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对聚合物在CO2环境中的玻璃化转变特性进行了研究。利用蠕变柔量法,在自建的实验装置上,对聚氯乙烯和聚甲基丙烯酸甲酯在CO2环境中不同压力下的玻璃化转变温度进行了测定,并利用间接法测定了对应状态下聚合物中CO2的质量分数。结果表明,在CO2环境中2种材料的玻璃化转变温度显著降低。利用基于经典热力学与统计热力学理论构建的模型,对聚合物中不同的CO2质量分数对应的玻璃化转变温度值进行了计算,得到的计算结果与实验结果较吻合。 相似文献
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本文分析了聚甲基丙烯酸甲酯热稳定性差的产生原因及处理方法。聚甲基丙烯酸甲酯热稳定性差产生的原因是:①在聚合过程中由于歧化终止产生C=C双键,形成不稳定的终端基团;②氧气参与过程反应生成活泼的过氧自由基,在夺取聚合物中的氢原子,形成C=C双键,因而降低了聚甲基丙烯酸甲酯的热稳定性。解决方法是:通过与其它单体共聚,消除不稳定终端基团,以及使用抗氧剂消除氧气对有聚合物自由基的氧化作用。 相似文献
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主要针对降低PMMA吸水率的要求,运用分子设计原理用苯乙烯、N-苯基马来酰亚胺进行PMMA共聚,并对其制备工艺进行改进,得到吸水率降低30%左右、力学性能变化不大、800nm透光率可达90%的PMMA共聚物。 相似文献
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低吸水性聚甲基丙烯酸甲酯的研究 总被引:1,自引:0,他引:1
主要针对降低PMMA吸水率的要求,运用分子设计原理用苯乙烯、N-苯基马来酰亚胺进行PMMA共聚,并对其制备工艺进行改进,得到吸水率降低30%左右,力学性能变化不大,800nm透光率可达90%的PMMA共聚物。 相似文献
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乳液法聚甲基丙烯酸甲酯/蒙脱土纳米复合材料的合成与表征 总被引:17,自引:1,他引:16
利用Na2SiO3的改性机理来纯化Na基蒙脱土,通过调节体系的pH值及其聚合阴离子的作用,使蒙脱土边面带负电荷,有效调节蒙脱土在水中的分散状态,使其与有机阳离子的交换反应充分进行,得到有机蒙脱土的阳离子交换量达115mmol/110g,并且能均匀分散在甲基丙烯酸甲酯9MMA)单体中,借助普通的乳液聚合方法,制备出PMMA/有机蒙脱土纳米复合材料,复合材料经甲苯抽提,FTIR,XRD,TEM,DSC,TGA等一系列分析方法表征,表明有机蒙脱土在PMMA基体中已达到纳米级分散,多数已发生剥离,而且复合材料的热性能较纯PMMA有很大提高,其Tg和Td最大分别提高31.45℃和42.13℃。 相似文献
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本文综述了聚甲基丙烯酸甲酯(PMMA)在耐热性能、耐磨损性能、阻燃等方面改性研究的途径及国内外研究的最新进展,分析了各种改性方法的特点,并展望了PMMA改性研究今后的发展方向。 相似文献
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The poly(vinlylidene fluoride) (PVDF) was incorporated within the compound matrix of poly(ethylmethacrylate) (PEMA)/poly(methylmethacrylate) (PMMA) using solution cast technique. The importance of PVDF in the miscibility of PEMA/PMMA matrix was investigated using FT-IR, DSC, SEM and AFM technique. Crystalline particle size of PVDF in PEMA/PMMA matrix was analyzed using XRD characterization. Single-phase compatibility with maximum crystallinity along with the maximum value of hardness was observed when PVDF/PMMA/PEMA were blended in equal weight ratio. The PVDF particle act as reinforcing material within the compound matrix of PEMA/PMMA, and hence, improves the properties of prepared ternary blends. 相似文献
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Poly(vinyl alcohol) (PVA) is a well-known biomedical polymer and is biocompatible. Methylmethacrylate and acrylic acid monomers were grafted onto PVA using a Ce(IV)–glucose redox system at three different temperatures (35, 45, and 55°C) under nitrogen atmosphere. More than 80% grafting could be achieved in the process. The grafted PVA was characterized through infrared spectra, thermal decomposition studies [thermogravimetric analysis (TGA) and decomposition thermal grafting (DTG)], differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The thermal stability and other properties of grafted PVA related to medical applications was found to be better than those of ungrafted PVA. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 677–683, 1999 相似文献
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利用自由基共聚制得聚(苯乙烯-丙烯酸-对氯甲基苯乙烯)(PSAA)寡聚体,季铵化后与蒙脱土进行离子交换得到聚(苯乙烯-丙烯酸-对氯甲基苯乙烯)修饰蒙脱土(PSAA/MMT)。利用红外、凝胶渗透色谱、热重、核磁共振和X衍射分析仪对其结构性能进行了表征。发现当寡聚体中丙烯酸含量为5%时,热稳定性较好。但是在其修饰蒙脱土中,当丙烯酸的含量为10%时,热稳定性更好,当失重10%时,其热降解温度为367℃。X衍射分析和透射电子显微镜结果显示,寡聚体季铵盐与蒙脱土进行离子交换,得到了剥离的有机修饰蒙脱土。 相似文献
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本试验合成了水性环氧-丙烯酸酯杂化乳液,通过对引发剂用量、乳化剂用量、不同乳化剂配比、种子乳液以及搅拌速度等聚合反应条件的考察,得出了聚合反应的最佳工艺条件,并简单探讨了单体转化率与乳胶膜玻璃化转变温度之间的关系。结果表明,当引发剂质量分数为0.8%、乳化剂质量分数为3%、m(OP-10):m(SDS)=2:1、种子乳液的用量为预乳化液的20%(质量分数)、转速为180r/min时,乳液聚合单体的最终转化率可以达到98%。且最终转化率的提高使乳胶膜玻璃化转变温度更接近于理论计算值。 相似文献
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The mechanical properties of the adhesively bonded joints with ethyl-2-cyanoacrylate and ethyl-2-cyanoacrylate modified with poly(methylmethacrylate) were determined. The modifier lowers tensile stiffness, increases deformability and relaxation of the adhesive bond and improves impact resistance. A morphological structure similar to an interpenetrating network system is suggested which arises from the rapid polymerization of the solvent. The results obtained may be helpful for the design of joints with cyanoacrylate bonding. 相似文献
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Summary: A novel intumescent flame retardant (PSiNII), containing silicon, phosphorus and nitrogen, has been synthesized and incorporated into poly(propylene) (PP). The flame retardancy of PP/PSiNII, evaluated by the limiting oxygen index (LOI) value, can be enhanced up to 29.5 vol.‐% from 17.4 vol.‐% with 20% total loading amount of PSiNII. The thermal degradation behavior of PP/PSiNII are investigated by thermogravimetric analysis (TGA) under nitrogen and air, and pressure differential scanning calorimetry (PDSC) under 1.5 MPa of oxygen. The PP/PSiNII‐3 degrades at 400 °C for different time, and the process is investigated by FTIR which indicates there is P? O in the char. The morphologies of char formed at 400 °C for 10 min and after LOI test are investigated by scanning electron microscopy (SEM). The morphological structure of the char exhibits the swollen cells in the inner and a smooth outer surface, which do good to the thermal properties and fire performance of PP. The thermal stability of PP is improved by incorporating PSiNII.