In this work, the self-reinforced polypropylene (PP)/noil ramie fiber (NRF) composites were prepared by the solid-state extrusion method. And the effect of die structure such as draw ratio and conical angle on the morphology, thermal and mechanical properties of samples was investigated. The results indicated that the solid-state deformation of PP/NRF composites conducted below the melt transition promoted the formation of the orderly arranged microfibrils inside the samples, which arranged along the extrusion direction and could be observed by scanning electron microscopy (SEM). Besides, the increased draw ratio and conical angle both contributed to the higher degree of orientation, which was obvious observed inside the sample prepared at the draw ratio of 5 and conical angle of 20°. The thermal properties tested by differential scanning calorimetry (DSC) also suggested that the intensified orientation of microfibrillar structure not only demonstrated the transformation of the spherulitic crystal into the aligned chain crystals, but also resulted in the enhanced crystallinity and narrowed melting peak. Moreover, the highly oriented fibrillar bundle structure endowed the samples with the excellent tensile strength and flexural strength, which were up to 80.9 MPa and 83.5 MPa respectively and increased by 182.8% and 102.7% compared with the commonly extruded samples.

在这项工作中，通过固态挤出法制备了自增强聚丙烯（PP）/无麻纤维（NRF）复合材料。并研究了拉伸比和圆锥角等模具结构对样品的形貌，热力学性能的影响。结果表明，在熔体转变以下进行的PP / NRF复合材料的固态变形促进了样品内部沿拉伸方向排列的有序排列的微纤维的形成，并且可以通过扫描电子显微镜（SEM）观察到。此外，增加的拉伸比和圆锥角都有助于较高的取向度，这在拉伸比为5且圆锥角为20°的样品内部观察到。通过差示扫描量热法（DSC）测试的热性能还表明，微纤丝结构的增强取向不仅证明了球晶转变为排列的链状晶体，而且还导致结晶度增强和熔融峰变窄。此外，高取向的原纤维束结构赋予样品优异的拉伸强度和弯曲强度，分别比普通挤出样品高80.9 MPa和83.5 MPa，分别增加了182.8％和102.7％。