Within the framework of the “Future Bridge” project, and its successor “Trans-IND”, Van Wees has developed a process for production of glass/polypropylene crossply laminate. This composite will be used for building lightweight bridges on-site as an alternative for traditional materials for building infrastructure.
Essential for making UD from continuous glass rovings is a facility to unwind the heavy packages from outside, since feeding them from the inside of the coil would introduce a twist and therefore disturb the fibre distribution. The alternative, using thin glass fibre yarns, is not advisable due to economic reasons. Prices are higher and larger creels with more spool positions are required. For this purpose, Van Wees designed and built a special creel with capacity for 80 packages. Each position is Carbon/PA equipped with an individual tension adjustment. This ensures even running tension and quick stopping without causing excessive tension in the running ends. The yarn tension can be varied from 400 to 1600 cN. The yarn tension is measured at two positions. With this input the control system will compensate the decreasing diameter of the packages. Gentle unwinding of 2400 Tex rovings from this new creel and dedicated spreading made it possible to achieve a fibre weight as low as 200 g/m².
Three point bending tests on multilayer crossply laminates from this UD revealed a strength and rigidity of 370 MPa and 20 GPa respectively, which is considerably higher than observed for panels pressed from commercially available glass/pp-UDs.
The excellent thermoplastic formability of these laminates was demonstrated in batch production by thermoforming at DTC in Almere, Netherlands and also by means of continuous compression moulding at IVW in Kaiserslautern, Germany.