环氧树脂硫化聚硫醚密封剂的性能研究

以液体聚硫醚橡胶作为密封剂的生胶、环氧树脂(EP)作为硫化剂,成功制备出一种综合性能良好的新型聚硫醚密封剂。结果表明:聚硫醚橡胶的热分解温度(296.4℃)高于聚硫橡胶(281.0℃),热循环后聚硫醚密封剂的拉伸强度变化率或断裂伸长率变化率(31%或42%)均低于聚硫密封剂(45%或64%),说明前者的耐高温性能优于后者;聚硫醚密封剂对多种基材表现出稳定的粘接性能,其常温剥离强度均超过7.5 kN/m(均为内聚破坏),并且其在60℃盐水/航空煤油双层液中浸泡7 d后仍为内聚破坏;聚硫醚密封剂受温湿度影响较小,其硫化速率较大,并且其硫化效果和加工性能良好。     

环氧胶改性丁苯橡胶可剥离涂料的制备

用环氧胶[由环氧树脂、固化促进剂2,4,6-三(二甲胺基甲基)苯酚和丁腈橡胶增韧剂组成]改性丁苯橡胶,制备了一种可剥离涂料。考察了环氧胶的用量及其成分的配比对所得涂层剥离强度、拉伸强度及耐介质性能的影响。当环氧胶用量为丁苯橡胶溶液(40%固含量)的5%时,涂层的180°剥离强度为0.93 kN/m,拉伸强度达到13.56 MPa。2 mm厚的涂层分别在6%氢氧化钠溶液,质量分数33%的硝酸溶液,以及90°C的水中浸泡5 min,质量变化率均小于0.30%,且剥离强度未降低。在铝基材化学镀镍和电镀金中的实际应用证明了该可剥离涂料适用于做局部电镀的保护涂层。     

高强度有机硅密封剂的耐热性能研究

以α,ω-二羟基聚二甲基硅氧烷为基础聚合物(基胶),经特殊表面处理的气相法白炭黑为补强填料,制备了高强度室温硫化有机硅密封剂;比较了基胶的结构、抗氧剂的种类、硫化体系对有机硅密封剂耐热性能的影响.结果表明,使用107硅橡胶为基胶,配以脱氢型硫化体系能配制高强度有机硅密封剂;密封剂的拉伸强度、伸长率和180°剥离强度分别达到7.0 MPa、550%和8.8 kN/m以上,可以作为电器灌封料和密封剂使用;密封剂的耐热空气老化性能优异,合适的抗氧剂是801种子胶和Fe2O3,制得的密封剂分别为白色和红色.     

一种非热压罐成型高性能玻璃布复合材料性能研究

对3233VB中温固化树脂进行流变性能和DSC分析分析,确定3233VB中温固化树脂的固化工艺;采用热熔法制备一种中温固化环氧玻璃布预浸料-3233VB/EW180B预浸料,通过真空袋法、模压法和热压罐法成型复合材料板,分别进行性能测试和对比。结果表明,3233VB/EW180B玻璃布预浸料适合真空袋法成型复合材料;3233VB树脂具有良好的韧性,夹层结构的抗滚筒剥离强度高,其预浸料可与蜂窝直接共固化;预浸料树脂质量分数相同时滚筒剥离强度随着预浸料层数的增加而提高。     

交联剂对保护膜用丙烯酸酯乳液压敏胶性能的影响

选用反应性乳化剂,采用预乳化半连续聚合方法,合成出了保护膜用丙烯酸酯乳液压敏胶。探讨了多官能度乙烯基内交联剂M和外加氮丙啶交联剂SC－100、环氧交联剂GA240用量对压敏胶初粘性、180°剥离强度、180°剥离强度增幅及湿热老化性能的影响。结果表明,随交联剂M、SC-100及GA－240用量增大,压敏胶的180°剥离强度及180°剥离强度增幅减小．湿热老化性能提高,初粘性随交联剂M用量增大变化不大,随SC－100及GA－240用量增大而降低;外交联剂GA－240在提高压敏胶湿热老化性能和抑制剥离强度增长方面比SC－100的效果好,相同用量下,使用GA～240的180°剥离强度高于SC－100;采用单体量0．2％的内交联剂M,胶液量03％的GA－240或05％的SC－100,制得的表面保护膜对PVC型材的贴附性良好,湿热老化后剥离时型材表面无残胶。     

防腐涂料和密封剂相容性试验研究

整体油箱具有载油量大、质量轻等特点而被各型飞机广泛采用,其内表面需采用特别的密封防腐涂层系统,以保证整体油箱具有较高的“三防”能力和密封性能,提高整体油箱的可靠性和长寿命。本文参照整体油箱材料配套性能中的试验设计,研究了飞机拟采用的 454-4-1防腐涂料与国内燃油以及与 HM113B-4、HM116C-8密封剂的配套相容性。试验结果表明： 454-4-1涂层具有良好的耐水性、耐盐水和燃油性以及耐 15号航空液压油性。 454-4-1涂料与 HM116C-8和 HM113B-4密封剂表面具有良好的粘接力。阳极化的铝合金 +454-4-1涂料 +NJD-3底涂 +HM116C-8/HM113B-4密封剂组成的整体油箱密封体系,材料之间相容性较好,可满足涂层体系各层间粘附性要求。     

环氧树脂对液体聚硫橡胶粘接及力学性能的影响

通过对密封剂180°剥离、拉伸试验、热空气老化及耐高温、耐油等测试,研究了不同类型环氧树脂以及环氧树脂用量对聚硫密封剂粘接性能、耐高温空气和耐高温燃油性能的影响,并对其机理进行讨论。结果表明,酚醛环氧树脂具有较好的增黏和增强效果,添加量为2～3份时,密封剂与铝合金基材间的破坏形式为100%内聚破坏,力学性能、耐热性能及耐油性能最佳。当其添加量继续增加时,密封剂性能逐渐下降。     

碳化硅涂层的离子注入改性

在SiC涂层表面注入Al^3＋,B^3＋,St^4＋,观察3种离子注入对涂层表面裂纹的封填情况,分析离子注入后涂层表面的相组成,考核离子注入对SiC-C／SiC材料抗氧化性能的影响。在1300℃模拟空气中氧化15h后,注入Al^3＋的复合材料的氧化质量损失比未经涂层改性的降低了0．3％,形成的玻璃氧化层中气泡和孔洞少,对涂层裂纹的封填效果较好但覆盖不均匀。注入B^3＋的复合材料的氧化质量损失比未经涂层改性的降低了0．1％,形成的玻璃氧化层的流动性好且覆盖均匀,但其表面多气泡和孔洞,破坏了玻璃氧化层对涂层裂纹的封填作用。注入Si^4＋的复合材料的氧化质量损失同注入B^3＋的试样基本相当,但是其氧化质量损失有增大趋势,表明Si^4＋的注入对改善材料的抗氧化性能无积极作用。     

金属橡胶热硫化型底胶的研制

研制了一种酚醛一橡胶型底胶,探讨了主要组分对底胶性能的影响。实验结果表明,以n甲醛：n苯酚：n氮氧化钾=2．25：1：0．1,在65℃／3h合成的甲阶酚醛树脂具有高羟基含量,能满足底胶主体树脂要求;当该酚醛树脂100质量份、氯化橡胶60~80份、硅烷偶联剂10-15份、钛白粉30~35份时底胶具有较高强度,扯离强度40MPa以上,剥离强度3．0kN／m以上,且试件破坏形式主要为橡胶内聚破坏。该底胶作为单涂层胶粘剂可实现极性橡胶与金属的热硫化粘接,与相适应的面胶配合构成的双涂层胶接体系还可实现非极性橡胶与金属或复合材料的热硫化粘接,目前已在金属橡胶粘接领域获得了应用。     

PBAT基生物降解胶带的制备及性能研究

以生物降解树脂聚对苯二甲酸己二酸丁二醇酯(PBAT)、聚乳酸(PLA)和硅灰石纤维为主要原料制备得到PBAT/PLA/硅灰石纤维复合材料,以该复合材料为原料,采用吹膜工艺制备得到PBAT基生物降解基材层,选取3种压敏胶,考察不同涂胶厚度对胶带初黏力等性能的影响,同时进行湿热老化实验,考察环境因素对胶带材料的影响。研究结果表明,环保压敏胶综合效果最好,涂胶厚度20μm时,180°剥离强度为4.92 N/cm,初黏力达到18号,指标远超行业标准要求。     

有机硅密封剂高温力学性能研究

在温度25~250℃对3类硫化体系的5种有机硅密封剂的拉伸强度、180o剥离强度和剪切强度的研究表明:随着温度的升高,5种有机硅密封剂的拉伸强度、180o剥离强度和剪切强度均不断下降,其中拉伸强度和剪切强度降低的速率递减。有机硅密封剂的高温性能变化与硫化体系类型密切相关,脱氢硫化体系HM321密封剂在25~150℃拉伸强度、剪切强度和180o剥离强度均最高,但在25~250℃拉伸强度、剪切强度和180o剥离强度保持率均最低。脱氨硫化体系XY-602S有机硅胶粘剂在232~250℃的拉伸强度和剪切强度最高,25~250℃的拉伸强度保持率也最高。     

In situ synthesis and properties of hydrogenated rosin/polyacrylate composite miniemulsions-based pressure sensitive adhesives

Hydrogenated rosin/polyacrylate composite miniemulsions-based pressure sensitive adhesives were synthesized by in situ miniemulsion polymerization method. The effect of HR amount on the monomer conversion rate, particle size and its polydispersity, coagulum rate, Zeta potential, and stability of the composite miniemulsions were studied, the effect of HR and crosslinker amount on the adhesion properties of the composite latex films were also investigated, and the composites were characterized by differential scanning calorimetry (DSC) and gel permeation chromatograph. The results showed that with HR amount increasing, the monomer conversion rate decreased, and the absolute value of Zeta potential and the molecular weight of the sol in the composite latex films also decreased, while the particle size and its polydispersity were almost unaffected. DSC analysis indicated that HR had relative good compatibility with polyacrylate. However, excess HR amount led to the decrease of the centrifugal stability and storage stability of the composite miniemulsions. Furthermore, with HR amount increasing, the ball tack of the latex films increased gradually, 180^o peel strength first increased and then decreased, and holding force decreased constantly. When HR amount exceeded 10 wt%, the failure style changed from interface failure to cohesion failure. The crosslinker CX-100 was helpful for the improvement of 180^o peel strength and holding force. When HR and CX-100 amount were 10 and 0.6 wt%, the ball tack, 180^o peel strength, and holding force were 9 #, 8.9 N/25 mm, and 178 h, respectively.     

保护膜用丙烯酸酯乳液压敏胶的研制

选用反应性乳化剂,采用预乳化半连续聚合方法,合成出了综合性能良好的保护膜用丙烯酸酯乳液压敏胶。探讨了单体组成、乳化剂和引发剂用量对压敏胶初黏力、180°剥离强度、180°剥离强度增幅及耐高温高湿老化性能的影响。结果表明:当2-EHA/BA为8/2～6/4,MMA/VAc为6/4～4/6,MAA为3份,乳化剂和引发剂用量分别为单体用量的0.75%和0.5%时,压敏胶综合性能良好,适用于PVC型材表面保护膜的制造。     

Effects of corona treatment on composite formation. Adhesion between incompatible polymers

Polypropylene–nylon 6 10 composites were prepared by the in situ polymerization of the nylon monomers on polypropylene films. The adhesion between the nylon and the polypropylene was markedly improved by a brief corona discharge treatment of the films in nitrogen prior to coating. This improvement was demonstrated by an increase in the peel strength of the nylon coating and a decrease in brittleness of photo-oxidized compesites when corona treatment was used. Adhesive bonding between the nylon and substrate was sufficiently strong to cause cohesive failure in the corona-treated polypropylene. Only interfacial failure was observed at untreated surfaces. These effects were demonstrated by electron microscopy of the surfaces produced in peel tests. The effects of corona treatment on adhesive bonding characteristics of surfaces are discussed in terms of the chemical and physical changes observed in treated surfaces.     

Scanning Electron Microscopic Studies on the Failure of Rubber-to-Metal Bonded Composites

Scanning electron microscopic studies were conducted to evaluate the failure mechanism of rubber-to-metal bonded composites in the 90° peel test (ASTM D 429-B). It was found that when cohesive failure in rubber takes place, the composites, failing by stick-slip mode, show high peel strength. Moreover, in such cases, there exists a linear correlation between the peel strength and the crosslink density of the rubber vulcanizate.     

Dependence of Peel Adhesion on Molecular Weight of Epoxidized Natural Rubber

The effect of molecular weight of two grades of epoxidized natural rubber (ENR)—i.e., ENR 25 and ENR 50—on the peel strength of an adhesive is studied using coumarone-indene resin, gum rosin, and petro resin as tackifiers. Toluene and polyethylene terephthalate (PET) film acted as the solvent and substrate, respectively. A SHEEN hand coater was used to coat the adhesive on the substrate to give coating thicknesses of 30, 60, 90, and 120 µm. The peel strength of adhesive was determined using a Lloyd Adhesion Tester operating at 30 cm/min. Results show that peel strength has a maximum value at a molecular weight of 6.8 × 10⁴ and 3.9 × 10⁴ for ENR 25 and ENR 50, respectively, an observation which is attributed to the combined effects of wettability and mechanical strength of the rubber at the respective optimum molecular weight of ENR. Peel strength increases with coating thickness for all the tackifiers investigated, with a gum rosin-based adhesive exhibiting the highest peel strength.     

Improvement of the adhesion of silicone to aluminum using plasma polymerization

The adhesion-in-peel test was used to determine peel strength and adhesion characteristics of a cured-in-place silicone elastomeric joint sealant on aluminum substrates. The sealant used was a Dow Corning Type 3145 RTV Adhesive Sealant. The results showed that the silicone sealant had poor adhesive bonding to the untreated aluminum. Plasma polymerization of hexamethyldisiloxane (HMDS) onto the aluminum was seen to move the locus of adhesive failure to being between the plasma film and the silicone. Plasma polymerization of HMDS with oxygen carrier gas produced excellent adhesion and cohesive failure in the silicone was observed.     

A Study on Structure and Mechanical Properties of Polyurethane/Organic-Montmorillonite Nanocomposites

The intercalated nanocomposites of polyurethane (PU) with organic-montmorillonite (OMMT) treated by cetryltrimethyl ammonium bromide was prepared. The interlayer spacing of PU/OMMT nanocomposites was 3–4 nm. The interface interaction of PU/OMMT nanocomposites was improved compared to that of PU/montmorillonite (MMT) composites. The orderly arrangement of the PU chains was hindered because of strong interface interaction between the silicate layers dispersed in the nanometer and PU chains. By adding 2 wt% OMMT to PU, tensile strength and tear strength of the PU/OMMT composites were increased from 10.5 MPa and 36.4 KN/m to 13.8 MPa and 42.2 KN/m, respectively. The tensile strength and tear strength increased with OMMT content firstly, reaching its maximum when the OMMT content was 8 wt%. After that, the tensile strength and tear strength decreased with the further increase of the OMMT content. Compared to that of PU, the elongation at break of the PU/OMMT nanocomposites increased, indicating that the stretch of PU/OMMT nanocomposites increased.