Curing Adhesives with Woven Fabrics Made of Polymer Optical Fibre and PET Yarn

Abstract

UV bonding technology’s biggest limitation is the need of a transparent joining part to be able to cure the adhesive with an external light source. This is to be solved with ribbon fabrics made with polymer optical fibres (POF) which guide the UV light into the adhesive bond. On the basis of previously published experiments, a set of POF fabrics with different thread densities and weft materials is evaluated optically regarding the emitted UV light intensity and mechanically regarding the shear strength of the adhesive bonds. A factorial experiment plan indicates that higher tensile lap-shear strength comes with lower weft fineness and higher weft density. The maximum shear strength achieved was 8.3 MPa with potential room for improvement due to non-cohesive failure, relatively high weft densities and a comparatively low powered UV light source.

Extra thin sidelight-emitting polymer optical fiber narrow fabrics for UV structural adhesive joints: design, preparation and performance experiments

“…12 Based on feedback from manufacturers, typical layer thicknesses for these adhesive systems range around 0.20 mm and below with a technical feasibility limit at around 0.05 mm. 12 As shown in a consecutive study by Kallweit et al, 20 the decrease in transmittable optical power connected to a reduction of the POF diameter can be overcome by adjusting the number of POFs in the adhesive joint accordingly. The authors explored this concept by weaving POFs into fabrics.…”

“…As shown in a consecutive study by Kallweit et al., 20 the decrease in transmittable optical power connected to a reduction of the POF diameter can be overcome by adjusting the number of POFs in the adhesive joint accordingly. The authors explored this concept by weaving POFs into fabrics.…”

“…5,21,22 The light loss is dependent on the chosen weave. 23,24 The motivation behind this study is to advance the concept proposed by Kallweit et al 20 significantly by developing a fabric design optimized for integration into structural adhesive joints. In this context, an important design goal is to enable uniform curing of the UV adhesive.…”

“…At the same time, a lower lap shear strength of the manufactured adhesive joints showed that additional parameters like impregnability of the fabric by the adhesive and mechanical behavior of the fabric as a structural element within the adhesive layer need to be taken into account adding to the complexity of the development of a POF fabric for this specific application. 20 The fabrics for these first exploratory trials were produced with 500 mm diameter POFs, consequently resulting in unsatisfactory thicknesses of the specimens' adhesive layers well above 0.50 mm. Considering that incorporating a fabric into an adhesive layer is likely to alter the load-bearing mechanisms of the adhesive joint, it is as yet unknown up to which thickness competitive mechanical properties for these (composite) adhesive layers are achievable.…”

“…Otherwise, there is a risk of variations in curing degree and depth within the adhesive matrix causing premature failure of the adhesive on the weakly cured side of the fabric. To the best knowledge of the authors, besides the work 20 laid out above, the only study involving POF fabrics with even-sided radiation properties is the previously introduced study by Quandt et al., 8 in which the fabric design was specifically adapted to the requirements of a phototherapy device. The multitude of parameters determining the emission profile of side-emitting fabrics underlines the current necessity for individual experimental approaches when developing POF fabrics for technical applications with specific constraints, such as in this case with regard to wavelength and fabric thickness.…”