Poly Sheet Extrusion

ISO 7823-3 2003 Plastics - Poly(methyl methacrylate) sheets - Types, dimensions and characteristics - Part 3 Continuous cast sheets ISO 8257-1 1998 Plastics - Poly(methyl methacrylate) (PMMA) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 8257-2 2001 Plastics - Poly(methyl methacrylate) (PMMA) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 12017 1995 Plastics - Poly(methyl methacrylate) double- and triple-skin sheets - Test methods... 

Polymethacrylates. Poly(methyl methacrylate) [9011-14-7] is a thermoplastic. It is the acrylic resin most used in building products, frequendy as a blend or copolymer with other materials to improve its properties. The monomer is polymerized either by bulk or suspension processes. For glazing material, its greatest use, only the bulk process is used. Sheets are prepared either by casting between glass plates or by extrusion of pellets through a slit die. This second method is less expensive and more commonly used. Peroxide or azo initiators are used for the polymerization (see Methacrylic POLYMERS). 

The methyl ester of methacrylic add (CH2=C(CH3)—COOH) is used to produce vinyl polymers used as cast sheets, molding and extrusion powders and coatings, besides being used in various copolymers. Poly(methyl methacrylate) production currently stands at over 2.8 million tons per year on a worldwide scale. 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acrylic sheet. PMMA is also used in molding and extrusion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acrylic latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic structure, acetone is found in the following major end use products acrylic sheet molding resins, impact modifiers and processing aids, acrylic film, ABS and polyester resin modifiers, surface coatings, acrylic lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see Methacrylic acid and derivatives Methacrylic polymers). 

Thermoplastic Foam Extrusion. Foamed plastics find applications as rigid profiles, pipe, sheet, packaging material, and thermal insulation. Polystyrene (PS) finds the widest application in foamed products while poly(vinyl chloride) PVC, low-density polyethylene (LDPE), and acrylonitrile-butadiene-styrene (ABS) (21) are also used in large quantities. All common thermoplastics can be foamed by various techniques as described hereafter. 

The most important member of the acrylic polymers is poly(methyl methacrylate). It is a hard, clear, colorless, transparent plastic that is usually available as molding and extrusion pellets, reactive syraps, cast sheets, rods, and tubes. 

Poly (methyl methacrylate) for molding or extrusion is produced commercially by fiee-radical-initiated suspension or bulk polymerization of methyl methacrylate. To minimize polymerization reaction exotherm and shrinkage, bulk polymerization, which is used in the production of sheets, rods and tubes, is carried out with a reactive syrup of partially polymerized methyl methacrylate, which has a viscosity... 

Biaxial orientation effects are important in the manufacture of films and sheet. Biaxially stretched polypropylene, poly(ethyleneterephthalate) (e.g., Melinex) and poly(vinylidene chloride) (Saran) produced by flat-film extrusion and tentering are strong films of high clarity. In biaxial orientation, molecules are randomly oriented in two dimensions just as fibers would be in a random mat the orientation-induced crystallization produces structures which do not interfere with the light waves. With polyethylene, biaxial orientation often can be achieved in blown-film extrusion. 

Multilayer co-extrusion is another technique used in the preparation of starch/ synthetic sheets or films [164, 263-266], in which TPS is laminated with appropriate biodegradable polymers to improve the mechanical, water-resistance and gas-barrier properties of final products. These products have shown potential for applications such as food packaging and disposable product manufacture. Three-layer co-extrusion is most often practiced, in which a co-extrusion line consists of two single-screw extruders (one for the inner starch layer and the other for the outer polymer layers) a feedblock a coat-hanger-type sheet die and a three-roll calendering system [164]. Biodegradable polyesters such as PCL [164, 264], PLA [164, 263], and polyesteramide, PBSA and poly(hydroxybutyrate-co-valerate) [164] are often used for the outer layers. These new blends and composites are extending the utilization of starch-based materials into new value-added products. 

Poly(methyl methacrylate) is a transparent thermoplastic material of moderate mechanical strength and outstanding outdoor weather resistance. It is available as sheet, tubes, and rods, which can be machined, bonded, and formed into a variety of different parts. It is also available in bead form, which can be conventionally processed via extrusion or injection molding. The sheet form material is polymerized in situ by casting a monomer that... 

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