Are Polylactide-Based Fully Degradable Composites Greener than Semi- and Nondegradable Ones during Production? A Cradle-to-Gate Lifecycle Assessment in China

Existing research predominantly focuses on the degradation characteristics of polylactide-based fully degradable fibre-reinforced polymer (FRP) composites during end-of-life, while largely overlooking potential environmental bottlenecks during production. This is especially important for China, a leading global FRP composite market. This research addresses this gap through a cradle-to-gate lifecycle assessment model covering raw materials, transportation, manufacturing processes, and grid mixes across 74 scenarios, using a manufacturing base in Shanghai, China as a case. This study reveals for the first time that, within the cradle-to-gate lifecycle scope and whether based on mass or specific strength functional units, fully degradable polylactide-based FRP composites do not necessarily offer greater environmental advantages than semi/nondegradable systems. For example, based on the specific strength functional unit, the weighted impact score of polylactide-based jute fibre reinforced composites within the cradle-to-gate scope is 16% (extrusion-injection) and 12% (hot-pressed) higher than that of its polypropylene-based ones. This study systematically reveals that the environmental burden during production of FRP composites shifts between corresponding raw material supply chains depending on the selected degradation type, and this approach may not necessarily reduce the cradle-to-gate comprehensive environmental impact. This finding corrects the cognitive bias that focuses solely on FRP composite degradability while overlooking its production-related environmental burdens.