乙烯-乙酸乙烯酯共聚物(EVA)的性能及应用

本文综述了乙酸乙烯酯(VA)含量和熔体流动速率(MFR)对乙烯-乙酸乙烯酯共聚物(EVA)性能的影响以及EVA树脂的应用。     

我国乙烯-乙酸乙烯共聚物现状及发展建议

阐述了乙烯-乙酸乙烯共聚物的特性、用途及国内外生产、消费和价格变化情况,介绍了乙烯-乙酸乙烯共聚物的生产技术,提出了发展建议.     

乙烯-乙酸乙烯酯共聚物中乙酸乙烯酯的红外光谱法测定

利用ATR技术测量样品的红外光谱,采用偏最小二乘法对所测光谱进行分析,建立了一种快速分析方法;对乙烯-乙酸乙烯酯共聚物中乙酸乙烯酯进行测定。结果表明：标准曲线线性关系良好,相关系数为0．99985,方法简单快速,结果可靠。     

抗水性和抗冻性聚乙酸乙烯酯乳液胶黏剂的制备

用乙烯-乙酸乙烯酯共聚乳液作为种子进行聚合，制备了抗水性和抗冻性的聚乙酸乙烯酯乳液胶黏剂。研究了乙烯-乙酸乙烯酯共聚物乳液的用量对改进型PVAC乳液的抗冻性、抗水性及表面张力的影响。     

高减震乙烯-乙酸乙烯酯橡胶发泡鞋用材料及其制备方法

<正>本发明公开了一种质轻高减震乙烯-乙酸乙烯酯橡胶发泡鞋用材料及其制备方法,由乙烯-乙酸乙烯酯橡胶、乙烯-乙酸乙烯酯树脂、乙烯-辛烯嵌段共聚物、相容剂、发泡剂、架桥剂、氧化锌、硬脂酸锌、助交联剂、填料组成。本发明工艺简单、易操作,产品更加轻量化,吸震性能优异,制备的产品冲击回弹率均低于     

乙酸乙烯含量对釜式法EVA生产中发生分解反应的影响

乙酸乙烯(VA)对热的稳定性低,在生产乙烯–乙酸乙烯共聚物(EVA)的高压聚合过程更容易发生分解反应;本研究结合实际生产过程中的两次局部分解反应案例,深入剖析了釜式法EVA生产过程中发生分解反应的原因,提出了相应安全控制措施,并通过生产实践得出了适合本装置的最优VA控制措施,为釜式法EVA生产提供有针对性的指导意见.     

乙烯-乙烯醇共聚物的生产技术及市场

综述了乙烯-乙烯醇(EVOH)共聚物的生产技术、市场现状及发展前景、下游应用展望。由于EVOH共聚物主要用于各种包装,且大部分都与食品相关,因此,采用适当的方法生产乙烯-乙酸乙烯(EVA)共聚物是生产合适EVOH的必要条件。目前,EVA共聚物大多采用高压法连续本体聚合工艺生产,乙酸-乙烯酯摩尔分数一般为5%~40%,而EVA共聚物的醇解多采用均相皂化法。国内聚乙烯醇(PVA)生产企业应加速开发EVOH共聚物,实现EVOH共聚物的国产化,从而缓解国内供需矛盾,为PVA生产商提供新的经济效益增长点。     

乙烯-乙烯醇共聚物

乙烯-乙烯醇是一种广泛使用的高性能材料。概述了乙烯-乙烯醇共聚物的各项性能;介绍了乙烯-乙烯醇共聚物在结构材料、包装材料、医用材料和改性剂方面的应用;总结了乙烯-乙烯醇共聚物的生产厂家和生产工艺;最后对乙烯-乙烯醇共聚物的发展前景做出分析。     

用EVA做的太阳电池板

据“Modern Plastics Worldwide，2008，（7）：24”报道，Evatane 33—45PV是一种含大量EVA（乙烯-乙酸乙烯酯共聚物）的专用共聚物牌号，它是专门针对光电太阳电池板而开发出来的。这种含乙酸乙烯酯18％～42％的新牌号，是专为一种密封材料（晶硅或薄膜）设计的，而这种材料可用来生产太阳电池板。     

天然橡胶/乙烯-乙酸乙烯酯共聚物/高密度聚乙烯热塑性硫化胶的制备及其性能研究

制备天然橡胶（NR）/乙烯-乙酸乙烯酯共聚物（EVA）/高密度聚乙烯（HDPE）热塑性硫化胶（TPV）并研究其性能。结果表明：当动态硫化时间为8 min、EVA用量为12份、炭黑N330用量为40份时，NR/EVA/HDPE TPV的综合物理性能最好。     

Morphological and mechanical properties of polypropylene [PP]/poly(ethylene vinyl acetate) [EVA] blends. II: Polypropylene‐(ethylene‐propylene) heterophasic copolymer [PP‐EP]/EVA systems

Morphological characteristics and mechanical properties of PP‐EP/EVA blends were studied and compared to those of PP/EVA previously reported. For the PPEP/EVA blends, interfacial interactions in amorphous zones, which were associated with shifts in T_g, were well defined compared to those of PP/EVA blends, although the nature of crystalline zones was similar for both systems. At EVA concentrations up to 20%, the elongation at break and impact strength slightly increased in both systems. However, PP‐EP/EVA displayed higher values of these properties compared with PP/EVA. At high EVA concentrations (above 20%), the indicated properties were enhanced in both polymeric systems, and the same proportional behavior was maintained. The decrease in tensile strength of PP‐EP/EVA was not as marked as in PP/EVA with the addition of EVA, and it remained below PP/EVA at high EVA concentrations. The improvement in properties of PP‐EP/EVA was attributed to favorable interactions between the ethylene groups contained in both copolymers. These interactions rendered a high degree of compatibility between the PP‐EP and EVA components.     

Viscoelastic and adhesion properties of hot-melts made with blends of ethylene-co-n-butyl acrylate (EBA) and ethylene-co-vinyl acetate (EVA) copolymers

Several hot-melts (HMAs) were prepared by using blends of ethylene-co-n-butyl acrylate (EBA) and ethylene-co-vinyl acetate (EVA) copolymers - EBA/EVA. HMAs were prepared with mixtures of EVA copolymers with 18 (EVA18) and 27 (EVA27) wt% vinyl acetate contents and EBA copolymer with 27 wt% n-butyl acrylate, polyterpene resin and mixture of microcrystalline and Fischer-Tropsch waxes. HMAs made with EBA/EVA blends showed lower viscosities and reduced shear thinning than the ones made with EBA or EVA due to differences in compatibility, but both the set time and the open time were not affected as they depended mainly on the wax nature and amount. The increase of the vinyl acetate (VA) content in EVA copolymer reduced the crystallinity of the EBA/EVA blends. Even EBA copolymer was more compatible with EVA27 than with EVA18 (the α- and β-transitions shown in DMTA plots were closer) and the compatibility did not vary with the EBA content in the blends. The addition of polyterpene resin and the mixture of waxes decreased the compatibility of the EBA/EVA blends, the higher compatibility was observed for the HMAs made with only one copolymer. The tack of the HMAs depended on their EBA/EVA contents, EBA/EVA27 HMAs showed broader temperature interval with higher tack, while the tack of EBA/EVA18 HMAs blend decreased and the temperature interval with tack was shortened and shifted to lower temperatures. Adhesion to polypropylene film was improved in HMAs made with 75 wt% EBA/25 wt% EVA18 and 50–75 wt% EBA/50-25 wt% EVA27. The adhesion to aluminum film of EBA or EVA hot melts was improved only in the joints made with EBA/EVA 27 HMAs, more noticeably when they contained higher EBA content.     

Effect of vinyl acetate content on the mechanical and thermal properties of ethylene vinyl acetate/MgAl layered double hydroxide nanocomposites

Ethylene vinyl acetate (EVA)/Mg‐Al layered double hydroxide (LDH) nanocomposites using EVA of different vinyl acetate contents (EVA‐18 and EVA‐45) have been prepared by solution blending method. X‐ray diffraction and transmission electron microscopic studies of nanocomposites clearly indicate the formation of exfoliated/intercalated structure for EVA‐18 and completely delaminated structure for EVA‐45. Though EVA‐18 nanocomposites do not show significant improvement in mechanical properties, EVA‐45 nanocomposites with 5 wt % DS‐LDH content results in tensile strength and elongation at break to be 25% and 7.5% higher compared to neat EVA‐45. The data from thermogravimetric analysis show that the nanocomposites of EVA‐18 and EVA‐45 have ≈10°C higher thermal decomposition temperature compared to neat EVA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Rheology, Morphology and Estimation of Interfacial Tension of LDPE/EVA and HDPE/EVA Blends

Summary Rheological characteristics and morphology of low-density polyethylene (LDPE) /ethylene vinyl acetate copolymer (EVA) and high-density polyethylene (HDPE)/EVA blends were compared. Morphological examinations clearly reveal a two-phase morphology in which the LDPE/EVA blends have smaller dispersed domain size than HDPE/EVA Furthermore, LDPE/EVA shows a finely interconnected morphology at 50wt% of EVA while HDPE/EVA exhibits a coarse co-continuous morphology at the same composition. The morphological observations can be attributed to the lower viscosity ratio and lower interfacial tension in the LDPE/EVA system. The Palierne model also successfully fits to the experimental data giving higher values for interfacial tension of HDPE/EVA system as compared to LDPE/EVA.     

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     

EVA对HDPE光交联反应的影响

采用测定凝胶含量的方法,以二苯甲酮(BP)作为光引发剂、三羟甲基丙烷三丙烯酸酯(TMP-TA)为交联剂,研究了辐照时间、乙烯-醋酸乙酯共聚物(EVA)含量对EVA/HDPE复合材料光交联的影响,并且考察了光交联后EVA/HDPE复合材料的力学性能。研究结果表明,EVA的加入会显著改变体系的凝胶含量;而辐照时间对EVA/HDPE体系交联反应影响很大;体系的力学性能随着EVA含量的增加而变化。     

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     

Mechanical properties of ethylene–vinyl acetate/polystyrene blends studied by in situ polymerization

This study examined ethylene–vinyl acetate (EVA)‐toughened polystyrene (PS). EVA is well‐known to be incompatible with PS; thus, the PS graft to the EVA backbone (EVA‐g‐PS) was used as a compatibilizer and provided good adhesion at the interface of PS and EVA. In addition, the mechanical properties and impact resistance of the PS matrix were obviously improved by EVA‐g‐PS and by EVA itself. Meanwhile, differential scanning calorimetry results showed that the grafted PS chain influenced the crystallization of EVA; for example, the melting temperature, the crystallization temperature, and the percentage crystallinity related to EVA were reduced. Moreover, the addition of 10% EVA increased the impact strength by a factor of five but reduced the modulus by the same factor. Additionally, a lower number‐average molecular weight EVA delayed phase inversion and resulted in poor mechanical properties. A fracture surface photograph revealed that the major mechanism of EVA‐toughened PS was craze and local matrix deformation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 699–705, 2003     

EVA/铕配合物薄膜的制备及光学性能研究

通过溶液浇铸法将四元铕配合物掺杂到乙烯醋酸乙烯酯（EVA）中交联固化得到EVA复合膜,优化了制备EVA膜时固化温度、固化时间和引发剂加入量等工艺条件。通过紫外可见光光谱、荧光光谱研究了EVA复合膜的光学性能。结果表明,配合物在EVA中均匀分散;其掺杂量为1 %时,EVA复合膜具有良好的可见光透过率,对200~400 nm的紫外光有强吸收,并且能够发射出较强的红色荧光。     

Toughening effects of ethylene–vinyl acetate copolymers with different vinyl acetate content and viscosity on nylon 1010 blends

Nylon 1010 blends with ethylene–vinyl acetate copolymer (EVA) and maleated ethylene–vinyl acetate (EVA‐g‐MAH) were prepared through melt blending. The vinyl acetate (VA) content and viscosity of EVA significantly affected the notched impact strength of nylon/EVA/EVA‐g‐MAH (80/15/5) blends. The nylon/EVA/EVA‐g‐MAH blends with high notched impact strength (over 60 kJ/m²) were obtained when the VA content in EVA ranged from 28 to 60 wt%. The effect of VA content on the notched impact strength of blends was related to the glass transition temperature for EVA with high VA content and crystallinity for EVA with low VA content. For nylon blends with EVA with the same VA content, low viscosity of EVA led to high notched impact strength. Fracture morphology of nylon/EVA/EVA‐g‐MAH (80/15/5) blends showed that blends with ductile fracture behavior usually had large matrix plastic deformation, which was the main energy dissipation mechanism. A relationship between the notched impact strength and the morphology of nylon/EVA/EVA‐g‐MAH (80/15/5) blends was well correlated by the interparticle distance model. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers