Thermoplastic foam extrusion

Fogarty, L, Thermoplastic Foam Extrusion Screw with Circulation Chaimels, U. S. Patent 6,015,227 (2000)... 

Foams 2000 Second International Conference on Thermoplastic Foam. Conference proceedings. Parsippany, N.J., 24th-25th October 2000, p. 149-61 CHALLENGE TO THE PRODUCTION OF LOW DENSITY PROPYLENE FOAMS IN EXTRUSION Nagnib H E Park C B Toronto,University (SPE)... 

Throne JL (2004) Thermoplastic Foam Extrusion. Carl Hanser, Miinchen, p 63... 

Gendron, R. Daigneault, L. Rheology of Thermoplastic Foam Extrusion Process In Foam Extrusion Lee, S.-T., Ed. Technomic Pennsylvania, 2000 35-80. 

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. 

As an alternative to these materials the objective in this research will be to produce starch based resilient thermoplastic foams based totally on native potato starch. This is done in two steps the production of expandable thermoplastic starch beads by extrusion and foaming of the expandable beads after conditioning in a successive foaming step. The properties of these foams will be studied as a function of processing parameters and material composition. A further objective is to determine the ultimate properties of pure starch based foams. 

C.D Han, Analysis of the Performance of a Cooling Extruder in Thermoplastic Foam Extrusion, Conference Proceedings, 45 SPE ANTEC (1987)... 

Several rheological aspects of thermoplastic foam extrusion have been described as a phenomenological model of the flow in an extrusion die, growth and physical properties of thermoplastic material with respect to extrusion foaming. 

Throne JL. Thermoplastic foam extrusion an introduction. Cincinnati, OH Hanser Gardner Pubhcations, Inc 2004. 

Furthermore, extrusion allows the use of both chemical and physical blowing agents, which need specific treatments to be correctly handled. The most critical operations for producing thermoplastic foams by extrusion are summarized in the following. 

Throne JL. Thermoplastic foam extrusion, an introduction. Munchen, Cincinnati Hanser-Gardner... 

A review is presented of developments by Berstorff in machinery for the processing of thermoplastic elastomers, including co-rotating twin-screw extruders for continuous compounding and extrusion and coextrasion lines for the production of solid and foamed profiles. Reference is also made to the development by Berstorff and Advanced Elastomer Systems of a process for the extrusion of foamed profiles using water as blowing agent. 

Important are behaviors associated and interrelated with plastic materials (thermoplastics, thermosets, elastomers, reinforced plastics, etc.) and fabricating processes (extrusion, injection molding, blow molding, forming, foaming, reaction injection molding, etc.). They are presented so that the technical or non-technical reader can readily understand the interrelationships. 

Polystyrene (PS), a highly rigid and surface-hardened thermoplastic, is glass clear and almost colorless. Its typical slight yellow tinge is easy to compensate for by adding transparent blue colorants to adjust the color. Polystyrene softens between 80 and 100°C. It is processed between about 170 and 280°C, up to a maximum of 300°C, without color change, by any of the methods which are recommended for thermoplastics. The list of products includes extrusion made sheets, profiles, and films, which are often foamed. 

An interesting development initiated by Neste and Norsk Hydro is a multilayer coating for the insulation of deep-water pipelines. The steel pipe is protected by a layer of solid thermoplastic, a core of polypropylene foam and a coating of solid plastic, all of which are built up by cross head extrusion. 

Theres a lot of competition between PS and the other five big thermoplastics LDPE, LLDPE, HDPE, PP, and PVC. Polystyrene continues to lose marker share, but it seems to have a permanent place in some applications, particularly molded foams (for carryout food containers), some extrusions, and sheet and film applications. About half the polystyrene ends up in packaging, 17% in electrical/electronics applications, 13% in construction, building products and furniture, and 7% in medical applications. 

Brookfield, Ct., SPE, 2002, Paper 353, Session T25-Applied Rheology, Extrusion I, Thermoplastic Materials and Foams. Interactive Presentations, pp.5, CD-ROM, 012... 

Orlando, FI., 7th-llth May, 2000, paper 49 EXTRUSION OF CLOSED CELL VERY LOW DENSITY FLEXIBLE SYNTACTIC FOAMS USING METALLOCENE CATALYZED POLYOLEFINS AND THERMOPLASTIC MICROBALLOONS Trainer L J Beauregard D Orroth S Schott N Massachusetts,University (SPE)... 

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