Dynamic mechanical analysis of fiber-reinforced phenolics

Abstract

Dynamic mechanical analysis (DMA) was used to investigate the thermomechanical behavior and the effects of postcuring on a range of glass-reinforced phenolics. The materials examined were a pure resol (reinforced with S-and E-glass), a pure novolac (reinforced with S-glass), and three derivatives of the resol and/or novolac: a resol/novolac blend, a phenolic-furan graft copolymer, and a rubber-modified resol (all reinforced with S-glass). The blend and copolymer were prepared to obtain phenolic resins with improved impact strength, without degeneration of their high-temperature performance. They have a more loosely crosslinked structure compared to the pure resol or novolac. The rubber-modified resol was prepared with the intention of reducing the brittleness of the resin structure by incorporating an elastomeric phase within the resol resin matrix. It was found that the stiffness and glass transition temperature (T g ) of the materials could be increased by postcuring, which also produced a decrease in their damping capacity. Knowing that the postcure process is a function of time and temperature, a master curve was constructed that allowed prediction of the T g of the resol/novolac blend over a broad range of postcure times and temperatures. The effect of frequency on the storage modulus of the pure resol (S-glass), copolymer, and blend was also studied from 0.01 to 100 Hz. Master curves were constructed by timetemperature superpositioning that allowed prediction of the storage modulus at times and temperatures that are not experimentally accessible.

Dynamic Mechanical Analysis and Three-Body Abrasive Wear Behaviour of Thermoplastic Copolyester Elastomer Composites

“…The damping peak usually occurs in the glass transition region and is associated with the movement of side groups or low molecular-weight units and molecular chains within the rubbers. Therefore, the higher the damping peak, the greater the degree of molecular mobility [44]. It can be seen from Figure 2, that the incorporation of 32 wt.% fiber + filler loading into the TCE composite decreased the damping characteristics of the composites, causing a lower and broader damping peak.…”

Development of a biocomposite based on green epoxy polymer and natural cellulose fabric (bark cloth) for automotive instrument panel applications

“…The source of crack initiation is usually weak fiber to matrix bond interface; therefore higher energy is dissipated than strong interfaces. The high tand peak therefore shows green epoxy polymer is viscous when loaded compared to the reinforced composites [34,35].…”

Phenylethynyl-terminated polyimide, exfoliated graphite nanoplatelets, and the composites: an overview

“…The cure accelerates around the imidization temperature. The extent of cure of the cumulatively cured sample in the imidization temperature re- [39] and polymeric composites [40,41] but also at the interface or sizing interphase [42][43][44] between fiber and matrix in a composite system. Also, the reaction behavior can be observed using this method, because changing thermal conditions can change molecular states during the transformation from amide acid to fully cured polyimide.…”