Polyvinyl Acetate and Vinyl Acetate-Ethylene Hybrid Adhesive: Synthesis, Characterization, and Properties

The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were effectively synthesized. Emulsions with various characteristics have been developed by adjusting the weight ratios between the vinyl acetate monomer and the VAE component. The impacts on the mechanical, thermal, and physical properties of the films were investigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and viscosity. When 5.0 weight percent VAE was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid PVAc emulsion as primary bonds does not directly attach to PVAc and VAE chains. The addition of VAE reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that PVAc adhesives containing VAE had increased water resistance when compared to conventional PVA stabilised PVAc homopolymer-based adhesives. When compared to virgin PVAc Homo, the water resistance of the PVAc emulsion polymerization was enhanced by the addition of VAE.

Sound Absorption Properties of Discarded Feathers/Ethylene Vinyl Acetate Copolymer Thermoplastic Composite Materials

The discarded feathers / ethylene vinyl acetate copolymer( EVA) thermoplastic composite materials was obtained with discarded feathers as reinforced material and EVA powders as matrix material by hot pressing method. Sound absorption properties were studied by changing mass ratio of discarded feathers and EVA,thickness of composite materials,hot pressing pressure and hot pressing temperature. It was found that the sound absorption properties of composite materials were good when the mass ratio of discarded feathers and EVA was 1: 1,thickness of composite materials was 30 mm,hot pressing pressure was 8 MPa,and hot pressing temperature was 80 ℃. Under the optimum conditions,the effect of composite density on sound absorption property was analyzed. In a certain range,the sound absorption property was enhanced with the decrease of the composite density.When the composite density was 0. 1g /cm^3, the maximum absorption coefficient was 0.96. Finally,the capillary theory was used to calculate the maximum sound absorption coefficient of discarded feathers / EVA thermoplastic composite materials. The good agreements of experimental results and calculated results proved the validity of the theoretical models.

Effect of ethylene vinyl acetate content on the performance of VMD using HDPE co-blending membrane

Membranes were fabricated with high-density polyethylene (HDPE) and ethylene vinyl acetate (EVA) blend through thermally induced phase separation and were then used for vacuum membrane distillation (VMD). The membranes were supported by non woven polyester fabric with a special cellular structure. Different membrane samples were obtained by adjusting the polymer concentration, HDPE/EVA weight ratio, and coagulation bath temperature. The membranes were characterized by scanning electron microscopy (SEM) analysis, contact angle test, and evaluation of porosity and pore size distribution. A series of VMD tests were conducted using aqueous NaCI solution (0.5 mol·L^-1) at a feed temperature of 65 ℃ and permeate side absolute pressure of 3 kPa. The membranes showed excellent performance in water permeation flux, salt rejection, and long-term sta-bility. The HDPE/EVA co-blending membranes exhibited the largest permeation flux of 23.87 kg·m^-2·h^-1, and benign salt rejection of ≥99.9%.

Regulating the Localization of Intumescent Flame Retardant for Improving the Flame Retardancy of Ethylene-vinyl Acetate Copolymer Using Polyamide 6 as a Charring Agent

Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT)showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy.Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend withthe localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix,a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8%to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36%decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy.

Sensing Property of Carbon Nanotube Yarn Embedded in Ethylene Vinyl Acetate (EVA) Elastomer

Carbon nanotube (CNT) has remarkable piezoresistive properties,which makes its extremely sensitive to the mechanical force. In this study,the CNT yarn with the strength of 90 MPa and the strain sensing gage factor of 1.75 was selected and embedded into the ethylene vinyl acetate (EVA) elastomer as a sensing material.By measuring the electric resistance changing under the stretching,bending,longitudinally and transversely compressing of the CNT embedded EVA, the resistance changing curves and their linear correlations were obtained and analyzed. The result shows that the gage factor under the tensile test is the highest( 2.51),which is higher than the original value of CNT yarn (1.75). The gage factors of the CNT yarn embedded into EVA elastomer under bending and longitudinal and transverse compression are 2.29,1.55 and 0.79,respectively.

Effects of Nano-Filler on the Thermal and Fire-Resistant Properties of Ethylene-Vinyl Acetate Copolymer

Sepiolite （S9, B10, B20, B40） and boehmite have been added to an intumecent flame retardant （IFR） system to produce the halogen-free and fire-resistant ethylene-vinyl acetate copolymer （EVM） rubber. The rubber contains ammonium polyphosphate （APP） as acid source, double pentaerythritol （D-PER） as carbon source and melamine （MN） as gas source. The effects of nano-filler sepiolite and boehmite on the fire-resistant property of EVM rubber based on IFR system were investigated. The test results show that the system with nano-filler of sepiolite B10 has the best fire-resistant property. The process of smoke emission and thermal decomposition, the element composition of char surface and the micro morphology of intumecent char layer of the EVM IFR system with nano-filler were also studied by NBS chamber, thermogravimetric （TG） analysis, X- ray photoelectron spectroscopy （XPS） and scanning electron microscope （SEM）.

Difference in Surface Roughness of Ethylene-Vinyl-Acetate Sheet before and after Application of Finishing Liquid

Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. Therefore, finish polishing is extremely important. The aim of this study was to investigate the difference in the surface roughness after finishing polishing of ethylene-vinyl-acetate (EVA) sheets and after application of the finishing liquid, and to evaluate its effectiveness. Total of 48 specimens of EVA (3 × 3 mm) were divided into 4 groups according to polishing condition (control = unpolished;condition A = Robinson-brush;condition B = Lisko-Fine, and condition C = Mouthguard-wheel). Polishing was performed at low speed by using a straight headpiece. The rotation speeds were 5000, 4000 and 6000 rpm for condition A, B, and C, respectively. Next, a finishing liquid was applied to each specimen. For application, a cotton swab was used, and it was applied by three reciprocations. A non-contact surface shape measuring machine was used for measuring surface roughness;the measurement range is 1.65 mm and the resolution is 0.01 nm. The arithmetic average height (Sa) was measured. The differences in the surface roughness before and 15 min after the application of the finishing liquid were analyzed by two-way analysis of variance and Bonferroni’s multiple comparison tests. Surface roughness of the specimen before application became coarse in the order of control, condition C, B and A, and Sa was about 0.20, 1.98, 2.92, and 4.71 μm, respectively. The degree of reduction in roughness was about 1.0 μm or more than each polished state in conditions A and B. Condition C was not significantly different before and after application. No significant difference was observed between condition B and C after application. The results of this study showed that the surface roughness decreased due to the application of the finishing liquid when the surface roughness after finish polishing was about 2.0 μm or more.

Difference in Surface Roughness of Ethylene-Vinyl-Acetate Sheet before and after Application of Finishing Liquid: Part 2 Changes over Time in Surface Roughness

Surface texture of the mouthguard affects the sense of adaptation in the athlete and further affects hygiene. The aim of this study was to investigate the changes over time in surface roughness after finish polishing of ethylene vinyl acetate (EVA) sheets and before and after finishing liquid application, and to evaluate its effectiveness. Total of 160 specimens of EVA (3 × 3 mm) were divided into 4 groups according to polishing condition (control = unpolished;RB = Robinson-brush;LF = Lisko-Fine, and MW = Mouthguard-wheel). Polishing was performed at low speed by using a straight headpiece. The rotation speed was 5000, 4000 and 6000 rpm for RB, LF, and MW, respectively. Next, a finishing liquid was applied to each specimen. Changes over time in surface roughness before and after application of the finishing liquid were compared by a non-contact surface shape measuring machine. The arithmetic average height (Sa) was measured. The measurement time points were before application, immediately after application, and at 5, 10, and 15 min after application. The changes over time of the surface roughness of the sheet before and after application of the finishing liquid were analyzed by two-way analysis of variance and Bonferroni’s multiple comparison tests. Surface roughness of the specimen before application became coarse in the order of control;MW, LF and RB, and Sa were about 0.21 μm, 2.03 μm, 2.94 μm, and 4.72 μm, respectively. That showed the same order after finishing liquid application. Significant decrease in Sa for RB and LF were seen at 10 min after application and at 5 min after application, respectively. Sa of MW was not significantly different before and after application. The results of this study showed that a lubricity of about 1.0 μm increases within 5 - 10 min of application of finishing liquid, but in cases where polishing was performed to about 2.0 μm;the application of finishing liquid has no ef-fect.

Steady State Simulation of a Novel Process for the Co-production of Vinyl Acetate and Acetic Acid

A new process for the co-production of vinyl acetate monomer and acetic acid from ethane feedstock was studied. Various configurations were proposed and simulation results were given for each case to optimize process variables. This new process offers an overall yield values above 70% with minimum separation steps involved and the possibility of utilities integration. The process does not involve any CO production, thus becoming environmentally more favorable. The initial capital investment of the proposed process is much lower compared to the conventional route.

高乙烯含量VAE乳液的研究与生产

以聚乙烯醇(PVA1788、PVA0588)复配做保护胶体,醋酸乙烯酯及乙烯为单体,采用氧化还原法制备不同乙烯含量的VAE乳液。研究原料、聚合工艺和反应条件及加料方式对VAE乳液乙烯含量、固含量、粘度、玻璃化转变温度和相对分子质量的影响,考查改性PVA对VAE乳液耐水性能的影响。结果表明,最佳初始反应温度为65℃,后期温度为70℃~85℃,最佳乳化剂含量为4%,最佳引发剂用量为2.5%,VAE乳液的乙烯含量为9%~23%,使用疏水基改性PVA代替部分保护胶体,乳液耐水性明显提高。

NON-ISOTHERMAL CRYSTALLIZATION OF ETHYLENE-VINYL ACETATE COPOLYMER CONTAINING A HIGH WEIGHT FRACTION OF GRAPHENE NANOSHEETS AND CARBON NANOTUBES

The effect of the different geometrical dimensionality of two dimensional graphene nanosheets （2D GNSs） and one dimensional carbon nanotubes （1D CNTs） on the non-isothermal crystallization of an ethylene-vinyl acetate （EVA） copolymer at high loading （5 wt%） was studied. Transmission electron microscopy indicated a homogeneous dispersion of GNSs and CNTs in EVA obtained by a solution dispersion process. Fourier-transform infrared spectroscopy and differential scanning calorimetry measurements showed that 1D CNTs and 2D GNSs acted as effective nucleating agents, with a noticeably increased onset crystallization temperature of EVA. A high weight fraction of nano-fillers slowed the overall crystallization rate of composites. At the same crystallization temperatute, the crystallization behavior of GNS/EVA composites was slowed compared to that of the CNT/EVA ones owing to larger nucleus barrier and activation energy of diffusion. Dynamic mechanical relaxation and rheology behavior of CNT/EVA and GNS/EVA composites demonstrated that the planar structure of the GNSs had an intensively negative effect on EVA chain mobility due to interactions between nano- fillers and polymer chains, as well as spatial restriction.

VAE乳液胶粘剂的应用发展

简单介绍了VAE(醋酸乙烯-乙烯共聚物)的种类以及国内VAE乳液胶粘剂的品种,重点探讨了VAE乳液胶粘剂的传统工艺流程以及改进工艺流程。总结了共混、共聚、交联和转向乳化改性VAE乳液胶粘剂的优缺点及其应用范围。最后展望了国内VAE乳液胶粘剂的发展方向。

VAE改性水泥砂浆微观结构及性能研究

以醋酸乙烯-乙烯共聚物(VAE)、水泥、石英砂等材料,制备出一种混凝土路面修复用聚合物改性水泥砂浆,研究了VAE掺量对水泥砂浆流动度、强度、干缩、抗碳化特性及界面粘附性的影响,并采用扫描电镜(SEM)观测其微观结构。结果表明,抗折强度、界面粘结强度随VAE掺量的增加先增加后降低,表明VAE可以提高水泥砂浆的柔韧性、界面粘结强度;随着VAE掺量的增加,1 h流动度损失率、干缩率、碳化深度逐渐降低,表明VAE可以改善水泥砂浆的保水能力、干缩率、抗碳化侵蚀能力;SEM测试结果显示,聚合物胶膜填充于砂浆内部的有害孔隙,裹附于水化产物表面,提高了砂浆的密实程度。综合考虑水泥砂浆物理力学及经济性能,推荐VAE作为改性聚合物的合理掺量为胶凝材料用量的8%。

VAE/增粘剂共混胶对PP──纸的粘接及粘合机理的探讨

讨论了以VAE为主基材料的胶粘剂对PP—纸的粘接中，增粘剂的加入量对剥离强度的影响．并通过接触角的测量、表面张力和界面张力的计算，探讨了胶粘剂与PP之间的粘合机理，表明了胶粘剂与被粘材料之间的界面张力是影响粘接强度的重要因素．

PVAc/VAE共混乳液与聚烯烃界面行为的研究

通过接触角的测量及表面和界面张力的计算 ,对PVAc/VAE共混乳液与聚烯烃的界面行为进行了研究 。

改性MMT/VAE纳米复合水性阻隔涂层的制备及性能研究

以γ缩水甘油醚氧丙基三甲氧基硅烷(KH560)为改性剂对蒙脱土(MMT)表面改性,随后将其与乙烯醋酸乙烯酯共聚乳液(VAE)进行复合制备了MMT/VAE纳米复合阻隔涂层。采用傅里叶红外光谱分析仪与X射线衍射对KH560改性前后的MMT进行了表征,通过场发射扫描电子显微镜、X射线衍射分析、热失重分析、差示扫描量热仪、水蒸气与氧气透过率、拉伸性能对阻隔涂层的结构、热稳定性、阻隔性能及力学性能进行了测试。结果表明,KH560成功接枝在MMT表面,并对MMT进行了插层,插层后MMT的层间距由1.210nm扩大至1.447nm;表面改性后的MMT在VAE基体中呈均匀的片状分布,MMT的层间距扩大至2.758nm;随着MMT含量的增加,MMT/VAE的热稳定性也随之提高;当复合涂料中MMT含量为50%(质量分数,下同)时,涂布了MMT/VAE纳米复合涂层的聚对苯二甲酸乙二醇酯(PET)薄膜的水蒸气透过率和氧气透过率比纯PET薄膜分别下降了81.79%和95.3%,屈服强度增加了52.68%;当复合涂料中MMT含量为30%时,弹性模量增加了74.16%。

VAE改性乳化沥青及其性能研究

针对普通乳化沥青冷再生混合料水稳定性与温度稳定性较差的问题,文章提出醋酸乙烯-乙烯(vinyl acetate-ethylene,VAE)水性胶改性乳化沥青;通过改性乳化沥青在集料表面的剥落率、蒸发残留后的沥青技术指标优选出VAE改性剂的种类为DA-1410胶粉;采用动态剪切流变仪(dynamic shear rheometer,DSR)试验及荧光显微镜试验,测试VAE质量分数(简称“掺量”)对改性乳化沥青蒸发残留物性能的影响。结果表明:随着VAE掺量增加,改性乳化沥青蒸发残留物的三大指标、沥青标准黏度及沥青在集料表面的剥落率都显著提高;复数剪切模量G*和车辙因子G*/sinδ逐渐增大;当VAE掺量为3%~4%时,沥青的各项性能指标都优异,且其固化物颗粒在沥青中均匀分布,形成紧密结合的交联结构,乳化沥青的性能得到改善。研究结果可为拓展冷再生技术及其应用提供参考。

共混改性VAE乳液性质分析及其胶黏剂性质研究

通过共混法将VAE乳液(醋酸乙烯-乙烯共聚乳液)与PVA、甲苯、松香树脂、萜烯树脂、邻苯二甲酸二丁酯进行混溶,制备了一系列基础性能不同的VAE胶黏剂基础母液。采用电子万能试验机、傅里叶变换红外光谱仪、热重分析仪等分析手段对该母液得到的胶膜进行表征。利用正交设计考察了影响胶黏剂胶膜的机械性能。结果表明:以胶膜的剥离强度为评价指标时,最佳工艺条件为PVA质量分数6%,甲苯溶液质量分数4%以及邻苯二甲酸二丁酯质量分数3%。此时,胶膜的剥离强度最大,为(2.123±0.128)kN/m,同时,胶膜的拉伸强度为(6.732±0.159)MPa,断裂伸长率为(123.334±0.968)%。

纳米SiO_(2)与VAE复合改性水泥基材料的耐久性能

研究了单掺乙烯-醋酸乙烯酯共聚乳胶粉(VAE)和复掺VAE/纳米SiO_(2)(NS)对水泥基材料抗氯离子渗透性能、抗硫酸盐侵蚀性能和吸水率的影响,并通过X射线衍射仪、热分析仪、扫描电子显微镜、压汞仪和红外光谱仪等探究了其作用机理.结果表明:单掺VAE和复掺VAE/NS均可提高材料的抗氯离子渗透性能以及抗硫酸盐侵蚀性能,降低其总吸水率,且复掺效果优于单掺;单掺VAE可以改善材料的水化特性,有害孔和多害孔减少了65.3%,但增大了最可几孔径和界面过渡区的钙硅比;复掺VAE/NS可进一步改善材料的水化特性,有害孔和多害孔减少了82.6%,提高了水化硅酸钙(C-S-H)的生成量和聚合度,增强了材料的耐久性能.

绿色环保型VAE微乳液生产工艺设计

依托广西广维化工有限责任公司现有的VAE乳液生产线,以D-异抗坏血酸钠替代甲醛次硫酸锌,作为氧化还原引发体系中的还原剂,对新增一套年产3万t绿色环保型VAE微乳液生产车间进行工艺设计、物料衡算、热量衡算、主要设备计算以及生产过程三废处理。设计结果表明,采用间歇法制备VAE微乳液,需每釜生产VAE微乳液16.67t,每釜消耗醋酸乙烯5.84t,乙烯0.98t。聚合釜选用磁力搅拌高压釜,体积为30.97 m3,直径为3.0 m,总高为4.27 m,壁厚为50 mm,材料为0Cr18Ni9Ti。