The role of the polymer/metal interphase and its residual stresses in the critical strain energy release rate (Gc) determined using a three-point flexure test

The critical strain energy release rate (G _c), the residual stresses (σ), Young's modulus (E), and the practical adhesion, characterized by ultimate parameters (F_max or d_max), of organic layers made of DGEBA epoxy monomer and IPDA diamine hardener were determined. The prepolymer (DGEBA-IPDA) was deposited both as thick coatings and as a mechanical stiffener onto degreased aluminum alloy (5754) or chemically etched titanium alloy (Ti-6Al-4V). During the three-point flexure test used as a practical adhesion test [this test is also called the double cantilever adhesion test (DCAT)], the failure may be regarded as a special case of crack growth. To understand the real gradient properties of the interphase, substrate, and bulk polymer properties, a three-layer model was developed for quantitative determination of the critical strain energy release rate (G_c). The particular characteristic of this model was to consider the residual stresses developed within the entire three-layered system, leading to an intrinsic parameter representing the practical adhesion between a polymer and a metallic substrate. Moreover, to determine the residual stresses generated in such three-layer systems, the gradient of interphase mechanical properties was considered. The maxima of residual stress intensities are found at the interphase/substrate interface, leading to an adhesional (interfacial) failure that is experimentally observed. The determination of the critical strain energy release rate by the three-point flexure test (DCAT) shows that residual stresses cannot be neglected. A comparison between the results obtained from the three-point flexure test (DCAT) and those obtained by the tapered double cantilever beam (TDCB) test is presented.     

Particle Cleaning of EUV Reticles

The practical adhesion, characterized by either ultimate parameters (F _max or d _max) or the critical strain energy release rate (G _Ic) using the three-point flexure test (ISO 14679-1997), and the residual stress (σ ) profiles within systems of organic layers made of DGEBA epoxy monomer and IPDA diamine hardener were determined. The prepolymer (DGEBA-IPDA) was deposited as thin and thick coatings onto degreased or chemically etched aluminum alloy (5754). To understand the role of the interphase, either a tri-layer (bulk coating/interphase/substrate) or a bi-layer model (bulk coating/substrate) were used for quantitative determination of the critical strain energy release rate. Indeed, as the interphase formation results from both dissolution and diffusion phenomena, we were able to control the interphase formation within coated systems by controlling the liquid-solid contact time and then to make tri- or bi-layered systems. In the three-point flexure test used to determine the practical adhesion, the failure may be regarded as a special case of crack propagation. The model considers residual stresses developed within the entire system leading to an intrinsic parameter representing the practical adhesion between the polymer and the metallic substrate. Moreover, to determine the profiles of residual stresses generated in such systems, the Young's modulus gradient of the interphase was also considered. The maxima in residual stress intensities were found at the interphase/substrate interface for a tri-layer system and at the coating/substrate interface for a bilayer system leading for all systems to an adhesional (interfacial) failure as experimentally observed. A comparison between the results obtained from the three-point flexure test and the Tapered Double Cantilever Beam (TDCB) was made. The determination of the critical strain energy release rate shows that residual stresses cannot be neglected. G _Ic depends on the substrate surface treatment when the residual stresses were neglected. Moreover, we have determined the role of the interphase formation on the practical adhesion before and after hydrothermal aging. The results obtained emphasize that the epoxy/metal interphase affects significantly the initial practical adhesion. However, organo-metallic complex formation improves considerably the hydrothermal durability, as these complexes act as corrosion inhibitors.     

Anticorrosive polyurethane paints with nano- and microsized phosphates

Two types of phosphate fillers (nanosized aluminum phosphate and microsized aluminum–zinc phosphate) were tested as anticorrosive fillers in 2 K solvent-borne polyurethane paints based on commercial acrylic resin with OH groups and an isophorone diisocyanate-type hardener. Three coating compositions containing commercial fillers (mica/quartz, TiO₂, wollastonite, talc) and also mentioned nanosized aluminum phosphate or microsized aluminum–zinc phosphate were prepared using a pearl-mill as well as a laboratory dissolver, applied onto a steel substrate and cured at room temperature for 14 days. An influence of the type and content of a phosphate filler on properties of polyurethane paints and coatings has been investigated. Incorporation of nanosized aluminum phosphate into coating compositions increases their viscosity while cured paints exhibit reduced adhesion to steel substrates. The results of corrosion tests in a salts spray chamber as well as immersion in an aqueous NaCl solution indicated that the paint system with 9.8 wt.% of applied nanofiller had similar protective properties to a polyurethane coat containing a higher dose (i.e. 15.6 wt.%) of commercial microsized aluminum–zinc phosphate.     

高附着耐水煮玻璃漆的研制

合成了玻璃环氧底漆,讨论了附着力促进剂、树脂和固化剂种类及用量对涂料性能的影响.结果表明,以1.5%3-缩水甘油醚氧基丙基三甲氧基硅烷为附着力促进剂,以E-20环氧树脂为成膜物、腰果壳油改性酚醛胺为固化剂制成底漆,配合丙烯酸聚氨酯黑面漆,获得了高附着,耐水煮的玻璃漆.     

PP塑料表面涂料的研制

用氯化聚丙烯(CPP)、附着力促进剂(C)、热塑性丙烯酸树脂(BS)等原料制出PP塑料用涂料,并对所用的溶剂、反应过程、操作条件和结果作了较为详细的叙述。     

太阳能反射镜镜背保护涂料的应用研究

以灰色环氧磷酸锌防腐涂料为底漆、丙烯酸改性聚硅氧烷涂料或丙烯酸聚氨酯涂料为面漆,作为太阳能反射镜镜背保护涂料,对保护涂料的施工工艺以及2种面漆的防护性能等进行了研究,研究表明:丙烯酸改性聚硅氧烷涂料配套体系的附着力、反射率、中性盐雾、CASS喷雾试验、人工加速老化、湿热试验及抗气候循环试验等各项性能指标达到了相应的技术标准,较传统的丙烯酸聚氨酯面漆在恶劣环境中更适合太阳能反射镜的保护。     

Performance of paint systems with polyurethane topcoats, proposed for atmospheres with very high corrosivity category

The EN ISO Standard 12944-5 describes the types of paint and paint systems commonly used for corrosion protection of steel structures. In this work four paint systems, applied on steel, including polyurethane topcoats, recommended for atmospheres with high corrosivity (C5 category), codified by 1–4, were studied. Systems 1 and 4 include zinc rich primers and epoxy/polyamide intermediates, system 2 has solvent free epoxy/polyamide primer and intermediate and, system 3 is a hybrid system with vinyl–acrylic water based primer and a high solids epoxy/polyamide intermediate. Systems 2–4 have acrylic–polyurethane topcoats and, the topcoat of the system 1 was identified as an aliphatic polyurethane.

According to EN ISO 12944-6, water condensation and neutral salt spray tests were performed. Three exposure times were considered taking into account the durability ranges of paint systems: low, medium and high, respectively. The paint systems were complementary submitted, during 30 days, to ultraviolet radiation with water condensation test according to ASTM G 154. At the same time, natural exposure was conducted in the marine atmosphere of Sines, with very high corrosivity (>C5).

The paint adhesion, before and after artificial ageing, was evaluated by cross-cut test and, for the systems with dry thickness greater than 250 μm, by pull-off test. Visual inspections were carried out.

For the exposure in UV radiation test chamber and at test site, gloss reduction, colour change and chalking were measured. Chemical changes on polyurethane topcoats exposed in the UV radiation test chamber were studied by Fourier transform infrared spectroscopy (FTIR).

In spite of the higher aesthetic degradation by UV radiation, of the aliphatic polyurethane topcoat of the system 1 relatively to the acrylic–polyurethane topcoats of the other systems, system 1 with ethyl silicate zinc rich primer and epoxy intermediate, was the one that presented the best corrosion protection when exposed in artificial and natural salty environments. At the test site, the worst anticorrosive behaviour seems to be presented by the system 2 with two coats of solvent free epoxy paint.     

A three-point flexure test configuration for improved sensitivity to metal/ adhesive interfacial phenomena

A three-point flexure test was used to evaluate the effects of chemical surface treatments on the performance of adhesively-bonded structures of Ti6A14V. A single adherend/adhesive structure rather than a double adherend sandwich configuration is shown to be sensitive to pre-bonding adherend surface treatments. Data is presented which relates mechanical properties with chemically treated adherend surfaces. Photoelastic isochromatic fringes were recorded simultaneously with the flexure test as a means to monitor stress distribution, failure initiation, and crack propagation.     

丙烯酸改性无油醇酸树脂聚氨酯涂料

以活性羧基丙烯酸改性无油醇酸聚氨酯涂料具有较好的流平性、丰满度、耐候性,且生产成本低,是一种综合性能优异的自干型涂料.本文简介了其反应原理、合成工艺、测试结果以及影响产品性能的主要因素.     

Adherence evaluation of paint coatings using a three‐point flexure test and acoustic emission

The adherence of paint coatings on aluminum substrates was tested using a three‐point flexure test (TPFT) combined with acoustic emission (AE) evaluation. The mechanical test was defined according to the French Standard. During bending of the paint‐coated specimen, acoustic emission signals were recorded and analyzed. Substrate pretreatments were chosen to show a set of visual interfacial ruptures and a set of visual cohesive ruptures in the paint. The formulation of the paint was fixed by industrial regulations. The varying nature of systems showed different AE patterns, particularly for two types of specimens: those that corresponded to solvent degreasings and the others to aqueous chemical pretreatments. The behavior of the paint coating differed, with significant AE, damage, and crack propagation in the first case and instantaneous phenomena in the other case. It is then possible to establish a relationship between the analysis of the recorded AE signal and the type of joint rupture. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1848–1857, 2001     

拉开法附着力试验测试结果影响因素的探讨

选择若干种油漆样品和若干种底材,按标准方法进行拉开法附着力试验,对试验结果进行了分析比较,并由此探讨了拉开法附着力试验测试结果的影响因素。结果表明底材越粗糙或越厚测试数据越大,样板与试柱对接与否对试验数据的影响略小,底材越厚越坚硬对测试结果影响越小,胶粘剂的粘结力越强,测试数据越大,拉伸速度对测试结果无明显影响。     

开放式透明涂饰工艺探索及漆膜性能分析

分析了水性木器漆在应用过程中存在的优势与不足,深入探索了水性聚氨酯木器漆开放式有色透明涂饰工艺,同时对干燥后的漆膜与溶剂型聚氨酯木器漆漆膜在硬度、耐磨性、耐干热性、附着力、耐冲击性、耐液性等性能上进行了对比。结果表明：所选水性木器漆漆膜在硬度、耐磨性、耐冲击性方面与溶剂型漆膜差别不大,在耐干热性、附着力、耐液性方面相差较大。     

丙烯酸阴极电泳漆的研制

介绍了采用甲基丙烯酸缩水甘油酯与常用的丙烯酸单体通过溶液聚合,制备丙烯酸阴极电泳漆的简单可行方法。研制的电泳漆克服了环氧-聚氨酯阴极电泳漆的缺点,具有可着色性、高装饰性、高耐候性等特点。讨论了影响电泳漆性能的诸种因素。列举了电泳原漆的技术指标、施工参数和漆膜性能指标。     

不同加速试验对环氧/聚氨酯涂层失效机制的影响

研究了模拟南海海洋大气环境下铝合金表面环氧锌黄/丙烯酸聚氨酯涂层体系的失效过程,通过循环加速、紫外/冷凝和中性盐雾的对比试验,探讨了在循环加速试验中紫外-冷凝试验和盐雾试验分别对复合涂层失效过程以及对聚氨酯面漆和环氧底漆失效机制的影响。结果表明,紫外-冷凝过程对丙烯酸聚氨酯面漆有较强的破坏作用,但对复合涂层体系整体的阻抗变化影响较小;紫外-冷凝过程中,位于面漆玻璃化转变温度范围内的试验温度,以及紫外光对氨基甲酸酯基团的破坏作用,是导致面漆发生破坏的主要原因。盐雾试验对面漆的失光率和色差变化影响不大,但连续的盐雾渗透对涂层体系的阻抗下降具有明显的加速作用,同时导致涂层与基材的附着力显著降低。相比单独的紫外-冷凝试验或盐雾试验,循环加速试验综合考虑了南海海洋大气中强太阳辐射、高温高湿、高盐分和温差等环境因素,能更准确反映南海大气环境中复合涂层的失效过程。     

拉开测试法评定机械镀锌层的结合强度

分别采用划格法和拉开法测量了机械镀锌层与A3钢片的结合强度。结果表明:划格法只能定性地对镀层结合性能进行评价,其结果不能准确反映镀层的结合强度;拉开法则能较准确地定量反映镀层的结合强度,且随着镀层厚度的增加,镀层结合强度呈下降趋势。     

常温固化耐磨防腐涂料的研制

以聚氨酯为基体,添加聚四氟乙烯、氧化铁、钛白粉等填料,研制出一种双组分常温固化涂料。通过正交试验和极差分析得出最佳配方。当聚氨酯的用量为10g、聚四氟乙烯为4g、钛白粉为0．5g、氧化铁为0．5g时,测试结果表明涂层综合性能最佳,即：涂层的附着力为0级,硬度为3H,磨耗量为0．018g。     

水性树脂复配与成膜助剂选择对单组份水性木器漆性能的影响

介绍了一种高硬度单组份自交联水性木器漆的制备,通过水性聚氨酯分散体和水性丙烯酸乳液进行复配,选择合理复配比例,并讨论了成膜助剂对涂料综合漆膜性能的影响。结果表明：水性聚氨酯分散体E与丙烯酸乳液A按质量比1：1复配,漆膜各性能达到最佳。通过FTIR分析可知,两种树脂发生的自交联反应,两者之间存在氢键的作用。选用二丙二醇甲醚（DPM）与二丙二醇丁醚（DPnB）为成膜助剂,按质量比1：1复配,漆膜硬度较高,表面效果好,其他性能也显著提高。     

4D printing of polyurethane paint-based composites

ABSTRACT

In recent studies, polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing. In this study, we present a simple and inexpensive additive method to print waterborne polyurethane paint-based composites by adding carboxymethyl cellulose (CMC) and silicon oxide (SiO₂) nanoparticles to the paint. The first function of CMC and SiO₂ is to improve rheological properties of the polyurethane paint for making a printable precursor, which improves the printing resolution and enhances additive manufacturability. Second, the composite precursors improve the curing rate of the polyurethane paint without changing its inherited shape memory properties. Third, the printed composite parts shown enhanced mechanical strength compared with that of the parts printed with pure polyurethane. Finally, the 3D printed polyurethane-CMC and SiO₂ parts exhibit time-resolved shape transformation upon heat stimulation. To the best of our knowledge, this is the first study of using the polyurethane paint as the precursor for 4D printing, which would open new possibilities in future applications in biomedical engineering, soft robotics and so on.     

用脱漆剂脱漆膜后的处理工艺

通过试验确定了喷涂锌黄丙烯酸聚氨酯底漆的金属零件脱漆膜之后的脱漆处理工艺及脱蜡后处理工艺，采用该工艺对喷涂零件进行处理后，进行产品粘接，效果良好。     

水性集装箱外面漆的制备及性能研究

以水性丙烯酸和聚氨酯树脂作为成膜物质,制备出一种有较高耐老化和耐腐蚀性能的集装箱外用面漆.对影响面漆耐蚀性能的一些因素进行了研究,如树脂和颜料类型,消泡剂种类,分散剂种类及用量,以及纳米浆料添加量等.结果表明,当苯丙乳液与聚氨酯乳液以1:2的质量比复配作基料,选用浓缩型分子级消泡剂E,嵌段共聚物分散剂D用量为0.6%,...