ABSTRACTIn this article, a conductive foam based on a novel styrene‐based thermoplastic elastomer called poly(styrene‐b‐butadiene‐co‐styrene‐b‐styrene) tri‐block copolymer S(BS)S was prepared and introduced. S(BS)S was particularly designed for chemical foaming with uniform fine cells, which overcame the shortcomings of traditional poly(styrene‐b‐butadiene‐b‐styrene) tri‐block copolymer (SBS). The preparation of conductive foams filled by the carbon black was studied. After the detail investigation of cross‐linking and foaming behaviors using moving die rheometer, the optimal foaming temperature was determined at 180°C with a complex accelerator for foaming agent. Scanning electron microscopy (SEM) images shown that the cell bubbles of conductive foam were around 30–50 µm. The conductivity of foams was tested using a megger and a semiconductor performance tester. SEM images also indicated that the conductivity of foams was mainly affected by the distribution of carbon black in the cell walls. The formation of the network of the carbon black aggregates had a contribution to perfect conductive paths. It also found that the conductivity of foams declined obviously with the foaming agent content increasing. The more foaming agent led to a sharp increasing of the number of cells (from 2.93 × 106 to 6.20 × 107 cells/cm3) and a rapid thinning of the cell walls (from 45.3 to 1.4 µm), resulting in an effective conductive path of the carbon black no forming. The conductive soft foams with the density of 0.48–0.09 g/cm3 and the volume resistivity of 3.1 × 103−2.5 × 105 Ω cm can be easily prepared in this study. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41644.
为了探究熔融混炼制备弹性体/导电填料复合材料的压力传感性能及其应用价值,对良好生物相容性的热塑性聚氨酯弹性体(TPU)和氧化石墨烯(GO)进行熔融混炼,该过程中GO发生原位热还原,从而制得柔性TPU/还原氧化石墨烯(rGO)纳米复合材料.以此为介电层组装电容式压力传感器,并进行传感性能测试分析.结果表明,GO的掺杂可有效改善传感器的性能,1.0％GO质量分数时传感器的灵敏度为0.069 MPa-1(0.06～2 MPa),明显高于未掺杂的(0.046 MPa-1),这与GO掺杂显著提高介电层的介电常数有关.当GO含量过高时,传感器灵敏度反而降低,这可能与材料内rGO渗流网络形成有关.所研制的传感器响应性较好,以GO 1.0％质量分数为例,其响应时间约110 ms、迟滞误差1.4％、稳定性良好.该传感器可成功应用于人体手指点击和弯曲运动监测,在柔性可穿戴领域展现出良好的应用前景.
综述了氧化锌(ZnO)及其复合材料的制备及其在抗菌塑料上的研究成果.阐述了ZnO作为抗菌剂的抗菌机制,着重介绍了ZnO产生活性氧物种、释放锌离子、破坏细胞膜的抗菌机理;总结了ZnO与金属离子、金属氧化物、有机抗菌剂、碳材料或者天然黏土矿物等复合材料的最新研究进展;展示了ZnO及其复合材料在医用塑料、食品包装、管材制品、家用器材和汽车内饰等塑料上的应用案例;分析和展望了目前ZnO及其复合材料作为抗菌剂存在的主要问题和今后的研究方向.
为提高聚四氟乙烯(PTFE)中空纤维膜的亲水性,以聚乙烯醇(PVAL)与聚乙烯吡咯烷酮(PVP)的混合溶液为亲水剂,戊二醛(GA)溶液为交联剂,采用表面涂覆交联改性的方法制备亲水性PTFE中空纤维膜.从纯水通量与表面亲水性的测试结果可以看出,制备的PTFE中空纤维膜具有良好的亲水性能,改性后膜通量为1 037 L/(m2·h),膜接触角为53.6°,接触角降为0°消耗的时间为1.5 s.从扫描电子显微镜与衰减全反射傅里叶变换红外光谱可以明显看出,经过PVAL/PVP/GA表面涂覆交联改性后,PTFE中空纤维膜表面含有羟基官能团,使膜丝具有一定优异的亲水性能.羟基成功地附着在PTFE中空纤维膜表面.从模拟人工加速清洗可以看出,改性后的PTFE中空纤维膜在经过10 d强碱(pH=13)、强酸(pH=1)和氧化剂(5 000 mg/L NaClO)的清洗下还保持的不同的性能,其通量分别降为478,521,152 L/(m2·h),表面接触角分别提高为90°,76.5°,94°,接触角降为0°消耗的时间分别为4,3.2,45 s.
以透光窗控制器面板为研究对象,分析了塑件的成型工艺性,产品为长方形框状结构,外包塑料最小壁厚仅0.5 mm的塑件,填充较为困难,为保证流道废料的自动切除,增加塑料的流动性,第一射注射成型无色透明塑件,基体注塑模具采用热流道+冷流道相结合的方式进行浇注;第二射注射成型的黑色塑件,设计了单点浇注的热流道点浇口浇注系统;因型腔深度较浅,为确保塑件留在动模型腔中,设计了一套塑件压紧装置.设计的一副旋转式双色注射成型倒装热流道模具,由均为1模4腔的基体塑件注塑模具和包塑注塑模具组成,设计了斜顶式外抽芯机构及定模顶出结构;因型腔在动模上,设计了两套定模顶出机构.实践证明,设计的倒装双色热流道模具结构合理,动作可靠,塑件质量满足设计要求.
