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A range of cross-linkable latex copolymers with biobased content of up to 90% was synthesized from isobornyl methacrylate combined with acrylic monomers based on high-oleic soybean oil (HO-SBM) or camelina oil (CMM) through miniemulsion polymerization. By varying the HO-SBM and CMM macromolecular fractions, the cross-linking density of the resulting materials can be altered due to differences in the fatty acid profiles of the plant-oil-based monomers. The glass transition temperature of the synthesized copolymers correlates very well with the calculated Flory–Fox values. A higher cross-linking density of the biobased copolymer films leads to a notable growth in the modulus of the materials, while the elongation at break decreases due to more restricted macromolecular mobility. Remarkably, the copolymer with the highest unsaturation degree in the investigated range (based on CMM) shows an increase in both the modulus and elongation at break, due perhaps to extended entanglements of fatty-acid-based side chains. The adhesion performance of the cross-linked biobased copolymers was evaluated by performing shear and peel strength measurements on steel and polypropylene. Based on the obtained results, the unsaturation degree of CMM and HO-SBM (determined by plant oil composition) can be applied as a criterion for adjusting adhesion by choosing plant-oil-based monomers (or their mixtures) with different unsaturation degrees to achieve properties and performance required for specific applications. 

A growing concern of climate change and waste pollution is causing a shift in products towards green materials. The automotive industry is exploring environmentally friendly alternatives to glass fibers (GF). This research focuses on understanding interactions between constituents of biocomposites made up of basalt fiber (BF) and hemp hurd particle fiber (HF) reinforced polypropylene (PP), and statistically comparing the mechanical properties. The addition of a coupling agent has significantly improved the performance and fiber-matrix interactions in the biocomposite blends. The elastic modulus of some BF/HF/PP mixtures were comparable to the GF/PP composite; however, the GF still outperformed in strength. Rotational and capillary rheometer analysis determined the viscosities of all formulations displaying that basalt composites were consistently lower in viscosity than the glass fiber composite, indicating easier processing conditions. 

Moisture absorption into hygroscopic/hydrophilic materials used in fused deposition modeling (FDM) can diminish desired mechanical properties. Sensitivity to moisture is dependent on material properties and environmental factors and needs characterization. In this article, moisture sensitivity of four grades of polylactic acid (PLA) filaments and four different ratios of PLA/polybutylene succinate (PBS) blended filaments were characterized through FDM printed American society for testing and materials (ASTM-D638) test samples after conditioning the filaments at different relative humidity levels. The tensile testing and scanning electron microscopy (SEM) of the samples' fracture surfaces revealed that PLA 4043D was the most moisture-sensitive among the chosen grades of PLA filaments. Through filament tension test and melt flow index (MFI) testing it was observed that moisture had a significant detrimental effect (20% reduction in tensile strength and 50% increase in MFI) on PLA 4043D filaments. Samples from moisture-conditioned PLA/PBS 75/25 blended filaments displayed a significant reduction (10%) in tensile strength. Moreover, the MFI of 75/25 filaments was increased with subsequent increases in moisture level. Investigation of tensile properties of ASTM samples made from four grades of PLA filaments exposed to room temperature and humidity conditions for 3 months showed an even more significant decrease in strength (ranging from 24% to 36%). 

To investigate the utility of acrylic monomers from various plant oils in adhesives manufacturing, 25–45 wt. % of high oleic soybean oil-based monomer (HOSBM) was copolymerized in a miniemulsion with commercially applied butyl acrylate (BA), methyl methacrylate (MMA), or styrene (St). The compositions of the resulting ternary latex copolymers were varied in terms of both “soft” (HOSBM, BA) and “rigid” (MMA or St) macromolecular fragments, while total monomer conversion and molecular weight of copolymers were determined after synthesis. For most latexes, results indicated the presence of lower and higher molecular weight fractions, which is beneficial for the material adhesive performance. To correlate surface properties and adhesive performance of HOSBM-based copolymer latexes, contact angle hysteresis (using water as a contact liquid) for each latex-substrate pair was first determined. The data showed that plant oil-based latexes exhibit a clear ability to spread and adhere once applied on the surface of materials differing by polarities, such as semicrystalline polyethylene terephthalate (PET), polypropylene (PP), bleached paperboard (uncoated), and tops coated with a clay mineral paperboard. The effectiveness of plant oil-based ternary latexes as adhesives was demonstrated on PET to PP and coated to uncoated paperboard substrates. As a result, the latexes with high biobased content developed in this study provide promising adhesive performance, causing substrate failure instead of cohesive/adhesive break in many experiments. 

Dr. Xiao Zhang’s group at Washington State University has developed new methods of producing high purity nano-dimension lignin, DESL (Figure 1) with controlled structural properties. With the support from NSF/IUCRC/CB2, we have demonstrated the preparation of high DESL containing semi-rigid polyurethane foam (Figure 2) with good physical properties. In addition to foam, DESL-based polyurethane has shown potentials for adhesives, sealants, and coatings applications. We are working with CB2 ember companies, including: AkzoNobel, BASF, Ford, Idaho Forest Group, etc., toward commercialization of this new technology. This technology will optimize the utilization of agricultural/forest wastes to decarbonize PU industry and create new economic and job opportunities in US. 

Synthetic fibers such as glass, carbon, etc., are used as reinforcement in polymer composites due to their high strength and modulus. However, synthetic fibers contribute to high costs and have a significant environmental impact. To overcome this challenge, various natural fibers, including banana, kenaf, coir, bamboo, hemp, and sisal fiber, as reinforced in a polymer matrix are investigated for mechanical properties. In this study, biocomposites with natural fibers as reinforced are developed and characterized. Treated and untreated natural fibers such as flax, maple, and pine as reinforced in thermoplastic, in this study, polypropylene (PP), are investigated for the mechanical properties, including tensile, flexural, and impact test. Mechanical test results exhibited that adding the natural fibers enhanced the tensile, flexural, and impact properties. It can be inferred that these biocomposites can be used as potential materials for the automobile industry.