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- Processing of carbon reinforced thermoplastic pre-impregnated materialsPublication . Novo, P. J.; Nunes, J. P.; Silva, João F.; Marques, A. T.The aim of this work is to produce and optimize the processing of carbon fibres thermoplastic matrix pre-impregnated materials (towpregs and PCT´s). Pultrusion and heated compression moulding were the selected manufacturing methods for processing all carbon fibres thermoplastic matrix pre-impregnated materials into composite parts. The optimization of those processes was made by studying the influence of the most relevant processing parameters in the final properties of the produced carbon fibres thermoplastic matrix pre-impregnated materials and composites. The method of Taguchi / DOE (Design of Experiments) was used to achieve this aim as it allowed making more rational choices of processing windows. The composite relevant mechanical properties were determined and studied. The final composites were also submitted to SEM microscopy analysis.
- Advanced Thermoplastic Carbon Fibre Reinforced Pultruded CompositesPublication . Novo, P. J.; Silva, João; Nunes, J. P.; Marques, A. T.The aim of this work is to optimize the production of new continuous carbon fibers reinforced thermoplastic matrix pre-impregnated materials (towpregs) continuously processed by dry deposition of polymer powders in a new equipment developed by the Institute for Polymers and Composites (IPC). The processing of the produced towpregs by pultrusion, in a developed prototype equipment existing in the Engineering School of the Polytechnic Institute of Porto (ISEP), was also optimized. Two different thermoplastic matrices were studied: one for commercial applications (polypropylene) and another for advanced markets (Primospire®). The optimization was made by studying the influence of the most relevant processing parameters in the final properties of the produced towpregs and composites. The final pultruded composite profiles were submitted to mechanical tests in order to obtain relevant properties.
- Thermoplastic matrix composites – new generation of eco-friendly materialsPublication . Esfandiari, Puria; Silva, João; Novo, P. J.The biggest advantagein the use of thermoplastic composites is the possibility of recycling and reprocessing, which is not possible with thermosetting composites. The shorter manufacturing cycle time and lower chemical emissions are, as well, other advantages. The use of thermoplastic matrix composites creates new engineering challenges concerning the manufacturing due to their high viscisity during manufacture. For all the advantages that these materials present, it becomes useful to study and evolve the universe of composites in the direction of thermoplastics. In this work, continuous fiber thermoplastic composites were produced and transformed by pultrusion and heated compression moulding. The manufactured composites were then tested, and mechanical properties were determined and studied.
- Producing LFT composite parts for large consumption markets from thermoplastic powder-coated towpregsPublication . Nunes, J. P.; Rodrigues, F. M.; Novo, P. J.; Silva, João F.Thermoplastic matrix composites are receiving increasing interest in last years. This is due to several advantageous properties and speed of processing of these materials as compared to their thermoset counterparts. Among thermoplastic composites, Long Fibre Thermoplastics (LFTs) have seen the fastest growth, mainly due to developments in the automotive sector [0, 2]. LFTs combine the (semi-)structural material properties of long (>1 cm) fibres, with the ease and speed of thermoplastic processing. This paper reports a study of a novel low-cost LFT technology and resulting composites. A patented powder-coating machine [3, 4] able to produce continuously pre-impregnated materials directly from fibre rovings and polymer powders was used to process glass-fibre reinforced polypropylene (GF/PP) towpregs. Such pre-impregnated materials were then chopped and used to make LFTs in a patented low-cost piston-blender developed by the Centre of Lightweight Structures, TUD-TNO, the Netherlands [5, 6]. The work allowed studying the most relevant towpreg production parameters and establishing the processing window needed to obtain a good quality GF/PP powder coated material. Finally, the processing window that allows producing LFTs of good quality in the piston-blender and the mechanical properties of final stamped GF/PP composite parts were also determined.
- Processing of carbon reinforced thermoplastic compositesPublication . Novo, P. J.; Nunes, J. P.; Silva, João; Marques, A. T.The aim of this work is to produce and optimize the processing of carbon fibres thermoplastic matrix pre-impregnated materials (towpregs and PCT´s) using the dry powder coating equipment from our own laboratories. Pultrusion was the selected manufacturing method for processing all carbon fibres thermoplastic matrix pre-impregnated materials into composite parts. The optimization of the pultrusion processe was made by studying the influence of the most relevant processing parameters in the final properties of the produced carbon fibres thermoplastic matrix pre-impregnated materials and composites. The composite relevant mechanical properties were determined and studied. The final composites were also submitted to Scanning Electron Microscopy (SEM), optical microscopy and calcination tests. The determination of the fiber volume fraction of a composite with a high melting temperature thermoplastic polymer used as matrix was obtained comparing the results of thermogravimetric analysis (TGA) with the calcination tests.
- Advances in thermoplastic pultruded compositesPublication . Novo, P. J.; Silva, João F.; Nunes, J. P.; Marques, A. T.Pultrusion is a versatile continuous high speed production technology allowing the production of fibre reinforced complex profiles. Thermosetting resins are normally used as matrices in the production of structural constant cross section profiles. Although only recently thermoplastic matrices have been used in long and continuous fibre reinforced composites replacing with success thermosetting matrices, the number of their applications is increasing due to their better ecological and mechanical performance. Composites with thermoplastic matrices offers increased fracture toughness, higher impact tolerance, short processing cycle time and excellent environmental stability. They are recyclable, post-formable and can be joined by welding. The use of long/continuous fibre reinforced thermoplastic matrix composites involves, however, great technological and scientific challenges since thermoplastics present much higher viscosity than thermosettings, which makes much difficult and complex the impregnation of reinforcements and consolidation tasks. [1] In this work continuous fibres reinforced thermoplastic matrix towpregs were produced using equipment developed by the Institute for Polymers and Composites (IPC). The processing of the towpregs was made by pultrusion, in a developed prototype equipment existing in the Engineering School of the Polytechnic Institute of Porto (ISEP). Different thermoplastic matrices and fibres raw-materials were used in this study to manufacture pultruded composites for commercial applications (glass and carbon fibre/ polypropylene) and for advanced markets (carbon fibre/Primospire®). To improve the temperature distribution profile in heating die, different modifications were performed. In order to optimize both processes, towpregs production and pultruded composites profiles were analysed to determine the influence of the most relevant processing parameters in the final properties. The final pultruded composite profiles were submitted to mechanical tests to obtain the relevant properties.
- Compression molding of pultruded carbon reinforced thermoplastic compositesPublication . Novo, P. J.; Nunes, J. P.; Silva, João F.; Marques, A. T.Historically, thermoset resins have dominated the composite industry but they start to be replaced by thermoplastics. In this study two different thermoplastic matrix carbon reinforced pre-impregnated materials were used, one produced in our laboratories (towpreg) and another obtained from coextrusion process (PCT). Carbon fibre and two different thermoplastic matrices (polypropylene and PRIMOSPIRE®) were selected for the production of the pre-impregnated materials. Heated compression moulding and pultrusion were the two manufacturing technologies used to obtain composite plates and profiles for study. The optimization of those processes was made by studying the influence of the most relevant processing parameters in the final properties of the produced carbon fibres thermoplastic matrix pre-impregnated materials and composites. The composite relevant mechanical properties were determined and the final composites were submitted to Dynamic Mechanical Analysis (DMA), Scanning Electron Microscope (SEM), optical microscopy and calcination tests. The determination of the fiber volume fraction of all studied composite was obtained comparing the results of thermogravimetric analysis (TGA), SEM and calcination tests.