastic modulus (G′), and lower tan δ obtained by rheology measurement at 150°C. Crosslinking caused improvement in high‐temperature creep and room temperature and also elevated temperature elastic properties. Differential scanning calorimetry revealed that e‐beam irradiation has caused a gradual reduction in crystallinity and a presence of a fraction with higher melting temperature. In the case of EOC, as the extent of crosslinking increased, stress at break showed an increasing trend whereas irradiation dosage had an inverse effect on elongation at break. Radiation dosage has positive effect on thermal stability estimated by thermogravimetric analysis. After 30 min of thermal degradation at 220°C, slightly higher C?O peak for crosslinked sample was found by Fourier transform infrared spectroscopy while for room temperature samples no C?O peak was detected. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of high‐energy electron beam on low‐density polyethylene materials containing EVA

A series of low‐density polyethylene (LDPE) blends with different amounts of ethylene–vinyl–acetate (EVA) was prepared and irradiated with 10 MeV electron beam in the range of 0–250 kGy at room temperature in air. EVA was used as a compatibilizer and softener in four different amounts: 5, 10, 20, and 30 wt %, based on polyethylene (PE). The crosslinking of the samples was studied on the basis of gel‐content measurements as well as some thermal and mechanical properties of the specimens. The results indicated that the LDPE and LDPE–EVA blends could be crosslinked by a high‐energy electron beam, of which their thermal and mechanical properties changed effectively, however, because of EVA content of the polymer; the blends were more sensitive to lower doses of radiation. These studies were carried out to obtain a suitable compound for heat‐shrinkable tubes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1049–1052, 2004     

Preparation and properties of high performance phthalide‐containing bismaleimide reinforced polydicyclopentadiene

A series of phenolphthalein‐containing bismaleimide (PPBMI) reinforced polydicyclopentadiene blends (PPBMI/polyDCPD) were prepared via the ring‐opening metathesis polymerization of DCPD in the presence of PPBMI. The crosslinked networks between PPBMI and polyDCPD backbones resulted in the reinforced structures. The curing behavior, thermal, and mechanical properties were investigated. Differential scanning calorimetry investigations showed the samples exhibit similar singular exothermic peak, and the exothermic peak of the PPBMI/polyDCPD blends slightly shifted to a lower temperature direction compared with the unfilled polyDCPD, meanwhile, the exothermic peak of the PPBMI/polyDCPD blends slightly shifts back to a higher temperature direction with the PPBMI content increased. Both dynamic mechanical analysis and thermo gravimetric analysis measurements revealed the optimal thermal performance of PPBMI/polyDCPD was obtained with 20 wt % loading of PPBMI. In addition, while PPBMI content increased, the weight loss peak at 100–200°C disappeared and the temperature of maximum rate of decomposition (T_d,max) increased. Moreover, bending tests showed the best mechanical performance was achieved at 5 wt % loading of PPBMI in blends. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40474.     

TPS/EVA泡沫复合材料的制备及其阻燃与力学性能

以热塑性淀粉(TPS)为成炭剂与聚磷酸铵(APP)、可膨胀石墨(EG)复配组成膨胀型阻燃剂,通过熔融密炼、开炼塑化、硫化发泡制备了热塑性淀粉/乙烯-醋酸乙烯酯共聚物(TPS/EVA)泡沫复合材料,探讨了TPS用量对泡沫复合材料阻燃性能、力学性能的影响。结果表明,TPS的加入显著提高了TPS/EVA泡沫复合材料阻燃性能,可起到良好的成炭作用;TPS/EVA泡沫复合材料的拉伸强度、断裂伸长率以及撕裂强度随着TPS用量的增加呈现先增大后减小的趋势,相对密度则是小幅度上升。当TPS用量为6%时,TPS/EVA泡沫复合材料综合性能最好,其LOI可达26.5%且UL-94为V-0级,拉伸强度、断裂伸长率、撕裂强度以及相对密度可达2.395 MPa、177.48%、10.59 N·mm^-1、0.21452。     

Effect of surfactant on EG dispersion in EVA and thermal and mechanical properties of the system

The influence of expanded graphite (EG) and sodium dodecyl sulfate (SDS) modified EG on the structure, thermal stability, and mechanical properties of ethylene vinyl acetate (EVA) was investigated in this study. The EVA filled with EG platelets, with and without anionic SDS modification, was prepared by melt mixing using a Brabender Plastograph mixer. The extent of dispersion and morphology of the composites were characterized using scanning electron microscopy (SEM), optical microscopy (OM), and X‐ray diffraction (XRD). The optical microscopy results show better distribution of the modified EG platelets in the EVA matrix, while the SEM results show an improved interfacial adhesion between the polymer and the SDS‐EG particles. Both the EVA18 copolymer and the EG platelets have monoclinic phases, and both EG and SDS do not seem to have any influence on the melting and crystallization behavior of the EVA18. The addition of EG enhanced the thermal stability of EVA18, and this stabilizing influence was further improved when the EG was treated with SDS. All the tensile properties of EVA/EG improved after surface modification. The storage modulus of EVA generally increased with increasing both the unmodified EG and the SDS modified EG content. There was a shift in the T_g to higher temperatures with an increase in both the EG and modified EG content. The α‐relaxation peak in the SDS modified EG curves was less intense than the β‐relaxation peak, even for the untreated EG composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41352.     

Antimicrobial silicone rubbers based on photocatalytically active additives

The modification of plastics to generate germ-reducing surface materials is a promising strategy to decrease nosocomial infections in hygiene-sensitive areas. In this paper, photocatalytically active nanoparticles were incorporated as additives, not as a coating, into silicone rubber matrix material to produce elastic antibacterial bulk materials. Samples with 5 wt% and 10 wt% of two different types of TiO₂ and ZnO were prepared and investigated. The thermal analysis of the developed materials showed a complete vulcanization of the developed materials and slight modifications of mechanical properties were found. Investigations of the surface of the materials indicated no changes in the wettability of the surfaces or in their fourier transform infrared spectrometer (FT-IR) spectra, suggesting no degradation of the developed material. The photocatalytic activity on the surface of the test samples was investigated by microbial tests with Escherichia coli, Pseudomonas fluorescens, and Staphylococcus aureus bacteria. Depending on the additive type and the test germs, the samples showed different intensities of a germ-reducing effect (up to >99,999%).     

EVA/大麻秆芯粉复合材料及其力学性能

以新型植物纤维大麻秆芯粉作为填料制备EVA复合材料.研究秆芯粉质量含量、粒径、不同相容剂对填充体系力学性能的影响.结果表明,从秆芯粉对复合体系综合性能贡献考虑,40%的400目大麻秆芯粉得到较好的复合材料的力学性能;EAA对体系的改性效果明显优于MAH-g-PP.经TGA和SEM图分析表明:改性后的大麻秆芯粉表面引入新的基团并与基体产生一定的反应,提高了EVA与大麻秆芯粉的界面相容性.