Life Cycle Assessment of Direct Ink Writing Additive Manufacturing Process with Hemp-Based Silicone Elastomer Materials

Direct ink writing (DIW) is an emerging additive manufacturing technique capable of processing highly viscous materials, including elastomer composites reinforced with bio-based fillers. However, limited information is available on the environmental impacts associated with DIW processing and the use of natural fiber reinforcements. This study assesses the environmental performance of hemp-silicone elastomer (SE) composites fabricated using DIW through a comparative life cycle assessment (LCA). The analysis compares a composite containing 5 wt.% hemp powder with a neat SE reference specimen under identical printing conditions. Environmental impacts were quantified using the ReCiPe 2016, Cumulative Energy Demand (CED), and IPCC 2021 GWP100 methods. Results show that replacing a portion of the SE with hemp reinforcement reduces environmental impacts, with the ReCiPe endpoint score decreasing from 6.12 mPt for neat SE to 5.95 mPt for the 5 wt.% hemp-SE composites. Similarly, the CED decreased from 2.35 MJ to 2.32 MJ, while greenhouse gas emissions decreased from 0.133 kg CO2-eq to 0.132 kg CO2-eq per printed specimen. Sensitivity analysis further indicates that increasing hemp loading to 10 wt.% reduces the ReCiPe score to 5.77 mPt, highlighting the potential environmental benefits of more biobased filler substitution. Overall, the results show that impacts are dominated by SE production, while DIW printing energy contributes only a minor fraction of the total life cycle impacts.

直接墨水书写（Direct Ink Writing，DIW）是一种新兴的增材制造技术，可用于加工高粘度材料，包括生物基填料增强的弹性体复合材料。然而，目前针对DIW加工过程及天然纤维增强材料应用相关的环境影响，公开研究数据较为匮乏。本研究采用对比性生命周期评估（Life Cycle Assessment，LCA）方法，对通过DIW制备的大麻纤维-硅酮弹性体（Silicone Elastomer，SE）复合材料的环境性能展开评估。本次分析将含5%质量分数大麻粉末的复合材料，与纯SE参照试样在完全一致的打印条件下进行对比测试。环境影响量化采用了ReCiPe 2016评估框架、累计能源需求（Cumulative Energy Demand，CED）以及政府间气候变化专门委员会（Intergovernmental Panel on Climate Change，IPCC）2021年版全球增温潜势100年尺度（GWP100）三种方法。结果显示，采用大麻纤维增强材料替代部分SE可降低环境影响：ReCiPe终点分值从纯SE试样的6.12毫点（mPt）降至5%质量分数大麻-SE复合材料的5.95毫点；累计能源需求从2.35兆焦（MJ）降至2.32兆焦；每个打印试样的温室气体排放量则从0.133千克二氧化碳当量（CO₂-eq）降至0.132千克二氧化碳当量。敏感性分析进一步表明，将大麻填料添加量提升至10%质量分数时，ReCiPe分值可降至5.77毫点，凸显了进一步采用生物基填料替代方案所具备的潜在环境效益。总体而言，研究结果表明，整个生命周期的环境影响主要来源于SE的生产环节，而DIW打印能耗仅占总影响的极小部分。