Morphological evolutions during the production of microfibrillar composites can be investigated by considering two main steps: (1) the melt blending in the extruder and (2) the drawing process. Deformation, coalescence and break-up of dispersed phase droplets under shear and elongational flow fields applied in these two main steps lead to the formation of fibrillar morphology. Therefore, it can be stated that the fibrillar morphology is controlled by dispersed phase content, rheological and interfacial properties of the components as well as dispersed phase domains relaxation. In this study, the effect of dispersed phase content on the morphology of the polypropylene/polyethylene terephthalate microfibrillar composite was investigated. Also, three following processing parameters were considered to evaluate the kinetics of in-situ formation of the microfibrils: Extruder die temperature, water bath temperature and the drawing path length. Linear and nonlinear rheological tests were used as an efficient tool to investigate the rheology–morphology relationship. Among the processing parameters studied, the drawing path length and die temperature had the most and least effect on microfibrillar morphology, respectively. By increasing the drawing path length from 20 to 30 cm, the break-up of the fibrils and non-uniformity in the cross section of the fibrils caused a weaker strain recovery after stress removal and also a rapid reduction of stress after cessation of steady shear flow field. Increasing the die temperature has a similar but weaker effect on the final morphology. The rheological results in the linear viscoelastic range all indicated the formation of a physical network of microfibrils within the matrix.

中文翻译：

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研究加工条件和分散相含量对聚丙烯/聚对苯二甲酸乙二醇酯微纤维复合材料流变-形态关系的影响

可以通过考虑两个主要步骤来研究微纤维复合材料生产过程中的形态演变：(1) 挤出机中的熔融共混和 (2) 拉伸过程。在这两个主要步骤中应用的剪切和拉伸流场下，分散相液滴的变形、聚结和破碎导致纤维状形态的形成。因此，可以说纤维状形态受分散相含量、组分的流变学和界面性质以及分散相域松弛控制。在本研究中，研究了分散相含量对聚丙烯/聚对苯二甲酸乙二醇酯微纤复合材料形态的影响。还，考虑以下三个加工参数来评估原位形成微纤维的动力学：挤出机模具温度、水浴温度和拉伸路径长度。线性和非线性流变测试被用作研究流变-形态关系的有效工具。在所研究的加工参数中，拉伸路径长度和模具温度分别对微纤维形态的影响最大和最小。通过将拉伸路径长度从 20 厘米增加到 30 厘米，原纤维的断裂和原纤维横截面的不均匀性导致应力消除后应变恢复较弱，并且稳态剪切停止后应力迅速降低流场。增加模具温度对最终形态有类似但较弱的影响。