Structure - Impact properties relationships of carbon fiber reinforced poly(methyl methacrylate) composite

In the present study, the relationships between poly(methyl methacrylate) (PMMA) structure modified by nanoparticles and the impact behavior of carbon fiber (CF) reinforced PMMA (CF/PMMA) thermoplastic nanocomposite were explored. CF/PMMA composite was prepared by nanofiller-containing methyl methacrylate monomer impregnation of fibers followed by in-situ polymerization in the mould. Composite matrix PMMA was modified by halloysite, multiwalled carbon nanotubes, and organically modified and unmodified layered silicate clays. The structure of modified PMMA was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. SEM results show that nanotubes are uniformly distributed in the PMMA matrix without formation of aggregates. XRD studies of PMMA with layered silicates indicate poor unmodified clay exfoliation in polymer monomer. A low-velocity impact test was performed and an air-coupled ultrasonic non-destructive testing technique was used to size delamination type defects in the composite samples after impact. The impact damage behavior was explained by microstructural parameters of composites obtained by optical microscopy. It was obtained that CF/PMMA composite modified by nanotubes both multiwalled carbon and halloysite absorbs 10 % more energy at the low velocity impact compared to that of unmodified one, due to high interaction of the nanotubes and PMMA. Layered silicate clays adversely affected the composite impact properties compared with unmodified CF/PMMA. Organic modifications of clays slightly improve their dispersion into the monomer, but does not have an observed effect on the impact properties of the composite. POLYM. COMPOS., 40:E333-E341, 2019. (c) 2017 Society of Plastics Engineers