Photo-polymerized epoxy primer for adhesion improvement at thermoplastics/metallic wires interfaces

Basile Golaz, Jan-Anders Månson, Véronique Michaud
Elsevier Sci Ltd, 2013
Article

Résumé

We report results on the development of an innovative fast-curing coupling method using a UV-curable epoxy primer based on a cycloaliphatic di-epoxide resin to bond metallic wires and a thermoplastic polyurethane matrix. The curing kinetics of the primer and its mechanical properties were analysed to optimize the formulation. Adhesion and durability were then tested by pull-out tests before and after hydrothermal ageing for several formulations and composites. The proposed UV-curable primer outperformed a conventional surface treatment and a thermally cured silane primer used for comparison in terms of processing time, adhesion and durability. (C) 2013 Elsevier Ltd. All rights reserved.

Official source

https://infoscience.epfl.ch/record/189191?ln=fr

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Concepts associés

Chargement

Publications associées

Chargement

, ,

When a thermoplastic polyurethane elastomer (TPU) is co-molded with galvanized steel, the subsequent adhesion and its durability are very sensitive to the chemical bonds created at the interface. Silane coupling primers are known for enhancing adhesion between inorganic substrates and several polymers and this study addresses their efficiency at the TPU-metal interface. gamma-APS aminosilane was deposited with different parameters, including pH and solvents. Several other surface treatments were studied for comparison: degreasing, corona discharge, acidic etching, gas flame, and a zinc phosphate conversion coating. The adhesion was characterized with a single wire pull-out test derived from the microbond test geometry, after different aging conditions. Results confirmed that gamma-APS worked as a coupling agent in between TPU and the inorganic substrate, outperforming all other surface treatments tested in term of strength and durability, but the silane required the appropriate deposition parameters to be really efficient. In parallel, a finite element approach was proposed for the modeling of fiber reinforced thermoplastic elastomer composites accounting for the non-linear viscoelastic material properties and its results compared to an analytical elastic shear-lag interpretation of the single filament pull-out test. The analytic interpretation was found to be sufficiently accurate for stress analysis but not for fracture mechanics. The FEM analysis offered an evaluation of the internal stresses developed within the entire system, which helped the interpretation of results. The model, compared to experimental results, also revealed that it is important to account for internal stresses, mostly for treatments leading to low intrinsic interfacial shear strength values. (C) 2011 Elsevier Ltd. All rights reserved.

Elsevier2011

Chargement

UV-curable epoxy primer for adhesion in steel reinforced polymer composites

Basile Golaz, Jan-Anders Månson, Véronique Michaud

In continuous composite production, for example the continuous impregnation of steel wires or cords with a thermoplastic polyurethane matrix, an ideal and cost-effective solution to improve interfacial adhesion and durability would be to deposit and cure a primer, on-line, at high processing speeds. A UV-curable epoxy primer was investigated for this purpose; it is reticulated by cationic photo-polymerisation, possibly followed by dark-curing and/or post-cure during further processing. The primer base formulation was tailored using additives including a hyperbranched monomer for tailoring cross-linking and flexibility and trimethylolpropane oxetane to increase curing speed and reduce viscosity. Curing kinetics, coating mechanical properties, and adhesion and durability at the steel-TPU interface were assessed for several combinations of coating formulation and processing parameters (time, temperature, UV intensity). Pull-out tests were analysed by finite element methods to refine interpretation of the experimental results for process-induced stresses, interfacial shear strength and energy release rate. The results demonstrated the fast-curing capability together with adhesion and durability improvements between galvanized or stainless steel reinforcements and a thermoplastic polyurethane elastomer by forming physico-chemical bonds with both the polymer and the substrate, while maintaining low internal stresses at the interface. The proposed UV-curable primer outperformed conventional surface treatments and thermally cured aminosilane primers used as benchmark in terms of processing time, adhesion and durability.

2012

Chargement

Fast-curing coatings for adhesion promotion between metallic oxides and thermoplastic polyurethane

Basile Golaz, Jan-Anders Månson, Véronique Michaud

The cost-effective production of high-performance and durable steel reinforced thermoplastic composites requires improvement of the adhesion encountered at the interface between metallic substrates (galvanized steel) and a thermoplastic elastomer (TPU). Combined requirements of processing speed, adhesion and durability were assessed by using cationic photo-polymerized coatings at the TPU-metal interface. The adhesion was studied by pull-out tests on co-molded TPU matrix - galvanized steel wires samples before and after different aging conditions. Several fast benchmark surface treatments were first studied and resulted in average adhesion and poor durability. Coupling primers were then investigated with γ-APS aminosilane films formed from different solutions and deposition parameters. They resulted in excellent adhesion and durability at the cost of a very low processing speed. Finally, cationic UV-curable coatings were used as an innovative adhesion-promoting interface achieving fast curing together with excellent adhesion and durability. The curing kinetics and the final degree of cure of these coatings was also investigated in order to reach the fastest processing rate. Maximum interfacial shear strength and energy release rate adhesion criteria were defined and discussed for the case of an elastomeric matrix in the light of FEM simulations considering residual stress, viscoelastic relaxation and temperature dependence.

2011

Chargement