Due to the increasing popularity of additive manufacturing with continuous fibers thermoplastic composites (TPC), this paper investigates the process of in situ impregnation of dry fiber tow with molten thermoplastic resin as a means to reduce material cost. To better understand impregnation with high-viscosity polymer melts, a 1D version of Darcy’s Law is derived along with Gebart’s equations for estimating fiber tow impregnation and permeability. Rheology of the two polymer melts tested, nylon 6/12 and polycarbonate, were measured using a capillary viscometer. The experimental setup consisted of a heated and weighted plunger system to maintain polymer melt pressure in a temperature-controlled pultrusion chamber, through which a dry 3 K carbon fiber tow passes through at a constant velocity for in situ impregnation. The resulting TPC tape was collected on a reel and not used directly for AM. The setup allowed three process variables in Darcy’s equation, i.e. chamber pressure, polymer viscosity (via temperature), and exposure time, to be varied. The degree of impregnation of the thick tape specimens – quantified using digital microscopy and image analysis on polished cross-sections – matched theoretical predictions quite well (average errors of ∼10% for nylon and ∼15% for polycarbonate). However, despite pressures up to 1.2 MPa and exposure times (5.5−15 sec) consistent with current AM system feed rates, the extremely high melt viscosities (290–980 Pa⋅sec) make full impregnation of thick tapes nearly impossible in a practical setting. Improvements to the in situ impregnation process based on experimental results and impregnation models are suggested.

由于使用连续纤维热塑性复合材料（TPC）进行增材制造的日益普及，本文研究了用熔融热塑性树脂原位浸渍干纤维丝束以降低材料成本的方法。为了更好地理解高粘度聚合物熔体的浸渍，导出了一维达西定律以及Gebart方程，用于估算纤维束的浸渍和渗透率。使用毛细管粘度计测量了测试的两种聚合物熔体（尼龙6/12和聚碳酸酯）的流变性。实验装置由加热和称重的柱塞系统组成，以维持温度控制的拉挤成型室中的聚合物熔体压力，干燥的3 K碳纤维丝束以恒定速度通过该通道进行原位浸渍。将所得的TPC磁带收集在卷盘上，而不直接用于AM。该设置允许改变Darcy方程中的三个过程变量，即腔室压力，聚合物粘度（通过温度）和暴露时间。厚带状试样的浸渍度（使用数字显微镜和抛光截面的图像分析进行了量化）与理论预测非常吻合（尼龙的平均误差约为10％，聚碳酸酯的平均误差约为15％）。但是，尽管压力高达1.2 MPa，暴露时间（5.5-15秒）与当前的增材制造系统进料速率一致，但极高的熔体粘度（290-980 Pa·sec）使得在实际设置中几乎不可能完全浸渍厚胶带。建议基于实验结果和浸渍模型对原位浸渍工艺进行改进。