Long fiber thermoplastic pet-based composites: Fiber content and consolidation pressure

PET-based long glass fiber thermoplastic (LFT) composites manufactured from PET fibers and E-glass fibers have been studied. To manufacture these composites, PET and glass fibers are first cut to the same length and laid-down into a mold in thin alternate layers to obtain a regular distribution of the polymer and feinforcing fibers. The charge is then compression molded in a steel mold into rectangular plates. In this study, the influence of the glass fiber content and consolidation pressure on the void content, void distribution and mechanical properties is investigated. Results obtained for the influence of the fiber content show significant improvements of the tensile properties with increasing glass fiber content. Only small improvements are however measured for the flexural properties. This is thought to be related to the presence of large and continuous voids in the fiber bundles. Results of mechanical tests also show an improvement of the tensile modulus with increasing consolidation pressure. Finally, mechanical properties obtained in this work for the composites manufactured from glass and PET fibers and compared with polypropylene-based-D-LFT and GMT composites.Peer reviewed: YesNRC publication: Ye

Polyamide 12 (PA12) / clay nanocomposites fabricated by conventional extrusion and water-assisted extrusion processes

This work aims at comparing the efficiency of three melt compounding methods for preparing polyamide 12 (PA12)/untreated clay composites. Conventional extrusion was compared with two water-assisted extrusion methods previously described in the literature and respectively involving injection of water in the polymer/clay stream or injection of aqueous clay slurry in the polymer stream. The dispersion of the clay in the composites was analyzed at the microscale and at the nanoscale using microscopy (optical and electronic) and wide angle X-ray diffraction (WAXD). The tensile properties of the composites were evaluated. The results showed that injection of aqueous clay slurry in the polymer stream was the most efficient method for preparing PA12/untreated clay composites, although clay particles remained mainly dispersed at the microscale. This method allowed for a drastic size reduction of the microparticles, accompanied by enhancements of ca. +10 % in tensile modulus and tensile strength (compared with equivalent composites obtained by conventional extrusion). The influence of the pH of the aqueous clay slurry was also investigated: neutralization of the clay slurry generated finer dispersions, probably resulting from a better pre-exfoliation of the clay in the water medium. PA12/organophilic clay composites were also prepared as control samples. When an adequate surface treatment was selected, nanoscale dispersion of the clay platelets was easily achieved. In this case, composites prepared by conventional extrusion showed overall similar properties as their equivalents prepared using injection of water in the polymer/clay stream.Peer reviewed: YesNRC publication: Ye

Thermoset-natural fiber composites using nanocomposites for mass transit applications

Mass transit vehicle weight has grown significantly over the last 20 years penalizing the road infrastructure, fuel consumption and environmental signature. Increased use of lightweight, high-strength and new sustainable composites for mass transit vehicle components is a promising avenue to explore since weight reduction is one of the few ways Canadian mass transit vehicle manufacturers can influence fuel consumption and hence help reduce greenhouse gases emissions. Weight saving opportunities could possibly be obtained by the use of natural fiber and hybrid composites as compared to \u201ctraditional\u201d glass fiber based composites. The use of nanocomposites to improve the property of resins without any significant increase in density could also be a possible avenue to obtain the high performance composite with weight saving. In this paper, the role of nanoparticles on the performance improvement of natural fibers thermoset composites was investigated. Different nanoparticles such as Cloisite Na+, 10A, 20A and 30B, Perkalite G100, Nanocryl C140 were first dispersed in a thermoset resin before performing the impregnation of the natural fiber fabric. Natural fiber composites were prepared by hand lay-up followed by a vacuum step and by infusion. The quality of dispersion and intercalation/exfoliation was analyzed by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEGSEM) and transmission electron microscopy (TEM). Mechanical performance and fire resistance of nanoreinforced thermoset resin and natural fiber composites were also evaluated. The results obtained demonstrate that the presence of nanoparticles can improve the the tensile strength, tensile modulus and fire resistance performance of the resin and of the natural fiber composites. The levels of improvement of the properties were seen to vary with the type of nanoparticles used.Peer reviewed: YesNRC publication: Ye