ABSTRACT
The concept of using bio-inspired healing mechanisms in fiber-reinforced polymer (FRP)-based laminated composites is one of the trending areas of research for lightweight high-performance materials. To introduce self-healing in laminated composites, we developed Diels-Alder (DA) grafted graphene nanoplatelets (GNPs) and introduced them into carbon-fiber-reinforced polymer (CFRP) composites. The DA-grafted GNPs provided dual benefits, such as repetitive self-healing along with an increased mechanical performance of the modified CFRP. The GNPs were functionalized with DA adducts, i.e., bismaleimide and furfurylamine via a facile functionalization approach. The highest healing efficiency evaluated using double cantilever beam (DCB) tests was observed as â¼87% with more than 10 times repeated healing cycles. The innovative concept and strategy proposed in this work could be a gateway to a new area of research to upscale for industrialization of DA-based repetitive self-healable and durable CFRP-based composites.
ABSTRACT
Emerging ex-situ technique, ultrasonic dual mixing (UDM) offers unique and hitherto unapproachable opportunities to alter the physical and mechanical properties of polymer nanocomposites. In this study, triangular lattice-like arranged dispersion of TiO2 nanoparticles (average size â¼â¯48â¯nm) in the epoxy polymer has been attained via concurrent use of a probe ultra-sonicator and 4 blades pitched impeller which collectively named as UDM technique. The UDM processing of neat epoxy reveals the generation of triangular lattice-like arranged nanocavities with nanoscale inter-cavity spacing. The UDM processing of epoxy-TiO2 nanocomposites reveals two unique features such as partial and complete entrapping of the nanoparticles by the nanocavities leading the arranged dispersion of particles in the epoxy matrix. Pristine TiO2 nanoparticles were dispersed in the epoxy polymer at loading fractions of up to 20% by weight. The results display that the arranged dispersion of nanoparticles is very effective at enhancing the glass transition temperature (Tg) and tensile properties of the epoxy at loading fractions of 10â¯wt%. We quantify a direct relationship among three important parameters such as nanoparticle content, cluster size, and inter-particle spacing. Our results offer a novel understanding of these parameters on the Tg and tensile properties of the epoxy nanocomposites. The tensile fracture surfaces revealed several toughening mechanisms such as particle pull-out, plastic void growth, crack deflection, crack bridging and plastic deformation. We show that a strong nanoparticle-matrix interface led to the enhanced mechanical properties due to leading toughening mechanisms such as crack deflection, plastic deformation and particle pull-out. We showed that the UDM has an inordinate prospective to alter the dispersion state of nanoparticles in viscous polymer matrices.
ABSTRACT
Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO2) nanoparticles (0.5-20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (Tg) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle-matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation.
