The material extrusion (ME) process, which is an additive manufacturing technology applicable to a wide range of polymers, has a drawback in that the inherent bonding between the deposited layers is vulnerable. To this end, we present an efficient strengthening method for the ME process by introducing bidirectional in situ infrared (IR) heating during the polymer melt deposition in the 3D-printing process. The auxiliary IR irradiation was applied to heat as-printed polymers in the deposited area along the printing paths at their glass transition temperature, which expectedly led to molecular diffusion and chain re-entanglement at the deposited interface. Consequently, the heating technique not only helped eliminate the structural defects due to the thermal stress but also helped enhance the mechanical strength, particularly of structures layered in transverse and upright directions. The reinforcement effects were confirmed by conducting tensile tests and thermal imaging analysis on typical polymers such as polylactic acid and polycarbonate. The experimental results demonstrated the feasibility of the proposed heating technique in extending the applicability of a wide range of engineering plastics or composite materials for the ME printing method.

作为适用于多种聚合物的增材制造技术的材料挤压（ME）工艺的缺点在于，沉积层之间的固有键合很脆弱。为此，我们通过在3D打印过程中的聚合物熔体沉积过程中引入双向原位红外（IR）加热，提出了一种有效的ME工艺强化方法。辅助红外辐射沿印刷路径在其玻璃化转变温度下沿印刷路径加热沉积区域中的印刷态聚合物，从而有望在沉积界面处引起分子扩散和链重新缠结。因此，加热技术不仅有助于消除由于热应力引起的结构缺陷，而且还有助于提高机械强度，特别是在横向和直立方向上分层的结构。通过对典型的聚合物（例如聚乳酸和聚碳酸酯）进行拉伸测试和热成像分析，确认了增强效果。实验结果证明了所提出的加热技术在扩大多种工程塑料或复合材料用于ME印刷方法的适用性方面的可行性。