环氧-聚砜结构胶粘剂耐环境性能的研究

报导了SY-14环氧-聚砜胶粘剂体系的耐环境性能研究结果。在北京、南昌、广州和海口四个不同气候条件下的10年大气曝晒试验表明,各项胶接强度均末发生明显变化。含有抑制腐蚀底胶的胶接试板进行的10年室温盐水浸泡试验也取得了优良的试验结果。     

轨道客车用聚氨酯胶粘剂自然老化行为的研究

为评价高速列车用PU(聚氨酯)胶粘剂在我国不同气候环境中的适应性,选择武汉、漠河、尉犁和万宁地区作为样品自然老化的试验区,对曝晒90、183、365 d后的PU胶粘剂本体试样及铝合金胶接件进行力学性能、粘接性能和结构的测定。研究结果表明:试样表面裂纹扩展受湿热老化、光老化过程的协同作用影响较大;老化初期,光降解作用萌生细裂纹龟裂,而湿热水解作用产生凹坑,并且对裂纹扩展影响较大;水渗透至基底金属处产生腐蚀,使PU胶粘剂/铝合金胶接件的界面粘接力明显降低。     

胶粘剂大气腐蝕试验研究

本文论述九个牌号胶粘剂在我国五个气候区域,进行了6年大气腐蚀试验,同时还在广州市进行了贮存老化试验。用拉伸剪切强度,拉伸破坏时间和破坏类型等作为评定胶粘剂使用性能变化的测试指标,也观察了胶粘剂外观颜色和金属试片的腐蚀情况。试验结果表明,不同的气候条件对胶粘剂的性能变化影响很大。     

SBS在不同地区大气老化腐蚀试验

三种SBS材料在我国海南万宁、广州、内蒙海拉尔地区经过半年的户外曝露试验,该材料在光氧作用下其力学性能迅速下降,凝胶含量急剧增加,说明它不耐大气老化,对紫外光极为敏感,应用前景在于改性。     

大气曝晒试验场环境条件的初步研究

玻璃钢在大气中曝晒后外表颜色变淡,玻璃纤维显露较快,机械性能降低,这除了与广州地区气候炎热、湿度大有关外,是否也与玻璃钢试件投放在屋面上有关呢?我们通过这几年的测试和观察,初步认为有一定     

聚酯粉末涂层在典型气候环境下耐老化性的研究

为了探究聚酯 /三缩水甘油基异氰尿酸酯（ TGIC）、聚酯 /β-羟烷基酰胺（ HAA）和聚酯 /异氰酸酯（ B1530）3种粉末涂料涂层在不同气候环境下服役性能，制备了 3种体系涂层并将其置于湿热气候（迈阿密）、干热气候（凤凰城）、湿热沿海气候（三亚）、湿热气候（琼海）、亚湿热气候（广州）、寒冷气候（海拉尔）、高原气候（西藏拉萨）、干热气候（新疆吐鲁番） 8种气候环境下进行自然曝晒，以保光率和色差作为评判涂层老化的依据。结果表明：聚酯粉末涂料涂层在寒冷气候（海拉尔）和干热气候环境（吐鲁番）下老化速度最慢，亚湿热气候（广州）次之，而在湿热沿海气候环境（三亚）下涂层老化速度最快。     

典型大气环境对低密度聚乙烯老化严酷度评价方法

为评价典型大气环境对低密度聚乙烯(PE–LD)材料的老化严酷度,选取我国武汉、漠河、拉萨、万宁地区进行PE–LD大气环境自然老化试验,对曝晒3个月、6个月、12个月、18个月后的PE–LD试样进行力学性能、黄色指数、光泽度与红外光谱测试与分析。结果表明,PE–LD试样表面的红外羰基峰强度随老化时间延长出现饱和极大值,各地区出现极大值的老化时间因环境因素不同而不同,可用红外羰基峰强度变化来评价环境对PE–LD的老化严酷度;各地区对PE–LD的老化严酷度从大到小依次是万宁、武汉、拉萨、漠河。     

工程塑料在温热气候下大气老化

工程塑料在湿热气候下的大气老化是工业界十分关心的问题。本文叙述了8种工程塑料在海南岛东部琼海县室外(内)曝晒(露)结果,对应用单位选用工程塑料有参考价值。     

节约代用植物油涂料大气曝晒试验(二)

根据75年6月石化部全国天然曝晒网座谈会要求,甘肃油漆厂涂料工业研究所与广州老化研究所一起,于75年底,将64年以来至75年上半年在兰州和广州两地区的油漆样板大气曝晒试验数据进行了总结。其中节代油涂料大气曝晒总结已发表在《老化通讯》1976第2期上。     

钢件油漆表面以电化学方法测定其保护能力

过去对钢铁件表面涂漆后,要想知道这种漆对钢铁件是否有保护能力,多半使用大气曝晒的方法,细心用肉眼观测才能了解使用情况。后来发展了使用人工气候箱,摹仿大气情况,箱内有日晒、雨霖、刮风甚至于寒冷等恶劣的气候条件进行加速试验。还有用盐水喷雾箱或二氧化硫腐蚀箱及化学品浸溃法等加速腐蚀试验。     

A Review of Certain Recent Work on the Durability of Aluminium Alloy Bonded with Epoxide and Phenolic Adhesives

Single lap joints of aluminium alloy, bonded with a number of structural adhesives, have been aged at 100% or 50% relative humidity (r.h.) at 50°C for up to 10000 hours. The adhesives used have included a simple epoxide and some modified phenolics and epoxides. Whilst joints are not significantly weakened on exposure at 50% r.h., significant weakening occurs at 100% rh. There is an initial fall in strength in the early stages of exposure, but after this period joints remain fairly stable, retaining approximately 40–60% of the strengths they had before exposure. Water diffusion coefficients in the adhesives have been obtained from experiments on the mass uptake of water by films of the adhesives. Water concentration profiles and overall levels of water in adhesive joints have been calculated from diffusion coefficients, and these show that the initial fall in strength is controlled by water diffusing through the adhesive layer. Joint strengths recover significantly when they are dried out. The behaviour of joints can be interpreted by there being ion-pairs at the interface. Water reduces the interionic force by raising the permittivity of the surroundings, and this is reversed when the water is removed.     

A Review of Certain Recent Work on the Durability of Aluminium Alloy Bonded with Epoxide and Phenolic Adhesives

Single lap joints of aluminium alloy, bonded with a number of structural adhesives, have been aged at 100% or 50% relative humidity (r.h.) at 50°C for up to 10000 hours. The adhesives used have included a simple epoxide and some modified phenolics and epoxides. Whilst joints are not significantly weakened on exposure at 50% r.h., significant weakening occurs at 100% rh. There is an initial fall in strength in the early stages of exposure, but after this period joints remain fairly stable, retaining approximately 40-60% of the strengths they had before exposure. Water diffusion coefficients in the adhesives have been obtained from experiments on the mass uptake of water by films of the adhesives. Water concentration profiles and overall levels of water in adhesive joints have been calculated from diffusion coefficients, and these show that the initial fall in strength is controlled by water diffusing through the adhesive layer. Joint strengths recover significantly when they are dried out. The behaviour of joints can be interpreted by there being ion-pairs at the interface. Water reduces the interionic force by raising the permittivity of the surroundings, and this is reversed when the water is removed.     

Preparation,structural evolution,and performance of heat-resistant organosilicon polymer adhesives for joining SiC ceramics

There is an urgent need for heat-resistant adhesives with high bonding strength in order to able to fabricate large and complex SiC components for aeronautical and astronautical applications. In this study, heat-resistant organic adhesives prepared using an organosilicon polymer and inorganic additives (B₄C and SiO₂) were used successfully to bond SiC ceramics. The prepared adhesives were characterised through shear strength tests as well as using thermogravimetry-differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-diffraction analysis, and scanning electron microscopy. The adhesives exhibited high room-temperature shear strengths (greater than 15 MPa) after being subjected to heat treatments at 200–1200°C. Further, the high-temperature shear strengths of the adhesives at 200, 400, 600, 800, and 1000°C were 10.5, 10.1, 7.7, 8.6, and 8.4 MPa, respectively. The high performance of the adhesives indicated that they should be suitable for joining SiC-based materials for use in high-temperature applications.     

环氧树脂胶粘剂工程应用研究

采用某种型号的环氧树脂(EP)胶粘剂胶接LY12-CZ铝合金试片,在110～170℃范围内加热4 h后测定胶接件的剪切强度,并对该胶接件的不同加载速率与拉伸剪切强度的关系进行了研究。结果表明:短时高温加热对该胶粘剂的剪切强度没有影响,这有利于飞机组件的整体修复;拉伸剪切强度随着加载速率的增加而增大,这又为探讨加载速率对不同胶粘剂性能的影响提供了试验依据。     

Durability of Adhesive Bonds to Zinc-Coated Steels: Effects of Corrosive Environments on Lap Shear Strength

The effects of corrosive environments on adhesive bonds to electro-galvanized, zinc/aluminum alloy coated, coated electro-galvanized, and cold-rolled steels have been investigated. Bonds prepared using a rubber-modified dicyandiamide-cured epoxy adhesive, an epoxy-modified poly(vinyl chloride)-based adhesive, an acrylic-modified poly(vinyl chloride)-based adhesive a one-part urethane adhesive, and a two-component epoxy-modified acrylic adhesive were exposed under no-load conditions to constant high humidity or cyclic corrosion exposure for 50 days or 50 cycles (10 weeks) respectively.

Over the course of this study, exposure to constant high humidity had little effect on lap shear strength for any of the systems studied. Bond failures were initially cohesive, and with few exceptions remained so.

Bond strength retention under the cyclic corrosion exposure conditions employed was strongly dependent on adhesive composition and on substrate type. On galvanized substrates, lap shear strengths for the poly(vinyl chloride)-based adhesives were reduced by 90-100% during the course of the corrosion exposure, and a change in the mode of bond failure (from cohesive to interfacial) was observed. On the coated electro-galvanized steel substrate, the poly(vinyl chloride)-based adhesives showed about 50% retention in lap shear strength and a cohesive failure throughout most of the corrosion test. The dicyandiamide-cured epoxy adhesive used in this study generally showed the best lap shear strength retention to zinc-coated substrates; bonds to cold-rolled steel were severely degraded by corrosion exposure. The performance of the acrylic and urethane adhesives were intermediate to the dicyandiamide-cured epoxy and poly(vinyl chloride)-based adhesives in strength retention.     

Durability of Adhesive Bonds to Zinc-Coated Steels: Effects of Corrosive Environments on Lap Shear Strength

The effects of corrosive environments on adhesive bonds to electro-galvanized, zinc/aluminum alloy coated, coated electro-galvanized, and cold-rolled steels have been investigated. Bonds prepared using a rubber-modified dicyandiamide-cured epoxy adhesive, an epoxy-modified poly(vinyl chloride)-based adhesive, an acrylic-modified poly(vinyl chloride)-based adhesive a one-part urethane adhesive, and a two-component epoxy-modified acrylic adhesive were exposed under no-load conditions to constant high humidity or cyclic corrosion exposure for 50 days or 50 cycles (10 weeks) respectively.

Over the course of this study, exposure to constant high humidity had little effect on lap shear strength for any of the systems studied. Bond failures were initially cohesive, and with few exceptions remained so.

Bond strength retention under the cyclic corrosion exposure conditions employed was strongly dependent on adhesive composition and on substrate type. On galvanized substrates, lap shear strengths for the poly(vinyl chloride)-based adhesives were reduced by 90–100% during the course of the corrosion exposure, and a change in the mode of bond failure (from cohesive to interfacial) was observed. On the coated electro-galvanized steel substrate, the poly(vinyl chloride)-based adhesives showed about 50% retention in lap shear strength and a cohesive failure throughout most of the corrosion test. The dicyandiamide-cured epoxy adhesive used in this study generally showed the best lap shear strength retention to zinc-coated substrates; bonds to cold-rolled steel were severely degraded by corrosion exposure. The performance of the acrylic and urethane adhesives were intermediate to the dicyandiamide-cured epoxy and poly(vinyl chloride)-based adhesives in strength retention.     

Benchmark tests on adhesive strengths in butt, single and double lap joints and double-cantilever beams

The RC99 committee of the Japan Society for Mechanical Engineers conducted the benchmark tests on strengths of adhesive joints using different testing methods. The effects of joint configuration, loading mode, adherend yield strength and so on, on the strength and data scatter were investigated using two typical epoxy adhesives. The strengths obtained by various tests were compared with each other. The relationships among strengths of butt, single lap and double lap joints and fracture toughness were given. Thirteen member institutes of the committee participated in this project. The benchmark results allow us to recognize that the joint strengths are strongly affected by the curing process. The key to obtaining the appropriate joint strength, is precise temperature control inside the adhesive layer for curing. Toughened adhesives do not always give higher joint strengths than untoughened adhesives. The yield strength of adherends much affects the observed lap joint strength of adhesives.     

Preconditioning of epoxy film adhesives for bond strength improvement

The moisture level of two commercial overaged epoxy film adhesives has been controlled by drying under vacuum and/or exposure to humid atmosphere. Shear and peel bond strengths of the conditioned adhesives were evaluated. Predrying of the uncured adhesive under vacuum (3–5 mm Hg) at room temperature is shown to be very effective for bond strength enhancement. Additional humidifying/drying circles show the same effect but some irreversible degradation occurs and only partial improvement of adhesive bond strength is achieved.     

Aromatic imide polymers for high-temperature adhesives

During the past decade the aerospace industry has sought materials for bonding stainless-steel and titanium alloys that have a high degree of thermal and oxidative stability. The Air Force Materials Laboratory has anticipated these requirements and sponsored many development programs aimed at achieving these goals. This paper describes the results of one such program devoted to development of high-temperature adhesives from aromatic imide polymers. The family of polymeric materials known as aromatic polyimides possess excellent thermal and oxidative resistance at temperatures up to 650°F. Mechanical and electrical properties of glass-fiber-reinforced laminates prepared with these polymers have been reported. This work has been extended to the development of structural adhesives that will withstand long-time exposure in air at 600°F. Stainless steel and titanium have been successfully bonded with adhesives made from aromatic imide and benzimidazole imide polymers. Bonds made with stainless steel have retained approximately 80% of their original strength at 600°F. after 1000 hr. of aging at 600°F. Adhesives made with benzimidazole imide polymers are the prepared materials for bonding titanium. Initial bond strengths of 1300 psi have been measured at 600°F. After 1000 hr. at 600°F. the bond strengths drop to 800 psi. The processing conditions for making a bond are quite moderate, except that a high temperature is required. The preparation and processing conditions associated with these adhesives are described. A large number of aromatic imide and amide-imide polymers have been prepared and adhesives formulated. By comparing the bond strengths obtained with these adhesives it is possible to deduce the effect of molecular weight and various molecular components on bond strength.     

Investigation of fast-setting acrylic adhesives for bonding attachments to human tooth surfaces

Some of the problems encountered in adhesive bonding of plastic attachments to human tooth surfaces were investigated. Acrylic adhesives based on poly(methyl methacrylate)–methyl methacrylate monomer mixtures with benzoyl peroxide initiation and N,N-dimethylaniline acceleration were utilized. Both homopolymers and copolymers were investigated. Recently extracted upper central incisors were employed in the bonding experiments. Bond strengths were improved by pretreating the tooth surfaces with mineral acids such as H₃PO₄. Surface wetting by the liquid adhesive was shown to be improved by the acid treatment. The molecular weight of polymer or copolymer employed in the liquid adhesive had an important effect on bond strengths. The optimum molecular weight for obtaining maximum bond strengths was around 20,000 g./mole. Water immersion of the bonded specimens at 37°C. for periods up to 6 weeks had a deleterious effect on bond strengths. Nevertheless, it was shown that some of the adhesives formed reasonably strong bonds for periods exceeding 6 months even with water immersion.