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朱振华, 邵柏军, 王俊, 邵宇, 陈建康, 张明华. 老化对PP/SSFs导电复合材料结构及 应力松弛性能的影响[J]. 力学学报, 2018, 50(3): 517-526. DOI: 10.6052/0459-1879-18-080
引用本文: 朱振华, 邵柏军, 王俊, 邵宇, 陈建康, 张明华. 老化对PP/SSFs导电复合材料结构及 应力松弛性能的影响[J]. 力学学报, 2018, 50(3): 517-526. DOI: 10.6052/0459-1879-18-080
Zhu Zhenhua, Shao Baijun, Wang Jun, Shao Yu, Chen Jiankang, Zhang Minghua. EFFECT OF AGING ON STRUCTURE AND STRESS RELAXATION OF PP/SSFs COMPOSITES[J]. Chinese Journal of Theoretical and Applied Mechanics, 2018, 50(3): 517-526. DOI: 10.6052/0459-1879-18-080
Citation: Zhu Zhenhua, Shao Baijun, Wang Jun, Shao Yu, Chen Jiankang, Zhang Minghua. EFFECT OF AGING ON STRUCTURE AND STRESS RELAXATION OF PP/SSFs COMPOSITES[J]. Chinese Journal of Theoretical and Applied Mechanics, 2018, 50(3): 517-526. DOI: 10.6052/0459-1879-18-080

老化对PP/SSFs导电复合材料结构及 应力松弛性能的影响

EFFECT OF AGING ON STRUCTURE AND STRESS RELAXATION OF PP/SSFs COMPOSITES

  • 摘要: 导电高聚物复合材料具有柔性好、导电性可调、容易成型及生产成本低等优点,并具有抗静电、电磁屏蔽/吸波、压力/温度敏感性 等特点,可以作为功能材料在诸多领域应用. 但是在加工、储运和使用过程中,由于多种因素综合影响,不可避免发生老化并导致其性能劣化. 通过熔融共混、注塑成型的方法制备不锈钢短纤维(SSFs)填充聚丙烯(PP)导电复合材料,将其进行加速湿热老化和紫外老化,测定应 力松弛曲线以及松弛条件下电阻率变化规律,通过X射线粉末衍射仪分析老化前后结晶度的变化,借助扫描电子显微镜(SEM)观察研究老化前后材 料的微观形貌,并进行能谱(EDS)分析. 研究结果表明,应力松弛曲线有明显的三阶段特征,且湿热老化材料松弛后的应力水平降低. 材料的初始电阻率随填料含量的增加而降低,老化使材料的初始电阻率增大. 由于导电高聚物的压阻效应,使得达到应力松弛起始应力前,即材料在获得特定应力的加载阶段,电阻率随载荷增加显著降低,而在随后 的松弛阶段,材料电阻率则趋于一个稳定值并在较小的范围内波动. SEM/EDS分析结果表明,随着老化时间的延长,试样表面氧元素含量增加,且氧元素含量随距表面深度的增加而减小. XRD分析结果表明,材料的结晶度随填料含量的增加而减小,随老化时间的延长也呈减小趋势. 研究结果可为研究导电高聚物复合材料的老化性能提供实验依据.

     

    Abstract: Conductive polymer composites, with good flexibility, adjustable conductivity, easy forming and low production cost, can be used as functional material in many fields for its antistatic properties, electromagnetic shielding/microwave absorbing properties, and pressure/temperature sensitivity. However, in the process of processing, storage and use, due to comprehensive influence of many factors, aging will inevitably occur which will lead to deterioration of the properties. In this paper, PP/SSFs (stainless steel fibers) conductive composites were prepared by melt-blending and injection molding. The specimens were subjected to accelerated hygrothermal aging and UV aging. Stress relaxation curves, resistivity and crystallinity were experimentally measured. Micromorphology and elemental distribution of specimens before and after aging have been observed and dectected by scanning electron microscope (SEM) and energy spectrometer (EDS). The results show that the stress relaxation curves display three-stages in characteristics. And the stress reduces after hygrothermal aging due to the breaking and cross-linking of molecular chain caused by aging. The initial resistivity of PP/SSFs composites decreases with the increase of filler content, while it will increased with aging time. Due to the piezoresistive effect of the conductive polymer, the resistivity of the specimens decreases significantly with the increase of initial load, and then it tends to a stable value and fluctuation in a smaller range. The results of SEM/EDS analysis show that with the increase of aging time, the oxygen content on the specimens surface increases, and it will decreases with distance (depth) to the surface of specimen. XRD results show that the crystallinity of composites decreased with the increase of SSFs content and aging time. The present research will provide an experimental basis for the study of aging properties of conductive polymer composites.

     

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