New thermoplastic matrix composites for demanding applications J. P. Nunes* 1 , J. F. Silva 2 , J. C. Velosa 1 , C. A Bernardo 1 and A. T. Marques 3 A new thermoplastic polymer for highly demanding applications (PrimospireH PR 120) was studied in this work. The relevant properties of the polymer were determined and a new piece of prototype powder coating equipment was designed and built to produce carbon fibre reinforced Primospire matrix towpregs. The towpregs were subsequently processed by compression moulding into final composite plates that were used to determine mechanical properties. Although significantly below from the theoretical expected ones, those properties were adequate for advanced composite applications. Keywords: PrimospireH, Carbon fibres, Towpreg, Thermoplastic matrix composite, Powder coating equipment Introduction Higher performing composites are currently needed to face the new requirements that advanced markets demand. Good examples of this are the manufacture of composite overwrapped pressure vessels for space applications such as pressurised tanks for rocket trust vector control systems, propellant pressurisation, nitro- gen inertly, cold gas propulsion and liquid propellant storage systems and structural components for the new generation of reusable launching vehicles (RLV). In recent years, composites based on high perfor- mance thermoplastic matrices (PEEK, PPS, PES, PI, PAI, PEI) have successfully replaced the thermosetting based ones, due to their lower weight, easier reparability and reusability associated with an higher durability and, above all, better toughness, damping and fatigue behaviour, even under severe temperatures. The authors have been working in the production and characterisation of thermoplastic coated long fibre pre- impregnated materials (towpregs) and their processing for a long time, in cooperation with international groups. This allowed not only obtaining new materials, but also the manufacture of prototype equipment to produce them. 1–4 In this paper, a preliminary work on the production of a new towpreg material using a piece of recent developed powder coating equipment will be reported. 5 A novel amorphous highly aromatic thermo- plastic polymer in powder form, PrimospireH PR 120 from Solvay Advanced Polymers, was used to that effect. The towpregs thus produced were subsequently processed into composites by compression moulding and their relevant flexural mechanical properties determined. The work performed allowed testing the prototype equipment with a different system and also ascertaining the processability of the new polymer with this technology. Experimental Raw materials The towpregs studied in this work were produced using PrimospireH PR 120, a new highly aromatic thermo- plastic polymer developed from rigid rod paraphenylene copolymers by Solvay Advanced Polymers, and 760 Tex M30SC carbon fibre tows from Torayca respectively, as matrix and reinforcement. The densities of the fibres and the polymer are 1?73 and 1?21 Mg m 23 respectively. The Primospire supplier recommends using processing tem- peratures in the range of 310–350uC for this material. Developed equipment and towpreg production A piece of new prototype powder coating equipment was designed and manufactured to produce Primospire/ carbon and Primospire/glass towpregs. 5 It consists of six main parts (see Fig. 1): a windoff system, a fibres spreader unit, a heating section, a coating section, a consolidation unit and a wind-up section. In order to produce the desired amounts of pre-impregnated mate- rial, the process starts by winding off fibres from their tows. In the next stage, the fibres pass trough a pneumatic spreader and are heated in a convection oven. Immediately after, the heated fibres pass into a vibrating bath of polymer powder to be coated. A gravity system ensures that the amount of polymer powder is kept constant in the bath. The oven of the consolidation unit softens the polymer powder, promot- ing its adhesion to the fibre surface. Finally, the thermoplastic matrix towpreg is cooled down and wound up on the final spool. The photograph in Fig. 2 shows a general overview of the new equipment. With the operational conditions summarised in Table 1 it was possible to produce continuously Primospire/carbon towpregs with about 1 Polymer Engineering Department, University of Minho, Guimara ˜ es, Portugal 2 Mechanical Engineering Department, ISEP, Porto, Portugal 3 DEMEGI, FEUP, Porto, Portugal *Correponding author, email jpn@dep.uminho.pt ß Institute of Materials, Minerals and Mining 2009 Published by Maney on behalf of the Institute Received 30 October 2008; accepted 5 November 2008 DOI 10.1179/174328909X387946 Plastics, Rubber and Composites 2009 VOL 38 NO 2/3/4 167