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Nowadays the use of natural fiber composites has gained significant interest due to their low density, high availability, and low cost. The present study explores the development of sustainable 3D printing filaments based on rice husk (RH), an agricultural residue, and recycled polypropylene (rPP) and the influence of fiber weight ratio on physical, thermal, mechanical, and morphological properties of 3D printing parts. Thermogravimetric analysis revealed that the composite’s degradation process started earlier than for the neat rPP due to the lignocellulosic fiber components. Mechanical tests showed that tensile strength increased when using a raster angle of 0° than specimens printed at 90°, due to the weaker inter-layer bonding compared to in-layer. Furthermore, inter layer bonding tensile strength was similar for all tested materials. Scanning electron microscope (SEM) images revealed the limited interaction between the untreated fiber and matrix, which led to reduced tensile properties. However, during the printing process, composites presented lower warping than printed neat rPP. Thus, 3D printable ecofriendly natural fiber composite filaments with low density and low cost can be developed and used for 3D printing applications, contributing to reduce the impact of plastic and agricultural waste.

Achieving adhesive bonding in wet environments remains a significant challenge in both day-to-day life and industrial applications. Inspired by how marine shellfish stick to rocks, a wide variety of innovative polymer adhesives containing catechol moieties have been developed by several research groups. Despite displaying impressive performance, these adhesives have not yet emerged on the market. Difficulties associated with translating small-scale academic research to industrial production have persisted. In this paper, we focus our attention on poly(vinylcatechol-styrene), a biomimetic polymer that has shown considerable bonding in both dry and underwater conditions. Herein, we tackled three issues to help bring this polymer beyond academic laboratories: monomer sourcing, polymerization processes, and deprotection steps. Thus, we propose a new route to produce poly(vinylcatecholstyrene) made of (i) a 3,4-dimethoxystyrene monomer preparation from 3′,4′-dimethoxyacetophenone, a low-cost and highavailability reagent, (ii) a suspension polymerization to yield the intermediate poly(3,4-dimethoxystyrene-styrene) at the large scale, and (iii) an iodocylohexane-induced methyl cleavage to obtain the final poly(vinylcatechol-styrene). In our laboratory, we could synthesize this adhesive polymer at up to 60 g scales, avoided harsh reaction conditions, and reduced the cost of the polymer by half. Cost calculations are described both for materials only and also when considering labor and energy. An unexpected bonus was improved performance in both dry and wet conditions.