| 摘要 |
<p>Elements for window or door frames and for other structural purposes consist of rigid polyurethane foam which has been reinforced by an embedded profiled core. The pref. matrial for the inlaid core is a hollow profile of glass fibre reinforced plastic. The latter is pref. composed of two shells which are bonded together at the flanges. The core, thus produced, is also bonded to the polyurethane foam surrounding it and has the same thermal elongation characteristics. This prevents the difficulties caused by differential elongation of steel or Al cores.</p> |
