A study of the influence of a new promoter on the adhesion of rubber to a metal cord

A promoter of adhesion of a rubber to a metal cord based on precipitated silica modified by cobalt was developed. The analysis of its qualitative and quantitative composition was carried out. The effect of the obtained compounds on the technological and physico-mechanical properties of filled elastomeric compositions based on synthetic polyisoprene rubber and on the properties of metal cord–rubber systems was studied. It was shown that application of modified precipitated silica allows both making elastomeric compositions cheaper and improving their adhesive properties.     

硼酰化钴在橡胶与镀锌钢丝粘合中的应用研究

研究硼酰化钴的用量变化对丁苯橡胶／天然橡胶与镀锌钢丝粘合的影响,通过表面分析对其粘合机理进行了研究。研究表明：硼酰化钴对丁苯橡胶／天然橡胶与镀锌钢丝粘合的粘合增强作用十分明显。硼酰化钴添加2phr左右,粘合性能最佳,同时硫化胶的物理性能得到改善。X-射线光电子能谱分析表明,粘合物镀锌钢丝界面中存在ZnO、ZnS、CoS2,说明粘合时发生了Zn的硫化反应,硼酰化钴中的钴向钢丝表面迁移,继而在锌层中扩散,提高了ZnO和ZnS晶格的缺陷浓度,这两种行为的共同作用,使橡胶与镀锌钢丝的粘合强度显著提高。     

Synthesis and Application of Epoxidized Natural Rubber

Abstract

North Vietnamese NR latexes were successfully epoxidized using peracetic acid at moderate temperature and pH range. The epoxide contents of pure epoxidized natural rubber (ENR) are from 5 to 70 mol%. The ENR products were characterized and determined by spectral and thermal analysis besides the chemical titration. Conditions of longlasting or excessive temperature, or high acidic pH led to side ring opened products, proved easily by IR, ¹H-NMR, and DSC analysis. The ENR were vulcanized using a semiefficient system. The epoxidation increased the adhesion between rubber and tire cord and metal. This effect becomes stronger beyond 25 mol% and tends to be limited at over 60 mol%. The ENRs were used to formulate special-purpose adhesives. The shear strength of the adhesive ranges from 32 to 45 kg/cm² for bonding rubber to nylon and rubber to metal, respectively.     

Adhesive properties of rubbers with promoters based on modified silica filler

The influence of new adhesion promoters on the strength of bonding between unfilled rubber materials based on synthetic isoprene rubber SKI-3 and a brass-plated metal cord was studied. The synthesized adhesion promoters are silica fillers modified with cobalt, nickel, or a combination of cobalt and nickel, and they contain on their surface a lower number of ions of metals with variable valency compared to industrial cobalt stearate. It was shown that, among the synthesized adhesion promoters, silica fillers modified with cobalt are the most promising.     

Physicomechanical properties of nanocomposites based on cellulose nanofibre and natural rubber latex

Cellulose nanofibres (CNF) with diameter 10–60 nm were isolated from raw banana fibres by steam explosion process. These CNF were used as reinforcing elements in natural rubber (NR) latex along with cross linking agents to prepare nanocomposite films. The effect of CNF loading on the mechanical and dynamic mechanical (DMA) properties of NR/CNF nanocomposite was studied. The morphological, crystallographic and spectroscopic changes were also analyzed. Significant improvement of Young’s modulus and tensile strength was observed as a result of addition of CNF to the rubber matrix especially at higher CNF loading. DMA showed a change in the storage modulus of the rubber matrix upon addition of CNF which proves the reinforcing effect of CNF in the NR latex. A mechanism is suggested for the introduction of the Zn–cellulose complex and its three dimensional network as a result of the reaction between the cellulose and the Zinc metal which is originated during the composite formation.     

Role of Divalent Metals in Polymer Degradation

The role of divalent metals in the degradation of the physico-mechanical properties of radiation-vulcanized natural rubber latex (RVNRL) films was investigated. RVNRL films were prepared by the addition of metals (Cu, Mg, etc.) of different concentrations (0–30ppm) to natural rubber latex and irradiated with various radiation doses (0–20kGy). The radiation doses were optimized (12kGy), and the adverse effect of metal ions was studied against a reference film prepared with no metal ions. Tensile strength, tear strength, and cross-linking density of the irradiated rubber films decreased with increasing metal ion concentrations and decreasing radiation doses. The mechanical properties of the films were reduced by 10–15% for 30ppm metal ions and at the optimum dose. In contrast, elongation at break, permanent set, and swelling ratio of the films increased at the same conditions. The relative effect of metal ions can be explained by the classical electron concept, reported in this article.     

Adhesion of fluorinated polyester cord to rubber

Surface fluorination of polyester cord increases adhesion of the cord to rubber fivefold. Fluorinated polyester fabric retains the high tensile strength necessary for efficient reinforcement of rubber tires.     

Investigation of polymer degradation by addition of magnesium

The effect of alkali metal magnesium on polymer degradation of physico-mechanical properties of radiation-vulcanized natural rubber latex (RVNRL) films was investigated. RVNRL films were prepared by the addition of Mg of different concentrations (0–30 ppm) to natural rubber latex and irradiation with various radiation doses (0–20 kGy). The radiation doses were optimized (12 kGy), and the adverse effect of Mg was studied against a reference film prepared without metal. Tensile strength, tear strength, and cross-linking density of the irradiated rubber films were decreased with increasing metal ion concentrations and decreasing radiation doses. The mechanical properties of the films were reduced by nearly 10% for 30 ppm Mg ions and at the optimum dose. In contrast, elongation at break, permanent set, and swelling ratio of the films were increased at the same conditions. The maximum tensile and tear strengths of irradiated rubber films without additive were 29.33 MPa and 47.95 N/mm, respectively, at a radiation dose of 12 kGy, and these values were about six times higher than those of blank samples. With the addition of Mg, the corresponding values decrease continuously, and the minimum values were found to be 26.35 MPa and 42.675 N/mm, respectively. The effect of divalent alkali metal on polymer chain scission can be explained by the classical electron concept reported in this article.     

Addition of Transition Metals to Improve Physico-Mechanical Properties of Radiation-Vulcanized Natural Rubber Latex Films

The effect of transition metals as a promoter of physico-mechanical properties of radiation-vulcanized natural rubber latex (RVNRL) films was investigated. RVNRL films were prepared by the addition of transition metals (Fe, Mn, etc.) of different concentrations (0–30 ppm) in natural rubber (NR) latex and irradiated with various radiation doses (0–20 kGy). The concentrations of metal ions and radiation doses were optimized and found to be 20 ppm and 12 kGy, respectively. Tensile strength, tear strength, and cross-linking density of the irradiated rubber films were increased with increasing concentration of metal ions as well as radiation doses. The mechanical properties of the films were enhanced by approximately 20% at the optimum conditions. In contrast, elongation at break, permanent set, and swelling ratio of the films were decreased under the same conditions. The comparative effect of metal ions can be explained by Fajan's rules, reported in this article.     

Investigation on effects of dynamic fatigue frequency,temperature and number of cycles on the adhesion of rubber to steel cord by a new testing technique

The effects of dynamic fatigue frequency, temperature and number of cycles on the adhesion of rubber to steel cord in a carcass recipe were examined. A new test method with special rubber/steel cord specimens was developed for the dynamic fatigue measurements which were carried out on a De Mattia Rubber Flexometer. It was found that the dynamic “pull-out forces” decreased with increase of fatigue frequency, but first increased and then decreased with increasing temperature and the number of fatigue cycles. The adhesion failure mainly occurred in the rubber phase rather than at the rubber/steel cord interface. The covered rubber on the “pulled-out” cord after fatigue appeared to form a screw thread and the greater pull-out force corresponded to more uniform and clearer screw threads in the rubber remaining on the cord. Steel cord with an outer wrapping wire had greater static adhesion force and better adhesion after fatigue; the adhesion failure mainly occurred in the rubber phase but some occurred at the contact point of the outer wrapping wire and the wrapped main steel wires. The screw threads of rubber coverage appeared along the twist direction of the outer wrapping wire. SEM indicated that un-dispersed filler agglomerates may initiate adhesion failure.     

MODIFICATION OF CeO2 AND ITS EFFECT ON THE HEAT-RESISTANCE OF SILICONE RUBBER

By means of the wet chemical surface modification,the surface of CeO_2 was modified by vinyltrimethoxysilane (VTMS).Infrared spectroscopy was used to investigate the structure of the modified CeO_2 and the result showed that VTMS has been attached onto the surface of CeO_2.Effect of VTMS concentration on the active index of the modified CeO_2 was also studied,and the result indicated that the active index of the modified CeO_2 increases with the increase of VTMS concentration and the optimal concentratio...     

EB-promoted recycling of waste tire rubber with polyolefins

Despite the fact that more and more methods and solutions are used in the recycling of polymers, there are still some problems, especially in the recycling of cross-linked materials such as rubber. Usually the biggest problem is the lack of compatibility between the cross-linked rubber and the thermoplastic matrix. In this study we applied ground tire rubber (GTR) as recycled material. The GTR was embedded into polyethylene (PE) and polyethylene/ethylene-vinyl acetate copolymer (PE/EVA) matrices. In order to increase the compatibility of the components electron beam (EB) irradiation was applied. The results showed that the irradiation has a beneficial effect on the polymer–GTR interfacial connection. The EB treatment increased not only the tensile strength but also the elongation at break. The irradiation had also positive effect on the impact strength properties.     

质子辐照对有机硅树脂增强甲基硅橡胶的性能损伤及机理

硅橡胶具有优良的电绝缘性以及耐高低温、耐电晕、耐化学腐蚀、耐大气老化、耐臭氧和耐辐射等性能，近年来在航天领域得到了广泛应用．在宇宙空间的带电粒子如质子、电子等的辐照作用下，硅橡胶会发生性能退化，其质损率上升，产生析气现象，从而直接影响航天器的可靠性和寿命．自80年代以来，人们就对不同辐照源及不同粒子注量对硅橡胶材料的影响进行了研究，但直到近几年才将研究热点转向辐照场中硅橡胶的性能退化及微观结构的演变规律，其辐照环境大多集中于γ射线、Si^＋和F^＋离子、He^2＋离子等．对于空间环境下带电粒子辐照对硅橡胶材料的影响，国外由于相应的研究工作保密性强，报道甚少；国内哈尔滨工业大学则对我国自行研制的白炭黑增强空间级甲基硅橡胶质子辐照作用后的性能与微观结构的变化做了较为深入的研究。     

剥离型硅橡胶/黏土纳米复合材料研究

利用层状硅酸盐制备有机 无机纳米复合材料是当前人们研究的热点[1,2 ] ,这类材料具有较常规聚合物 无机填料复合材料无法比拟的优点 ,可以明显改善高分子材料的物理机械性能、热稳定性、气体阻隔性、阻燃性、导电性、光学性等 .一般来说 ,聚合物 层状硅酸盐 (Ｐｏｌｙｍｅｒｌａｙｅｒｅｄｓｉｌｉｃａｔｅ ,ＰＬＳ)纳米复合材料可分为插层型和剥离型两种类型 .插层型纳米复合材料即聚合物插入到硅酸盐层中 ,硅酸盐在近程仍保持原有的有序晶体结构 ,在远程则是无序的 .对弹性体而言 ,硅酸盐含量在插层型杂化材料中的含量比较高 ,力学性能…     

Effects of cellulose nanocrystals on the vulcanization of natural rubber/cellulose nanocrystals nanocomposite and corresponding regulating strategies

Vulcanization is a vital process in rubber processing, it endows rubber with valuable physical and mechanical properties, making rubber a widely used engineering material. In addition to vulcanization agent, reinforcing fillers play a non-ignorable influence on the vulcanization of rubber nanocomposites. Herein, the effects of cellulose nanocrystals (CNCs) on the vulcanization of natural rubber (NR)/CNCs nanocomposite was studied. It was found that even though the addition of CNCs can effectively improve the dispersion of ZnO in NR matrix, the vulcanization of NR was inhibited. This may be attributed to the CNCs' adsorption of vulcanizing agents (DM, ZnO) and the acidic chemical environment on the surface of CNCs. In order to improve the vulcanization properties of NR/CNCs nanocomposite, tetramethyldithiochloram (TMTD) and triethanolamine (TEOA) were used as a combination accelerator and curing activator, respectively, and polyethylene glycol (PEG) was introduced to screen hydroxyl groups on the surface of CNCs to prohibit the CNCs' adsorption of vulcanizing agents. The results indicate that TMTD and TEOA effectively improved the vulcanization rate of NR/CNCs nanocomposite and increased the crosslink density by an order of magnitude. Subsequently, the tensile strength, tear strength, and so forth. of NR/CNCs nanocomposite were significantly improved. However, PEG hardly help to improve the vulcanization properties of NR/CNCs nanocomposite. In addition, the control samples without CNCs were prepared and characterized, the comparation between NR and NR/CNCs nanocomposite shows that the synergistic effect of crosslink density and CNCs' reinforcement more effectively improve mechanical properties of NR. This work not only elucidates the inhibiting mechanisms of CNCs on the vulcanization of NR, but also provides practical strategies for improving the vulcanization and properties of NR/CNCs nanocomposite. It may accelerate the application of CNCs as rubber reinforcing filler.     

The effect of grass fiber filler on curing characteristics and mechanical properties of natural rubber

Natural rubber is reinforced with a novel type of grass fiber (Cyperus Tegetum Rox b). The effects of fiber loading of different mesh sizes on curing characteristics and mechanical properties of grass fiber filled natural rubber composite are studied. Since 400 mesh grass fiber loaded natural rubber composite shows superior mechanical properties, therefore the effect of silane coupling agent was studied for this particular composite. Here composites were prepared by using water leached grass fiber. Optimum cure time increases with the increase in fiber loading but the change in scorch time is less. The same trend of increase in optimum cure time is observed in the presence of Si69. But the value is higher compared to that of rubber composite without Si69. With increase in the fiber loading, modulus and hardness of the composite increases but tensile strength decreases. The mechanical properties of the composite, namely moduli at 200 and 300% elongation and hardness increase in the presence of Si69 but tensile strength is less compared to that of the composite without Si69. Elongation at break is not much affected due to the presence of Si69. Copyright © 2004 John Wiley & Sons, Ltd.     

Radiation vulcanization of NR/SBR composite enhanced with different polyfunctional monomers

The effect of different polyfunctional monomers (PFMs) as enhancing agents on the properties of natural rubber/styrene-butadiene rubber blend reinforced with 40 (phr) part per hundred part of rubber, by weight of HAF carbon black and vulcanized with gamma irradiation was investigated. The coagents N,N’ methylene diacrylamide (MDA), trimethylol propane-trimethacrylate (TMPTMA) and trimethylol-methane tetraacrylate (TMMTA) were used at a constant content of 5 phr. The physico-chemical properties such as tensile strength, tensile modulus at 100 % elongation, elongation at break, gel fraction and swelling number were studied. The results indicated that the properties are greatly improved by PFMs at lower doses. TMMTA as coagent is more effective than TMPTMA and MDA.     

An investigation of dynamic mechanical, thermal, and electrical properties of housing materials for outdoor polymeric insulators

The present paper reports the results about a study of mechanical, thermal, dynamic mechanical and electrical properties of housing (weather shed) materials for outdoor polymeric insulators. Silicone rubber, ethylene-propylene-diene monomer (EPDM) and alloys of silicon-EPDM are known polymers for use as housing in high voltage insulators. The result of dynamical mechanical measurement shows that the storage modulus of blends enhances with increase EPDM in formulation. It can be seen from the result of TGA measurement that initial thermal degradation of silicone rubber improves by the effect of EPDM in blends. The blends of silicone-EPDM show good breakdown voltage strength compared to silicone rubber. Surface and volume resistance of silicone rubber improve by EPDM content. The mechanical properties of EPDM such as strength, modulus and elongation at break improve by silicone.     

Effect of plasticizer concentration on the hysteresis,tear strength and stress-relaxation characteristics of black-loaded rubber vulcanizate

The effect of plasticizer concentration on the stress softening, tear strength and stress relaxation of black loaded bromobutyl rubber vulcanizate has been investigated. The stress softening in the rubber vulcanizate, an energy dissipative process at higher strain, may be explained primarily by changes that take place in the rubber phase of the filled vulcanizate. Increased plasticizer concentration leads to decrease in the equilibrium hysteresis. A quantitative relationship between energy density and hysteresis has been derived, which is applicable at and below the elongation at break. Increase in plasticizer concentration results in decrease in the effective diameter of the tip of the tear, which in turn decreases the tear strength. Rate of relaxation decreases with increase in the plasticizer concentration in the carbon-black-filled vulcanizate.     

基于乘用车轮胎胎面胶粉的再生橡胶的制备及性能

通过力化学再生法制备了以废轮胎胶粉为原料的再生橡胶，研究了不同活化剂420用量对再生橡胶性能的影响，测试表明：再生橡胶含硫键断裂生成了硫自由基，随着活化剂含量的增加，再生橡胶的邵氏硬度和交联密度持续降低；拉伸强度、断裂延伸率和凝胶含量均先升高后降低，在活化剂用量为0.9 phr时，拉伸强度和断裂延伸率最大，再生橡胶的凝胶含量最大为19.7%。 微观形貌发现，废轮胎胎面胶粉的颗粒较为分散，再生橡胶的结构颗粒相互粘连，孔洞和缺陷较多，再生橡胶的门尼黏度随着活化剂含量的增加而降低。 综合来看，活化剂420的最佳含量为0.9 phr，再生橡胶各项性能最优。