Blending of Natural Rubber/Recycled Ethylene-Propylene-diene Rubber: Promoting the Interfacial Adhesion Between Phases by Natural Rubber Latex

This article deals with blends based on natural rubber (NR) and recycled ethylene-propylene-diene rubber (R-EPDM). Natural rubber latex (NRL) was introduced into the blends to enhance interfacial adhesion between NR and R-EPDM. A new route of compounding was also suggested. The blends were prepared by mixing R-EPDM and other additives in NRL before blending with natural rubber on a two-roll mill. By applying this method, the homogeneity of the blends and cross-linking distribution are significantly improved. The blends exhibited superior state of cure, swelling resistance, mechanical properties and dynamic mechanical properties. The degree of entanglement between NR and R-EPDM also increased after NRL modification.     

填充粒子对复合型导电硅橡胶电阻温度特性的影响

研究了炭黑填充复合型导电硅橡胶的电阻温度特性,分析了升温过程中导电硅橡胶电阻特性的详细变化过程。研究了导电粒子和白炭黑含量对导电硅橡胶电阻温度特性的影响,测量了在不同热处理温度下电阻率的变化及加力时电阻的驰豫时间。分析了热处理对电阻特性影响的机理。     

Simultaneous Enhancement of Mechanical and Dynamic Mechanical Properties of Natural Rubber/Recycled Ethylene-Propylene-Diene Rubber Blends by Electron Beam Irradiation

Mechanical and dynamic mechanical properties of natural rubber/recycled ethylene-propylene-diene rubber (NR/R-EPDM) blends were simultanoeusly enhanced by electron beam (EB) irradiation. The cross-linking promoter, trimethylolpropane triacrylate (TMPTA), was also introduced into the blends to induce the cross-linking. By applying EB irradiation, the tensile modulus, hardness, swelling, cross-link density, and storage modulus increased with increase in the irradiation dose; an irradiation dose of 50 kGy was efficient to gain optimum tensile strength. The formation of irradiation-induced cross-links after EB irradiation is a major concern for the enhancement of mechanical, swelling resistance, and dynamic mechanical properties of the blends.     

包覆重钙粉为填充剂的橡胶加工及性能

重钙粉作为填充剂被广泛应用于橡胶加工过程,但由于其表面具有极性,分散性较差,导致与橡胶材料界面结合较差,影响了橡胶产品的抗拉强度、断裂伸长率等力学性能。 本文采用沉淀法,在CaCl₂-H₂O-NH₃-CO₂体系中生成碳酸钙直接结晶于重钙粉颗粒表面,实现对重钙粉的表面包覆,将n(CaCl₂)：n(重钙粉)=1：100、5：100、10：100的包覆重钙粉填充到天然橡胶和再生胶中,橡胶的力学性能与填充未包覆重钙粉的橡胶相比有了一定的提升。 通过比较,在填充量较大(8.5%、15%)时,包覆重钙粉橡胶产品在硬度、定伸应力等力学性能上要好于轻钙粉橡胶产品;在填充量(5%、8.5%)时,包覆重钙粉橡胶产品的抗拉强度、断裂伸长率接近于白炭黑,硬度高于白炭黑橡胶产品。     

Preparation of High-Performance Composite Hydrogel Reinforced by Hydrophilic Modified Waste Rubber Powder

In order to reduce the environmental pollution caused by waste rubber and to realize the recycling of resources, we proposed a facile method for the hydrophilic modification of waste rubber powder (HRP) and used it to reinforce a composite hydrogel. In the presence of toluene, dibenzoyl peroxide (BPO) diffused into the waste rubber powder. After the solvent was removed, BPO was adsorbed in the rubber powder, which was used to initiate the grafting polymerization of the acrylamide monomer on the rubber–water interface. As a result, the polyacrylamide (PAM) molecular chains were grafted onto the surface of the rubber powder to realize hydrophilic modification. The success of the grafting modification was confirmed by FTIR, contact angle testing, and thermogravimetric analysis. The hydrophilic modified waste rubber powder was used to reinforce the PAM hydrogel. Mechanical tests showed that the tensile strength and elongation at the break of the composite hydrogel reached 0.46 MPa and 1809%, respectively, which was much higher than those of pure PAM hydrogel. Such a phenomenon indicates that the waste rubber particles had a strengthening effect.     

相容剂对氯丁橡胶/天然橡胶并用胶性能的影响

本研究利用氯化丁基橡胶和腰果酚作为氯丁橡胶(CR)/天然橡胶(NR)并用胶的相容剂,将其按照一定比例在混炼过程中加入得到CR/NR混炼胶.CR/NR混炼胶在160℃下根据最佳硫化时间硫化得到并用胶.通过橡胶加工分析仪(RPA)研究发现腰果酚的加入,降低了CR/NR混炼胶的储能模量并且降低正硫化时间,提高了CR/NR混炼...     

Effect of Manganese on Radiation Vulcanization of Natural Rubber

Manganese was added as a promoter to investigate physico-mechanical properties of radiation-vulcanized natural rubber latex (RVNRL) films. RVNRL films were prepared by the addition of Mn with the concentration range 0–30 ppm to natural rubber latex and irradiated with various radiation doses (0–20 kGy). Tensile strength, tear strength, and cross-linking density of the irradiated rubber films increased with increasing the concentration of Mn ions as well as radiation doses. In contrast, elongation at break, permanent set, and swelling ratio of the films were decreased under the same conditions. The concentration of Mn ions and radiation doses were optimized and found to be 20 ppm and 12 kGy, respectively. The maximum tensile and tear strengths of irradiated rubber films were observed as 29.12 MPa and 44.78 N/mm, respectively at the optimum conditions. The mechanical properties of the films increased markedly with the addition of Mn until they attained the highest values of 33.88 MPa and 54.77 N/mm, respectively. These enhancements, which reached approximately 20% at the most favorable conditions, can be explained by the effect of transition metals in view of Fajan’s rules regarding the covalent character of ionic bonds and suggest that the higher the difference in charges between cation and anion, the higher the ability to form distortion or polarization of ions.     

Properties of Natural Rubber/Recycled Chloroprene Rubber Blend: Effects of Blend Ratio and Matrix

The present study investigated the effects of two types of natural rubber and different blend ratios on the cure, tensile properties and morphology of natural rubber/recycled chloroprene rubber blends. The blends of natural rubber/recycled chloroprene rubber were prepared by using laboratory two-roll mill. The result showed that the cure time prolonged with the addition of recycled chloroprene rubber (rCR). Comparability, natural rubber/recycled chloroprene rubber (SMR L/rCR) blendcured rapidly than epoxidized natural rubber/recycled chloroprene rubber (ENR 50/rCR) blend. The addition of rCRalso caused a decrement in the tensile strength and elongation at break for both rubber blends. The SMR L/rCR blendsshowed higher tensile strength and elongation at break compared to those of ENR 50/rCR blends at any blend ratios.     

Molecular Structures and Mechanical Properties of Microbe Rapid Coagulation Natural Rubber

In this work,molecular structures,dynamic mechanical properties and glass transition temperatures of microbe coagulated natural rubber(NR) samples were analyzed by using pyrolysis gas chromatography-mass spectrometry(py-GC/MS),rubber process analyzer(RPA) and dynamic mechanical thermal analysis(DMA).And the cross-linked network structures and mechanical properties of the corresponding NR vulcanizates were further determined by using nuclear magnetic resonance(NMR) crosslink density spectrometer(XLDS-15) and universal testing machines.The results show that NR raw rubber produced by rapidly coagulated with microorganism exhibits a simple molecular structure composition and good dynamic mechanical properties,and the corresponding NR vulcanizates possess the aggregation structure of high cross-linked density,a high glass transition temperature of-61.5 ℃ and high mechanical properties(tensile strength reaches 25.2 MPa),as compared with that coagulated with acetic acid.     

硅土/白炭黑复合填料对天然橡胶硫化胶性能的影响

硅土主要是由低温石英和粘土矿物组成的非金属矿物,具有独特的粒片叠置结构。本工作采用经改性处理的硅土与白炭黑并用,测定硅土/白炭黑复合填料对天然橡胶(NR)的硫化特性和力学性能,探讨填料并用对天然橡胶性能的影响。实验结果表明:经改性处理,硅土平均粒径减小,疏水性增强。硅土与白炭黑并用,有利于增强NR硫化初期的流动性,延长焦烧时间而不明显降低硫化速率,能改善橡胶的加工性能。拉伸性能测试结果表明,复合填料与白炭黑或硅土单独使用相比,能显著提高填充NR硫化胶的拉伸强度、定伸应力、交联密度,而不降低橡胶弹性。当硅土占复合填料质量为40%时,NR硫化胶的拉伸强度达到最大。动态机械性能测定结果表明,相比白炭黑,硅土更有利于减小硫化胶的生热和滚动阻力。     

亲水性聚硅氧烷改性天然乳胶的性能

以亲水性聚硅氧烷KGF-903共混改性天然乳胶,通过拉力试验、老化试验、接触角测量和扫描电子显微镜等研究了聚硅氧烷的添加量对天然乳胶力学性能、抗老化性能、亲水性能和表面形貌的影响。结果表明,KGF-903含量在1.5%时拉伸强度有最佳的改性效果;KGF-903添加量约为3%时断裂伸长率达到最大,老化前后的断裂伸长率比改性前分别提高57%和50%。随着KGF-903含量的增加,改性天然乳胶片的水接触角逐渐减小;扫描电子显微镜观察的结果表明,添加聚硅氧烷能改变乳胶的分散状态。利用小试的最佳配方(即KGF-903的添加量为1.5%)生产了2批次医用导尿管,其表面光洁度、导尿管球囊的成品率、管身硬度、连接器与导尿管排泄锥形接口所承受的拉力和充气漏斗与引流漏斗连接处所承受的拉力等均有显著的提高,有效改善了产品的质量。     

Mechanical Properties of Silicone Rubber Using Carbosilane Dendrimers as the Cross-linker

Peroxide-cured high-temperature vulcanized （HTV） silicone rubber was prepared by using allyl-capped carbosilane dendrimers, in which the core molecule is Si（CHaCH=CH2）4, as the cross-linker. It showed that this kind of allyl-capped carbosilane dendrimer improved the mechanical properties of silicone rubber.     

橡胶活性官能团对增韧环氧树脂动态力学性能的影响

用动态扭摆法测试聚丙烯酸丁酯橡胶增韧环氧树脂的动态力学行为,研究在环氧树脂低固化度和高固化度时,橡胶活性官能团种类(环氧基官能团与羧基官能团)和数量(官能度)对其影响。研究体系中橡胶玻璃化转变温度(Tg)的移动大小,与橡胶和基体树脂健合程度之间的关系。     

丁苯橡胶/天然橡胶复合体系动态力学性能

生热;动态力学损耗;丁苯橡胶/天然橡胶复合体系动态力学性能