Folding of continuous fibre thermoplastic composites

Abstract

Abstract. Thermoplastic composites with continuous fibres are attractive construction materials because of their good specific mechanical properties and their possibility to be processed very rapidly. An extremely fast processing method is folding of sheet material. Folding can be performed by local heating of a sheet along a line. Heating is done to a temperature, well above the softening or melting point of the thermoplastic polymer. Subsequent folding along the heated line requires very low forces. The folded geometry becomes permanent after cooling below the softening point of the polymer. Unfortunately, folding causes microbuckling of the reinforcing fibres at the compression side of the fold causing a severe reduction in the local strength. The present report describes a method for the folding of thermoplastic composites, which controls the direction of fibre microbuckling. The method results in a smaller strength reduction.The folding equipment is designed in such a way that microbuckling of the fibres occurs in a direction in the local plane of the sheet rather than being perpendicular to that plane. The result is a folded sheet with a reduction of about half of the original strength, as compared to a strength of only 15% of the original strength, which is typical for folds produced with more conventional means. In other words, the remaining strength is more then doubled using the new folding technology.

Influence of the particle size of the MgCl2 support on the performance of Ziegler catalysts in the polymerization of ethylene to ultra‐high molecular weight polyethylene and the resulting polymer properties

“…Ultra‐high molecular weight polyethylene (UHMWPE) has outstanding physical and mechanical properties such as high impact toughness, high abrasion resistance, low coefficient of friction, good corrosion and chemical resistance, resistance to cyclic fatigue, and resistance to radiation . Due to its excellent properties UHMWPE finds use in highly demanding applications . However, this exceptional performance, comes at a cost.…”

“…Due to its high melt viscosity, UHMWPE cannot be processed via conventional melt processing routes, such as injection molding or blow molding. UHMWPE reactor powder is therefore processed via compression molding, ram‐extrusion or via dissolution in gel processes (fiber and film/tape) . Therefore, control of the morphological properties, such as particle size, particle size distribution (SPAN), polymer bulk density (BD) and flow behavior, as well as the structural properties, like M w and melting behavior, of the UHMWPE reactor powders, is critical in the safe and efficient processing of the polymer and the performance of the final product.…”

A Modeling Approach to Fiber Fracture in Melt Impregnation

“…Continuous fiber reinforced thermoplastic composite materials have been widely used in many fields of aerospace, automobile, chemical and electronic appliances, etc [1][2][3][4][5]. These materials can be processed by numerous techniques including filament winding, pultrusion and prepreg.…”

Manufacturing of Self-Reinforced All-PP Composites

“…In contrast to glass or carbon reinforced composites, slight draping irregularities in selfreinforced fiber composites can be evened out via plastic squeeze flow and the stretching of fibers [69][70][71].…”