JEC COMPOSITES MAGAZINE - Issue #75 - August/September 2012 - 31

Resintex Technology, based in Frosinone, central Italy, specializes in providing vacuum infusion technical expertise, product selection advice and the distribution of a wide range of composite products from leading suppliers.

Focus

laminate, producing moulded parts with greater consistency. To provide a tough, marine-approved laminate construction for the hull and deck, Scott Bader’s Crystic VE679-03PA infusion-grade low-shrink DCPD modified VE resin was specified in combination with a ‘matched system’ Crystic VE679PA skincoat. The supplier developed DCPD modified VE resins and skin coats to provide the mechanical performance needed for marine applications, while also reducing print-through to improve the aesthetic finish of the gelcoated surfaces of visible glass fibre parts; this is a key quality parameter for luxury power boat and yacht manufacturers. In addition to significantly lower resin material costs compared with openmould hand layup, the vacuum bagging infusion process provides converters with the added production benefits of reducing overall labour costs, increasing productivity and significantly improving environmental and shop floor health and safety working conditions. Styrene volatile organic compounds (VOC) emissions are typically reduced by over 70% in closed moulding.

Fig. 2: CorecellTM M-Foam was specified for the sandwich structure as it provides high strength, low density and very low resin absorption to significantly reduce laminate weight

Crestomer 1152PA urethane acrylate structural adhesive to bond the structural bulkheads in the hull. By using this adhesive instead of over-laminating, the Revolver 42 hull weight was reduced by over 45%. This structural adhesive has a much higher fatigue resistance, flexural modulus and ultimate tensile strength than the glass fibre laminate sections being bonded together, so failure is always in the substrate, with no adhesive or cohesive failure. According to the supplier’s technical data sheet, fully-cured Crestomer 1152PA achieves a tensile strength of 26 MPa, with a tensile modulus of 500 MPa. Due to its high yield stress performance and a 100% elongation to break, the adhesive can absorb the enormous impact deformation and shock loading which occur in the most critical slamming area of the hull. This range of adhesives has Lloyds Acceptance, as well as DNV and RINA approvals for a variety of GRP marine bonding applications including bulkhead bonding. Resintex Technology was very confident to recommend it for this proven hull bulkhead bonding application as it has been specified for many years by leading luxury glass fibre boat builders.

constructions. This foam was selected because it provides a combination of high strength, low density and very low resin absorption to significantly reduce laminate weight. For easy moulding, the double-cut configuration of the foam provides flexibility in two directions in the mould; intersecting flow channels on both sides optimise resin flow and avoid resin accumulation in sections of the mould.

Structural adhesive further reduces hull weight
To further reduce the hull weight while improving the overall mechanical performance of the hull construction, Resintex Technology also recommended Scott Bader’s long-established Crystic

Additional shop floor bonding benefits
In addition to significantly reducing the weight of the glass fibre hull, bonding in the bulkheads instead of over-laminating offers boat builders a combination of additional quality, shop floor and productivity benefits, such as improved external hull aesthetics by eliminating shrinkage print-through at bulkhead joints, reduced labour costs and increased productivity by avoiding the need to grind surfaces prior to joint over-laminating, and improved shop floor health and safety working conditions due to significantly reduced styrene emissions. n

Strong, low-weight laminate design
To help minimise the overall weight of the Revolver 42, carbon fibre fabrics were used to reinforce the maximum loading points in the cockpit hard top. Other critical performance areas subject to very high stresses and loads in the superstructure, such as the slamming area of the hull, were designed with a foam-cored sandwich laminate structure. The marine-approved CorecellTM M-Foam DC core material manufactured by SP-High Modulus, the marine division of Gurit, was specified for the infused hull and deck sandwich

Feature Marine

Fig. 3: The Crystic Crestomer 1152PA structural adhesives can absorb the enormous impact deformation and shock loading which occur in the most critical slamming area of the hull

More information: www.scottbader.com www.revolverboats.com www.resintex.it

No75 August - September 2012 /

jec composites magazine 31
http://www.scottbader.com http://www.revolverboats.com http://www.resintex.it
JEC COMPOSITES MAGAZINE - Issue #75 - August/September 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #75 - August/September 2012
