Dynamic Mechanical Properties of Carbon Black Filled Ethylene Vinyl Acetate Rubber

Abstract

The dynamic mechanical properties of ethylene vinyl acetate (EVA) rubber filled with different loadings of carbon black and at different degrees of crosslinking were studied over a wide range of temperatures (-150° to +200°C). The loss tangent (tan δ) versus temperature plots indicated presence of different transitions. The α-transition (or the glass-rubber transition) corresponding to the maximum in tan δ value, occurred at ?17°C, which is the principal glass-transition temperature (abbreviated as T _g) of EVA rubber. The γ-transition occurred in the temperature region of ?125° to ?135°C, while the β-transition appeared as a shoulder in the temperature region of ?65° to ?75°C. Besides, there was also a high tempeature transition around +62°C which is known as liquid to liquid transition (T _1.1). Incorporation of carbon black filler did not cause any shift of T _g, while the tan δ peak values at T _g decreased sequentially with increase in filler loading. The γ- and β-relaxations were found to be insensitive to filler loading. The T _1.1 transition, however, was found to be suppressed by incorporation of carbon black filler particularly at high loading. Extent of crosslinking did not influence the T _g But, the T _1.1 transition, which was prominent with the lightly crosslinked system was found to be suppressed at high level of crosslinking. Strain dependent dynamic mechanical properties under isothermal conditions showed that the secondary structure breakdown of carbon black filler under the effect of strain amplitude is influenced by the degree of crosslinking of EVA rubber.     

EVA增韧聚乳酸的性能研究

对乙烯-醋酸乙烯共聚物(EVA)增韧聚乳酸(PLA)体系的力学、热学和结晶性能进行了研究,并分析了增塑剂邻苯二甲酸二辛酯(DOP)对PLA/EVA增韧体系性能的影响。结果表明,PLA/EVA的质量比为80/20时,二元共混体系的力学性能最佳;PLA/EVA/DOP的质量比为80/20/8时,三元共混体系的力学性能最佳;EVA对PLA的T_g、T_m和结晶度影响不大,但DOP会使T_g和T_m降低,而结晶度得到很大提高;偏光显微镜观察结果也证实了DOP的加入有利于PLA的结晶。     

Miscibility Between Ethylene Vinyl Acetate Copolymers and Tackifier Resins

A series of ethylene vinyl acetate copolymer (EVA) were blended with various kinds of tackifiers and the miscibility between the components was investigated. The miscibility of the blend is illustrated as a phase diagram. The EVA and modified rosin systems tended to have a phase diagram with lower critical solution temperature (LCST), whereas the EVA and petroleum resin systems tended to have that with upper critical solution temperature (UCST). The phase diagrams of EVA/tackifier resins systematically changed as VAc content in the copolymer increased, which is accounted for by the classical Flory-Huggins theory.     

Miscibility Between Ethylene Vinyl Acetate Copolymers and Tackifier Resins

A series of ethylene vinyl acetate copolymer (EVA) were blended with various kinds of tackifiers and the miscibility between the components was investigated. The miscibility of the blend is illustrated as a phase diagram. The EVA and modified rosin systems tended to have a phase diagram with lower critical solution temperature (LCST), whereas the EVA and petroleum resin systems tended to have that with upper critical solution temperature (UCST). The phase diagrams of EVA/tackifier resins systematically changed as VAc content in the copolymer increased, which is accounted for by the classical Flory-Huggins theory.     

Fabrication and Properties of Ethylene Vinyl Acetate-Carbon Nanofiber Nanocomposites

Carbon nanofiber (CNF) is one of the stiffest materials produced commercially, having excellent mechanical, electrical, and thermal properties. The reinforcement of rubbery matrices by CNFs was studied in the case of ethylene vinyl acetate (EVA). The tensile strength was greatly (61%) increased, even for very low fiber content (i.e., 1.0 wt.%). The surface modification of the fiber by high energy electron beam and gamma irradiation led to better dispersion in the rubber matrix. This in turn gave rise to further improvements in mechanical and dynamic mechanical properties of EVA. The thermal conductivity also exhibited improvements from that of the neat elastomer, although thermal stability of the nanocomposites was not significantly altered by the functionalization of CNFs. Various results were well supported by the morphological analysis of the nanocomposites.     

阻燃EVA材料的研制

本文重点研究了ＥＶＡ阻燃配方的设计与应用,在试验的基础上,对几种常见阻燃剂的阻燃效果进行分析对比,选择出最佳阻燃配方,尤其使用新型磷系阻燃剂,不但提高了阻燃效果,而且起到较好的抑烟作用     

PP/EVA色丝力学性能研究(英文)

研究了 PP/EVA中 EVA含量及 EVA中 VA含量对 PP色丝力学性能的影响。结果表明 :当EVA2 1添加量为 0～ 5 .0 % (质量 )时 ,色丝断裂强度及初始模量随所用色母粒种类的不同而呈现不同的变化规律 ,但均有一极大值出现 ,此时 EVA2 1添加量均小于 5 %。在色丝共混体系中 ,初始模量均在EVA2 1添加量为 2 %时出现极值。 EVA中 VA含量 ( 14 %～ 2 8% )对共混色丝力学性能的影响不同 ,当EVA添加量为 2 % ,EVA中 VA含量为 18%时 ,共混色丝有最佳的力学性能。     

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。     

Comparison Properties of Natural Rubber (SMR L)/Ethylene Vinyl Acetate (EVA) Copolymer Blends and Epoxidized Natural Rubber (ENR-50)/Ethylene Vinyl Acetate (EVA) Copolymer Blends

Mixing torque, morphology, tensile properties and swelling studies of natural rubber/ethylene vinyl acetate copolymer blends were studied. Two series of unvulcanized blends, natural rubber/ethylene vinyl acetate (SMRL/EVA) copolymer blend and epoxidized natural rubber (50% epoxidation)/ethylene vinyl acetate (ENR-50/EVA) copolymer blend were prepared. Blends were prepared using a laboratory internal mixer, Haake Rheomix polydrive with rotor speed of 50 rpm at 120°C. Results indicated that mixing torque value and stabilization torque value in ENR-50 blends are lower than SMRL blends. The process efficiency of ENR-50/EVA blends is better due to less viscous nature of the blend compared to SMRL/EVA blends as indicated in stabilization torque graph. Tensile properties like tensile strength, M100 (modulus at 100% elongation) and E _b (elongation at break) increase with increasing EVA fraction in the blend. At the similar blend composition, ENR-50 blend shows better tensile properties than SMRL blends. In oil resistance test, swelling percentage increased with immersion time and rubber composition. At a similar immersion time, ENR-50 blends exhibit better oil resistance compared to SMRL blends. Scanning electron microscopy (SEM) of tensile fractured surface indicated that EVA/ENR-50 blends need higher energy to cause catastrophic failure compared to EVA/SMRL blends. In etched cryogenically fractured surface, size and distribution of holes due to extraction of rubber phase by methyl ethyl ketone (MEK) were studied and holes became bigger as rubber composition increased due to coalescence of rubber particle.     

Exploring the Combined Effect of Electron Beam and Conductive Carbon Black on the Mechanical,Dynamic Mechanical,Thermal, and Electrical Properties of Ethylene Acrylic Elastomer

The electron beam-crosslinked and conductive carbon black-reinforced ethylene acrylic elastomer composites have been developed for various applications. The inter-connectivity of conductive carbon black agglomerates are clearly observed from the high-resolution transmission electron photo micrographs. The tensile strength of the composites has remarkably increased with increasing conductive carbon black loading up to 350 radiation dose. The dielectric permittivity (?′) and AC conductivity (σ_ac) increase with an increase in conductive carbon black loading. The electron magnetic shielding interference of the developed composites has been measured using X-band frequency range, and the electron magnetic shielding interference increases with an increase in conductive carbon black loading.     

A Study on Physical Properties of Melt Blended Acrylonitrile Butadiene Styrene/Ethylene Vinyl Acetate Modified with Linear Low Density Polyethylene and Montmorillonite

In this study, acrylonitrile butadiene styrene/ethylene vinyl acetate-based melt blends were prepared using linear low-density polyethylene as modifier. Commercially available sodium montmorillonite clay was organically modified and incorporated in blends. Fourier transformed infrared was used to confirm the structure of the blend and composites. Morphology of acrylonitrile butadiene styrene / ethylene vinyl acetate blend showed two-phase structure that formed a well-aligned pattern with fine nanoclay distribution. Addition of organo-modified clay depicted increase in tensile strength (43%) and modulus (89%) in damage-free range. XRD results of sodium montmorillonite, organically modified Na-montmorillonite, and PNCs were compared to investigate the degree of dispersion in matrix.     

Preparation of Silane-Grafted and Moisture Crosslinked Low Density Polyethylene. Part II: Electrical,Thermal and Mechanical Properties

Among different polyethylene cross-linking methods, such as peroxide, irradiation, and silane cross-linking, silane-based methods are the most suitable methods for producing cable insulation and hot water pipe materials due to process simplicity and superior properties of its product. Some electrical, thermal and mechanical properties of silane-grafted water-cross-linked polyethylene were investigated. The effects of silane grafting and gel content on volume resistivity, tensile properties and melting behavior of low density polyethylene (LDPE) were studied. Results indicated that volume resistivity increased with increasing gel content. Stress at break increased with increasing grafting level and gel content. Elongation at break increased with grafting and decreased with gel content. High temperature tensile properties showed that cross-linked polyethylene (XLPE) is more stable than LDPE at high temperature. In differential scanning calorimetry (DSC) analysis a broad endothermic peak appeared for XLPE due to phase separation. Melting point and crystalline percentage decreased with increased grafting level and gel content. Incorporation of carbon black into XLPE reduced the volume resistivity and degree of crystallization.     

Long Term Effects of Air Dielectric Barrier Discharge Treatment on the Surface Properties of Ethylene Vinyl Acetate (EVA)

This paper discusses the long term effects of dielectric barrier discharge (DBD) treatment on the surface properties of ethylene vinyl acetate (EVA) film. The EVA surface was characterised using contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and 180° peel tests. EVA subjected to two different treatment times was compared to as-received and solvent cleaned film. The long term stability of the surface modification induced by the DBD treatment was studied over a period of 466 days. On initial application of DBD treatment to the EVA surface an increased wettability was observed, evident from a decreased water contact angle, improved peel strength when bonded, and an increased level of carbon–oxygen moieties measured using XPS. However, over the storage period of 466 days the material reverted to almost its original state with the contact angle being only ～3° lower than that of as-received EVA compared to a difference ～25° directly after treatment. AFM measurements showed that the treatment had a slight smoothing effect on the surface topography.     

Preparation and Properties of Ethylene Vinyl Acetate (EVA)/Organoclay/Compatibilizer Nanocomposites: Effects of Organoclay Loading and Methyl Ethyl Ketone

Ethylene vinyl acetate (EVA)/organoclay/compatibilizer nanocomposites were produced using a melt compounding technique in an internal mixer, Haake Rheometer, at 120°C and 50 rpm rotor speed. Effects of organoclay loading (from 2 to 10 phr—parts per hundred of resin and methyl ethyl ketone (MEK), used as a compatibilizer, on the processing properties, tensile properties, morphology, thermal degradation, and water absorption behavior of EVA/organoclay nanocomposites were studied. Results indicate that the presence of organoclay increase the processing torque, tensile properties, thermal degradation, and resistance to water absorption. The optimum organoclay loading was achieved at 2 phr. This was caused by the dispersion state of individual silicate layers (intercalation/exfoliation) in EVA matrix. The intercalation/exfoliation structure affects the properties of EVA/organoclay nanocomposites as evidenced from the morphology studies such as x-ray diffraction (XRD) and transmission electron microscopy (TEM) evaluation. The addition of MEK has the ability to improve the tensile properties, thermal degradation, and slightly reduces the resistance of water permeation of EVA/organoclay nanocomposites. The enhanced properties were seen as a result of the better matrix and filler interaction. The EVA/organoclay/MEK nanocomposites shows better intercalation/exfoliation of individual silicate layers in the EVA matrix as indicated by TEM. Moreover, the XRD evaluation shows that intercalation/exfoliation of the organoclay was formed in the EVA matrix.     

电子束辐照和氢氧化铝对LLDPE/EVA共混物凝胶含量和力学性能的影响

研究了电子束辐照剂量和氢氧化铝(ATH)的含量对线性低密度聚乙烯(LLDPE)/乙烯-醋酸乙烯酯(EVA)共混物凝胶含量和力学性能的影响。辐照剂量是影响LLDPE/EVA/ATH阻燃体系凝胶含量的主要因素,而ATH对其凝胶含量的影响较小。随着ATH含量的增加,LLDPE/EVA共混物的拉伸强度逐步增加,断裂伸长率迅速下降。所有阻燃体系的拉伸强度均是随着辐照剂量的增加而逐步增大,但辐照剂量对这些阻燃体系的断裂伸长率的影响却比较复杂。     

Investigation into Paraffin Wax and Ethylene Vinyl Acetate Blends for Use as a Carrier Vehicle in Ceramic Injection Molding

An experimental study into paraffin wax and ethylene vinyl acetate-28 blends has been undertaken to investigate the potential for their use as carrier vehicles for ceramic injection molding applications. Carrier systems are critical for the fabrication of this type of molded component, making their properties at all stages of the process of great importance. Paraffin wax and ethylene vinyl acetate-28, in most circumstances, combine to form stable homogeneous blends, which experience relatively small changes in the melting and solidification phase transition behavior. However, these blends exhibit notable viscosity shifts and flexural strength performance changes with increasing ethylene vinyl acetate-28 content. The melt flow behavior of the blends at shear rates of 100 s^?1 varies from 0.01 Pa.s for paraffin wax to 10 Pa.s for the composition by weight of 50% paraffin wax and 50% ethylene vinyl acetate-28, which suggests the upper viscosity limit for successful carrier systems. All paraffin wax/ethylene vinyl acetate-28 blends experience shear thinning behavior with increasing shear rate, which can be modeled with reasonable accuracy using the Cross and Carreau models. Increasing the ethylene vinyl acetate-28 content in a blend causes the initiation of shear thinning at progressively lower shear rates and also forms a blend with an increasing elastic character at typical injection temperature. Yield stress is not developed for blends containing less than 50 wt% ethylene vinyl acetate-28. The addition of ethylene vinyl acetate-28 significantly alters the mechanical properties of the blends, modifying the brittle nature of paraffin wax to develop increasing flexible and plastic properties. Although with less than 25 wt% ethylene vinyl acetate-28 in a blend fracture failure still results, greater ethylene vinyl acetate-28 content represses the failure mechanisms, developing the increasing degrees of plastic deformation.     

Thermoplastic Elastomer Composites of Palm Ash-Filled Ethylene Vinyl Acetate/Natural Rubber Blends: Effects of Palm Ash Loading and Size

Thermoplastic elastomer composites of ethylene vinyl acetate (EVA)/natural rubber (NR) blends filled with palm ash were prepared by melt-mixing using a Haake Rheomix Polydrive R600/610 at 120°C with rotor speed of 50 rpm for 10 minutes. Increase in palm ash loading in composites resulted in increase the value of stabilization toque, Young's modulus and swelling resistance of the composites, but decreased the tensile strength and elongation at break. Scanning electron microscope micrographs revealed that higher filler loading resulted in agglomeration of palm ash in the composites. When smaller particle size of palm ash was used, further improvement in tensile strength, elongation at break, swelling resistance and stabilization torque value were observed.     

Influence of Electron Beam Irradiation on High‐Temperature Mechanical Properties of Ethylene Vinyl Acetate/Carbon Fibers Composites

The purpose of this study was to investigate the effect of carbon fiber (CF) and electron‐beam (EB) radiation on high‐temperature mechanical properties of ethylene‐vinyl acetate (EVA). Polymer composites were prepared by mixing on a two‐roll mill. After compression molding, the samples were irradiated between 60 and 180 kGy, and dynamic mechanical analysis (DMA) was used to characterize physical properties. The effects of filler content and radiation level on the mechanical properties of EVA/CF were evaluated. The shear stress and modulus were observed to increase with increasing of the filler level. However, there was a dramatic decrease in creep compliance. It was also shown that introduction of irradiation on EVA composite increases the shear stress and the real part of the dynamic shear modulus G' due to the increase in molecular weight and cross‐linking of the polymer after irradiation. J. VINYL ADDIT. TECHNOL., 26:325–335, 2020. © 2019 Society of Plastics Engineers     

Preparation of Ethylene Vinyl Acetate Copolymer/Graphene Oxide Nanocomposite Films via Solution Casting Method and Determination of the Mechanical Properties

Ethylene vinyl acetate/graphene oxide (EVA/GO) nanocomposite films were prepared via solution casting method. The morphological studies investigated using SEM and XRD methods and the results confirmed the formation of likely exfoliation structures and good interaction between matrix and fillers. The results of permeability measurements showed that films have good resistance against oxygen. Mechanical measurements revealed that Young’s modulus and tensile strength of EVA have improved with introducing GO because of proper dispersion of GO into matrix and good interaction between them; however, elongation at break decreased due to formation of strong and rigid polymer/filler network preventing to elongate polymer chains.     

Characterization,Thermal, and Mechanical Behaviours of Gamma Irradiated Gum Arabic/Poly Vinyl Alcohol Polymer Blends

Polymer blends based on various compositions of natural macromolecule gum arabic (GA) and poly vinyl alcohol (PVA) were prepared by solution casting technique. It was found that the maximum concentration of gum from which a compatible blend can be obtained was found to be from 10–30%. Compatible blend were exposed to gamma irradiation at different doses of 20, 30, and 50 kGy to evaluate the effect of irradiation on different properties of the blend. Physical, thermal and mechanical properties of the blend were investigated. Also, structural properties in terms of scanning electron microscope (SEM) were studied. The Results obtained show a decrease in glass transition temperature of the blend with increasing GA content. Moreover, there is an improvement in mechanical properties in terms of stress-strain behavior.