典型放热型、吸热型和吸-放热型发泡剂热分解特性的研究

研究了典型的放热型发泡剂ＡＣ、吸热型发泡剂ＨＹＤＲＯＣＥＲＯＬ ＢＩＨ和吸放热型发泡剂ＥＸＯＣＥＲＯＬ２３２分解热力学和动力学特性,用ＤＳＣ差示扫描量热仪测定了动态分解温度和热效应以及发泡助剂对分解热力学的影响。并用自行设计的发泡剂的改进提供了参考数据。     

偏氯乙烯共聚物颗粒发泡能力的影响因素

以1-氟-1,1-二氯乙烷(HCFC-141b)作发泡剂,研究了偏氯乙烯(VDC)共聚物颗粒的发泡能力、中空颗粒的泡孔结构及发泡倍率。实验发现,VDC-甲基丙烯酸甲酯(MMA)共聚物的发泡能力较强,而VDC-丙烯腈(AN)共聚物颗粒很难发泡,当引入第三单元苯乙烯(St)后可改善其发泡性能。VDC—AN—St共聚物颗粒的发泡倍率随着发泡剂浓度的增加或发泡温度的提高而先增加后减小,气泡将随着发泡温度的提高而最终全部破裂塌陷。由破泡和扩散造成的发泡剂损失对VDC共聚物颗粒发泡能力的影响已不能忽略。     

硬质聚氨酯发泡体系发泡动力学模拟

通过流体动力学和热力学理论,建立了描述硬质聚氨酯发泡体系发泡动力学的模型,模拟了模塑反应体系的发泡过程,预报了模塑体的密度和分布,探讨了影响气泡涨大、模塑体密度和分布、气泡迁移和泄出等的因素,模型是合理的,结果是可信的,对实际应用具有指导意义,并为通过理论进行材料设计提供了手段。     

竹纤维/淀粉发泡复合材料制备及性能研究

目的研究竹纤维/淀粉发泡复合缓冲材料的制备方法,分析组分含量变化对发泡材料力学性能的影响规律,确定最佳的组分配比和最佳配比条件下竹纤维/淀粉发泡复合材料的能量吸收性能。方法将按一定比例配置的竹纤维、淀粉、碳酸氢铵、丙三醇和水置于模具中,采用烘焙发泡法制备竹纤维/淀粉发泡复合材料,并从能量吸收的角度分析了发泡剂、胶黏剂、增塑剂对竹纤维/淀粉复合发泡材料缓冲性能的影响规律,从而确定各组分的最佳配比。结果随着发泡剂和淀粉含量的增加,竹纤维/淀粉发泡复合材料的平台应力和总吸收能量呈现出先增加后减小的趋势,增塑剂含量的增加可改善制品的弹塑性,但降低了制品的平台应力和能量吸收能力;竹纤维、淀粉、水、碳酸氢铵、丙三醇最佳质量比为1∶2∶3∶1∶0.8。结论最佳质量配比条件下的竹纤维/淀粉发泡复合材料具有一定的缓冲吸能效果,其静态缓冲性能与EPS接近,可用于产品的物流防护。     

木薯渣纤维制备发泡缓冲包装材料的研究

以木薯渣为原料,加入可溶性淀粉、交联剂、催化剂和发泡剂后烘焙发泡,制备了新型植物纤维发泡缓冲材料。分析了木薯渣粒度和胶粘剂、发泡剂、催化剂用量等对发泡缓冲材料静态缓冲特性的影响;通过Statis-tics Analysis System 9.0软件对实验进行了中心组合设计。结果显示最佳发泡条件为:胶粘剂、发泡剂、催化剂添加量分别为2.0,6.0,2.4g;发泡温度为63～68℃,发泡时间为14～17h。     

植物纤维发泡材料的研究背景、现状及工艺探讨

植物纤维发泡制品的发泡方法主要有2种:采用化学发泡剂发泡及利用水蒸气发泡,应重点发展对环境无影响的发泡技术.制品的制作方法主要有2种:一步法成型和两步法成型.对该产品的制作、工艺及发泡剂的选用以及国内外发展的状况进行了介绍.     

废纸浆纤维增强淀粉基复合发泡材料的制备及其性能

以NH4HCO3为发泡剂,废纸浆纤维为增强体,玉米淀粉、PVA为基质,甘油和尿素作为复合增塑剂,辅以其它的各种助剂,利用挤出发泡法制备出一种可生物降解的复合发泡材料。并分别讨论该发泡材料的密度、发泡倍率、吸水性、回弹性以及泡孔形态。研究结果显示,材料的密度随着发泡剂含量的增加先减少后增加,当发泡剂含量为1.2%时,材料的密度最小为0.16g/cm3;发泡倍率、吸水率、线性尺寸变化量均随着发泡剂含量的增加先增加后减少,且在发泡剂含量为1.2%时,均达到最大值;随着发泡剂含量的增加,材料泡孔数量先增加后减少,孔径逐渐增大;当废纸浆含量为20%时,材料的泡孔数量多,孔径较小且分布比较均匀;当复合增塑剂含量为30%时,淀粉与废纸浆相容性较好,材料泡孔数量较多,且泡孔大小分布均匀。     

不同发泡剂制备废纸浆增强淀粉基复合发泡材料性能的对比

分别以水、碳酸氢氨、偶氮二甲酰胺/氧化锌(m(AC)/m(ZnO)=2∶1)为发泡剂,废纸浆为增强体,木薯淀粉为基质,聚乙烯醇(PVA)为增韧体,甘油和尿素作为复合增塑剂,辅以其它的各种助剂,利用挤出发泡法制备出可生物降解复合发泡材料,它们分别记作WPS、NPS、APS。并分别讨论和比较这些发泡材料的密度、发泡倍率、吸水性、热稳定性以及泡孔形态。研究结果显示,随着发泡剂含量的增加材料的表观密度先减少后增加,发泡倍率、吸水率则先增加后减少;NPS的热稳定性能最佳,APS稳定性次之,WPS稳定性最差;随着发泡剂含量的增加,材料泡孔数量先增加后减少,孔径先减小后增大,APS泡孔大小较WPS、NPS分布均匀,泡孔数量较WPS、NPS分布多。     

聚氯乙烯/杨木粉模压发泡材料的制备及性能研究

目的制备聚氯乙烯杨木粉发泡材料并研究其性能。方法采用模压法制备发泡材料,利用压缩试验表征其性能。结果随着杨木粉填充量的增加,聚氯乙烯杨木粉发泡材料的密度呈上升趋势。添加木粉后,压缩强度呈先升高后下降的趋势,当木粉填量为10份时,压缩强度达到最大。随着木粉粒度的增加,聚氯乙烯木粉发泡材料压缩强度也呈先上升后下降的趋势,在木粉粒度为100目时压缩强度达到最大。结论可采用模压法制备聚氯乙烯杨木粉发泡材料,发泡剂用量、木粉填量和粒度对发泡材料性能有一定影响。     

基于复配发泡剂的纸纤维发泡缓冲包装材料制备工艺

以纸质纤维为主料制得的植物纤维基发泡制品,是近年来出现的一种新型缓冲材料。设计了3个单因素试验,以废纸纤维和淀粉类胶黏剂为主要原料,将2种不同种类的发泡剂以3种组合方式施加到混合物中,采用微波发泡的方法制备了纸纤维发泡材料。通过测定样品成型后的密度、发泡倍率、发泡失重率和干燥失重率,比较了3种不同的发泡剂配方对样品性能及制备过程的影响程度。结果表明:利用各种发泡剂分解温度相异的特点将发泡剂复配,使纸纤维材料在加热过程中分段发泡,具有较好的发泡效果,而且后期干燥的能耗也少。     

放射性废液罐液位计故障分析研究与处理

核设施的放射性废液收集与处理系统通常采用吹气式液位计,本文根据一次吹气式液位计的故障,基于其现象及试验进行故障分析,得到压差变送器和吹气系统管路对仪表测量值的具体影响,并通过现场排查确定故障原因,总结吹气式液位计故障分析策略,目的是在液位计故障发生后,可以通过实际现象精准快速地判断故障原因,完成维修,保障核设施正常运行的同时,减少运行和维修人员的受照剂量,降低维修成本。     

Blowing snow at Mizuho station, Antarctica

Blowing snow observations were carried out at Mizuho station, Antarctica, from October to November 2000. A blowing snow observation system including snow particle counters, which can sense not only the number of snow particles, but also their diameters, was situated on a 30 m tower. All instruments worked correctly and the data obtained revealed profiles of mass flux and particle size distributions as a function of the friction velocity. Measurements were compared with a blowing snow model that accounted for most physical processes including aerodynamic entrainment, grain/bed collisions, wind modification, particle size distribution and turbulent fluctuations on the particle trajectories. Simulated and measured results showed close agreement, and the validity of the model was demonstrated. Vertical profiles of horizontal mass flux from saltation to suspension, as well as the particle size distributions were expressed precisely, which could not be achieved using the previous models.     

Aluminum integral foam castings with microcellular cores by nano-functionalization

The goal of the present work is the refinement of the pore morphology of aluminum integral foam castings. Integral foam molding, a modified high pressure die casting process, is used where a mixture of melt and blowing agent particles (magnesium hydride, MgH₂) is injected at high velocity into a permanent steel mold. At the mold surface, decomposition of the blowing agent and pore formation is suppressed due to the high solidification rate whereas solidification of the core is much slower allowing blowing agent decomposition, pore nucleation, and growth. Blowing agent particles not only act as gas suppliers but also represent pore nuclei. Thus, microcellular foam cores can be attained by increasing the number of MgH₂ particles. But increasing the number of powder particles by powder milling strongly decreases the flowability and strong particle agglomeration as a result of the increasing cohesive forces leads to inhomogeneous foams. Flowability of the powder can be restored by coating it with SiO₂-nano-particles resulting in a homogeneous microcellular foam morphology.     

绿色冰箱内衬材料研究

采用ＨＩＰＳ与聚烯烃共混，制得冰箱内衬材料，该材料具有抗ＨＣＦＣ－１４１ｂ腐蚀性能，并具有良好的成型性。     

聚合物-无机纤维复合泡沫材料吸声性能的研究

以聚合物和无机纤维为主要原料,用化学发泡方法制成了一种新型泡沫吸声材料,它具有质轻,阻燃强度大,成本低的特点,尤其是它在中低频范围内具有优异的吸声性能,克服了一般多孔性吸声材料在低频处吸声性能欠佳的缺陷,文中对发泡剂用量,无机纤维用量,交联剂用量及空腔对材料吸声性能的影响进行了测试分析,结果表明,这些因素对材料吸声性能均有重要影响。     

第三代ODS替代品FIC-1311

介绍了三氟碘甲烷(FIC-1311)的各种性质、合成方法和用途.三氟碘甲烷具有良好的环境性能和安全性能,在灭火、制冷、发泡、医药等领域有着广阔的应用前景.     

Influence of foaming process on the structure–properties relationship of foamed LDPE/silica nanocomposites

In this paper LDPE/silica nanocomposites are foamed by two different processes. First one is the pressure quench method which is based on the use of a physical blowing agent and second one is the improved compression moulding technique. As the latter process uses a chemical blowing agent, both types of foamed nanocomposites will provide very useful information about the relationship between foaming process-microstructure and macroscopic properties. Results have revealed how silica nanoparticles are able to act as nucleating sites during foaming step in both processes; however, the optimum amount of particles strongly depends on the foaming route. Thermal and mechanical properties of solid and foamed nanocomposites have been analyzed by means of thermogravimetric analysis and compression tests. Results have revealed that nanosilica particles act as effective nucleating agents, not only reducing cell size and increasing cell density but also achieving more homogeneous cellular structures. Thermal and mechanical properties are improved due to the presence of silica nanoparticles. It has been found that the improvement degree reached for samples produced using chemical blowing agents is greater than that achieved for samples produced using physical blowing agents.     

HCFC——一类过渡发泡剂

简单地介绍了几种用于聚氨酯泡沫塑料的ＣＦＣ替代物——ＨＣＦＣ发泡剂的性能特点。