A lab scale structural reaction injection molding (S-RIM) piece of equipment was designed and used to fabricate glass fiber reinforced polydicyclopentadiene (p-DCPD) composites for three different fiber contents. In order to obtain information regarding the optimal process temperature (>80°C) and the curing time (<30 s), differential scanning calorimetry (DSC) was used to investigate the curing behavior of DCPD resin under isothermal conditions. Further, a norbornene-based silane treatment was used to improve the interfacial adhesion between the glass fibers and DCPD as confirmed by the micro-droplet pull-out test and scanning electron microscopy (SEM). Fabrication of glass fiber/p-DCPD composites with improved mechanical properties was carried out based on the optimized process conditions and surface treatment of glass fiber.
The aim of this study was to determine the rheological property and crystallization behavior of polylactic acid (PLA) with improved heat resistance (Ingeo™ Biopolymer 4032D) through investigation of the melt viscosity and crystallization kinetics of PLA at different process temperatures. The viscosity was measured using a rotational rheometer under conditions of shear rates of 0.01, 0.1, and 1/s. The obtained rheological data show that the viscosity tended to decrease slightly as the shear rate increases and decrease sharply as the temperature increases from 180°C to 210°C. To investigate the effect of the process temperature on the crystallization kinetics and final crystallinity of PLA, thermal analysis using isothermal differential scanning calorimetry (DSC) were also performed. The Avrami equation was successfully applied for the isothermal crystallization kinetics model. From crystallization temperature of 85°C to 120°C, we found that the Ingeo™ Biopolymer 4032D PLA had the fastest crystallization rate (t
1/2: 26.0 min) and the largest crystallinity (47.4%) at 100°C.
Dicyclopentadiene (DCPD) resin has gained popularity owing to its fast curing time and ease of processing with a low viscosity in the monomer state. In the present study, the impact and shear properties of a carbon fiber (CF)/p-DCPD composite were investigated. The CF/p-DCPD composite was manufactured by vacuum-assisted resin transfer molding with CF as the reinforcement and p-DCPD as the resin with a maximum fiber volume fraction of 55 weight percent. Impact and shear properties of the CF/p-DCPD composite were evaluated and compared with those of a CF/Epoxy composite. The maximum shear stress and modulus of the CF/p-DCPD composite were lower than that of the CF/Epoxy composite. However, the CF/p-DCPD composite had higher toughness than that of the CF/Epoxy composite; this indicates that it is tougher and exhibits a more ductile load-displacement response with a lower modulus and larger failure deformation. The impact strength of the CF/p-DCPD composite was about three time that of the CF/Epoxy composite. The higher impact strength of the CF/p-DCPD composite is attributed to the resin characteristics: epoxy resin has a more brittle behavior, and hence, higher energy is required for crack propagation due to fracture.
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