聚醚弹性体对几种不饱和聚酯树脂的增韧作用

<正>增韧不同于增柔,增柔使材料整体柔化,而增韧使材料呈多相结构:树脂基质连续相和弹性体颗粒分散相(亦可称此种多相体系为“海岛结构”)。这种结构特点,使树脂韧性提高,而机械性能、耐热性能损失较少。     

高性能热塑性树脂增韧酚醛树脂的研究

研究热塑性树脂PEK-C、PES-C增韧酚醛树脂体系的反应特征、微观结构和增韧机理。结果表明酚醛树脂/热塑性树脂体系的结构不是"海岛结构"而是热塑性树脂连续相包络固化酚醛球粒的"网络-球粒"结构。     

环氧树脂增韧剂J-N的应用研究

本文研究了J－N增韧剂在环氧树脂浇铸体系中的增韧效果，指出J－N增韧剂增韧的环氧树脂固化物呈互穿网络的海岛结构，浇铸材料的断裂韧性得到明显改善。     

聚醚多元醇磷酸酯增韧改性环氧树脂的研究

以多聚磷酸与聚醚多元醇反应制备得到聚醚多元醇磷酸酯,利用聚醚多元醇磷酸酯对环氧基团的反应活性,研究其对环氧树脂-酸酐体系的增韧效果。通过力学性能、热性能以及扫描电镜等研究发现,聚醚多元醇磷酸酯可将与环氧树脂相容性差的聚环氧丙烷链段强制引入到环氧网络中,增强界面性能,具有较好的增韧效果。聚醚在环氧固化网络结构中析出,形成"海岛"结构,SEM测试显示随着磷酸酯化程度的不同,聚醚分相的"海岛"结构的程度和尺寸可以调控;当分散相保持一定的密度和尺寸时,才能达到最佳的增韧效果。同时结果显示,聚醚多元醇磷酸酯的加入基本不影响环氧树脂的力学性能和耐热性能。     

环氧树脂的增韧

添加一种分相的橡胶粒子到环氧树脂中可增加其破坏韧性。已知的这些改性剂有 Ｃ Ｔ Ｂ Ｎ、微凝胶和核壳粒子等。这些橡胶增韧环氧树脂体系形成海岛结构,增韧的原因是橡胶粒子的撕裂并诱发母体的塑性变形。另一类替代反应性橡胶用于改性环氧的是多种强韧的热塑性塑料,环氧树脂变韧是形成了双连接相结构。综合讨论了改性剂和母体的性质对环氧树脂共混物韧性的影响以及增韧机理。     

颗粒特性对聚氯乙烯树脂基本性能的影响

研究了牌号为QS-800F的聚氯乙烯(PVC)树脂的颗粒形态及其粒径分布、颗粒微观结构对QS-800F树脂基本性能的影响,并与国内应用较好的同类型树脂进行了对比分析.结果表明,QS-800F树脂具有良好的颗粒形态,粒径分布适中,颗粒表皮多为不连续结构,颗粒内部孔隙率高,具有很高的增塑剂吸收值和较强的增塑剂吸收能力.     

高柔性聚氨酯环氧树脂新品问世

<正>姜堰市恒创绝缘材料有限公司联合有关院校,日前开发成功一系列环氧预浸料专用增韧剂产品-高柔性聚氨酯环氧树脂,型号为102D-1及102D-1H。该树脂为黄色或红色高粘稠液体或半固体,常温下可和脂肪胺、脂环胺、芳香胺等反应,中高温下可和双氰胺或酚醛树脂、酸酐等反应,主要用于环氧结构胶粘剂的增韧,固化后形成环氧树脂-聚氨酯互穿聚合物网络或海岛结构。     

环氧粉末涂料的增韧改性

采用国产增韧剂对市售的环氧树脂进行改性,得到效果良好的增韧环氧粉末涂料。SEM分析表明,增韧剂的加入,在树脂集体内部形成了海岛结构,增韧剂微粒的存在,使得粉末涂料的韧性得到了极大的提高。DMA分析表明,增韧前后粉末涂料的储能模量和玻璃化转变温度均有所升高。DTA分析表明,少量增韧剂的引入有益于树脂的热稳定性能的提高。     

高性能氢化丁腈橡胶密封胶料的制备及性能

研究了硫化剂过氧化二异丙苯(DCP)和增塑剂聚己二酸乙二醇酯(QS-1)用量对氢化丁腈橡胶(HNBR)硫化特性、力学性能、耐老化性能及动态力学性能的影响,并对其进行了差示扫描量热分析。结果表明,QS-1对胶料的焦烧时间、正硫化时间及硫化速率基本没有影响。DCP用量相同时,随着QS-1用量的增加,硫化胶的邵尔A硬度和200%定伸应力降低,扯断伸长率和压缩永久变形增大,但对拉伸强度影响不大;DCP用量对胶料扯断伸长率和压缩永久变形的影响远高于QS-1;高交联密度的胶料具有较好的耐热、耐油老化性能;QS-1对HNBR硫化胶的玻璃化转变温度以及耐热、耐油老化性能影响不大,但可降低胶料的Payne效应,进而改善炭黑在HNBR中的分散性。DCP用量在3.5份左右、QS-1用量在3～5份时可获得性能优异的密封胶料。     

Al2O3/TiO2纳米复相陶瓷的增韧机理研究

纳米结构与纳米添加剂对陶瓷体的增韧是多种增韧方式共同存在的.对于1350℃烧结的ATZ陶瓷,其增韧机理为相变增韧和纳米颗粒增韧;对于1 450℃的ATZ陶瓷烧结体,增韧机理主要为纳米颗粒增韧、微裂纹增韧.ATZ陶瓷体在1 450℃烧结时的增韧效果优于1 350℃烧结时的增韧效果.     

Prediction of later-age compressive strength of normal concrete based on the accelerated strength of concrete cured with microwave energy

Microwave energy can accelerate the hydration of cement, resulting in rapid strength development of concrete in an early period. In this paper, prediction of later-age compressive strength of normal concrete, made with rapid-hardening and ordinary Portland cement, based on the accelerated strength of concrete cured with microwave energy was investigated. To accelerate curing properly, the optimal microwave curing process for concrete was first determined and then was applied to concrete. The possible early ages for the strength prediction were found to be at 3.5 and 5.5 h for concrete made with rapid-hardening and ordinary Portland cement, respectively. For each cement type, a formula for the strength prediction was derived from the relationship between accelerated early-age strength of concrete cured with microwave energy and later-age strength of normally cured concrete. Predictions of strength at 7 days for concrete made with rapid-hardening Portland cement and 28 days of concrete made with ordinary Portland cement were within 15% agreement with actual test results.     

具有高伸长率的二异氰酸酯改性不饱和聚酯

介绍了1种新型二异氰酸酯改性不饱和聚酯,该树脂可以室温固化,固化后树脂的拉伸强度和断裂伸长率分别可达20 MPa和106%。该树脂可用于制作高柔韧性制品,亦可以加入到其他不饱和聚酯中,提高其冲击性能和断裂伸长率。     

Effect of temperature and aging on the mechanical properties of concrete: Part II. Prediction model

In Part I, empirical relationships between compressive strength and splitting tensile strength or elastic modulus with temperature and aging were proposed. This paper investigates new prediction models estimating splitting tensile strength and elastic modulus without knowing compressive strength. The prediction model is suggested on the basis of the equation that was suggested to predict compressive strength. The mechanical properties calculated by the model are compared with empirical results presented in Part I. To evaluate in-place applicability of the model, the empirical data on strength and elastic modulus of concrete cured at variable temperature are compared with the values estimated using the prediction model. The prediction model properly estimates the strength and elastic modulus of Types I and V cement concretes cured at constant and variable temperature conditions.     

一种低成本室温固化双组分环氧密封胶的研制

采用低分子质量双酚A型环氧树脂及改性胺类固化剂研制了一种低成本室温固化双组分环氧胶粘剂。探讨了其固化机理,考查了温度、配比对适用期的影响,以及硅微粉、邻苯二甲酸二辛酯的用量对胶接强度的影响。结果表明,温度变化对该产品的适用期影响较大。温度升高,适用期变短。硅微粉加入量在30~75份时,胶的湿润性变差,固化后的胶层缺陷增多,拉伸剪切强度随硅微粉用量的增大而下降。邻苯二甲酸二辛酯的加入降低固化后的交联密度,使环氧胶的胶接强度下降。     

固化剂对环氧树脂耐水性能的影响研究

采用不同环氧树脂(EP)固化剂,并对固化物吸水率及吸水后的力学性能变化情况进行了研究。实验结果表明,新酸酐固化EP体系的平衡吸水率最小(0.95%),当达到吸水平衡时,弯曲强度和模量保持率分别为91%和96%左右,冲击强度略有下降,热变形温度下降10℃;新型酸酐固化EP体系是综合性能优良的耐水EP基体。     

Effect of temperature and aging on the mechanical properties of concrete: Part I. Experimental results

This paper reports the results of curing temperature and aging on the strength and elastic modulus and the Part II paper suggests a prediction model based on these experimental results. Tests of 480 cylinders made of Types I, V, and V cement+fly ash concretes, cured in isothermal conditions of 10, 23, 35, and 50 °C and tested at the ages of 1, 3, 7, and 28 days are reported. According to the experimental results, concretes subjected to high temperatures at early ages attain higher early-age compressive and splitting tensile strengths but lower later-age compressive and splitting tensile strengths than concretes subjected to normal temperature. Even though the elastic modulus has the same tendency, the variation of elastic modulus with curing temperature is not so obvious as compressive strength. Based on the experimental result, the relationships among compressive strength, elastic modulus, and splitting tensile strength are analyzed, considering the effects of curing temperature, aging, and cement type.     

强酸性条件下合成的脲醛树脂浸渍纸的拉伸强度

将采用强酸性条件下缩合方法合成的低F/U摩尔比脲醛树脂浸债纸的拉伸强度与采用通常合成方法合成的低F/U摩尔比脲醛树脂没演纸的拉伸强度相比较,并由树脂浸清纸拉伸强度研究树脂固化物的物性。强酸性条件下合成树脂固化物自身的干燥状态强度与通常条件下合成树脂的干燥状态强度相近,但是,湿强度较低。在145T下固化3分钟其强度大幅提高。     

预聚物对UV固化胶黏剂性能的研究

预聚物作为胶黏剂的主要成膜物质,它的性能基本决定了固化后胶黏剂的主要性能.采用不同类型的丙烯酸酯共混聚合的方法研究了预聚物对紫外光固化胶黏剂性能的影响.主要讨论了预聚物的种类、含量及复配对胶黏剂的固化速率、黏附力及粘接强度的影响.实验发现预聚物的种类和含量是胶黏剂的主要影响因素,脂肪族聚氨酯丙烯酸酯6148J和改性脂肪族聚氨酯丙烯酸酯6079性能较好,且二者比列为3:7,含量为50%时胶黏剂综合性能较好.     

Synthesis and Characterization of Solventless Polyester Varnish Based on Di Cyclo Penta Diene (DCPD)

Solventless polyester varnish was synthesized by polyesterification reaction of fumaric acid (FA), propylene glycol (PG) and dicyclo penta diene (DCPD) using triphenyl phenol (TPP) as accelerator. The resulting material was characterized by FT-IR and NMR spectroscopy. The electrical properties of varnish were also measured; volume resistivity was found 5.22 × 10¹⁷ Ohm-cm at room temperature, which fulfills main requirement of electrical insulating material. Solventless polyester varnish was crosslinked with styrene, vinyl toluene, and blend of both monomers, respectively in different ratios. Tensile strength of different type of the cured varnish with vinyl monomers was also determined, which was very high for vinyl toluene cured varnish. Thermal stability of the cured samples was determined by Thermogravimetric analyzer (TGA).     

水泥窑灰-粉煤灰体系的水化与强度发展(英文)

研究了配合比与养护温度对水泥窑灰(cement kiln dust,CKD)—粉煤灰(fly ash,FA)净浆的水化与强度发展的影响。净浆采用5种不同的水泥窑灰与粉煤灰比例配制,部分试件添加硅酸盐水泥作添加剂。试件在24、38℃及50℃的条件下进行养护。采用热重分析与X射线衍射测试试件的水化产物。结果表明在50℃的养护条件下,75%CKD+25%FA与45%CKD+45%FA+10%OPC试件的28 d与56 d强度分别达到了100%OPC水泥净浆强度的70%与80%以上。CKD-FA体系中的主要结晶水化产物是钙矾石。无论CKD与FA比例多大,CKD-FA浆体中钙矾石的含量显著高于水泥净浆。CKD-FA体系中钙矾石在90d的龄期仍可保持稳定。