Sheet extruded

Extruded sheet is cheaper than cast sheet but because there is some residual molecular orientation, is somewhat less satisfactory optically and more difficult to machine. On the other hand, no doubt a function of its lower molecular weight, it may be thermoformed more easily. 

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. 

Processes basically go through the following stages (1) starts with an extruded sheet,... 

Rubber toughened polystyrene is widely used in electronic and kitchen appliances. This type of application requires a good balance of stiffness, impact resistance, and ready coloration. Telephones, which are frequently dropped, are an excellent example of the benefits of rubber toughened polystyrene. The high surface gloss that we desire is obtained by minimizing the size of the rubber particles. Larger items, such as canoes, can be thermoformed from extruded sheet. 

A manufacturer of extruded plastic sheeting had been experiencing problems with small contaminants appearing in their polypropylene-polyethylene (PP-PE) extruded sheets. The source of this contamination needed to be determined in order to overcome the problem. Several sheets containing particles were submitted for investigation, as well as some isolated particles taken from an extruder breaker plate. 

Pigment powders continue to be used in thick-walled articles, such as extruded sheets, or hollow objects, or in injection-molded products although color concentrates are beginning to be more important even in these areas. 

A well-established application for extruded unreinforced PCT (copolymerized with isophthalate) is crystallized, thermoformed trays for foods. Crystallized PET is widely used for this application, but where higher-temperature performance is needed the PCT-based polymer may be chosen. Such trays are formed from extruded sheet, using a hot mold to promote crystallization. Isophthalate-modified PCT polymers are approved by the Food and Drug Administration for high-temperature food contact use. 

Figure 7.9 Point-of-purchase displays fabricated from Eastman Spectar copolyester extruded sheet. Photograph provided by courtesy of Eastman Chemical Company...

Cast and extruded sheets, cell-cast sheets, stretched sheets, films down to 50 microns laminated protective surfaces on ABS, PVC or other plastic sheets that are thermo-formed into parts requiring resistance to outdoor weathering for residential siding and transformer housings... 

Cast and extruded sheets, cell-cast sheets for greenhouses... 

ISO 14631 1999 Extruded sheets of impact-modified polystyrene (PS-I) - Requirements and test methods... 

ISO 14236 2000 Plastics pipes and fittings - Mechanical-joint compression fittings for use with polyethylene pressure pipes in water supply systems ISO 14616 1997 Plastics - Heatshrinkable films of polyethylene, ethylene copolymers and their mixtures - Determination of shrinkage stress and contraction stress ISO 14632 1998 Extruded sheets of polyethylene (PE-HD) - Requirements and test methods... 

ISO 15013 1998 Extruded sheets of polypropylene (PP) - Requirements and test methods ISO 15494 2003 Plastics piping systems for industrial applications - Polybutene (PB), polyethylene (PE) and polypropylene (PP) - Specifications for components and the system -Metric series... 

ISO 2897-1 1997 Plastics - Impact-resistant polystyrene (PS-I) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 2897-2 2003 Plastics - Impact-resistant polystyrene (PS-I) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 14631 1999 Extruded sheets of impact-modified polystyrene (PS-I) - Requirements and test methods... 

ISO 7823-2 2003 Plastics - Poly(methyl methacrylate) sheets - Types, dimensions and characteristics - Part 2 Extruded sheets... 

Films, extruded sheets and plates, thin-gauge extruded tubes. .. 

Methyl methacrylate is polymerized to poly(methyl methacrylate), which is used in cast and extruded sheet (32%), surface coatings (24%), molding powder and resins (15%), impact modifiers (13%), and emulsion polymers... 

After shaping, the articles are most often subjected to a step to remove the processing oil or solvent from the gel. An extraction, washing, or leaching step is introduced in order to remove the processing oil and the lubricant (36). In formulations with filler, the extruded sheets are preferably subjected to an extraction step to remove processing oil. 

After extraction, these sheets may have about 10-20% of residual oil. It is impossible to remove all of the processing oil and lubricant from any of the mixtures, so at least a trace amount will remain in the final sheets. In formulations without fillers, the extruded sheets are preferably subjected to an extraction step. After extraction, these sheets may have only residual amounts of oil and lubricant. 

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