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Natural fiber composites offer an advantage in terms of weight saving for many automotive applications; however, many natural fiber composites lack properties to justify substitution for synthetic composites. Hybridizing the natural fiber composites by adding a fraction of synthetic fibers is an innovative approach to provide a balance between composite's performance and weight savings. In this study, coir fiber (40 wt%)-reinforced polypropylene (PP) composites were hybridized by substituting a fraction of coir fiber with glass fiber (0–30 wt%). The composites were prepared using a novel wet-laid technique followed by compression molding, where the fiber length is preserved. The composites prepared by hybridizing PP/coir fibers with glass fibers were light in weight (6–20% lighter compared to 40 wt% glass fiber reinforced PP) with significantly enhanced tensile (strength – 49–182%, modulus – 54–130%), flexural (strength – 41–104%, modulus – 64–193%), and impact properties (157 - 474%) compared to 40 wt% coir fiber reinforced PP composites. Furthermore, the addition of glass fiber (10–30 wt%) to coir fiber reduced the water-absorbing tendency (by 18–74%) of PP/coir fiber composites. All in all, this work has potential applications in automotive, mass transit, and truck applications where natural fiber composites are being investigated as alternatives to metal and/or fully synthetic composites.

Owing to its low cost and sustainable nature, lignocellulosic biomass has been utilized for reinforcing polymers, but it is crucial to understand the impact of high-ash concentrations in biomass on composite strength and processing. Biomass is not only desirable for biofuel production but could also have a strong market, if high-ash biomass is acceptable, for biocomposites. In this work, natural fibers (switchgrass and corn stover) were used to reinforce polylactic acid (PLA) to produce biocomposites. Natural fibers were pretreated to obtain fibers that contain different percentages of ash. The mechanical properties (such as Young's modulus, tensile strength, failure strain, storage modulus) of corn stover/PLA composites remained largely unaffected by the ash concentration of the biomass fibers, despite the large range of ash contents (2.2–11.9 wt%). However, the tensile strengths of switchgrass/PLA composites were slightly negatively affected by the ash concentration of the switchgrass fibers (0.7–2.1 wt%). Both the switchgrass/PLA and the corn stover/PLA composites exhibited a high-enough tensile strength (49–57 MPa) and suitable complex viscosity (2.0−7.0 kPa·s at the frequency of 3.2 rad/s). They are expected to be 3D-printable through an extrusion-based additive manufacturing process.

The Apitong wood species has long been the most popular choice for transportation, such as in trailer decking and shipping container floors. However, Apitong is depleting due to its excessive usage. Bamboo fiber provides as an alternative due to its low density (608–780 kg/m3) and lightweight attributes. This study explores 1) development and properties of bamboo-thermoplastic composites with different fiber content, and 2) application of bamboo composite in trailer decking (a transportation application) as an alternative to Apitong. Extrusion-compression and compression molding was used as processing approaches for the bamboo-thermoplastic composites. The basic panels were tested for flexural loading and nail pull out to evaluate the feasibility as a viable trailer decking material. The flexural strength and modulus of bamboo composite were found to be 17 and 98% higher than Apitong, respectively. The density of the bamboo-thermoplastic was 670 kg/m3 compared to Apitong (737 kg/m3), hence 10% lighter. The nail pull-out strength was comparable between the two. The work progressed to producing prototype trailer decking members via extrusion-compression and compression molding. The bamboo-composite decking was evaluated on a trailer test bed and exhibited excellent surface wear response, minimal internal damage and withstood 400 fatigue cycles with onset of failure only at the supports, which the span did not exhibit damage.

The effect of palladium acetylacetonate on the pore structure evolution of isotropic petroleum pitch-based activated carbon fibers (ACFs) is characterized by comparing the pore structure evolution of ACFs that have been prepared from pure pitch and from palladium acetylacetonate-containing pitch. The pore structure was interpreted by applying chi-theory, Brunauer−Emmett−Teller (BET) surface area analysis, Barrett−Joyner−Halenda (BJH) methodology, t-plots, adsorption potential distribution (APD), and nonlocal density functional theory (NL-DFT) to experimental N 2adsorption isotherms. Pore size and pore volume calculations from chi-theory are in agreement with those from APD and NL-DFT, respectively, whereas, those from the BET, BJH, and t-plot methods are not. However, chi-theory underestimates the total surface area. The validated porosity and surface area results, pore size distribution, and APD were then studied as a function of burnoff value. The pore structure evolution analysis of both types of ACFs showed that the addition of palladium acetylacetonate to the pitch, prior to fiber formation, causes (i) the formation of macropores, (ii) a small increase in microporosity during the early stages of activation, and (iii) increased mesoporosity at burnoff values of >60%. The presented data and analysis provide a new understanding of the porous structure of novel pitch-based activated carbon adsorbents and potential hydrogen storage materials. [ABSTRACT FROM AUTHOR]