Title: Next generation rPET structural foam core with significantly lower resin uptake
Authors: Stefan Reuterlöv
Abstract: PET foam core has in the past 10+ years rapidly grown and established a position as the preferred choice for replacing other foam cores such as PVC and SAN foam in wind energy blades and other applications. Still compared with most other core materials available, PVC foam, SAN foam or Balsa wood it is still a very young material. This also means that the development rate for PET foam core is rapid, and the full potential has not by far been reached yet.PET cores success is a combination of excellent fatigue properties, very good temperature stability compared with most other foam cores as well as excellent compatibility with all resins and manufacturing methods. The basic properties of the PET foam core being thermoplastic enable wider processing possibilities with both thermoset but also thermoplastic resins. This enables higher curing or post curing temperature resulting in quicker cycle times as well as better mechanical properties in the laminates. But it also means that thermoforming and thermo-molding is possible, and this ability of the PET core opens up a wider range of applications. Being thermoplastic also means that recycling in the same or other products is possible. However, due to the anisotropic cell structure inherent to its production process, PET cores show a disadvantage in resin uptake when using infusion-type manufacturing processes. This has restricted the use of PET core to substitute other traditional core materials with lower resin uptake, especially when the need to minimize weight is important, e.g for the largest blades (>100 m in length). With the latest development of rPET this disadvantage has now been mitigated as resin uptake can be lower by 40-60 % compared to standard PET core depending on if it is also combined with surface treatment. At the same time the improvement in cell structure significantly impacting resin uptake also have positive effect on some of the mechanical properties. Most notable is the improvement in shear elongation of 25-40 % that has a significant influence on the damage tolerance and peel strength of the core material.
References: 1. Wikström. Niklas, A study of the effect of different infusion techniques on sandwich beam properties, Skrift 2002-2, KTH, Stockholm, Sweden 2. Technical Data Sheet ArmaPET GRX grade, April 2023, Armacell Benelux S.C.S. www.armacell-core-foams.com 3. Technical Data Sheet ArmaPET GR grade, January 2022, Armacell Benelux S.C.S. www.armacell-core-foams.com 4. ASTM Standard C393/C393M-11, ""Standard Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure"" ASTM International, West Conshohocken, PA, November 2011, www.astm.org.
Conference: CAMX 2023
Publication Date: 2023/10/30
Price: $18.00Get This Paper