聚氨酯耐热降解性能的研究进展

聚氨酯材料热性能的研究一直是材料科学研究的热点。本文简述了聚氨酯材料的热降解原理和提高其耐热降解性能的方法。     

聚丙烯复合材料热稳定性能研究进展

本文简述了提高聚丙烯复合材料耐热降解性能的方法,为填料改性聚丙烯复合材料热解性能研究提供了参考,并展望了热降解研究在填料改性聚丙烯复合材料中的应用前景。     

聚氨酯弹性体耐热形变性能的改善

简述通过改变聚合物多元醇结构 ,选择适当多异氰酸酯和扩链剂 ,在聚氨酯分子内引入杂环 ,用其他树脂进行改性 ,加入填料 ,以及改变工艺条件等改善聚氨酯弹性体耐热形变性能的方法     

改性纳米碳酸钙对天然胶乳胶膜热性能的影响

探讨改性纳米碳酸钙对天然胶乳胶膜耐热老化性能和热降解性能的影响。结果表明，加入改性纳米碳酸钙可以改善天然胶乳胶膜的耐热老化性能和热降解性能；改性纳米碳酸钙用量为3份的天然胶乳胶膜耐热老化性能和热降解性能与防老剂264用量为1份的天然胶乳胶膜相当，而生产成本较低。     

聚氨酯的化学降解及其性能

简单介绍了聚氨酯的水解、热降解、热氧化降解和紫外线降解的反应机理。举例比较了加入或未加入稳定剂的聚氨酯弹性体在降解试验前后的拉伸强度及其它性能变化,指出了添加稳定剂可改善聚氨酯弹性体的抗降解稳定性。     

石油树脂/聚氨酯防水材料热性能研究

以聚氨酯预聚体为基料，以石油树脂为改性剂，制备了石油树脂／聚氨酯防水材料；分析了石油树脂／聚氨酯防水材料的热降解过程，研究了石油树脂／聚氨酯防水材料的热降解动力学。根据求得的热降解活化能讨论了石油树脂含量对防水材料热稳定性的影响。结果表明，石油树脂／聚氨酯防水材料的热降解分为两个阶段，起始平衡降解温度是231．04℃，热降解机理符合Freeman—Carroll假设，防水材料的热稳定性随着石油树脂用量的增大而有所降低。     

聚氯乙烯耐热性研究的现状与进展

介绍了采用各种类型的热稳定剂、耐热高聚物、无机填料、交联、氯化、纳米复合等方法和手段改善PVC制品的耐热性能 ,并对改善PVC的耐热性进行了展望 ,指出了今后研究开发出来的热稳定剂应低污染 ,性能价格比平衡 ,且与聚合物具有较好的相容性和协同性     

聚氨酯耐热性能研究进展

综述了聚氨酯的热降解过程及产物,探讨了热降解条件、软段、NCO:OH摩尔比、异氰酸酯种类、扩链剂、交联度、杂环基团对聚氨酯耐热性能的影响,并对聚氨酯耐热性能改进方法进行了总结。     

纤维增强聚氨酯拉挤复合材料：Ⅱ.工艺参数对机械和耐热性能的影响

本文提出了一种制造拉挤聚氨酯(PU)复合材料新颖的工艺。研究了工艺参数对纤维增强PU拉挤复合材料的机械性能(如弯曲强度、弯曲模量等)和耐热性能(热变形温度,HDT)的影响。这些工艺参数包括牵引速率(模内线速度),模具温度,填料种类和含量以及后固化时间和温度。研究结果表明,复合材料在不同模具温度下具有不同的最佳牵引速率。以DSC固化曲线为基础可确定溶胀率,复合材科的机械性能和耐热性能,最佳的模具温度。研究发现复合材料的机械性能和耐热性能随着各类填料的含量增加而提高。机械性能在一适宜的后固化温度和时间下也提高。此外,对复合材料的性能在经长时间后固化,由于降解而使性能下降的情况也进行了讨论。     

聚醚聚氨酯胶黏剂湿热老化机制研究

通过傅里叶红外光谱、热失重法、凝胶渗透色谱、差示扫描量热法以及力学性能测试等测试方法，对合成的聚醚聚氨酯胶黏剂的老化降解现象进行研究。研究表明：聚醚聚氨酯胶黏剂抗老化降解性能略差，在70℃高温老化后，其初始分解温度下降了11℃；通过分子质量及分子质量分布测试统计进一步证明其高温抗老化降解性能较差。老化降解试验后，聚醚聚氨酯胶黏剂的拉伸强度下降了11.7%，断裂伸长率降低10.8%，表明老化降解对其力学性能及其使用性能影响严重。     

A study of the thermal resistance of carbon fillers in carbon plastics

Conclusions -- The effect of preparation conditions and of the action of aggressive media on various fabrics used as fillers in chemically resistant hybrid carbon plastics has been investigated.-- Comparison of the thermal behavior of various carbon fabrics and other fabrics used as fillers in hybrid carbon plastics indicates an effect of the chemical nature and technological conditions in preparing them on the temperature ranges of thermo-oxidative and degradative processes.-- An increase in the temperature for the start of thermo-oxidative degradation on increasing the preparation temperature of carbon fabrics has been found. Ural fabric is more thermally resistant than UVK fabric.-- The action of distilled water reduces the thermal resistance of carbon fabrics to a small degree and that of plasticizing bath reduces it more significantly.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 44–45, May–June, 1991.     

多壁碳纳米管改性聚碳酸酯型聚氨酯的研究

通过原位聚合法用多壁碳纳米管(MWCNTs)对聚碳酸酯型水性聚氨酯(CWPU)进行改性,讨论了MWCNTs的加入对CWPU/MWCNTs复合材料的低温性、耐热性、机械性能和耐水性等性能的影响。结果表明,加入质量分数为0.3%的MWCNTs,其在CWPU中分散情况较好;所制复合材料的Tg及耐热稳定性明显提高,加入MWCNTs质量分数0.3%的CWPU/MWCNTs复合材料,其热分解温度提高了近20℃;随着MWCNTs含量的增加,材料拉伸强度逐渐增加,而伸长率呈现先减少后增加的趋势;由于CWPU本身具有很好的耐水性能,MWCNTs的加入,进一步提高了聚氨酯材料的耐水性能。     

硬硅钙石复合隔热涂料制备与隔热性能测试

以硬硅钙石作阻隔型填料,以金红石型二氧化钛和中空玻璃微珠为反射型功能填料,制备建筑外墙隔热涂料。研究了单掺硬硅钙石、金红石型二氧化钛、中空玻璃微珠以及复合添加3种填料对涂层隔热性能的影响。结果表明:单掺硬硅钙石、金红石型二氧化钛或中空玻璃微珠均可提高涂层隔热性能,硬硅钙石的适宜掺量为9%,金红石型二氧化钛的适宜掺量为30%,空心玻璃微珠的适宜掺量为20%;复合掺入硬硅钙石、金红石型二氧化钛和空心玻璃微珠可进一步提高涂层隔热性能,掺量为9%、30%和15%时,涂层的热反射率可达93.69%。按建筑行业标准JG/T235—2008《建筑反射隔热涂料》进行检测,涂料对波长为250～2 500 nm范围内的太阳反射比为0.85,半球发射率为0.87,隔热温差为13℃,符合标准要求;空心玻璃微珠、二氧化钛和硬硅钙石复合掺入后,发挥协同作用,能更加有效地提高涂层的隔热性能。     

聚二甲基硅氧烷涂层材料的研究

采用一定粘度的聚二甲基硅氧烷为基体,加入适量填料和助剂,成功制备了室温硫化硅橡胶涂层。研究了气相法SiO2和交联剂对涂层材料的影响,并进行了TG和SEM测试。研究结果表明：填料的添加明显改善了涂层的力学性能和耐高温性能,拉伸强度迭1．42MPa,可耐温288℃;并且该涂层有较好的耐水和耐酸、盐性能,耐碱性能有待进一步改善。     

Bond Strength and Elastic Properties of Ceramic Adhesives

Ceramic or inorganic-type adhesives, which are relatively resistant to thermal and mechanical shock and can sustain strengths at temperatures up to 1500°F, have been developed. Several alterations of the basic glassy phase were studied to attain optimum adhesion properties. Included were the incorporation of metal fillers and recrystallizable materials and the application of special formulation techniques to the basic glassy phase. The basic physical properties, thermal expansion, residual stress, and tensile strength, were correlated with bond strength. Average tensile strength values of 5000 psi at room temperature and 3000 psi at 800°F were found. The addition of selected covalent-bonding-type oxides to a barium borosilicate glass resulted in increased strengths at temperatures above 1000°F. The incorporation of metal fillers improved the physical properties of the basic ceramic adhesives. Recrystallized-type adhesives would not develop strong cohesive bonds unless a glassy phase was also present.     

不同高度淋水填料的热力及阻力性能试验

通过对逆流式冷却塔淋水填料性能试验,给出了常用的PVC淋水填料不同组装高度的热力性能及阻力性能方程式,并结合工程实例对出塔水温进行计算。试验表明在自然通风冷却塔常用气水比工况条件下,填料高度增加0.5m,冷却数提高约25%,阻力约增加6Pa。     

用于冲压发动机补燃室热防护的硅橡胶绝热层研究

通过分析影响冲压发动机补燃室热防护层性能的因素,研究了粉状填料和纤维填料对硅橡胶绝热层耐烧蚀性能的影响和填料的组合作用;研究了硅橡胶绝热层与发动机壳体的粘接性能,将几种偶联剂对绝热层与壳体粘接性能的影响进行了对比.结果表明,通过有机填料与无机填料以及纤维的共同作用,可以显著提高硅橡胶绝热层的耐烧蚀性能,降低其烧蚀率;WD-60偶联剂可显著提高硅橡胶与钢的粘接强度.初步探索出适合于冲压发动机补燃室热防护所用的硅橡胶绝热层配方.     

Preparation and characterization of novel chitosan‐based mixed matrix membranes resistant in alkaline media

In this work, mixed matrix membranes (MMMs) based on chitosan (CS) and different fillers (room temperature ionic liquid [emim][OAc] (IL), metallic Sn powder, layered titanosilicate AM‐4 and layered stannosilicate UZAR‐S3) were prepared by solution casting. The room temperature electrical conductivity and electrochemical response in strong alkaline medium were measured by electrochemical impedance spectroscopy and cyclic voltammetry (CV). The ionic conductivity of pure CS membranes was enhanced, from 0.070 to 0.126 mS cm^?1, for the pristine CS and Sn/CS membranes, respectively, as a function of the hydrophilic nature of the membrane and the coordination state of Sn. This hydrophilic and charge nature was corroborated by water uptake measurements, where only the introduction of IL in the CS membrane led to a water uptake of 3.96 wt %, 20 or 30 times lower than the other membranes. Good thermal and chemical stability in alkaline media were observed by thermogravimetric analyses and X‐ray photoelectron spectroscopy analyses, respectively, and good interaction between CS and the fillers observed by X‐ray diffraction, scanning electron microscopy and CV. Thus, thin CS‐based MMMs (40–139 µm), resistant in high alkaline media, show higher conductivity than pure CS membranes, especially those fillers containing tin, and although the electrochemical performance is lower than commercially available anion‐exchange membranes they have potential in pervaporation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42240.     

Thermal conductivity and mechanical properties of polyimide composites with mixed fillers of BN flakes and SiC@SiO2 whiskers

Polyimide (PI) composites with mixed fillers of BN flakes and SiC whiskers exhibit enhanced thermal conductivity and mechanical properties. In order to improve dispersion and interaction of these mixed fillers within the PI matrix, BN flakes were modified by a titanate coupling agent while SiC whiskers were oxidized at 750°C for 60 minutes to produce SiC@SiO₂ followed by silane coupling agent modification. PI composites reached a maximum thermal conductivity of 0.95 W/m K at volume fraction of mixed fillers of 27.6 vol% when the weight ratio of BN flakes to SiC@SiO₂ whiskers was 1:4. The enhanced thermal conductivity is likely attributed to the formation of heat conductive networks constructed by BN flakes and SiC@SiO₂ whiskers and the improved interfacial affinity between fillers and matrix. The optimized Nielsen-mold confirms the distribution and morphology of fillers affect the thermal conductivity of PI composites. In addition, SiC whiskers enhanced the mechanical property of PI composites and the influence of fillers on the mechanical property was further elaborated.     

浅淡中空填料在耐高温隔热涂料中的应用

介绍了中空填料(陶瓷微珠)在耐高温隔热涂料中的应用。与粉末填料(石棉粉)研制的隔热涂料相比,中空填料对提高涂料的耐高温隔热性能十分显著。