新型热平衡发泡体系分解特性及在R-PVC挤出低发泡的应用

研制了两类新型的吸放热平衡型发泡剂,即先吸热后放热平衡发泡剂和先放热后吸热平衡发泡剂,采用动力学与热力学相结合的方法对各体系的分解热力学和动力学进行了系统的研究,对各类典型发泡剂的优缺点进行了详细比较,并利用Brabender挤出机对复合发泡剂的实际发泡特性进行了验证。为发泡机理的研究和断裂吸放热发泡剂的开发应用提供了一些新思路。     

AC发泡剂的制备工艺及其微细化途径

综述了AC发泡剂的制备工艺 ,重点探讨了联二脲中间体氧化制备AC发泡剂的氧化工艺 ,并指出各种氧化工艺的优缺点。此外 ,由于传统氧化工艺制备的AC发泡剂粒径粗大 ,会给微孔泡沫制品的发泡带来困难 ,介绍了AC发泡剂颗粒微细化的途径。     

用于制备泡沫金属的发泡剂的种类及特性

利用发泡剂产气使得金属熔体泡沫化是制备泡沫金属的方法之一.发泡剂的产气特性是决定金属熔体泡沫化进程的重要因素.介绍了两类发泡剂:以氢化钛为代表的金属氢化物和以碳酸钙为代表的碳酸盐.总结和分析了各种发泡剂的产气原理、在不同气氛下的产气特性、发泡剂的预处理对金属熔体泡沫化的影响及不同发泡剂的优缺点和使用的范围.     

不同改性方式对发泡剂在铝熔体中分散性的影响

采用新型发泡剂制备了泡沫铝,研究了包覆改性和混合改性两种改性方式对新型发泡剂在铝熔体中分散性的影响。结果表明,采用Al溶胶和Si溶胶对新型发泡剂进行包覆改性处理,发泡剂分散性差,所制备的泡沫铝存在较多大孔和裂纹;采用TiB2粉末和AlSi合金粉末混合改性处理新型发泡剂时,发泡剂分散性良好,并且随着TiB2和AlSi含量的增加得到的泡沫铝样品裂纹明显减少、泡体趋于均匀,但孔隙率逐渐降低。相比较而言,合金粉末混合改性法比溶胶包覆改性法使发泡剂的分散更均匀,制备的泡沫铝裂纹较少,且泡体结构较均匀。     

霍尼韦尔低全球变暖潜值隔热材料助力美国普渡大学“零能耗之家项目”

正霍尼韦尔近日宣布,美国普渡大学在其"零能耗之家项目"中采用了具有超低全球变暖潜值的Solstice?液体发泡剂(LBA)。Solstice?液体发泡剂可以使闭孔泡沫喷涂隔热材料扩张,最大程度地发挥泡沫卓越的隔热性能。该发泡剂被应用在位于印第安纳州的普渡大学西拉法叶校区的房屋改造项目中。这标志着霍尼韦尔新一代发泡剂在泡沫喷涂墙体隔热系统中的首次成功应用。在此之前,Solstice液体发泡剂已经被     

发泡剂粒径对硅橡胶泡沫材料性能的影响研究

以硅橡胶为基体材料,采用发泡剂H制备硅泡沫材料.研究了不同发泡助剂对发泡剂H分解温度的影响,以及发泡剂粒径对硅泡沫材料密度、硬度、力学性能、压缩性能和泡孔大小及其分布状态的影响规律.结果表明:发泡剂H与发泡助剂尿素的比例为1:1时,两者之间具有良好的匹配性;在发泡剂粒径对硅泡沫材料性能的影响方面,随着发泡剂粒径的减小,硅泡沫材料的密度、硬度、拉伸强度和40％压缩应变下的压缩应力值逐渐变大,当发泡剂粒径达到300目时,上述性能参数达到最大值,之后又出现下降趋势;其中,原始目数和较大目数下制备的硅泡沫材料的性能变化情况相似.同时,采用SEM技术对不同发泡剂粒径时硅泡沫材料的泡孔大小和分布状态进行了分析.     

霍尼韦尔低全球变暖潜值隔热材料助力美国普渡大学“零能耗之家项目”

10月9日,霍尼韦尔宣布,美国普渡大学在其“零能耗之家项目”中采用了具有超低全球变暖潜值的Solstice液体发泡剂（LBA）。Solstice液体发泡剂可以使闭孔泡沫喷涂隔热材料扩张,最大程度地发挥泡沫卓越的隔热性能。该发泡剂被应用在位于印第安纳州的普渡大学西拉法叶校区的房屋改造项目中。这标志着霍尼韦尔新一代发泡剂在泡沫喷涂墙体隔热系统中的首次成功应用。在此之前,Solstice液体发泡剂已经被应用于节能环保冰箱的隔热材料中。     

发泡剂AK在硅橡胶海绵中的应用研究

采用发泡剂AK制作了硅橡胶海绵.研究了发泡剂AK用量对硅橡胶硫化速率和发泡速率的影响.实验结果表明,随着发泡剂用量的增加,混炼胶初始发泡时间缩短,制得的海绵材料的压缩应变和伸长率增加.     

双马来酰亚胺泡沫泡孔结构研究

研究了几种有机发泡剂偶氮二甲酰胺(AC),4,4 ′-氧代双苯磺酰肼(OBSH)和二亚硝基五亚甲基四胺(H)的热分解特性,用扫描电镜(SEM)表征了各种发泡剂对双马来酰亚胺(BMI)泡沫孔径的影响.结果表明,与单一发泡剂相比,通过发泡剂AC/H,AC/OBSH之间的复配可以优化泡孔结构,改善成型工艺性.树脂预聚程度是控...     

聚烯烃材料复合发泡剂的制备及应用

运用湿法研磨和溶液法将化学发泡剂加载到硅藻土的微孔中,通过浮选技术、TG以及EDS等表征方式,分析了湿法研磨和溶液法对复合发泡剂加载效果的影响因素,并通过注塑成型方式制备微发泡聚烯烃复合材料,研究其对发泡质量的影响规律。结果表明,湿法研磨不适于制备硅藻土/OBSH复合发泡剂,溶液法成功制备了硅藻土/OBSH复合发泡剂。添加硅藻土/OBSH复合发泡剂的微发泡聚烯烃材料,其发泡质量显著优于相同条件下使用纯OBSH发泡剂时的发泡质量,泡孔直径从275.47μm降低至176.45μm,泡孔密度从3.32×10~3个/cm~3增加至5.73×10~4个/cm~3。     

新型环保发泡剂HFC-245fa的现状及发展趋势

介绍了HFC-245fa发泡剂的各种性质、在聚氨酯硬泡中的应用及发展趋势。指出HFC-245fa体系将是未来普遍采用的体系。     

The effect of blowing agent choice on energy use and global warming impact of a refrigerator

A study, comparing the effect of blowing agent selection on energy consumption and the life cycle climate performance (LCCP) of a typical European refrigerator is discussed. Energy consumption of prototype European-style refrigerators made with a foam formulation with HFC-245fa as the blowing agent was measured and compared with energy consumption of the same model as currently produced (using a foam with a pentane blend for the blowing agent). Results were used in a LCCP study, considering both direct and indirect climate impacts due to blowing agent emissions and energy consumption in manufacturing processes and over the life cycle of the refrigerator. An assumption is made that the refrigerator is built and used in the European market.     

Effect of aluminium silicate filler on morphology and physical properties of closed cell microcellular ethylene–octene copolymer

The effect of aluminium silicate filler on the morphology of the microcellular ethylene–octene copolymer (Engage) has been studied from SEM photomicrographs with variation of blowing agent and silicate filler loading in comparison to the unfilled vulcanizates. The average cell size, maximum cell size and cell density varies with variation of blowing agent and filler loading. Physical properties like relative density, hardness, tensile strength, elongation at break, modulus, tear strength decreases with blowing agent concentration. However tensile strength, modulus (100%), tear energy and hardness varies linearly with the density of the filled vulcanizates. The elastic nature of closed cells reduces the hysteresis loss compared to solid compounds. Set properties improve with blowing agent concentration. It is observed that stress relaxation behavior is independent of blowing agent loading i,e., density of closed cell microcellular vulcanizates. Theoretically flaw sizes are found to be about 2.57 times larger than maximum cell sizes observed from SEM photomicrographs.     

Production of novel epoxy micro-balloons

Epoxy micro-balloons are prepared by dropping and stirring of epoxy mixture in heated silicon oil. The mixture of epoxy, curing agent and blowing agent forms sphere particles, which are then blown via the function of blowing agent and simultaneously cured to form epoxy micro-balloons. Different ratio of epoxy and hardener will produce different types of epoxy micro-balloons. Schematic illustrations to produce the epoxy micro balloons are also proposed.     

氟里昂发泡剂替代技术的新进展

介绍了各种氟里昂替代品的品种和特性 ,对CFC、HCFC、HFC和HC类发泡剂的特性进行了对比和讨论 ,认为HCFC 141b和HCFC 2 2 / 142b是替代CFC物质的过渡性替代发泡剂 ,环戊烷和HFC 2 4 5fa是最终长期替代CFC发泡剂的最有希望替代品。     

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。     

Moulded polypropylene foams produced using chemical or physical blowing agents: structure–properties relationship

Polypropylene (PP) foams have become essential items due to their excellent properties. Nevertheless, obtaining net-shaped PP foams with medium relative densities is a complicated issue. In this article, two processes able to produce moulded PP foams in this density range are presented. One of them is based on a modification of the pressure quench foaming method and therefore uses a physical blowing agent (CO₂). The second one is the improved compression moulding technique which uses a chemical blowing agent (azodicarbonamide). PP foams with relative densities in the range between 0.25 and 0.6 and cylindrical shape were prepared using these foaming techniques. A common PP grade (instead a highly branched one) was used to obtain the samples, showing, that by combining the appropriate foaming technique, the adequate moulds, suitable blowing agent and proper foaming parameters, net-shaped PP foams with excellent properties can be produced starting from a conventional PP grade. Samples were characterized by analyzing their cellular structure and their mechanical properties. Results have showed that depending on the chosen foaming route isotropic or anisotropic structures with cell sizes ranging from 40 to 350 μm and open cell content in the range between 0 and 65% can be obtained. Moreover, mechanical properties are highly influenced by the production route and chemical composition of the foams. For instance, the stiffer materials at relative densities higher than 0.4 are the ones produced using the chemical blowing agent while at relative densities lower than 0.4 are the ones produced using the physical blowing agent.     

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。     

以芳基乙炔为前驱体制备高强度炭泡沫(英文)

以硫酸为催化剂,芳基乙炔为前驱体,经聚合、正戊烷发泡、炭化获得了高强度炭泡沫。通过选择合适的制备条件,如:发泡剂的用量,催化剂的浓度及用量,以及匀泡剂吐温80的添加量,可以制得孔结构良好、韧带和接点光滑的炭泡沫。芳基乙炔聚合物泡沫炭化后高的残炭率(86%)和良好的孔结构赋予炭泡沫较高的机械强度;所制炭泡沫的耐压强度达到25.8MPa,强度/密度比为43.0MPa/(g.cm-3).