JEC COMPOSITES MAGAZINE - Issue #51 - September 2009 - 52

KNOW-HOW SMC An SMC-moulded ice axe Replacing metal with SMC (Sheet Moulding Compound) is one focus of the Polynt group’s compounds business. This is illustrated here with a patented foldable ice axe. The structural SMC used shows outstanding mechanical properties at low temperatures due to its matrix, which comprises a blend of thermosetting resins that form an interpenetrating network. DR OLIVER TÜRK, DEPUTY GLOBAL R&D AND MARKETING MANAGER COMPOUNDS, POLYNT S.P.A. Fig. 1: Microscopic analysis of breaking zones. ver the past years, the use of fibre-reinforced plastics Left: conventional-matrix SMC. Right: Dina-Lynt wit ha matrix forming an interpenetrating network. (FRP) to replace traditional construction materials like metal, concrete, and wood has intensified. To replace metals, an FRP material has to combine good mechanical results in outstanding mechanical properties, especially properties with low density to save weight. This frequently leads considering that glass fibres are the reinforcement. Table 1 to the choice of carbon fibres for the reinforcement. However, compares the mechanical properties of Dina-Lynt with a when moderate material cost is requested in addition to standard-matrix SMC and a thermoplastic construction material. mechanical properties, carbon fibres are excluded. Glass fibres Like Dina-Lynt S8000, the standard SMC has a high fibre are preferred in many cases. content (63%), but no IPN matrix combining different Optimizing the mechanical properties of Sheet Moulding thermosetting resins. Dina-Lynt S8000 has a remarkably high Compounds (SMC) under the restriction of glass-fibre use strength and rigidity, together with a high elongation at break requires focusing on the matrix properties and the fibre/matrix (2.7%) – a property of central importance for the application interaction to maximize the compounds’ mechanical introduced here. performance. For that purpose, a thorough breaking-zone analysis was conducted for SMC with conventional matrices. Beyond these properties, the material also possesses an Figure 1 (left) shows such a breaking zone, where the matrix exceptional dynamic load resistance. Figure 2 shows its residual separates neatly from the fibres during the breaking process. The strengths after a cycling load (1,000 cycles) with 10%, 20%, and fibre/matrix interaction was significantly improved by using a 30% of the load at break in a three-point bending experiment. matrix composed of a blend of different thermosetting resins Within the accuracy of measurement, the material shows no loss that form an interpenetrating network (IPN), as shown on the of strength in this load range. right side of Figure 1. Polynt S.p.A. Table 1: Mechanical properties of Dina-Lynt compared with a standard-matrix SMC introduced a group of SMC materials using and a thermoplastic construction material. this new type of matrix, the Dina-Lynt Density Flexural Tensile Elongation at Flexural range. (g/ml) strength (MPa) modulus (GPa) strength (MPa) break (%) O Apart from an exceptional fibre/matrix interaction, this particular blend of resins also allows thorough impregnation and fibre contents above 60% by weight. This Aluminium alloy PA 6.6 GF SMC standard matrix Dina-Lynt S8000 2.7 1.40 1.73 1.72 190 230 340 490 70 8 12,5 19 200 150 180 300 5 4 1.7 2.7 52 jec composites magazine / No51 September 2009

JEC COMPOSITES MAGAZINE - Issue #51 - September 2009

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #51 - September 2009