Polypropylene Thermoforming

Sheet Extrusion and Thermoforming. Sheet for thermoforming and analogous operations is usually formed by extmding the melt through a slot die onto a set of poHshed chill roUs. The sheet is usually approximately 150 cm wide. After rapid cooling, the web is coiled or cut into sheets. Polystyrene, PVC, polyethylene, polypropylene, and filled polypropylene are prepared in sheet form by extmsion. 

Thermoform able sheet may be mono- or multilayer with the latter produced by lamination or coextmsion. Multilayers are employed to incorporate high oxygen-barrier materials between stmctural or high water-vapor barrier plastics. Both ethylene vinyl alcohol copolymers and poly(vinyhdene chloride) (less often) are used as high oxygen-barrier interior layers with polystyrene or polypropylene as the stmctural layers, and polyolefin on the exterior for sealing. 

Thermoforming and Extrusion. Improved equipment and polymers have increased the capabiUty to extmde and thermoform polypropylene however, consumption of polypropylene in these areas has not grown dramatically. Drinking straws are commonly extmded from polypropylene, however most larger diameter tubes, such as pipes and conduits, are predominantly extmded from other thermoplastics. Extmded sheet is thermoformed into food containers and trays polypropylene is used when microwavabiUty is desired. 

In recent years general purpose polystyrene and high-impact polystyrenes have had to face intensive competition from other materials, particularly polypropylene, which has been available in recent years at what may best be described as an abnormally low price. Whilst polystyrene has lost some of it markets it has generally enjoyed increasing consumption and the more pessimistic predictions of a decline have as yet failed to materialise. Today about 75% of these materials are injection moulded whilst the rest is extruded and/or thermoformed. 

Polypropylene can be extruded into sheets and thermoformed by solid-phase pressure forming into thin-walled containers. Due to its light weight and toughness, polypropylene and its copolymers are extensively used in automobile parts. 

Plastic films represent the largest worldwide market for plastics with practically all extruded (6). They are used to meet different performance requirements particularly for its major packaging market. Worldwide just for biaxial oriented (Chapter 8) polypropylene consumption is about 5 /2 billion lb. Their use includes tape, food, tobacco, and confectionery. Thermoforming film (and extruded sheets) is a major processing technique producing all kinds of products. 

An increasing variety of automotive parts is being made by thermoforming processes. Many of these products are made from rubber-toughened polypropylene, which are relatively stiff and can withstand a high level of physical abuse over a ivide range of temperatures. When such parts are used in high visibility areas, such as wheel arches, air dams, truck fenders, and... 

Towflex (Hexcel Composites) is based on carbon, glass or aramid fibres impregnated with polypropylene, polyamide, PPS, polyetherimide, PEEK. Product forms include flexible Towpreg, woven fabric, braided sleeving, UD tape, chopped compression moulding compound, moulded plates, thermoformable laminates. 

Chicago, II., 29th Aug-2nd Sept.l993,p.403-6. 6A MULTILAYER EXTRUSION DIE GEOMETRY FOR THERMOFORMED POLYPROPYLENE FOAM SHEETS AND BIAXIALLY ORIENTED FOAM FILMS Raukola J Savolainen A Tampere,University of Technology (TAPPI)... 

Patent Number US 5286428 A 19940215 POLYPROPYLENE RESIN FOAMED SHEET FOR THERMOFORMING AND PROCESS FOR PRODUCING THE SAME... 

Polypropylene Resin Injection Molding Fiber Extrusion Sheet Forming Thermoforming... 

Many thermoplastics can be thermoformed, including polystyrene, polypropylene, APET, CPET, and PVC. EVOH is commonly incorporated into a co-extrusion for its superior barrier properties in food. Co-extrusions of these materials are commonly used to provide precise properties for specific applications. 

Autobar has worked with Italian supermarket chain, Iper, on the manufacture of PLA thermoformed trays and containers for fresh foods in place of polypropylene. The packaging consists of 12 sizes, categorised as small , medium , large and maxi , that offer a range of dimensions. 

By using NatureWorks PLA instead of polypropylene, Autobar was able to reduce the wall thickness of the containers, from 460 microns down to 330 microns. The downgauging allows Autobar to use less material, which helps reduce the production costs, without compromising the quality of the thermoformed container. 

Products A wide range of polypropylene products (homopolymer, random copolymer and impact copolymer) can be produced to serve many applications, including injection molding, blow molding, thermoforming, film, extrusion, sheet and fiber. Impact copolymer produced using this process exhibits a superior balance of stiffness and impact resistance over a broad temperature range. 

Petrothene [Quantum]. TM for polypropylene resins for blown, cast, and water-quenched films, substrate coating, wire and cable coating, injection molding, blow molding, thermoforming, pipe extrusion, calendering. 

Talc is always an attractive subject of such studies due to its platelet structure. In thermoforming and compression molding processes of three resins (PP, HDPE, and PPS), each containing 20% talc, the talc particles were always parallel to the specimen surface, regardless of the resin used. Crystallites grew in a direction normal to the surface of talc particles and thus were perpendicular to the specimen surface. But in the case of unfilled HDPE, crystallites grew parallel to the specimen surface. There was no difference in crystallite growth direction in the case of polypropylene with and without talc. 

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