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采用化学发泡法制备出聚丙烯/纳米二氧化硅(PP/nano-SiO2)微发泡复合材料,探讨了不同模具温度对PP/nano-SiO2发泡行为的影响。结果表明:模具温度对PP/nano-SiO2发泡材料发泡行为的影响主要体现在2个方面:一方面,影响PP/nano-SiO2复合发泡材料的泡孔结构参数,随模具温度升高,熔胶散热越慢,泡孔的直径越大,泡孔密度越小,分散状态越不稳定;另一方面,影响PP/nano-SiO2发泡材料制品内部区域面积,及随模具温度升高,发泡面积越大。发泡材料的冲击强度和拉伸强度随模具温度的升高明显下降。 相似文献
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采用"二次开模"注射成型工艺制备微发泡聚酰胺6(PA6)材料,研究了不同延时时间对PA6材料发泡行为及力学性能的影响.结果表明:延时时间能有效控制微发泡PA6材料的发泡过程,较短的延时时间内,模具型腔压力下降较大,压力降速率较快,有利于聚合物泡孔成核速率的提高.随着延时时间增加,微发泡PA6材料的泡孔平均直径增大,泡孔... 相似文献
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通过自行设计的模具,采用化学发泡法制备聚丙烯(PP)/纳米二氧化硅(nano-SiO2)与高抗冲聚苯乙烯(HIPS)/nano-SiO2微发泡复合材料。研究释压量对微发泡聚烯烃复合材料发泡行为的影响规律。结果显示:2种聚烯烃/nano-SiO2微发泡复合材料的泡孔平均直径、尺寸分散度,随着释压量的增大先减小后增大;泡孔密度则相反,随释压量的增大先增大后减小。在释压量为12%时,PP/nano-SiO2与HIPS/nano-SiO2的发泡效果最好。 相似文献
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针对采用常温发泡模具进行高温发泡时,常常产生树脂液溢出量及发泡压力不易控制的问题,设计了高温发泡模具.与常温发泡模具采用堵帽控制发泡压力不同,在高温发泡模具中采用压缩弹簧预紧的放气控制单元对树脂液溢出量及发泡压力进行控制,解决了树脂液溢出量过多的问题,发泡压力可调,模具结构可靠、拆装方便. 相似文献
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以己二酸丁二醇酯-对苯二甲酸丁二醇酯(PBAT)共聚物为基体,加入不同含量的扩链剂,经熔融共混后,制备扩链PBAT。结果表明,随着扩链剂含量的增加,熔融混合的扭矩值、凝胶含量和结晶温度逐渐升高,熔融温度基本不变,结晶度下降,黏弹性得到改善;以超临界CO2为物理发泡剂,通过间歇式釜压发泡法制备微孔PBAT泡沫,随着扩链剂含量的增多,发泡样品的泡孔尺寸变小,泡孔密度逐渐增加,当扩链剂的份数为0.8时,泡孔尺寸为4.4 μm,泡孔密度为1.65×1010个/cm3。 相似文献
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介绍了干气密封的基本原理,采用泵用串联式干气密封对液态烃泵密封结构进行了改造.详细介绍了泵的干气密封改造方案,并进行了改造效果评价.通过干气密封改造,解决了泵机械密封易泄漏的难题,提高了泵的性能及可靠性.此外,装置的长期稳定生产得到了保障,并为液体烃泵的干气密封改造提供了值得借鉴的经验. 相似文献
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阻燃剂在建筑材料中的应用进展 总被引:1,自引:0,他引:1
介绍了阻燃剂的种类及阻燃机理,结合绿色环保理念,探讨它在建筑材料中的防火应用。钢材防火以涂饰阻燃涂料为主,电线电缆及工程塑料的阻燃可以采用涂饰阻燃材料和添加阻燃成分改性,木材的阻燃则采用浸渍法,纸质的阻燃则采用浸渍法和添加阻燃成分法。综述了各类阻燃剂在这些建筑材料中的应用情况,展望了阻燃剂在建筑材料中的应用前景和发展趋势。 相似文献
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Boehmite sol was prepared by hot water hydrolysis of aluminum iso-propoxide using nitric acid as the catalyst. Hydrolysis was carried out at 80 °C for 80 min. Calcium nitrate was added and the peptization was complete at 80 °C for 1 h. The sol was precipitated in ammonia, the precipitate was aged for 24 h, dried at 120 °C and calcined at 500 °C for 3 h. The calcined powder was milled at 230 rpm for 6 h. The amount of calcium oxide was varied from 1 to 20 vol.%. The particle size and particle size distribution of the calcined powders were studied. The average particle size was found to increase with calcia content. The powder was compacted into cylindrical pellets using uni-axial press at 180 MPa and sintered at 1600 °C for 6 h. Mechanical properties such as hardness, fracture toughness, diametrical tensile strength and flexural strength for compacts containing various concentrations of strontium oxide was studied. There was a slight decrease in the density with increase in strontia content. Increase in the mechanical properties such as hardness, fracture toughness and diametrical tensile strength was observed with increase in strontia content. 相似文献
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用浊点法测定了四氟硼酸1-丁基-3-甲基咪唑—水—碳酸钠体系在常压30℃下的溶解度曲线及密度曲线,并用经验方程进行了关联。用浊点—密度法测定了该体系的液液相平衡数据,绘制了相应的相图。结果表明:双水相体系一相以离子液体和水为主,碳酸钠的含量很少,另一相以碳酸钠和水为主,离子液体的含量很少。该体系既可作为萃取分离体系,也可作为从水溶液中分离回收离子液体的初步体系。用Othmer-Tobias+Bancroft经验方程对相平衡数据进行关联,最大相对误差为94.99%, 最大平均相对误差为15.69%,关联结果不理想。提出用Othmer-Tobias经验方程+溶解度方程对其进行关联,最大相对误差为4.52%,最大平均相对误差为2.77%,关联精度较高,该方法可适用于有一组分含量较低的体系的液液相平衡的关联计算。 相似文献
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Carlos Martín Yosmel Gonzlez Teresa Fernndez Anne Belinda Thomsen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(10):1669-1677
Sugarcane bagasse was pretreated by wet oxidation (WO) at 195 °C for 15 min under either alkaline, neutral or acidic conditions, and by steam explosion (STEX) at 205 °C for 10 min. Alkaline WO was more favourable than neutral and acidic WO for the following enzymatic hydrolysis of cellulose, giving 792 g kg?1 glucose yield after 48 h. The enzymatic hydrolysis of the fibres in the whole slurry was inhibited by inhibitory compounds contained in the prehydrolysate in comparison with the hydrolysis of the washed solid fibres in buffer. The inhibition increased proportionally with formic acid concentration in the pretreated liquid fraction. Cellulose conversion was higher for simultaneous saccharification and fermentation (SSF) than for separate hydrolysis. The highest SSF conversion (829 g kg?1) was obtained for the material treated by alkaline WO. The fermentability of the prehydrolysates by Saccharomyces cerevisiae was evaluated. Stronger inhibition of ethanolic fermentation was observed in the prehydrolysate obtained by steam explosion. The inhibition was more noticeable for the volumetric productivity than for the ethanol yield. The volumetric productivity was reduced by 94.5 and 91.2% for STEX and WO, respectively, whereas the ethanol yield was reduced only by 45.2 and 31.0%, correspondingly, for STEX and WO. Furan aldehydes seemed to be mainly responsible for the inhibition of the fermentation. Copyright © 2006 Society of Chemical Industry 相似文献
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研究了精对苯二甲酸(PTA)的粒径与b值的关系,探讨PTA产品的b值形成机理。结果表明:PTA的粒径越大,其b值越小;经不同时间粉碎后,PTA的粒径越大,b值越大。说明PTA的b值形成机理是带黄色基团的杂质与PTA表面吸附共结晶的。 相似文献