Wieczorowski Michal, Pereira Alejandro, Prado Teresa, Lopez-Blanco Alberto, Grochalski Karol, Grabon Wieslaw, Perez M Consuelo
Faculty of Mechanical Engineering, Poznan University of Technology, Piotrowo Street 3, 60-965 Poznan, Poland.
Manufacturing Engineering Group (GEF) EEI Campus Lagoas, Universidade de Vigo, 36310 Vigo, Spain.
Materials (Basel). 2023 Sep 15;16(18):6231. doi: 10.3390/ma16186231.
The use of thermoplastic materials has had significant growth in recent years. However, with great mechanical requirements, thermoplastics have limitations to their use. To improve these restrictions, these materials are reinforced to obtain better properties. Polypropylene is one of the most versatile polymers and is used in almost all modern industries. Thus, the aim of this study is to create composite materials that offer performance for various industrial fields using carbon fiber fabric reinforcement, which is an inexpensive material widely used by the aerospace, automotive, and marine industries. The samples are produced by the over-injection molding of polypropylene. The investigation is focused on the impact of two critical control parameters in the injection molding process: temperature and pressure. Twelve experiments have therefore been considered, taking into account the combination of three factors: the presence or absence of carbon fiber fabric reinforcement, three levels of temperature (200 °C, 220 °C, and 240 °C), and two injection pressures (5000 kPa and 10,000 kPa). To evaluate the influence of these factors, three analyses were carried out: first, on the samples' shrinkage using a portable metrology-grade 3D laser scanner; second, on the internal defects using computed tomography (CT); and third, on the mechanical properties with tensile tests. From the results obtained, it is observed that the mold shrinkage fell slightly when PP samples were reinforced with carbon fiber, with both materials (PP and carbon-fiber-reinforced PP) having linear behavior with temperature. It is also noticed that polypropylene behaves as a crystalline material when processed at higher temperatures and pressures. From tests on the mechanical properties, it is concluded that the mean yield strength of PP-CF for injection temperatures of 220 °C and 240 °C represents an increase of 43% compared to the non-reinforced material.
近年来，热塑性材料的使用有了显著增长。然而，由于对机械性能有很高要求，热塑性材料在使用上存在局限性。为改善这些限制，对这些材料进行增强以获得更好的性能。聚丙烯是用途最广泛的聚合物之一，几乎应用于所有现代工业。因此，本研究的目的是使用碳纤维织物增强材料来制造能为各个工业领域提供性能的复合材料，碳纤维织物是一种价格低廉的材料，被航空航天、汽车和船舶工业广泛使用。样品通过聚丙烯的过注射成型生产。研究聚焦于注射成型过程中两个关键控制参数的影响：温度和压力。因此考虑了12个实验，涉及三个因素的组合：有无碳纤维织物增强、三个温度水平（200℃、220℃和240℃）以及两种注射压力（5000 kPa和10000 kPa）。为评估这些因素的影响，进行了三项分析：第一，使用便携式计量级3D激光扫描仪对样品的收缩率进行分析；第二，使用计算机断层扫描（CT）对内部缺陷进行分析；第三，通过拉伸试验对机械性能进行分析。从获得的结果可以看出，当用碳纤维增强PP样品时，模具收缩率略有下降，两种材料（PP和碳纤维增强PP）的收缩率与温度均呈线性关系。还注意到，聚丙烯在较高温度和压力下加工时表现为结晶材料。从机械性能测试得出结论，对于220℃和240℃的注射温度，PP-CF的平均屈服强度比未增强材料提高了43%。
