MA-SEBS对超高分子量聚乙烯/碳纳米管复合材料结晶和熔融行为的影响

以马来酸酐接枝SEBS (MA-SEBS)作相容剂,采用溶液共混的方法制备超高分子量聚乙烯(UHMWPE)/碳纳米管(CNTs)复合材料.熔融结晶的UHMWPE/CNT复合材料是将其熔体以20℃/分的速率降温结晶而成.采用差示扫描量热法(DSC)研究了以不同方式结晶制备的UHMWPE/CNT复合材料的结晶和熔融行为.结果表明UHMWPE/CNT复合材料中UHMWPE相在溶液态结晶比在熔融态结晶形成的晶片厚,因而表现出更高的熔点(Tm)和结晶度(Xc).随着CNTs含量增加,UHMWPE/CNT复合材料中UHMWPE相的结晶温度(Tc)趋于提高.而且MA-SEBS的加入降低了UHMWPE/CNT复合材料中UHMWPE相的Tm 和 Tc. 此外UHMWPE/CNT复合材料中UHMWPE相的结晶速率随CNTs的引入而提高; MA-SEBS起相容剂的作用,改善了CNTs在UHMWPE基体中的分散性,使UHMWPE相的结晶速率进一步提高.     

超高分子量聚乙烯纤维防弹复合材料的研究

讨论了不同基体种类、不同结构超高分子量聚乙烯(UHMWPE)纤维复合材料的防弹性能。实验结果表明：聚氨酯(PU)和低密度聚乙烯(LDPE)均可以作为UHMWPE纤维防弹复合材料的基体使用；正交辅层结构为UHMWPE纤维防弹复合材料的首选结构。另外，还研究了基体含量、模压工艺对UHMWPE纤维复合材料防弹性能的影响，确定以LDPE为基体时其最佳基体含量在26％左右，同时指出模压工艺对复合材料的防弹性能无显著相关性。     

电子束辐照对超高分子量聚乙烯纤维结构与性能的影响

用电子加速器对超高分子量聚乙烯纤维进行辐照交联，探讨了不同剂量、剂量率辐照下结构与性能的变化．结果表明：凝胶含量随剂量率增大先增大而又减少，断裂强度随剂量增大而降低，尤其是在高剂量时下降得更为明显，而且随着剂量的增大纤维表面形貌被刻蚀得更为严重；当剂量为400kGv时，剂量率为8．5kGy／s时的刻蚀最为严重。     

成型气氛对超高分子量聚乙烯生物摩擦学性能的影响

研究了热压成型气氛对超高分子量聚乙烯（UHMWPE）力学和生物摩擦学性能的影响.分别在常规气氛和10-3 Pa的低真空环境下通过热压成型工艺制备UHMWPE试样,对其断口形貌、密度、球压痕硬度、冲压剪切强度、抗划痕性能和生物摩擦学性能进行测试分析.结果表明,常规气氛模压成型UHMWPE会在试样内部残留有气孔缺陷;低真空环境下模压成型UHM-WPE能有效地消除试样内的气孔缺陷,并增加其密度、硬度、冲压剪切强度和抗划痕性能.小牛血清润滑下的往复式摩擦磨损结果显示,低真空环境模压成型UHMWPE试样的耐磨性能比常规气氛模压成型的耐磨性能提高18.9%.     

制样方法对超拉伸聚乙烯纤维DSC熔融行为的影响

用切断、揉球、定长三种制样方式测定不同拉伸倍率的ＵＨＭＷ－ＰＥ纤维的ＤＳＣ曲线存在着很大差别，切断使纤维处于完全松驰状态，ＤＳＣ曲线上只出现表征正交晶系串晶的熔融峰和六方晶系结晶熔融的小峰，定长方式抑制了纤维的收缩，使串晶的熔点提高，并促进其向六方晶系转化，表征六方晶系结晶熔融的小峰变大，而揉球方式制样测得高倍拉伸ＵＨＭＷ－ＰＥ纤维的ＤＳＣ曲线则出现多重熔融峰。     

i-PP-g-MAH对i-PP／CaSO4复合材料的影响

用在50L固相接枝反应器中合成的马来酸酐接枝聚丙烯(i-PP-g-MAH)作界面改性剂，制备了马来酸酐接枝聚丙烯／聚丙烯／硫酸钙晶须(i-PP-g-MAH／i-PP／CaSO4)复合材料．研究了i-PP-g-MAH／i-PP／CaSO4复合材料的形态结构和力学性能．结果表明：i-PP-g-MAH对i-PP／CaSO4复合物的缺口抗冲强度、弯曲强度和拉伸强度均有增强作用；i-PP-g-MAH对硫酸钙晶须填充的i-PP／CaSO4复合物表观粘度几乎没有影响．SEM观察发现i-PP-g-MAH对硫酸钙晶须填充的i-PP／CaSO4复合物相界面有明显的改善．     

制样方法对超拉伸聚乙烯纤维DSC熔融行为的影响

用切断，揉球，定长三种制样方式测定不同拉伸倍率的ＵＨＭＷ－ＰＥ纤维的ＤＳＣ曲线存在着很大差别，切断的使纤维处于完全松驰状态，ＤＳＣ曲线上只出现表征正交晶系串晶的熔融峰和六主晶系结晶熔融的小峰。定长方式抑制了纤维的收缩，使串晶的熔点提高，并促进其向六主晶系转化，表征六主晶系结晶熔融的小峰变大。     

Biotribological behavior of ultra high molecular weight polyethylene composites containing bovine bone hydroxyapatite

Wear particles of ultrahigh molecular weight polyethylene (UHMWPE) are the main cause of long-term failure of total joint replacements. Therefore, increasing its wear resistance or bioactivity will be very useful in order to obtain high quality artificial joints. In our study, UHMWPE composites filled with the bovine bone hydroxyapatite (BHA) were prepared by the method of compression moulding. A ball-on-disc wear test was carried out with a Universal Micro-Tribometer to investigate the friction and wear behavior of a Si3N4 ceramic ball, cross-sliding against the UHMWPE/BHA composites with human plasma lubrication. At the same time, the profiles of the worn grooves on the UHMWPE/BHA surface were scanned. The experimental results indicate that the addition of BHA to UHMWPE had a significant effect on the biotribological behavior of UHMWPE cross-sliding against the Si3N4 ceramic ball. The addition of BHA powder enhanced the hardness and modulus of elasticity of these composites and decreased the friction coefficients and wear rates under conditions of human plasma lubrication. When the added amount of BHA powders was up to 20%～30%, UHMWPE/BHA composites demonstrated the designed performance of the mechanical properties and biotribological behavior.     

Effect of strain on the electrical resistance of carbon nanotube/silicone rubber composites

Carbon nanotube (CNT) filled silicone rubber (SR) composites were synthesized by in situ polymerization.The effect of strain on the electrical resistance of the CNT/SR composites and the structure evolution of CNT networks during tensile deformation were investigated.The results showed that the CNT/SR composites had high sensitivity of resistance-strain response.In a wide strain range (0-125%),the change of resistivity could reach 107,which was closely associated with the evolution process of the conductive CNT-network structure.The volume expansion of the composites in the tensile process led to a gradual decrease in the volume fraction of CNTs with the strain increase.When CNT loading was lower than the percolation threshold,CNT network was in disconnected state with a rapid increase in electrical resistance of the composites.Furthermore,the CNT loading had remarkable effect on the sensitivity of resistance-strain response in the composites.     

聚合物/碳纳米管导电复合材料研究进展

在聚合物基体中加入碳纳米管可以制备综合性能优异的导电聚合物复合材料,而具有取向结构的聚合物/碳纳米管复合材料在光、电、磁、生物功能材料中具有潜在的应用前景.基于碳纳米管的电学性质,综述了聚合物/碳纳米管导电复合材料的三种制备方法(熔融共混法、溶液共混法和原位聚合法)以及国内外研究进展,着重介绍了具有取向结构的聚合物/碳纳米管导电复合体系的制备方法,包括模板组装、力场排列、电场排列以及磁场排列等,并分析比较了各种方法的基本原理和特点.最后对聚合物/碳纳米管导电复合材料的应用情况及研究前景进行了初步的探讨.     

超高分子量聚乙烯与钢的冲蚀磨损研究

用气流喷砂型冲蚀试验装置对超高分子量聚乙烯（Ｕｌｔｒａ Ｈｉｇｈ Ｍｏｌｅｕｌａｒ Ｗｅｉｇｈｔ Ｐｏｌｙｅｔｈｙｌｅｎｅ,ＵＨＭＷＰＥ）和４５＃钢的冲蚀磨损性能进行进行了比较,考察了冲蚀粒子（煤粉,二氧化硅）的入射角,冲蚀时间等对超高分子量聚乙烯和４５＃钢冲蚀磨损的影响,通过扫描电子显微镜对超高分子量聚乙烯和４５＃钢冲蚀磨损表面形貌的观察,并对超高分子量聚乙烯和４５＃钢冲蚀磨损机理进行了初步探讨。     

超高分子量聚乙烯耐热性能的改善

为了提高超高分子量聚乙烯的耐热性能,采用高岭土、碳酸钙两种材料作为填料进行耐热改性研究.通过实验,对复合材料的各种性能进行测试和分析,比较不同质量分数的填料对超高分子量聚乙烯各性能的影响.结论表明:高岭土和碳酸钙的填充明显改善了超高分子量聚乙烯的耐热性能,当填料质量分数为30%时,填充高岭土得到的复合材料的维卡软化温度为113℃,填充碳酸钙得到的复合材料的维卡软化温度为111℃,均提高30℃左右.其力学性能有不同程度的降低,当填料质量分数为10%时,复合材料的力学性能最好,之后随着添加比例的增大,其力学性能减小的速度也增加.综合考虑,填料质量分数在10%到20%之间时,能同时满足力学性能和耐热性能的需要.     

碳纳米管增强复合材料的界面破坏形态及改善措施

以碳纳米管增强树脂基复合材料的二维平面模型为对象,在考虑基体材料非线性的情况下,探讨碳纳米管增强复合材料的界面层特性对复合材料破坏形态的影响。通过对破坏端部的局部处理,提出两种提高复合材料抵抗损伤破坏能力的方法。第一种方法是改变纤维及界面层端部与基体的界面特性即软化界面,用内聚力模型模拟界面,通过内聚力阻扰裂纹的扩展;第二种方法是改变碳纳米管的端部形状即封闭碳纳米管及界面层,通过改变碳纳米管的应力分布状态来提高复合材料的抗破坏能力。     

Structure and properties of self-assembled narural rubber/multi-walled carbon nanotube composites

Natural rubber (NR)/multi-walled carbon nanotube (MWCNTs) composites were prepared by combining self-assembly and latex compounding techniques.The acid-treated MWCNTs (H2SO4:HNO3=3:1,volume ratio) were self-assembled with poly (diallyldimethylammonium chloride) (PDDA) through electrostatic adhesion.In the second assembling,NR/MWCNTs composites were developed by mixing MWCNTs/PDDA solution with NR latex.The results show that MWCNTs are homogenously distributed throughout the NR matrix as single tube and present a great interfacial adhesion with NR phase when MWCNTs contents are less than 3 wt%.Moreover,the addition of the MWCNTs brings about the remarkable enhancement in tensile strength and crosslink density compared with the NR host,and the data peak at 2 wt% MWCNTs loadings.When more MWCNTs are loaded,aggregations of MWCNTs are gradually generated,and the tensile strength and crosslink both decrease to a certain extent.