PEEL STRENGTH OF UNCROSSLINKED STYRENE-BUTADIENE RUBBER ADHERED TO POLYESTER FILM

Testpieces consisting of a fabric-backed styrene-butadiene rubber (SBR 1502) layer bonded directly to polyethylene terephthalate (PET) film were T-peel tested at various rates, R , and temperatures. Peel energies were superposed toformmastercurves using shift factors, a T , in accord with the universal WLF equation. When peeled at intermediate reduced rates, Ra T , failure was cohesive within the SBR 1502, while at sufficiently high or low Ra T interfacial separation between the rubber and PET occurred. These results markedly contrast with those found by Gent and Petrich using similar testpieces with another type of rubber, SBR 1513. They found cohesive failure at sufficiently low Ra T and interfacial failure when Ra T was high. The different behavior of the two elastomers is attributed to stronger interfacial attraction with SBR 1513 and its lower strength. General considerations governing the locus of failure during peel adhesion testing are discussed.     

Dielectric properties of styrene — butadiene rubber/silica mixtures

Rice husk ash (RHA) obtained from rice mill and hydrated silica from RHA were used as a filler in vulcanized SBR 1502 and the dielectric properties were measured at a frequency of 1592 Hz at room temperature. The optimum hydrated silica content giving a good dielectric constant and conductivity was 125 parts/100 parts rubber and the dielectric loss was also high so that it could be a good insulater. There was no significant change in dielectric constant, dielectric loss and conductivity of SBR 1502 filled with RHA which could be used as high frequency dielectric due to low dielectric loss.     

不同牌号丁苯橡胶的耐低温性能研究

研究3种牌号丁苯橡胶(SKMS-10,SL-4525-0,SBR1502)的硫化特性、物理性能和耐低温性能。结果表明:SKMS-10具有优异的耐低温性能,生胶的玻璃化转变温度(T_g)为-73.3℃,硫化胶的T_g为-59.8℃,适于在极寒条件下使用;SL-4525-0胶料的F_max-FL较大,硫化胶的拉伸强度为19.3 MPa,撕裂强度为53 kN·m^-1,T_g为-48.6℃,具有优异的综合性能;SBR1502硫化胶的拉伸强度高达24.9 MPa,撕裂强度为49 kN·m^-1,但T_g为-38.4℃,耐低温性能较差,适用于载荷较大且耐低温性能要求不高的橡胶减振制品。     

Peel Strength of Aluminium-Aluminium Joints Bonded by Adhesive Based on Carboxylated Nitrile Rubber-Chlorobutyl Rubber Blend

The peel strength of aluminium-aluminium joints bonded by an adhesive based on carboxylated nitrile rubber and chlorobutyl rubber was found to depend on surface topography and use of a silane primer. Anodization causes a marginal increase in bond strength while the silane primer improves the adhesive joint strength remarkably.

The peel strength was also found to be dependent on test conditions (test rate and temperature). The threshold peel strength value obtained by measurements at low peel rate and high test temperature was found to depend on the type of failure during peeling (cohesive or interfacial) which, in turn, is controlled by the presence of silica filler in the adhesive. Two different threshold values of peel strength were obtained: 60 N/m for interfacial failure (in silica-filled adhesive), 140 N/m for cohesive failure (in unfilled adhesive).     

环保型丁苯胶SBR1502E在农业子午线轮胎中的应用

研究环保型丁苯胶SBR1502E在农业子午线轮胎胎面胶和胎体帘布胶中的应用。结果表明：用环保型丁苯胶SBR1502E等量代替丁苯胶SBR1502,胎面胶的挤出性能明显改善,排胶温度降低,压延帘布温度降低,覆胶均匀,成型工艺性能良好,拉伸性能变化不大,门尼粘度明显降低,生热降低,弹性提高,耐磨性能及H抽出性能改善、耐热老化性能变化不大;成品轮胎的物理性能变化不大。     

Peel Adhesion of Poly(Vinyl Chloride) to Nitrile Rubbers

In addition to molecular interaction and physical entanglement of the molecular chains across the interface in poly (vinyl chloride)-nitrile rubber joints, at high temperatures and long contact times interfacial chemical bonds may be formed which seem to couple the two adherends thereby resulting in cohesive failure of the rubber matrix on peeling. This is verified by performing the peel tests at high temperatures, low peel rates and under swollen conditions. Infrared spectroscopic studies of the PVC/NBR blend reveal the formation of chemical bonds at the contact temperatures studied. The peel fracture energy is found to depend on the acrylonitrile content and presence of carboxylic content in the NBR, and the presence of stabilizer and plasticizer in the PVC phase, in addition to the molding and testing conditions.     

苯乙烯—丁二烯橡胶门尼黏度标准物质的均匀性和稳定性研究

对国内5家橡胶生产厂生产的苯乙烯-丁二烯橡胶(SBR) 1502,进行了分子量及分布、结构组成、门尼粘度均匀性检验,采用方差分析法对苯乙烯-丁二烯橡胶(SBR) 1502的均匀性进行统计,统计量F值均小于临界值2.31,说明各厂家的样品均匀.对均匀性较好的样品进行了稳定性考察,采用t检验法考察样品稳定性,在12个月内样...     

硬质PVC改性用粉末丁苯橡胶的开发及应用

以丁苯胶乳1502为原料，经交联及接枝改性，用凝聚法制得了粒径不大于0.9mm的粉末丁苯橡胶（PSBR）。结果表明，用PSBR对PVC的增韧作用优于氯化聚乙烯的，并对产品进行了加工应用测试。     

凝聚母液pH值的变化对环保型丁苯橡胶SBR1502E性能的影响

以中国石油吉林石化公司环保型丁苯橡胶SBR1502E为研究对象,研究了凝聚母液在不同pH值下对胶性能的影响.结果表明,在不改变母液温度、胶液进料量、高分子絮凝剂加入量情况下,凝聚母液pH值的变化对胶的性能产生较大影响,当初始pH值为3.0～3.5时,环保型丁苯橡胶SBR1502E的性能全部达到优级品技术标准.     

防老剂KY310和防老剂SPT的应用对比

吉林石化公司丁苯橡胶装置一直使用防老剂SPT生产丁苯橡胶SBR1502,在后处理生产过程中防老剂SPT是影响废水COD的主要因素之一。在当前环保压力日益增加的情况下,使用新型防老剂势在必行。本文对比考察了2种防老剂的热空气老化防护性能、对丁苯橡胶SBR1502性能的影响及对后处理废水的影响。实验结果表明,防老剂KY310热空气防老化性能优于防老剂SPT,对丁苯橡胶性能没有明显影响,且大大降低了污水的COD。     

Effect of molecular weight between crosslinks on the fracture behavior of rubber‐toughened epoxy adhesives

The effect of molecular weight between crosslinks, M_c, on the fracture behavior of rubber‐toughened epoxy adhesives was investigated and compared with the behavior of the bulk resins. In the liquid rubber‐toughened bulk system, fracture energy increased with increasing M_c. However, in the liquid rubber‐toughened adhesive system, with increasing M_c, the locus of joint fracture had a transition from cohesive failure, break in the bond layer, to interfacial failure, rupture of the bond layer from the surface of the substrate. Specimens fractured by cohesive failure exhibited larger fracture energies than those by interfacial failure. The occurrence of transition from cohesive to interfacial failure seemed to be caused by the increase in the ductility of matrix, the mismatch of elastic constant, and the agglomeration of rubber particles at the metal/epoxy interface. When core‐shell rubber, which did not agglomerate at the interface, was used as a toughening agent, fracture energy increased with M_c. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 38–48, 2001     

An investigation into the high temperature strength and reinforcement of natural rubber

The failure criterion for amorphous polymers relating hysteresis at break with energy input to failure in tensile stress–strain tests was found to be obeyed only at very high or very low temperatures in natural rubber. Tensile results between about 80°C and 130°C show a high degree of scatter, and this behavior is attributed to the ability of natural rubber to crystallize at high strains. The modification of tensile properties by the addition of carbon black in natural rubber is also discussed and compared with published results from SBR. The effect of changing the degree of crosslinking on the failure properties in both dicumyl peroxide and sulfur-cured vulcanizates of natural rubber is also considered. It is found that differences in failure properties can be accounted for by the use of a crosslinking parameter from simple rubber elasticity theory in some of the failure equations.     

高性能胎面胶用集成橡胶SBR-BR-SBR

以苯乙烯、丁二烯为单体，环己烷为溶剂，采用双锂引发剂负离子聚合工艺合成出了嵌段聚合物SBR-BR-SBR，考察了SBR-BR-SBR的动态黏弹行为。结果表明，该聚合物的动态损耗曲线呈双峰分布，分别对应着体系的BR相和SBR相；该聚合物耐寒性好，磨耗低，抗湿滑性能优异，滚动阻力低，是一类综合性能优异的胎面胶用集成橡胶，     

Influence of the degree of crosslinking on the stringiness of crosslinked polyacrylic pressure‐sensitive adhesives

The stringiness of crosslinked polyacrylic pressure‐sensitive adhesive (PSA) was observed during 90° peeling under the constant peel load. The random copolymer of butyl acrylate with 5 wt % acrylic acid crosslinked by N,N,N′,N′‐tetraglycidyl‐m‐xylenediamine was used as PSA. All observed stringiness upon peeling was sawtooth‐shaped, but it could be classified into three types dependent on the degree of crosslinking. The typical sawtooth‐shaped stringiness with interfacial failure was observed at the relatively higher crosslinker content ranging from 0.008 to 0.016 chemical equivalents (Eq.), where the PSA has high cohesive strength and low interfacial adhesion. The frame formed at the front end of stringiness at the content ranging from 0.002 to 0.004 Eq. Sufficient interfacial adhesion and deformability generate large internal deformation of the PSA layer. Internal deformation occurred preferentially over peeling as a result of front frame formation. The mode of peeling was changed from cohesive failure to interfacial failure in this range of crosslinker content. The sawtooth‐shaped with cohesive failure was observed at the lower content ranging from 0 to 0.001 Eq. The PSA has high interfacial adhesion and low cohesive strength, and thus exhibited cohesive failure. The PSA after peeling remained in the shape of belts. It was found that the shape of stringiness is strongly dependent on the balance between the interfacial adhesion and the cohesive strength of PSA. When the sawtooth‐shaped stringiness with frame formed, the peeling rate was lowest. This means the peel strength should be the maximum in this shape of stringiness. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40336.     

Adhesion strength and fracture behavior between carbon black-filled rubber sheets

Adhesion behavior at the interface between a partially-crosslinked and a fully-crosslinked sheet of carbon black-filled rubber compound was investigated over a temperature range from 30 to 120°C. The values of adhesion fracture energy G_a were compared with those of cohesive tear energy G_c. A considerable chemical, as well as physical, interfacial bonding is formed when the uncrosslinked or partially-crosslinked sheet is crosslinked in contact with even a fully-crosslinked sheet. However, there is only a small possibility of chemical bonding when the two fully-crosslinked rubber layers are again crosslinked in contact with each other. An interesting failure mode, termed 'interfacial knotty tearing' was found for a strain-induced crystallizable natural rubber.     

SEM/EDX studies of the influence of a cobalt adhesion promoter on the interface between rubber skim compounds and tire steel cord

The failed interfaces between natural rubber skim compounds and tire steel cord used as tire cord adhesion test (TCAT) specimens have been studied by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis in order to understand the influence of cobalt boroacylate in the rubber compound as an adhesion promoter. SEM studies indicated a mixture of cohesive failure in the rubber and interfacial failure between the rubber and the brass coating. Cobalt boroacylate leads to more cohesive failure of the rubber (about 88% of the cord area covered by the rubber compared with 73% by the control), due to its degradative effects on rubber. EDX analysis of the failed cord and rubber surfaces at various points gave the concentrations of copper, zinc, cobalt, iron, silicon, sulfur, oxygen, and carbon. Assuming van Ooij's model of interfacial sulfide film formation over the brass (Cu/Zn) layer and analyzing the EDX results, it is clear that the failure occurs at the Cu/Zn and Cu_xS/ZnS sub-layers.     

Quantitative characterization of interfaces in rubber–rubber blends by means of modulated‐temperature DSC

Rubber–rubber blends are used widely in industry, for example, in tire manufacture. It is often difficult to characterize interfaces in such rubber–rubber blends quantitatively because of the similarity in the chemical structure of the component rubbers. Here, a new method was suggested for the measurement of the weight fraction of the interface in rubber–rubber blends using modulated‐temperature differential scanning calorimetry (M‐TDSC). Quantitative analysis using the differential of the heat capacity, dCp/dT, versus the temperature signal from M‐TDSC allows the weight fraction of the interface to be calculated. As examples, polybutadiene rubber (BR)–natural rubber (NR), BR–styrene‐co‐butadiene rubber (SBR), SBR–NR, and nitrile rubber (NBR)–NR blend systems were analyzed. The interfacial content in these blends was obtained. SBR is partially miscible with BR. The cis‐structure content in BR has an obvious effect on the extent of mixing in the SBR–BR blends. With increasing styrene content in the SBR in the SBR–BR blends, the interface content decreases. NR is partially miscible with both BR and SBR. The NBR used in this research is essentially immiscible with NR. The maximum amount of interface was found to be at the 50:50 blend composition in BR–NR, SBR–BR, and SBR–NR systems. Quantitative analysis of interfaces in these blend systems is reported for the first time. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1791–1798, 2000     

Time Dependent Crack Growth and Loading Rate Effects on Interfacial and Cohesive Fracture of Adhesive Joints

Double cantilever beam fracture specimens were used to investigate rate dependent failures of model epoxy/steel adhesively bonded systems. Quasi-static tests exhibited time dependent crack growth and the maximum fracture energies consistently decreased with debond length for constant crosshead rate loading. It was also possible to cause debonding to switch between interfacial and cohesive failure modes by simply altering the loading rate. These rate dependent observations were characterized using the concepts of fracture mechanics. The time rate of change of the strain energy release rate, dG/dt, is introduced to model and predict failure properties of different adhesive systems over a range of testing rates. An emphasis is placed on the interfacial failure process and how rate dependent interfacial properties can lead to cohesive failures in the same adhesive system. Specific applications of the resulting model are presented and found to be in good agreement when compared with the experimental data. Finally, a failure envelope is identified which may be useful in predicting whether failures will be interfacial or cohesive depending on the rate of testing for the model adhesive systems.     

Functional thiol ionic liquids as novel interfacial modifiers in SBR/HNTs composites

Two kinds of thiol ionic liquids (ILs), 1-methylimidazolium mercaptopropionate (MimMP) and bis (1-methylimidazolium) mercaptosuccinate (BMimMS), were investigated as novel interfacial modifiers for styrene butadiene rubber/halloysite nanotubes (SBR/HNTs) composites. According to model compounds, it was found that their affinities toward HNTs were originated from hydrogen bonding and that they could be grafted onto SBR chains via thiol-ene reactions. The ILs addition could promote vulcanization and effectively facilitate HNTs dispersion in rubber matrix. The interfacial interaction, quantitatively evaluated by a proposed equation based on rubber elasticity and reinforcement theory, was consistently increased. Mechanical properties of SBR/HNTs vulcanizates were largely improved and better than those of the 3-mercaptopropyl trimethoxysilane modified system. The BMimMS’s efficiency on modifying SBR/HNTs vulcanizates was higher than the other for its Gemini structure. Significantly mechanical improvements and lowered mechanical loss in the range of 50-80 °C were correlated to the improved HNTs dispersion and strengthened interfacial interactions.     

BOND STRENGTH IMPROVEMENT OF POLYURETHANE ADHESIVE BY GRAFTING 2-HYDROXYETHYL METHACRYLATE ON POLYOL BACKBONE

A series of acrylated polyols were prepared by grafting 2-hydroxyethyl methacrylate (HEMA) on to polyol backbone prepared from vegetable oil fatty acid and epoxy resin. Grafting was carried out by free radical mechanism on conjugated double bond present in the polyol using benzoyl peroxide (BPO) as an initiator. Polyols and polyurethane adhesives were characterized by IR spectroscopy. Polyurethane adhesive synthesized from the modified polyols were found to provide better peel strength to styrene butadiene rubber (SBR) joints. Mode of failure was studied using Scanning Electron Microscopy (SEM). Improvement in cohesive strength of the adhesives resulted in high bonding strength. Comparative study has been carried out to determine the effect of acrylation on polyurethane adhesive by Green strength, Curing behavior, and Chemical resistance studies. Loading of 20% HEMA gave significant results. However, 15% loading of HEMA resulted in a sample with highest peel strength.