Ultra-high-molecular weight polyethylene (UHMWPE) fibers show promise for use in fiber-reinforced polymer composites but have poor interfacial adhesion to the epoxy resin that would serve as the polymer matrix. Here, we describe the development of a diazirine-grafted polyamine that can be used as a topically applied primer for UHMWPE fibers. Activation of the diazirine groups on the primer initiates C−H bond insertion on the polyethylene fiber, leading to strong covalent bonds between the fiber and the polyamine coating. The covalently functionalized surface can then engage in nucleophilic addition reactions with epoxy resinresulting in increased bonding to the epoxy matrix (demonstrated through lap-shear experiments) and increased performance for fiber-reinforced composite materials (demonstrated through lamination rates and short-beam stress measurements).

Biomaterials are increasingly being designed and adapted to a wide range of structural applications, owing to their superior mechanical property-to-weight ratios, low cost, biodegradability, and CO2 capture. Bamboo, specifically, has an interesting anatomy with long tube-like vessels present in its microstructure, which can be exploited to improve its mechanical properties for structural applications. By filling these vessels with a resin, e.g. an applied external loading would be better distributed in the structure. One recent method of impregnating the bamboo is plastination, which was originally developed for preserving human remains. However, the original plastination process was found to be slow for bamboo impregnation application, while being also rather complicated/methodical for industrial adaptation. Accordingly, in this study, an improved plastination method was developed that is 40% faster and simpler than the original method. It also resulted in a 400% increase in open-vessel impregnation, as revealed by Micro-X-ray Computed Tomography imaging. The improved method involves three steps: acetone dehydration at room temperature, forced polymer impregnation with a single pressure drop to − 23 inHg, and polymer curing at 130 °C for 20 min. Bamboo plastinated using the new method was 60% stronger flexurally, while maintaining the same modulus of elasticity, as compared to the virgin bamboo. Most critically, it also maintained its biodegradability from cellulolytic enzymes after plastination, as measured by a respirometric technique. Fourier transform infrared-attenuated total reflection, and thermogravimetric analyses were conducted and showed that the plastinated bamboo’s functional groups were not altered significantly during the process, possibly explaining the biodegradability. Finally, using cone calorimetry, plastinated bamboo showed a faster ignition time, due to the addition of silicone, but a lower carbon monoxide yield. These results are deemed as a promising step forward for further improvement and application of this highly abundant natural fiber in engineering structures.