常用建筑胶粘剂的改性

常用建筑胶粘剂产品众多。对之改性，是提高其性能、质量的一大途径。讨论了聚乙烯醇缩甲醛胶、聚醋酸乙烯酯胶、脲醛胶、淀粉胶的改性途径，介绍了各改性产品的配方及其性能比较。     

聚乙烯醇包覆玉米秸秆纤维对石膏性能的影响

利用玉米秸秆纤维增强石膏胶凝材料,并采用聚乙烯醇时玉米秸秆纤维进行表面包覆改性,研究其对玉米秸秆纤维/石膏复合材料性能的影响.利用扫描电子显微镜对试样进行了微观分析,探讨了未改性玉米秸秆纤维/石膏复合材料防水性能较差的原因,提出了聚乙烯醇包覆改性秸秆纤维的示意模型.结果表明:掺加未改性玉米秸秆纤维可提高石膏胶凝材料的力...     

改性聚乙烯醇的合成及应用

按文献介绍聚乙烯醇的改性方法和应用。     

糯米淀粉/聚乙烯醇复合改性氯氧镁胶凝材料性能的研究

研究了糯米淀粉/聚乙烯醇复合改性对氯氧镁胶凝材料(MOC)性能的影响,通过XRD、SEM、FT-IR等对样品的水化相、微观形貌和官能团键合情况进行了表征和分析。结果表明:糯米淀粉复合聚乙烯醇改性有利于保持MOC体系中的强度相,糯米淀粉和聚乙烯醇的活性官能团与MOC发生一定的化学键合,使水化物呈现重叠交叉网状形貌,结构更加致密;3%糯米淀粉+1.5%聚乙烯醇复合改性MOC的软化系数达到0.89,耐水性能得到较大改善。     

青海地区改性夯土材料抗压性能试验研究

为改善传统夯土墙的力学性能,使用青稞秸秆、石子、聚乙烯醇、固化剂、防水剂对夯土进行改性,通过对改性夯土试件进行无侧限抗压试验,分析改性试件的抗压强度、荷载-位移曲线.结果表明,添加青稞秸秆可以改善夯土试件脆性破坏的特性;夯土中掺入0.25％青稞秸秆、20％石子和0.8％固含量的聚乙烯醇时,改性试件的抗压强度比素土试件提...     

SQ—86耐洗擦内墙涂料

本文介绍了以改性聚乙烯醇缩甲醛为主要成膜物质的耐洗擦内墙涂料的配方、工艺流程及涂料和涂膜的性能,并对耐冼擦内墙涂料的成本作了经济对比分析。     

高炉渣纤维保温板新型粘结剂的配合比研究

针对高炉渣纤维的高附加值应用,选取适宜的聚乙烯醇溶液浓度,以不同用量戊二醛改性聚乙烯醇制备用于高炉渣纤维制品的新型粘结剂,制备高炉渣纤维保温板。通过测试其密度、吸湿率和耐酸碱性等性能指标,确定所制备的新型粘结剂中戊二醛的使用量。结果表明:制备高炉渣纤维保温板用新型粘结剂的最优方案是以聚乙烯醇固体分5%的戊二醛改性浓度3%的聚乙烯醇溶液。     

抗冻水性聚乙烯醇缩醛胶

为了提高胶水的抗冻性,本文介绍了采用羟甲脲与聚乙烯醇反应生成聚乙烯醇缩脲甲醛的方法,并对其配方和反应条件进行了初步探讨。     

高强抗冻改性乳胶生产与应用

介绍了一种用聚丙烯酸酯和硅溶胶改性聚乙烯醇缩甲醛的制备方法和用途。制得的改性乳胶同传统的聚醋酸乙烯酯白乳胶相比，具有抗冻性好、贮存稳定、成本低、性能好、用途更广等优点。     

ZQ系列涂料深受用户欢迎

武汉工业大学研制的ZQ系列涂料,其主要成膜物是改性聚乙烯醇,而这些改性剂大多是天然的,能与聚乙烯醇进行物理或化学的交联,且本身具有一定的粘结性。由于使用了改性剂,使这类涂料的成本均比106涂料低,而且耐水性、耐湿擦性和遮     

Modification of poly(vinylidene fluoride) ultrafiltration membranes with poly(vinyl alcohol) for fouling control in drinking water treatment

A commercial poly(vinylidene fluoride) flat sheet membrane was modified by surface coating with a dilute poly(vinyl alcohol) (PVA) aqueous solution followed by solid-vapor interfacial crosslinking. The resulting PVA layer increased membrane smoothness and hydrophilicity and resulted in comparable pure water permeation between the modified and unmodified membranes. Fouling tests using a 5 mg/L protein solution showed that a short period of coating and crosslinking improved the anti-fouling performance. After 18 h ultrafiltration of a surface water with a TOC of approximately 7 mg C/L, the flux of the modified membrane was twice as high as that of the unmodified membrane. The improved fouling resistance of the modified membrane was related to the membrane physiochemical properties, which were confirmed by pure water permeation, X-ray photoelectron spectroscopy, and contact angle, zeta potential and roughness measurements.     

改性废旧轮胎橡胶颗粒对水泥胶砂性能影响的试验研究

废旧轮胎橡胶颗粒的加入可提高水泥胶砂的抗冲击性能,增大其韧性,但大幅度降低了其抗压、抗折强度。通过采用NaOH、PVA、CCl43种溶液对橡胶颗粒进行改性,并测试其性能,可知掺入经PVA溶液改性的橡胶颗粒可有效降低强度损失,但对水泥胶砂的干缩率影响不大。     

PVA胶粘剂的改性技术

介绍了PVA改性方法、改性机理及制备工艺。实践表明,这类改性PVA胶粘剂可代替106胶、107胶、酚醛胶等,可用于制备建筑涂料。     

纤维橡胶砂浆的力学性能与砌体轴压试验

为提高橡胶砂浆的力学性能和适用性,通过单掺聚乙烯醇(PVA)纤维或钢纤维、复掺PVA-钢纤维对橡胶砂浆进行改性,探讨其对超声波传播速度、抗折强度和抗压强度的影响。将普通水泥砂浆、20%橡胶砂浆、复掺PVA-钢纤维橡胶砂浆分别与环保压缩砖结合制作砌体,通过试验研究轴心抗压强度和弹性模量。结果表明:掺入PVA纤维或复掺PVA-钢纤维降低了超声波在橡胶砂浆中的传播速度; 掺入PVA纤维或钢纤维提高了橡胶砂浆的抗折强度; 复掺一定量的PVA纤维和钢纤维能有效提高橡胶砂浆的抗压强度; 20%橡胶砂浆的抗压强度比普通水泥砂浆降低了46%,对应砌体的破坏荷载降低了12.8%; 复掺PVA-钢纤维橡胶砂浆的抗压强度比20%橡胶砂浆提高了14.9%,对应砌体的开裂荷载和破坏荷载分别提高了63.4%和4.5%; 掺入适量PVA纤维和钢纤维能改善橡胶砂浆的强度明显低于普通水泥砂浆的缺点,将复掺PVA-钢纤维橡胶砂浆应用于砌体工程能改善结构的隔音性,延缓试件的开裂,提高橡胶砂浆砌体的抗压强度。     

不同聚合物与玻璃纤维复掺砂浆性能的研究

对比了不同聚合物与玻璃纤维复掺时对砂浆抗折、抗压强度的影响,同时对复掺情况下玻璃纤维的表面状况及其耐碱腐蚀能力进行了试验研究。研究结果表明,玻璃纤维与聚乙烯醇(PVA)复掺时,砂浆的强度及耐碱性能均较其他聚合物高,在纤维掺量为水泥质量的1.0%、聚灰比为7.5%时,玻璃纤维-聚乙烯醇改性砂浆的柔性最大,通过耐碱性试验及扫描电镜分析发现玻璃纤维与聚乙烯醇(PVA)复掺时,有效填充了砂浆内部的宏观与微观缺陷,提高了界面过渡区的密实度,同时聚合物包裹在纤维表面,提高了纤维的耐碱性能。     

混杂PVA-ECC配合比优化设计及力学性能试验研究

为了降低工程用水泥基复合材料(ECC,Engineered Cementitious Composites)制造成本,使ECC能够在实际工程中大规模应用,将中国产PVA纤维和日本产PVA纤维以一定的比例混合,配制混杂PVA-ECC。基于ECC的材料设计理论,兼顾抗压强度和受拉能力,对掺有硅粉的混杂PVA-ECC中的纤维体积含量进行了优化设计。通过四点弯曲试验和轴心抗压试验,研究了混杂PVA-ECC在不同龄期下的弯曲性能和抗压性能。试验结果表明,混杂PVA-ECC试件均表现出明显的应变硬化和多缝开裂的特征,此外,其抗压强度后期增长明显。基于UM法,提出一种改进的反分析方法,可利用四点弯曲试验结果推导ECC的极限拉伸应变,并与试验结果进行了比较,结果表明,通过建议的反分析方法得到的预测值与试验值吻合较好。     

高性能聚乙烯醇纤维对水泥基材料性能的影响

对一种高性能聚乙烯醇(PVA)纤维在不同掺量下对混凝土和易性、力学性能和抗渗性能的影响展开研究,分析纤维种类及掺量对控制砂浆塑性收缩裂缝的作用机理。结果表明:掺入适量PVA纤维不会对混凝土的和易性产生影响,但当纤维掺量达到6.5 kg/cm3时,会对混凝土的和易性产生负面作用;PVA纤维可以适当提高混凝土抗压强度,显著增加其劈裂抗拉强度,但当掺量超过一定值时,力学性能会有所下降;在水泥基材料中掺入PVA和聚丙烯(PP)纤维,均可有效改善材料的抗裂性能,从而提高其抗渗性能,其中PVA纤维对抗渗性能改善效果更加明显。     

The effects of the alternate freezing and thawing cycles on the pore structure of cementitious composites modified by MHEC and PVA

Deterioration of mortars by weathering is usually of great importance and is brought about by the disruptive action of alternate freezing and thawing of free water within the material. As it appears that applications of methyl hydroxy ethyl cellulose (MHEC) and polyvinyl acetate (PVA) are very beneficial in improving frost resistance, special attention has been paid to observing the changes in microstructural features of polymer modified composites exposed to the destructive effects of water and low temperature. The presence of both admixtures in normally cured composites has been found to have a significant effect on their microstructure. The microstructure is mostly determined by the quantity of MHEC used, as it provides water retention. The application of PVA slightly affects the pore size distribution, significantly improving the adhesive properties of composites. The present research revealed an interrelationship between the quantity of admixtures used and the micro-structural features of composites subjected to freezing and thawing. The mercury intrusion porosimetry results suggest the significant effect of rehydration process with respect to the damage caused by the action of crystallised ice.     

The adsorption of basic dyes from aqueous solution on modified peat-resin particle

Modified peat was prepared by mixing thoroughly raw peat with sulfuric acid, and modified peat-resin particle was obtained, by mixing modified peat with solutions of polyvinylalcohol (PVA) and formaldehyde. In this paper, the adsorption of Basic Magenta and Basic Brilliant Green onto modified peat-resin particle is examined. The adsorption isotherm showed that the adsorption of basic dyes on modified peat-resin particle deviated from the Langmuir and Freundlich equations. The pseudo-first order, pseudo-second order and intraparticle diffusion models were used to fit the experimental data. By comparing the standard deviation, it was found that the intraparticle diffusion model could be used to well describe the adsorption of two basic dyes on modified peat-resin particle. According to the change of intraparticle diffusion parameter, the adsorption processes could be divided into different stages. The kinetics experiment also indicated that initial dye concentrations, particle dose and particle size could affect the adsorption processes of basic dyes.     

PVA-FRCC收缩性能试验研究

通过10组不同配合比的聚乙烯醇纤维增强水泥基复合材料(PVA FRCC)试件的收缩试验,研究了纤维体积分数、水胶比、砂胶比及不同养护环境下PVA FRCC试件的收缩性能.结果表明：PVA纤维的掺入减小了基材的收缩,但效果有限;PVA FRCC试件的收缩随水胶比的减小、砂胶比的增大及周围介质相对湿度的升高而减小.另外,根据试验结果并结合现有混凝土材料收缩计算模型,提出了PVA FRCC收缩估算模型,比较后发现,估算模型的计算值与试验值具有较高的吻合度.