高强度双组分室温硫化硅橡胶的

用钛酸酯和硅烷偶联剂KH－550合成了一种TH偶联剂。研究了偶联剂、活性高分子材料、促进剂和填料的各类和加入量对双组分硅橡胶性能的影响。结果表明,TH偶联剂双KH－550改性效果好。端痉基聚氨酯予聚物,106硅橡胶和TH偶联剂共同对107硅橡胶进行改性,可明显提高其粘接强度。例如,对铝的剪切强度可由1MPa左右提高到4MPa以上。     

Phosphorus modification of epoxidized liquid natural rubber to improve flame resistance of vulcanized rubbers

The use of phosphorus for improving flame retardancy of natural rubber vulcanizates was attempted by incorporating a modified form of natural rubber. By reacting epoxidized liquid natural rubber (ELNR) with dibutylphosphate it was possible to chemically modify the polymer. On a 25% epoxidized LNR, 5.2–6.8% w/w of phosphorus could be fixed on the polymer backbone. The reaction carried out in bulk and solution resulted in products with different T_g values probably due to the varying crosslink levels in the resultant products. Chemical analysis of the modified polymers prepared by two sets of reactions under identical conditions proved the reproducibility of the reactions in bulk and in solution. Incorporation of the phosphorus-modified ELNR in a natural rubber formulation decreased the flammability behaviors of the vulcanizate. On the other hand, a decrease of the rate of curing and mechanical properties was observed. The phosphorus addition could also be carried out by mixing ELNR and dibutylphosphate at the time of mixing the compounds and resulted in equally good flame retardance with relatively better processing and mechanical properties. © 1994 John Wiley & Sons, Inc.     

Chemorheological study of vulcanized rubbers under mechanical stress

At lower than the glass transition temperature, the cleavage of the molecular chains of extended vulcanized rubbers will occur. The crosslinking density of vulcanized rubbers, which were placed at room temperature for about 4 hr in nitrogen atmosphere, increased about 17% after extension of 200% at ?76°C. This may be due to the recombination of cleft chains, and this can be shown by the Maxwellian type of curves between crosslinking density and forced strain. Considering the decreasing proportion of crosslinking density by the radical acceptors included in the rubbers and the fact that crosslinking density increases because of recombination of cleft chains, this was attributed to the recombination of unstable chains produced by the added mechanical stimulus.     

The effect of moisture on the strength of polycarbonate-cyanoacrylate adhesive bonds

The effect of humid ageing on the bond strength of polycarbonate-polycarbonate and steel-steel joints bonded with cyanoacrylate adhesive has been investigated. The superior moisture resistance of the bond between the polymer adherends has been demonstrated. The improved stability can be attributed to the dissolution of the polycarbonate in the monomer during curing. The bond produced has no true adherend/adhesive interface. This prevents the entry of water into the joint and consequently precludes effects such as adhesive displacement or hydrolysis of the cured polymer.     

动态法热重分析（TG）推算硫化胶热寿命的方法

本文用换算时间的计算方法对石墨——硅橡胶复合物热重曲线(TG)进行动力学分析,用Doyle和Zsako积分公式及Sharp和Wentworth扩展法微分公式,从一条热重分析曲线推断出反应机理,算出活化能△E,频率因子A等动力学参数,计算寿命——温度关系。求得该复合物温度指数(寿命为20000小时的最高使用温度)为229℃,在250℃下寿命为2820小时,由算出的△E,A进行热重分析曲线反算,以验证所得结果的正确性。     

Surface modification of polyethylene by radiation-induced grafting for adhesive bonding. I. Relationship between adhesive bond strength and surface composition

A number of vinyl monomers have been surface grafted onto a polyethylene sheet by the mutual irradiation in monomer vapor and by a trapped-radical technique. The surface composition of the grafted sheets has been determined by means of ATR infrared spectrophotometry and compared with the peel strength of the joints bonded with conventional structural adhesives. In the methyl acrylate grafts followed by a saponification treatment, only the surfaces having graft compositions of more than 80 mole-% methyl acrylate give a high peel strength. A similar relationship between peel strength and surface composition is found in the surface grafts of vinyl acetate, acrylic acid, acrylamide, and methylolacrylamide. It is concluded that the formation of a surface with such a high monomer content is a necessary condition for the strong adhesive bonding of grafted polyethylenes at bonding temperatures below the softening point. Moreover, the adhesive bondability of the highly modified surfaces with epoxy adhesives is significantly enhanced by the introduction of carboxy and carbamyl radicals.     

Enhancement of adhesive joint strength by surface texturing

Proper substrate preparation is an indispensible step for achieving strong adhesive joints. One consequence of such surface treatment is the enhancement of degree of mechanical interlocking between polymers and substrates, which, according to the literature, seems to increase the strength of the joint. A novel method based on photolithography is developed to texture aluminum oxide surface by controlling the pit size and its spatial distribution. Surface profile, surface physical chemical properties of this sample, and the lap shear strength of epoxy adhesive joints are compared with those of the phosphoric acid anodized (PAA) sample. It is shown that the lap shear strength of the textured sample is superior to that of the PAA sample. Surface profile data and mathematical analysis suggest that the inferiority of the PAA sample is probably due to the trapped air in the large pit in the surface resisting the penetration of adhesives. It also concludes that the high surface area provided by the multitude small pits in PAA sample is far from being fully utilized. This study opens up a new avenue to rationally improve the strength of adhesive joint by controlling the surface profile, the surface chemical properties, and the pressure during bond formation.     

胶粉的表面改性

介绍了胶粉表面改性的方法。这些方法主要有机械力化学法、聚合物涂层法、再生脱硫法、接枝或互穿聚合物网络法、气体改性法、核／壳改性法、物理辐射和磺化法等。     

室温硫化硅橡胶粘接用胶粘剂的研究

研究了室温硫化硅橡胶生、熟片与不同材料(钢、合金铝、碳纤维／酚醛复合材料)粘接用胶粘剂及表面处理剂的合成方法和使用方法,较好地解决了硅橡胶熟片的粘接问题,粘接试件在室温下的剪切强度达到3.0MPa以上。     

Surface modification of synthetic vulcanized rubber

Surface modifications produced by treatments (mainly halogenation) of synthetic vulcanized styrene-butadiene rubber (SBR) leading to increased adhesion properties with polyurethane adhesives have been studied. T-peel tests, scanning electron microscopy (SEM), advancing contact angle measurements, infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) were used to analyze the nature of surface modifications produced in the rubber. Although some surface heterogeneities were created, physical treatments (ultrasonic cleaning, solvent wiping, abrasion) did not noticeably increase the adhesion strength because certain abhesive substances (e.g. zinc stearate, paraffin wax) cannot be removed from the rubber surface by such treatments. Chemical treatment (chlorination) was carried out using ethyl acetate solutions of trichloroisocyanuric acid (TCI) (1,3,5-trichloro-1,3,5-triazine-2,4,6-trione). Chlorination of SBR with trichloroisocyanuric acid produced a significant improvement in T-peel strength, due to the contribution of mechanical (surface roughness, microcracks), thermodynamical (increase of polar contribution to the surface energy) and chemical (removal of abhesive substances, creation of polar groups) rubber surface modifications. The strong adhesion between the chlorinated SBR surface and the polyurethane adhesive was due to the presence of oxidized species of >C=O, -C-OH and -COR type. Chlorination of SBR is a fast reaction which needs only a small concentration of chlorination agent (< 1 wt% TCI/ethyl acetate) to produce high adhesion levels. An increased amount of TCI facilitated the chlorination reaction progressing from the exterior to the internal rubber bulk; however, although a thicker layer of chlorinated rubber created no further increase in adhesion strength was obtained.     

Process variable effect on the strength of autoclave-bonded film adhesive joints

This study investigates the effect of five independently-controlled process variables and variable combinations on the shear strength of autoclave-bonded film adhesive joints. Studied variables include the cure temperature, cure pressure and their respective ramp rates, as well as the duration of cure time. A full factorial design of experiment (DoE) at two levels for each variable is conducted with 3 replicas of each test. Test coupons are made of two layers of polycarbonate lexan that are autoclave-bonded using aliphatic polyether film adhesive (Huntsman PE399). Two set of test joints are used for generating test data on shear strength and failure mode. Bonded joints in the first set are tested prior to any environmental cycling, in order to generate baseline data on joint shear strength and failure mode. However, samples from the second set of autoclave-bonded joints were heat-cycled, in an environmental chamber at high relative humidity, prior to testing for shear strength. Test data on shear strength and failure mode is statistically analyzed using ANOVA.     

室温硫化硅橡胶胶粘剂的增强方法

通过硅橡胶丙烯酸(酯)改性、自制偶联剂、选择活性高分子材料、改善填料在胶粘剂中的分散性等方法，较好地提高了双组份室温硫化硅橡胶的粘接强度。     

Improvement of impact fatigue strength of adhesive joint by CTBN modification

Impact fatigue behaviors of the steel/CTBN-modified adhesive/steel butt joint were investigated. The adhesive butt joint specimens used in the present work were bonded with epoxy–polyamide and CTBN-modified epoxy–polyamide adhesives. Fatigue tests were also conducted under nonimpact stress conditions to compare with the results from the impact fatigue test. The experiments showed that for the joint specimen from the adhesive modified with the CTBN the fatigue strength becomes higher under both of the stress conditions. In particular, the fatigue strength was improved remarkably under impact stress condition, that is, the distinct stress cycles dependence of impact strength was decreased by modifying the adhesive with CTBN. Furthermore, the effect of adhesive thickness on the fatigue strength was also discussed for the adhesive joint modified with CTBN. Under impact stress conditions, the relation between the fatigue strength and the adhesive layer thickness is different from that under the nonimpact one.     

Effects of the surface state of plastics on adhesive strength in electroless plating

Adhesive resins with high adhesive strength and high heat resistance have been studied in developing a novel iron-core printed circuit board with high mechanical strength and high heat radiation capability. A reticular pattern formed on the surface of an adhesive resin composed of nitrile rubber, phenolic resin and epoxy resin. It caused blisters in the plating or reduced the heat resistance of the printed board. This pattern was formed as a result of phase separation of epoxy resin or phenolic resin from the nitrile rubber. Using a high-molecular-weight epoxy resin led to high adhesive strength and high heat resistance, without phase separation. The relationships between the composition of adhesive resins and their characteristics were discussed on the basis of the state of their surface after being roughened by chemical etching. © 1996 John Wiley & Sons, Inc.     

硫酸处理对天然橡胶界面粘结性能的影响

采用硫酸溶液处理天然橡胶表面以改善其粘结性能。通过力学性能测试、电子扫描电镜（SEM）、能量分析光谱（EDX）、接触角分析等研究了不同处理时间对天然橡胶表面粘结性能的影响。随着处理时间的延长,天然橡胶表面的接触角先减小后增大;SEM测试结果表明经过硫酸处理后天然橡胶表面的粗糙度和微裂纹增多,有利于胶粘剂的润湿和渗透;EDX测试结果显示,橡胶表面氧元素含量增多,表明引入了含氧极性基团—C O、—COO-等。随着处理时间的延长,T-型剥离强度先增大后减小,用质量分数为80%的H2SO4溶液处理15 min时,剥离强度达到最大值10.67 kN/m。硫酸处理可改善天然橡胶表面的表面形貌、化学性质及其润湿性,有利于粘结强度的提高,从而提高天然橡胶的粘结性能。     

The effect of surface properties on the adhesion of modified polychloroprene used as adhesive

The adhesion properties of polychloroprene can be improved by addition of such materials as piperylene–styrene co-polymer (PSC), VeoVa-10 polymer, VeoVa-11/methyl methacrylate/2ethylhexyl acrylate co-polymer (VeoVa-11/MMA/2EHA) and poly(vinyl acetate) waste (wPVAc). Here, the relationship between adhesion properties and surface tension of polychloroprene was investigated. Contact angle measurements have been used to study the effects of nature and content of polymeric additives on the adhesion and surface properties of polychloroprene. Low-surface-tension VeoVa-10 polymer has the tendency to migrate to the surface of polychloroprene; thus, adhesion is determined mainly by this additive property. Enrichment of polychloroprene film bottom layer by the additive was observed using high-surface-tension PSC and wPVAc. In this case, the adhesion properties of polychloroprene depend on the interactions at the interface. Adhesion properties of polychloroprene were found to depend not only on compatibility between adhesive components, but also on compatibility between the adherend and the adhesive.     

Hysteresis in rubbers and its influence on strength

The most important dissipative mechanisms contributing to hysteresis when a rubber is stretched to breaking point are discussed. A quantitative examination of the influence of hysteresis on the work required to break the rubber produces a sensitive criterion of failure for a number of rubbers with and without carbon-black filler.     

丁苯橡胶表面处理技术对粘接强度的影响

丁苯橡胶表面是非极性的,为了增强丁苯橡胶与金属或者其他材料之间的粘接强度,需娶对橡胶表面进行处理。综述了当前国内外橡胶表面处理的常用方法、原理及研究进展。