A novel composite material from recycled constituents

The increasing industrial use of carbon fibre in e.g. aircraft and wind turbines calls for strategies for their recovery and possible reuse. In additional, tremendous amount of energy is needed to be able to manufacture pristine carbon fibres. The work that has been done was to manufacture engineering composite material made from recyclates. Processing scrap from PURE® was extensively studied in terms of its stability and process ability as a thermoplastic matrix material. In a second study polypropylene scrap material was reprocessed into a film by press forming and introduced into a stack of carbon fibre preforms made from recycled carbon fibres recovered via a pyrolysis process from aircraft structures. The preform stack was heated and the composite material was manufactured by press forming.A challenging issue in this work was to achieve the desired distribution of the recovered carbon fibres in the fibre preforms. It is well known that dispersion of reinforcement is of immense importance for quality and performance of the composite materials. Here, a paper making method is employed to distribute the recovered carbon fibres randomly in the plane. The quality of the manufactured novel, fully recycled, composite material regarding void content and consolidation was controlled by extensive microscopy. The resulting composite material was analysed in terms of its mechanical performance including elastic modulus, Poisson's ratio, strength and strain to failure as well as its creep resistance.Godkänd; 2009; 20091026 (magszp); LICENTIATSEMINARIUM Ämnesområde: Polymera konstruktionsmaterial/Polymeric Composite Materials Examinator: Adj Professor Leif Asp, Luleå tekniska universitet Diskussionsledare: Docent Roberts Joffe, Luleå tekniska universitet Tid: Fredag den 27 november 2009 kl 10.00 Plats: E 231, Luleå tekniska universite</p

Development and characteristics of a fully recycled CF/PP composite

The increasing industrial use of carbon fibre in e.g. aircraft and wind turbines calls for strategies for their recovery and possible reuse. In addition, tremendous amount of energy is needed to be able to manufacture pristine carbon fibres. In this work, an engineering composite material was manufactured from recyclates. Processing scrap from PURE was extensively studied in terms of its stability and processability as a thermoplastic matrix material. Polypropylene scrap material was reprocessed into a film by press forming and introduced into a stack of carbon fibre preforms made from recycled carbon fibres recovered via a pyrolysis process from aircraft structures. The preform stack was heated and the composite material was manufactured by press forming. A challenging issue in this work was to achieve the desired distribution of the recovered carbon fibres in the fibre preforms. Here, a paper making method was employed to distribute the recovered carbon fibres randomly in the plane. It is well known that the fibre/PP interface properties are often the weakest link in the composite performance. Several modifications, including the addition of maleic anhydride grafted polypropylene (MAPP), are often used. MAPP improves the interface bonding between the fibre and polymer matrix by two simultaneous reactions. Firstly, the long molecular chain is responsible for chain entanglements and co-crystallisation with the non-polar PP matrix. These entanglements provide mechanical integrity to the host material. Secondly, the anhydride groups chemically interact with the functional groups on the fibre surface. The addition of MAPP has been found to improve the interface and increase the stiffness and strength of the composite. Inelastic mechanical behaviour in tension of a recycled polypropylene (rPP) matrix and a rPP matrix with addition of 10% of maleic anhydride grafted polypropylene (rPP+MAPP) was characterised and compared. The time dependent response was decomposed into nonlinear viscoelastic and viscoplastic parts and each of them quantified. It was found that the elastic properties of the rPP matrix did not degrade during loading. The addition of MAPP to the rPP matrix did not change the mechanical properties of the material. A non-linear material model was developed and the involved parameters (stress dependent functions) were identified. The model was then validated in a stress controlled test at a constant stress rate. The inelastic and time dependent behaviour of the MAPP modified composite material in tension was analysed. A series of quasistatic tensile and creep tests were performed to identify the material model, which accounts for: a) damage related stiffness reduction, b) development of stress and time dependent irreversible strains described as viscoplasticity, c) nonlinear viscoelastic behaviour. Fibre length distribution was investigated before and after composite manufacturing process to investigate the influence of the processing conditions on the fibre degradation. The quality of the manufactured novel, fully recycled, composite material regarding void content and fibre orientation was examined by microscopy.Godkänd; 2011; 20110426 (magszp); DISPUTATION Ämnesområde: Polymera konstruktionsmaterial/Polymeric Composite Materials Opponent: Professor Geoff Gibson, School of Mechanical and Systems Engineering, Newcastle University, Newcastle, UK Ordförande: Adj professor Leif Asp, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet, Luleå. Tid: Torsdag den 8 september 2011, kl 10.00 Plats: E231, Luleå tekniska universite

The out-of-plane behaviour of spread-tow fabrics

In this paper the constitutive compressive behaviour of nearly parallel spread-tow textile reinforcement is studied. The striking result of our analysis is that the spread-tow type of reinforcement should obey linear relation between force and deformation. This is in contrast to standard textile reinforcements that obey a power-law type of behaviour. To support the theoretical investigation we have developed an test rig who\u27s chief purpose is to achieve compression between nearly perfectly parallel surfaces. This is achieved using a mechanical arrangement consisting of a ball-joint