成核剂对聚丙烯釜压发泡的影响

用超临界二氧化碳（CO2）釜压发泡的方法,研究了成核剂类型、成核剂粒径以及成核剂添加量对聚丙烯（PP）发泡材料泡孔结构的影响。结果表明,用碳酸钙（CaCO3）作成核剂时PP泡沫的泡孔完整性高,泡孔尺寸分布均匀,且发泡倍率比添加蒙脱土及滑石粉时的要大;成核剂粒子粒径越小,体系的成核点越多,发泡时产生的气泡核越多,所得到的PP泡沫的泡孔密度越大,但是由于纳米碳酸钙（nano-CaCO3）更容易出现团聚现象,直接导致最终发泡制品产生泡孔破裂以及发泡倍率的降低;成核剂CaCO3的添加量为3份时,与添加1份和5份相比,可得到发泡倍率更高,泡孔密度更大的PP泡沫。     

无机纳米粒子对聚苯乙烯泡孔结构影响的研究

以活性纳米碳酸钙(CaCO3)和有机化纳米蒙脱(土OMMT)为异相成核剂,制备了聚苯乙(烯PS/)无机纳米粒子发泡材料,并利用透射电镜和扫描电镜研究了纳米粒子种类和含量对PS挤出发泡制品的表观密度和泡孔结构的影响。扫描电镜分析结果表明:采用纳米CaCO3为成核剂时所得发泡制品的表观密度为0.451~0.485g/cm3;而用OMMT作为成核剂所得发泡制品的表观密度为0.514~0.573g/cm3,平均泡孔尺寸较小。透射电镜分析结果表明:OMMT在泡孔壁面的取向分布有利于得到闭孔形式的泡孔结构。     

聚乳酸/蒙脱土纳米复合材料的制备及其微孔发泡性能

通过双螺杆挤出机熔融混合制备聚乳酸/蒙脱土纳米复合材料,研究了纳米复合材料力学性能、流变性能和结晶性能。XRD和TEM测试结果表明:蒙脱土以插层结构分散在复合材料中。对于不同的蒙脱土含量,材料性能测试表明:2%蒙脱土所对应的纳米复合材料的力学性能和流变性能最好。文中选取了蒙脱土质量分数为2%的复合材料以超临界二氧化碳为发泡剂进行微孔发泡,泡孔形态分析表明:蒙脱土在发泡过程中起成核剂的作用,增加了PLA发泡材料的泡孔密度,减小泡孔尺寸。     

超临界二氧化碳发泡软质聚氯乙烯材料的性能研究

采用超临界二氧化碳作为物理发泡剂,进行软质聚氯乙烯(PVC)的发泡试验研究。探讨了实验过程中主要助剂用量对发泡材料的宏观性能和微观泡孔结构的影响。结果表明,当PVC用量为100份,交联剂为0.5份,泡孔调节剂为6份时,发泡材料各项性能较为优异。添加了成核剂纳米Ca CO3后,相比于纯PVC发泡体系,发泡材料的表观密度都有所减小,当成核剂含量为5份时,发泡材料的表观密度最小,为0.294 g/cm3,发泡倍率最大为3.873倍。材料微观的泡孔分布更为均匀,泡孔密度提高到原来的近3倍,泡孔的平均直径较没有添加成核剂的体系缩小了近一半,平均孔径为35.7μm。     

纳米蒙脱土对聚丙烯微孔发泡行为的影响

通过二次开模注塑成型法制备聚丙烯/蒙脱土复合材料的微孔发泡塑料.用扫描电镜对发泡样品的泡孔结构进行表征,研究蒙脱土含量对微孔发泡材料的泡孔结构和注塑成型温度的影响.结果表明:在聚丙烯中加入纳米蒙脱土可以使泡孔直径减小、泡孔密度增加.注塑成型温度范围变宽;加入的蒙脱土含量为5%时,泡孔直径最小、泡孔密度最大.     

聚丙烯微孔复合材料的研究

采用模压发泡法制备聚丙烯微孔复合材料,用扫描电镜对发泡样品的微观结构进行表征,研究了发泡剂、成核剂等对微孔发泡材料泡孔结构的影响。结果表明:当滑石粉用量为15phr或木粉用量为30phr时,泡孔直径最小且,分布较均匀;在聚丙烯中加入蒙脱土可使泡孔直径减小、泡孔密度增加。     

纳米蒙脱土对PVC微发泡体系的影响

研究了纳米蒙脱土对PVC微发泡体系的力学性能和泡孔结构的影响。试验表明：纳米蒙脱土具有成核作用，当纳米蒙脱土用量为6份时。材料体内孔洞较多，且分布均匀。微孔达到最好状态，此时材料的冲击强度较好，热变形温度较高；当蒙脱土用量为8份时。界面有丝络状结构，蒙脱土与基体树脂之间的相容性较好，此时，材料的弯曲强度和拉伸强度较好；电镜试验验证了此结论。     

发泡倍率对聚丙烯/纳米二氧化硅复合微孔发泡材料结构与性能的影响

采用双螺杆熔融共混法制备聚丙烯/纳米二氧化硅复合材料。用化学发泡法注塑成型制备聚丙烯/纳米二氧化硅复合微孔发泡材料。研究了发泡倍率对微孔发泡材料结构与性能的影响。结果表明:泡孔平均直径随着发泡倍率的增加先减小后增大,泡孔密度随着发泡倍率的增加先增加后减少;微孔发泡材料的缺口冲击强度随着发泡倍率的增加而增加,拉伸强度随着发泡倍率的增加而线性降低。     

连续挤出发泡聚乳酸泡孔结构的影响因素

介绍了采用超临界CO2作为发泡剂,连续挤出聚乳酸泡沫塑料的方法。在不同的实验条件下,对聚乳酸进行挤出发泡,得到聚乳酸发泡样品。通过对样品的ESM照片的分析研究,得出了不同的发泡条件对挤出聚乳酸泡沫泡孔结构的影响。结果表明螺杆转速的增加使得泡孔数量增加,泡孔形态更加规整均匀。模头温度影响了泡孔形态,较高的温度会使得样品的泡孔形态受到不利的影响。水分的存在不利于聚乳酸发泡成为均匀发泡倍率高的泡沫制品。成核剂促进异相成核,使发泡样品的泡孔结构更加均匀,大大提高了聚乳酸泡沫塑料的泡孔密度。     

有机蒙脱土/聚丙烯复合材料微发泡性能研究

采用均聚聚丙烯为树脂基体,通过添加有机蒙脱土(OMMT)、聚丙烯接枝马来酸酐(PP-g-MAH)等制得聚丙烯(PP)改性料,然后加入自制发泡母料通过化学发泡制得了性能优异的微发泡制品。利用扫描电镜(SEM)观察了在不同成核剂含量和不同发泡母料含量下PP发泡复合材料的泡孔结构,同时利用X射线衍射(XRD)分析了OMMT在PP中的插层情况。研究表明:PP-g-MAH的加入使OMMT的层间距在复合材料中发生变化;当添加3%OMMT和5%发泡母料时,可制得泡孔密度大、泡孔直径小并且分布均匀的高品质微发泡PP复合材料。     

软质PVC发泡材料的研究

采用化学发泡一步法模压成型制备了软质PVC发泡材料,研究了发泡剂、泡孔成核剂、改性剂等主要助剂用量对软质PVC发泡材料密度、泡孔结构以及力学性能的影响,并进行了软质PVC发泡材料的配方筛选.结果表明加入吸热发泡剂N能提高发泡体系的发泡效果,降低材料的密度,改善材料的力学性能,当发泡剂AC用量为2份,用量为0.6份时,材料的综合性能优异;当成核剂用量为1份时,体系发泡效果较好;加入粉末NBR不仅能提高发泡材料的断裂伸长率和柔韧性,还可降低发泡材料密度,改善泡孔结构;当NBR用量为20份时,发泡材料密度达到0.44 g/cm3,力学性能优异.     

软质PVC鞋底发泡材料的研究

采用化学发泡一步法模压成型．研究了放热发泡剂、吸热发泡剂、泡孔成核剂、改性剂等主要助剂用量对软质聚氯乙烯(PVC)发泡材料密度、泡孔结构及力学性能的影响．结果表明：放热发泡剂2．0份、吸热发泡剂0．6份．成核剂1.0份．改性剂丁腈橡胶(NBR)20．n份时．发泡材料性能较好．满足了软质PVL鞋底发泡材料的要求。     

微发泡聚丙烯复合材料发泡行为研究

以PP(聚丙烯)为基体材料,分别添加发泡剂母粒、发泡剂和助剂母粒及发泡剂、助剂、成核剂母粒,在二次开模条件下注塑制备微发泡PP复合材料,分析了发泡助剂及成核剂对微发泡复合材料发泡行为的影响规律。结果表明,添加发泡助剂以后,PP体系的发泡质量得到明显改善;助剂和成核剂同时添加,微发泡PP体系的发泡质量最好,泡孔平均直径为26.79μm,泡孔密度达到4.76×106个/cm3。     

CM与PVC共混发泡性能的研究

采用模压法进行发泡,研究了氯化聚乙烯(CM)与聚氯乙烯(PVC)的共混比和发泡剂用量对发泡体的泡体性能、泡孔结构的影响。结果表明,不同CM/PVC共混比的复合材料,随体系中CM的增加,发泡密度逐渐减小、泡孔体积和发泡倍率逐渐增大,当CM/PVC=50/50时,发泡材料具有较好的综合性能;改变共混体系中发泡剂AC的用量,测试泡体性能及观察泡孔结构得出,随AC发泡剂用量的增加,发泡材料的发泡密度减小,其相应的物理机械性能如拉伸强度、撕裂强度逐渐降低。     

Effect of dispersion method and process variables on the properties of supercritical CO2 foamed polystyrene/graphite nanocomposite foam

In this study, polystyrene/nanographite nanocomposite foams were made by different compounding methods, such as direct compounding, pulverized sonication compounding, and in situ polymerization, to understand the effect of the process variables on the morphology of the nanocomposites and their foam. The foam was made by batch foaming using CO₂ as the blowing agent. Various foaming pressures and temperatures were studied. The results indicated that the cell size decreased and the cell morphology was improved with the advanced dispersion of the nanoparticles. Among the three methods, the in situ polymerization method provided the best dispersion and the resulting nanocomposite foam had the finest cell size and the highest cell density. In addition, adding nanoparticles as a nucleating agent can make foams of similar cell size and cell density at a much lower foaming pressure. This result can be explained by the classical nucleation theory. This discovery could open up a newroute to produce microcellular foams at a low foaming pressure. POLYM. ENG. SCI., 53:2061–2072, 2013. © 2013 Society of Plastics Engineers     

纳米SiO_2对微发泡聚丙烯复合材料发泡行为的影响

将改性的纳米二氧化(硅SiO2)以不同含量加入到聚丙(烯PP)中,在二次开模条件下制备微发泡PP/纳米SiO2复合材料,分析了纳米SiO2含量对微发泡复合材料发泡行为的影响。结果表明:随着纳米SiO2含量的增加,复合材料的平均泡孔直径减小,泡孔密度增加,当纳米SiO2含量为4%时,复合材料的泡孔直径为16.3μm泡,孔密度达1.41×109个/cm3具,有理想的发泡效果。     

Foaming of aliphatic polyester using chemical blowing agent

Poly(butylene adipate‐co‐succinate) (PBAS), a saturated aliphatic polyester cured by dicumyl peroxide (DCP), was prepared and the viscoelastic property was investigated. The viscosity of crosslinked PBAS increased, and it exhibited rubbery behavior as the content of curing agent was increased. The results suggested that the viscosity and elasticity of PBAS could be regulated by adding a small amount of DCP; hence, the processibility could be improved. Prior to foaming, a proper formulation of blowing agent (blowing agent/urea activator = 100:8 phr) was examined to prepare expanded PBAS foam. Low‐density PBAS expanded foams were prepared using a chemical blowing agent and DCP. The effect of the foaming temperature, additive content, and curing agent content on the blowing ratio and morphology of expanded PBAS foams was investigated. A closed‐cell structure PBAS foam of high blowing ratio (density about 0.05 g/cm³) could be obtained by adding 3 phr DCP. To manufacture expanded PBAS foam under 0.1 g/cm³ using a chemical blowing agent, the storage modulus of the matrix polymer should exceed the loss modulus by enough to stabilize growing bubbles. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2443–2454, 2001     

采用二氧化碳／酒精复合发泡剂制备挤出聚苯乙烯发泡板材

采用二氧化碳（CO2）与乙醇（EtOH）组合物理发泡剂对聚苯乙烯（PS）进行连续挤出发泡,并探讨了2种发 泡剂组成比率对PS挤出发泡板材发泡倍率及泡孔形貌的影响。通过真密度测定仪和扫描电镜对发泡样品的密度、 发泡倍率和泡孔形态进行测试。结果表明,在组合发泡剂连续挤出PS发泡过程中,提高CO2的用量更有利于增加泡 孔成核数量和减小泡孔尺寸,而提高EtOH用量可以增大泡孔尺寸,提高发泡剂总量,有利于降低泡沫密度。     

Structure and properties of closed‐cell foam prepared from irradiation crosslinked silicone rubber

Silicone rubber foam was prepared through crosslinking with electron beam irradiation and foaming by the decomposing of blowing agent azobisformamide (AC) in hot air. The crosslinking and foaming of silicone rubber was carried out separately, which was different from the conventional method of chemical crosslinking and foaming. After foaming, the silicone rubber foam was irradiated again to stabilize the foam structure and further improve its mechanical properties. The effects of irradiation dose before and after foaming, and the amount of blowing agents on the structure and properties of silicone rubber foam were studied. The experimental results show that with the increase of AC content, the average cell diameter of silicone rubber foam increases a little, the foam density decreases to a minimum value when AC content is 10 phr. With the increase of irradiation dose before foaming from 10 to 17.5 kGy, the cell nucleation density of silicone rubber foam increases, the average cell diameter decreases, and the foam density increases. With the increase of irradiation before foaming, the tensile strength, tensile modulus, and the elongation at break of the silicone rubber foam increase. Through irradiation crosslinking again after foaming, the foam density is decreased and the mechanical properties of silicone foam are further improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009