Friction and wear mechanisms of PA66/PPS blend reinforced with carbon fiber

The mechanical and tribological properties of carbon fiber (CF) reinforced polyamide 66 (PA66)/polyphenylene sulfide (PPS) blend composite were studied in this article. It was found that CF reinforcement greatly increases the mechanical properties of PA66/PPS blend. The friction coefficient of the sample decreases with the increase of CF content. When CF content is lower (below 30%), the wear resistance is deteriorated by the addition of CF. However, the loading of higher than 30% CF significantly improves the tribological properties of the blend. The lowest friction coefficient (0.31) and the wear volume (1.05 mm³) were obtained with the PA66/PPS blend containing 30% CF. The transfer film and the worn surface formed by sample during sliding were examined by scanning electron microscopy. The observations revealed that the friction coefficient of PA66/PPS/CF composite depends on the formation and development of a transfer film on the counterface. The abrasive wear caused by ruptured CFs (for lower CF content) and the load bearing ability of CFs (for higher CF content) are the major factors affecting the wear volume. In addition, the improvements of mechanical properties, thermal conductivity, and self‐lubrication of bulk CFs are also contributed to the wear behavior of PA66/PPS/CF composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Mechanical and tribological properties of PA66/PPS blend. II. Filled with PTFE

The mechanical and tribological properties of 70 vol % PA66/30 vol % PPS blend filled with different content of polytetrafluoroethylene (PTFE) were studied in this paper. It was found that the addition of PTFE impairs the mechanical properties of PA66/PPS blend, but greatly increases the wear resistance and decreases the friction coefficient. When PTFE content exceeds 20 vol %, the friction coefficient of composite is minimum (0.15) and lower than that of pure PTFE under the same conditions (0.22). The lowest wear volume (0.44 mm³) is obtained with PA66/PPS/30 vol % PTFE composite, which decreased by 91% compared with unfilled PA66/PPS blend (4.99 mm³). The topography of transfer film and the elemental distribution were investigated by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS), respectively. Because of the characteristic crystalline structure, PTFE preferentially transferred to the steel ring surface and formed a thin, uniform and firmly adhered transfer layer, which reduced the ability of PA66/PPS blend to transfer and prevent the adhesion between the sample and the couterface. In addition, the superior lubrication of PTFE inhibited the frictional heat melting during sliding. All these aspects are close related to the friction and wear behavior of PA66/PPS/PTFE composite. Upon the addition of PTFE, thermal control of friction regime is not applicable to the PA66/PPS blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 969–977, 2006     

Mechanical and tribological properties of PA66/PPS blend. III. Reinforced with GF

Based on previous work, 70 vol % PA66/30 vol % PPS blend was selected as a matrix, and the PA66/PPS blend reinforced with different content of glass fiber (GF) was prepared in this study. The mechanical properties of PA66/PPS/GF composites were studied, and the tribological behaviors were tested on block‐on‐ring sliding wear tester. The results showed that 20–30 vol % GF greatly increases the mechanical properties of PA66/PPS blend. When GF content is 20 vol %, the friction coefficient of composite is the lowest (0.35), which is decreased by 47% in comparison with the unfilled blend. The wear volume of the GF‐reinforced PA66/PPS blend composite decreases with the increase of GF content. However, the wear‐resistance is not apparently improved by the addition of GF in the experimental range for comparison with unfilled PA66/PPS blend. The worn surface and the transfer film on the counterface were examined by scanning electron microscopy (SEM). The observations revealed that the friction coefficient of composite depends on the formation and development of a transfer film. The wear mechanism involves polymer matrix wear and fiber wear. The former consists of melting wear and plastic deformation of the matrix, while the latter includes fiber sliding wear, cracking, rupturing, and pulverizing. The contributions of the matrix wear and the fiber wear determine the ultimate wear volume of PA66/PPS/GF composite. In addition, the abrasive action caused by the ruptured glass fiber is also a very important factor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 523–529, 2006     

开发中的PET/PA66共混体系

塑料合金化是当今塑料工业的发展方向。PET和PA66树脂都是大品种工程塑料,两者如能构成共混体系理应引起人们的兴趣,但至今尚未见有商品出售。本文介绍了80年代开始国外对该共混体系的机械性能、酯-酰胺反应、氢键、结晶性能、结构和熔体的流变性能所作的研究工作。     

PA66／PP／POE—MAH合金的形态结构与力学性能

通过直接共混法制备了PA66／PP／POE－MAH合金,性能测试表明PA66／PP／POE－MAH合金的常温及低温缺口冲击强度较原PA66有较大提高,而吸水率则明显下降,拉伸强度变化不大。DSC测试显示,POE－MAH可降低PA66及PP的熔点及热焓,表明POE－MAH影响着PA66和PP的两相界面作用和结晶行为,SEM照片显示分散相粒径大小及两相界面结构与POE－MAH含量相关。     

PE-HD-g-MAH对PA66/PE-UHMW共混物力学与摩擦学行为的影响

用马来酸酐接枝高密度聚乙烯（PE-HD-g-MAH）与聚酰胺66（PA66）/超高相对分子质量聚乙烯（PE-UHMW）共混制备了共混物,并利用扫描电子显微镜、动态机械分析仪、毛细管流变仪和傅里叶红外光谱分析对共混物的力学性能及摩擦学性能进行了研究。结果表明,加入PE-HD-g-MAH可以促进PA66和PE-UHMW的界面相容性,提高了共混物的拉伸、弯曲与冲击性能;随着PE-HD-g-MAH含量的增加,共混物的摩擦因数逐渐降低;加入PE-HD-g-MAH并未使共混物发生摩擦化学反应,共混物的磨损呈现疲劳磨损特征;加入PE-HD-g-MAH抑制了疲劳裂纹的增长,使得摩擦转移膜逐渐均匀。     

一步法反应性共混制备PA66／HDPE合金

在双螺杆挤出机上通过一步法反应性共混制备了聚酰胺66（PA66）/高密度聚乙烯（HDPE）合金。使用扫描电镜，Molau实验等方法研究了共混物的形态，并且比较了由一步法反应性共混得到的合金材料与PA66/HDPE简单共混物，以及二步法共混合金在干，湿态下的力学性能。结果表明：采用将PA66、HDPE、马来酸酐，以及引发剂加入双螺杆挤出机进行一步法反应共混的方法可以得到与二步法共混合金形态和性能相似的塑料合金，PA66的韧性可以得到明显改善。     

HDPE/PA 6/有机蒙脱土复合体系的结构及性能

采用熔融共混法制备高密度聚乙烯(HDPE)/聚酰胺(PA)6/有机蒙脱土(OMMT)多元复合材料,借助X射线衍射仪、扫描电子显微镜、透射电子显微镜等分析了OMMT对HDPE/PA 6体系结构、性能的影响及作用机理。加入的少量OMMT以剥离形态分散在基体中,能起到较好的增容作用,并且改善了材料的冲击性能。但OMMT的加入使材料的熔体流动速率降低,剪切黏度增大。     

PE-HD／PA66原位复合材料的制备、形态与性能

用挤出-拉伸-注塑法制备了不含和含马来酸酐接枝聚乙烯(PE-MAH)的PE-HD/PA66原位复合(ISC)材料，以不拉伸的普通共混材料作对照，研究了PA66质量份数(fw)和引入PE-MAH(用量为0.2fw)对材料相形态、拉伸强度(σt)及模量(E)的影响及其作用机理，证明这种ISC材料能取得可观的增强效果：fw=15％条件下，不增容和增容材料的σ1分别比纯PE-HD提高45％和50％，E提高40％和25％，而相应增容普通共混材料的σt和E仅比纯PE-H13提高不到20％和30％。     

E-MA-GMA增容剂对PPS/PA66共混体系性能的影响

研究了增容剂乙烯(E)-丙烯酸酯(MA)-甲基丙烯酸缩水甘油酯(GMA)共聚物(E-MA-GMA)对聚苯硫醚(PPS)/聚酰胺(PA)66共混体系的相容性、力学性能、热性能、流变性能的影响。结果表明,增容剂的加入,增加了共混体系的相容性,提高了共混物的力学性能;DSC结果表明,E-MA-GMA影响共混体系的结晶和熔融行为;流变性能测试结果表明,增容PPS/PA66共混体系是假塑性流体,E-MA-GMA用量增加,使共混体系的表观黏度增大。     

不同接枝率的增容剂对PA66/PP共混物结构与性能的影响

用熔融接枝的方法以苯乙烯(St)作共单体将马来酸酐(MAH)接枝于乙丙共聚物VERSIFY(V)上,制得不同MAH相对接枝率的接枝物V-g-(MAH-co-St),用双螺杆挤出机制备了V-g-(MAH-co-St)增容的尼龙(PA)66/聚丙烯(PP)共混物。利用扫描电子显微镜、熔体流动速率(MFR)和力学性能等测试方法,研究了不同MAH相对接枝率的增容剂V-g-(MAH-co-St)对PA66/PP共混物形态结构和力学性能的影响。结果表明,提高St的含量可以得到高MAH相对接枝率的V-g-(MAH-co-St),当MAH/St质量比从2/1变为1/1时,接枝率显著提高,继续提高St含量,接枝率提高幅度减小。V-g-(MAH-co-St)可使共混物中PP分散相的尺寸减小、分散均匀。当增容剂质量分数从0%增加到10%时,共混物的力学性能在总体上得到提高,MFR迅速降低;增容剂中MAH相对接枝率越高,共混物的弯曲强度越高,MFR越低,而缺口冲击强度相差不大。当增容剂质量分数从10%增加到25%时,共混物的缺口冲击强度大幅提高,且MAH相对接枝率越高,其提高的幅度越大,但拉伸强度和弯曲强度均明显下降,MFR下降幅度变小。     

HDPE／PA共混物分散相形态的研究进展

通过对HDPE／PA层状掺混吹塑容器惨性能的研究,综述了HDPE／PA共混物分散相形态的研究进展。分散相PA形态直接决定共混物阻渗性能,而分散相PA形态依赖于HDPE／PA共混物的相容性、共混物中组分之间的相对粘度比以及加工条件。深入研究HDPE／PA共混物分散相的形态应着重探讨流场对HDPE／PA共混物分散相形态形成的影响机理。     

噁唑啉官能化聚苯乙烯对PA66/PET共混物性能的影响

研究了(口恶)唑啉官能化聚苯乙烯(RPS)对聚酰胺66/聚对苯二甲酸乙二酯(PA 66/PET)共混物力学性能和相容性的影响。结果表明,RPS使该共混体系的力学性能和相容性有了明显的提高。组成为PA 66/PET/RPS(80:20:5)的共混物缺口冲击强度达15.7 kJ/m~2,相当于纯PA 66的3倍。     

十八烷基缩水甘油醚的合成及其增容尼龙6/高密度聚乙烯共混体系的研究

利用十八醇和环氧氯丙烷反应合成了十八烷基缩水甘油醚(OGE),并将其作为熔融共混方法中的增容剂,制备了尼龙6(PA6)/高密度聚乙烯(HDPE)共混材料。研究了OGE用量对共混物的热性能、结晶行为、形态结构、力学性能及吸水性的影响。结果表明,OGE促进了HDPE在PA6基体中的分散,在保持共混材料吸水率的同时,有效改善了共混物的力学性能,与未加入增容剂的PA6/HDPE共混物相比,OGE含量为2.9%(m/m)时,共混材料的缺口冲击强度、拉伸模量、断裂伸长率、弯曲强度分别提高了12%、33%、95%、6%,拉伸强度基本保持不变,而弯曲模量下降了8%。     

PA6/EPDM-g-MAH/HDPE三元共混物的形态与性能

分别采用一步法和两步法制备了聚酰胺(PA)6/马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH)/高密度聚乙烯(HDPE)三元共混物,研究了不同加工方法对三元共混物形态和力学性能的影响。结果表明:与一步法相比,采用两步法所制PA 6/EPDM-g-MAH/HDPE三元共混物形成了更加完善的壳-核包覆形态;用一步法所制共混物的悬臂梁缺口冲击强度为24.50 k J/m2,约为用两步法所制共混物的1/3;具有壳-核包覆形态的分散相粒子在受到应力时发生纤维化,纤维的形成能够吸收大量的断裂能以及阻止裂纹的扩展,从而提高共混物的韧性。     

聚苯醚接枝马来酸酐/聚酰胺66共混物的制备与性能

通过辐照法将马来酸酐(MAH)基团接枝到聚苯醚(PPE)上,制备了PPE-g-MAH,将其和聚酰胺(PA)66通过熔融共混挤出方法制备了PPE-g-MAH/PA66共混物。采用差示扫描量热、吸水性实验、维卡软化和热变形实验、拉伸和冲击性能测试及动态力学性能测试等对PPE-g-MAH/PA66共混物性能进行了研究。结果表明,与PPE/PA66共混物相比,PPE-g-MAH/PA66共混物的耐热性能、力学性能和吸水性能均得到改善;随PPE-g-MAH含量的增加,PPE-g-MAH/PA66共混物中PA66的熔融温度和玻璃化转变温度均向PPE方向移动,表明两者的相容性有所提升,且共混物的维卡软化温度、热变形温度、25℃之前的储能模量均升高,吸水率降低;当PPE-g-MAH含量较低时,共混物拉伸强度提升明显而冲击强度升幅较小,当PPE-g-MAH含量较高时,共混物冲击强度提升明显而拉伸强度基本不变。因此,可以根据实际的应用要求选择合适的PPE-g-MAH含量。     

PPS/PA66共混物的结构与性能研究

为了制备燃油汽车发动机用新型塑料进气歧管,制备了几种不同配比的PPS/PA66共混物,并对其结构与性能进行了研究。DSC分析表明,PPS/PA66共混物出现了两组分的结晶熔融峰,当共混体系中PA66的质量分数低于60%时,共混物中的PA66破坏了PPS的结晶环境,PPS的结晶度降低,其拉伸强度也随之降低;随着PA66含量的增加,共混物的结晶度提高,拉伸强度和断裂伸长率也得到了相应的提高。SEM及红外光谱分析表明,随组分含量的变化,共混体系发生了相的转变。     

POE-g-MAH反应性增容HDPE/PA66共混合金性能研究

以乙烯-辛烯共聚物接枝马来酸酐(POE-g-MAH)作为高密度聚乙烯(HDPE)/尼龙66(PA66)共混合金的反应性增容剂,采用熔融挤出法制备了HDPE/PA66/POE-g-MAH共混合金。研究了POE-g-MAH用量对共混合金形态结构、力学性能、流变性能和热致形状记忆性能的影响。结果表明:通过POE-g-MAH的反应性增容作用,改善了HDPE/PA66合金的界面黏结,促进了分散相粒子的细化,显著提高了合金的力学和热致形状记忆性能,并缩短了塑化时间。     

原位增容PA6/PE-HD共混物的性能研究

在双螺杆挤出机上通过原位增容反应挤出制备了聚酰胺6(PA6)/高密度聚乙烯(PE-HD)共混物。通过力学性能测试、扫描电子显微镜观察和Molau实验,研究了PE-HD含量对PA6/PE-HD共混物的力学性能和体系增容作用的影响。结果表明,PE-HD与马来酸酐(MAH)在挤出共混过程中原位生成了PE-HD-g-MAH,其对PA6/PE-HD共混物有较好的增容作用;PA6/PE-HD共混物的力学性能与界面形态均有较大改善,吸水率有所降低。     

制备方式对PA6/PA6-66-1010共混物结构与性能的影响

采用原位共混和熔融共混分别制备了尼龙(PA)6/PA6-66-1010共混物。利用傅里叶变换红外光谱仪、差示扫描量热仪、动态热机械分析、力学性能测试和扫描电子显微镜对共混物的内部氢键作用、结晶熔融行为、玻璃化转变温度、力学性能及拉伸断裂形貌进行了表征。结果表明,原位共混物的分子链段的运动性和柔性好于熔融共混物,结晶温度、熔融温度、结晶度均低于熔融共混物,强度和韧性均优于熔融共混物。