Investigation of the specific adhesion between polyurethane foams and thermoplastics to suited material selection in lightweight structures

Abstract

Lightweight construction combines various materials to create resource efficient components. Thermoplastics (TPs) combined with polyurethane (PUR) foams are increasingly used to create hybrid composites. Optimizing the energy efficiency is one of the main issues in the development of production processes of components. Reducing the number of process steps offers great potential in this respect. PUR foam develops a strong adhesive bond with most materials. This is used for the manufacturing of hybrid composite components by filling complex cavities with PUR foam simultaneously bonded with other TP polymer components. This way, one process step for joining is saved. The interfaces in this composite structures are critical points of the failure. A huge variety of TP is used for the production of hybrid composite components and PUR foam develops varying bonding strengths with all of them. Selecting the suitable TPs for a durable bonding with PUR foam in the desired production process necessarily requires information about the respective specific adhesion. In this investigation, different TPs were processed with PUR foams in order to manufacture sandwich composites. The TP facings are produced in the injection moulding process. Subsequently, the facings are combined with the foam core during reaction injection moulding. The wetting behaviour

Manufacture of thermoplastic molds by fused filament fabrication 3D printing for rapid prototyping of polyurethane foam molded products

“…Furthermore, the results have shown that the use of RAs drastically affects the required “pull-off” stress, going from values around 1 and 3 kPa to 62 kPa, 60 times more when these are not used in the process. In this line, Schäfer et al have already demonstrated the high adhesion capacity of PUR in direct contact with different thermoplastic materials such as PA or PET, obtaining” pull-off” stress values between 25 kPa and 60 kPa for these materials (Schäfer et al , 2018). Besides, the low detachment stress in the first “pull-off,” when the RA is present on the surface of the specimen, is agree with the results published by other authors (Ashida, 2006; Romero et al , 2021), in which the ability of the RAs to drastically reduce the demolding force on the PUR foam has been proven.…”

Numerical simulation with experimental validation of the structural reaction injection moulding of 3D continuous fibre reinforced polyurethane foam

“…They consist of two fabric surfaces which are kept at a defined distance by spacer threads [17]. Schäfer et al described their processing in the SRIM and demonstrated the reinforcement effect using two different variants in a rigid and a flexible foam under pressure and bending load [18,19]. Chen et al reinforced a flexible PUR foam with six scientifically comparable spacer fabrics [20,21].…”

Lightweight Potential of 3D Endless Fiber Reinforcement of Polyurethane Foam Cores with Spacer Fabrics in Hybrid Sandwich Structures with Fiber Reinforced Thermoplastic Facings

“…This is based on own preliminary work. On the one hand these are studies on the adhesive strength between PUR foams and thermoplastics which were bonded in the RIM [16]. This enables the selection of suitable materials for loadable adhesive bondings in the sandwich.…”