Foam slip on surfaces of intermediate or low wettability

Wall slip of foams is important in several practical contexts. If the surface is not perfectly wetted by the interstitial liquid, the foam-wall interface may exhibit a yield stress. This paper represents the first quantitative study of this phenomenon. A simple model of the interface between disorganized foam and a solid surface is presented. This model treats the interface as a network of soap film contact lines. Experimental data are presented on the tension at soap film contact lines, and the stress at the foam-solid interface, at very slow translation speeds and for several surfaces. These agree broadly with theoretical predictions up to parity of the interface yield stress with the bulk yield stress of the foam. The experimental data include the yield tension for a soap film contact line pulled in an oblique direction with respect to the contact line normal. These data are also broadly consistent with theoretical predictions.     

影响橘纹漆效果的因素分析

阐述了双组分聚氨酯橘纹漆的配制及其施工工艺,研究了其生产工艺流程,列举了该涂料的物理机械性能和耐化学的性能指标,着重讨论了助剂、色浆、溶剂、施工条件对产品性能的影响。结果表明,色浆用量在50.0%,橘纹剂选择SP-902且用量0.5%,橘纹漆与固化剂比例为4:1时,橘纹效果良好。     

环氧/聚氨酯IPN连续梯度材料的制备和表征

利用控制组分流量的机械连续法制备得到了具有连续梯度的环氧/聚氨酯IPN梯度材料.通过傅立叶变换红外光谱分析、热分析以及扫描电镜等手段表征了材料的梯度结构.结果表明:所制备的材料具有较好的梯度结构,组分的含量从一端到另一端梯度渐变.通过梯度材料的硬度和密度的分析,计算得到了梯度材料中各组分体积分数沿轴向的变化情况.所制备的梯度材料中存在微孔结构,并且随着聚氨酯组分含量的增多,微孔孔径变大,数目增多.     

Hybridization of aqueous PU/epoxy resin via a dual self‐curing process

Amino‐terminated and carboxyl‐containing polyurethane (PU) is prepared by an isocyanate‐terminated PU prepolymer process. Carboxyl‐containing epoxy resin is obtained from a half‐esterification of epoxy resin with maleic anhydride. These two aqueous resins are obtained after neutralization with triethylamine and dispersion into water phase, respectively. A latent curing agent (TMPTA‐AZ) is prepared by a Michael addition of aziridine with trimethylolpropane triacrylate (TMPTA). A self‐curing system of PU/epoxy hybrid is obtained from a blending of these two aqueous resins with latent curing agent. PU/epoxy hybrid is derived from two self‐curing reactions on drying. The first curing for hybridization between PU amino groups with oxirane groups of epoxy resin is via a ring‐opening reaction and the secondary curing takes place on carboxyl groups of PU/epoxy hybrid with aziridine of TMPTA‐AZ. The final properties of these dual self‐cured PU/epoxy hybrids are reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

单组分聚氨酯防水涂料性能分析

防水涂料类型有许多种,其中聚氨酯防水涂料由于具有防水性能好、耐腐蚀性能高、硬度大、弹性高等优点,在建筑防水工程中得到了广泛的应用。聚氨酯防水涂料有双组分和单组分之分,本文论述了双组分聚氨酯防水涂料存在的不足及单组分聚氨酯防水涂料的优点,指出了影响单组分聚氨酯防水涂料性能的诸多因素。     

PU白面漆耐黄变性探讨

简单介绍了涂料黄变的机理及聚氨酯白面漆的制备,并对其进行加速老化实验,分析对比各种原料对聚氨酯白面漆黄变的影响。结果表明,影响黄变的最大因素是固化剂,其次是钛白粉和树脂,而紫外线吸收剂对其影响较小。     

配方因素对CR/PU并用胶性能的影响

研究CR/PU并用比、硫黄用量、炭黑品种和用量及增塑剂品种对CR/PU并用胶物理性能的影响,并确定并用胶优化配方.CR/PU并用胶的优化配方为:CR 80,PU 20,炭黑N220 30,硬脂酸锌 1,氧化镁 4,古马隆树脂5,硫黄2,促进剂DM 3.促进剂M 3.该配方并用胶的综合物理性能良好.     

水性光敏聚氨酯丙烯酸酯的合成与性能研究

用IPDI、DMPA、PTMG和HEMA合成了紫外光固化聚氨酯丙烯酸酯(PUA)水乳液。采用FTIR、国标GB12009.4-89等方法对该PUA预聚体合成过程和组分进行了测试和表征,考察了n(-NCO)/n(-OH)、羧基含量、pH值等对此乳液及涂膜性能的影响。结果表明:当n(-NCO)/n(-OH)=1.3左右,-COOH含量为1.4%～3.4%(质量分数),中和度为85%～100%时,合成的乳液制成的涂膜具有更加优良的机械性能、耐化学性、耐水性等。     

加压对铝合金消失模铸造的影响

试验研究了浇注后型腔压力对消失模铸造的铝件表面状态、力学性能影响的趋势。加压后提高了铝液充型能力,有利于消除铸件表面的颗粒状和冷隔,抑制气孔形成,使抗拉强度、密度略有提高;加大压力作用在浇口及铸件表面的时间差,铸件表面将出现凸起、粘砂;过早卸压将恶化铝件性能。