Glass mat reinforced thermoplastic polypropylene

Although GMTs are available with different pol)nneric matrices, the market is dominated by polypropylene (PP) based composites (GMT-PP) due to their low price. 

Manufacturing and forming of GMT-PP occur mostly separately. Due to economic reasons efforts are, however, being undertaken to combine the production and shaping on-line. 

A recent development of the dry-laid techniques can be ascribed to the preformed GMT produced by a fluidized bed process [3]. In this case, fiber rovings are cut and mixed with thermoplastic powder, conveyed and deposited by air stream onto a mold. The loose web formed on this mold is heated by hot gas stream prior to being transferred to a matched die compression mold. So, in this case, the web (i.e. the GMT preform) is consolidated and formed simultaneously in the compression molding 

PolymBr Powder Glau Fiber (chopped) Water 

Individual failure events within the damage zone 

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M.D. Wakeman, T.A. Cain, C.D. Rudd, R. Brooks, A.C. Long, Compression moulding of glass and polypropylene composites for optimised macro- and micro-mechanical properties II. Glass-mat-reinforced thermoplastics. 

One of the important applications of polypropylene is to make glass-mat-reinforced thermoplastic (GMT) composites. Such composites are extensively... 

Recendy, storm doors have been constmcted of advanced thermoplastic composites. Stampable, glass-mat reinforced polypropylene sheet is used to create a high strength outer skin. These compression molded skins are welded together using a friction or ultrasonic process then injection molded with a polyurethane foam core to produce an insulated structure. New technology for window frames incorporate the pultrusion of frame channels to produce a thermoset composite channel that can be filled with fiber glass for further insulation enhancement (12,31,33,34,48,49,54—56,60—67). 

Plate-shaped GMT is a glass mat reinforced, flat, semifinished thermoplastic, which is mostly based on polypropylene that is processed using compression processes. The glass content depends on the requirements and is between 20 and 40 weight %. GMT components show a high impact resistance and stiffness with comparatively low weight. Molded parts made out of GMT are mostly used in the automobile industry for trim and carrier components in nonvisible areas. 

Glass mat-reinforced sheets are composed of thermoplastic polypropylene (polyamides, polycarbonate, and PVC are occasion options) with glass fibers 1 in. (25 mm) or more in length. A variety of fiber layer types are available such as directional, random, shorter, longer, mats, or weaves. When a natural fiber such as flax is used, the composite is... 

Mat and continuous glass fibre reinforcements theoretically all the thermoplastics are usable in these forms, but up to now developments have concentrated on polypropylenes (PP), polyamides (PA) and thermoplastic polyesters (PET) fibre-reinforced PEEK, polyetherimide (PEI) and polyphenylene sulfide (PPS) are used for high-performance applications. They are presented in a range of forms from stampable sheets to pellets, prepregs, ribbons, impregnated or coated continuous fibre rods. More rarely (as in the case of PA 12, for example), the thermoplastic is provided in liquid form. 

Parallel to thermosetting SMCs and BMCs are thermoplastic moulding compounds in sheet form, known as glass mat thermoplastics (GMTs), and compounded into standard granules for injection moulding and extrusion. Most thermoplastics are theoretically capable of such combination with reinforcement, but the main types used commercially at present are polyamide (PA) and polypropylene (PP). 

Thermoplastic resins are generally reinforced with short fibres (for use with injection moulding and not considered in this book), with long fibres (thermoplastic sheet compound, Chapter 5) or with glass mat (i.e. glass mat thermoplastics or GMT). Polypropylene is the resin most used as the matrix for GMT and the reinforcement is usually a random mat, primarily chopped strand but it may be continuous filament or needled mat. 

Polypropylene sheet has been used most extensively however, thermoplastic polyester, polycarbonate, and nylon versions are available (see Elastomers, synthetic Polycarbonates). Continuous strand glass fiber mat is the typical reinforcement. The limited number of sheet suppHers reduces potential for competitive pricing. 

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