The utilization of multifunctional composite materials presents significant advantages in terms of system efficiency, cost-effectiveness, and miniaturization, making them highly valuable for a wide range of industrial applications. One approach to harness the multifunctionality of carbon fiber reinforced polymer (CFRP) is to integrate it with a secondary material to form a hybrid composite. In our previous research, we explored the use of carbonaceous material derived from coconut shells as a sustainable alternative to inorganic fillers, aiming to enhance the out-of-plane mechanical performance of CFRP. In this study, our focus is to investigate the influence of carbonized coconut shell particles on the non-structural properties of CFRP, specifically electromagnetic interference (EMI) shielding, thermal stability, and water absorption resistance. The carbonized material was prepared by thermal processing at 400 °C. Varying proportions of carbonized material, ranging from 1% to 5% by weight, were thoroughly mixed with epoxy resin to form the matrix used for impregnating woven carbon fabric with a volume fraction of 29%. Through measurements of scattering parameters, we found that the hybrid composites with particle loadings up to 3% exhibited EMI shielding effectiveness suitable for industrial applications. Also, incorporating low concentrations of carbonized particle to CFRP enhances the thermal stability of hybrid CFRP composites. However, the inclusion of carbonized particle to CFRP has a complex effect on the glass transition temperature. Even so, the hybrid composite with 2% particle loading exhibits the highest glass transition temperature and lowest damping factor among the tested variations. Furthermore, when subjected to a 7-day water immersion test, hybrid composites with 3% or less amount of carbonized particle showed the least water absorption. The favorable outcome can be attributed to good interfacial bonding at the matrix/fiber interface. Conversely, at higher particle concentrations, aggregation of particles and formation of interfacial and internal pores was observed, ultimately resulting in deteriorated measured properties. The improved non-structural functionalities observed in these biocomposites suggest the potential for a more sustainable and cost-effective alternative to their inorganic-based counterparts. This advancement in multifunctional composites could pave the way for enhanced applications of biocomposites in various industries.
This content will become publicly available on August 22, 2024
Waterborne pressure sensitive adhesives (PSAs) consisting of polymer microparticle emulsions (i.e. latex) are more commonly used in commercial applications than solvent‐borne alternatives, as the use of water as a suspension medium provides better consumer safety and reduces environmental impact. However, the lower mechanical performance of waterborne PSAs prevents their use in applications requiring permanent adhesion or strong bonding between substrates. This reduction in mechanical strength is often attributed to void spaces that form during water evaporation and coalescence of the latex particles, and thus a potential strategy to improve PSA strength would be to add filler materials to occupy these voids. Fundamental studies investigating how interfacial interactions between the latex and fillers affect the collective strength of the films would enable better design of adhesive compositions to tailor PSA mechanical properties. Here we report the use of polymer brush‐grafted nanoparticles (PGNPs) as a means of mechanically reinforcing the PSAs, and determine how different aspects of the particle and polymer brush designs enable this improvement in adhesive performance. The PGNPs investigated here are intentionally designed to phase segregate into the aqueous phase of the initial latex suspension, which allows them to both fill free pore volume and also form multivalent supramolecular interactions with the latex particles to form polymer bridges that improve the interconnectivity of the final film. These studies provide insight into potential design strategies for tuning PSA properties with PGNPs, and enable up to 32% improvements to the cohesive strength of the PSAs without the typical deterioration of adhesive strength observed in PSAs using non‐brush‐coated particle fillers.
more » « less- NSF-PAR ID:
- 10491058
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science
- Volume:
- 62
- Issue:
- 4
- ISSN:
- 2642-4150
- Format(s):
- Medium: X Size: p. 743-752
- Size(s):
- ["p. 743-752"]
- Sponsoring Org:
- National Science Foundation
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Abstract Latex, an aqueous dispersion of sub-micron polymer particles, is widely used as polymer binder in waterborne coatings and adhesives. Drying of a latex is inhomogeneous, during which the spatial distribution of particles is non-uniform and changes with time, usually resulting in a compromise of the integrity of a dried film. To study drying inhomogeneity of latex, we developed a system integrating optical coherence tomography (OCT) with gravimetric and video analysis (OCT-Gravimetry-Video method) to non-destructively monitor the drying process of non-film-forming latexes consisting of hard polystyrene spheres over time. OCT structural and speckle images of the latex’s internal structure show the packing process of particles, the detachment of latex and the formation of apparent shear bands in cross-sectional views. Video recordings show the formation of cracks and the propagation of the drying boundary in the horizontal direction. The drying curve, measured by gravimetry, shows the drying rate and the water content of the latex at each drying stage. Furthermore, we find that the particle size affects packing and cracking phenomena remarkably. The OCT-Gravimetry-Video method serves as a general and robust approach to investigate the drying process of waterborne latex system. This method can be employed for fundamental studies of colloids and for evaluations of industrial latex products.
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