Extruded foams

Foams 2000 Second International Conference on Thermoplastic Foam. Conference proceedings. Parsippany, N.J., 24th-25th October 2000, p. 139-48 USING POLYMER CHARACTERISATION TECHNIQUES TO PREDICT LDPE RESIN SUITABILITY FOR EXTRUDED FOAM APPLICATIONS Anger J Ngnyen L Nova Chemicals Corp. 

Patent Number US 6066393 A1 20000523 POLYOLEFIN/IONOMER BLEND FOR IMPROVED PROPERTIES IN EXTRUDED FOAM PRODUCTS... 

New York City, 2nd-6th May 1999, p.2084-9. 012 STUDY OF SURROUNDING TEMPERATURE EFFECTS ON EXTRUDED FOAM STRUCTURE Lee S T Lee K Sealed Air Corp. 

Atlanta, Ga., 26th-30th April 1998, p.3527-32. 012 SHEAR AND PRESSURE EFFECTS ON EXTRUDED FOAM NUCLEATION Lee S-T Kim Y Sealed Air Corp. 

Journal of Applied Polymer Science 68, No.8, 23rd May 1998, p.1237-44 EFFECT OF ADDITION OF EVA ON THE TECHNICAL PROPERTIES OF EXTRUDED FOAM PROFILES OF LOW-DENSITY POLYETHYLENE/EVA BLENDS Rodriguez-Perez M A Duijsens A de Saja J A Valladolid,Universidad Sekisui Alveo BV... 

PP bead foams of a range of densities were compressed using impact and creep loading in an Instron test machine. The stress-strain curves were analysed to determine the effective cell gas pressure as a function of time under load. Creep was controlled by the polymer linear viscoelastic response if the applied stress was low but, at stresses above the foam yield stress, the creep was more rapid until compressed cell gas took the majority of the load. Air was lost from the cells by diffusion through the cell faces, this creep mechanism being more rapid than in extruded foams, because of the small bead size and the open channels at the bead bonndaries. The foam permeability to air conld be related to the PP permeability and the foam density. 15 refs. 

Patent Number US 5276064 A 19940104 COLOURED EXTRUDED FOAM CROSS-LINKED BACKER ROD... 

This certificate relates to Climatube extruded foam PE pipe insulation. It is used in the thermal insulation of water supply pipes and heating pipework. The insulation is semisplit for ease of fitting, and polychloroprene adhesive and climatape adhesive tape are supplied for sealing cut ends and joints. Thermal conductivity data are tabulated. EUROPEAN COMMUNITY UK WESTERN EUROPE... 

Polyarylates are injection molded, using standard screw machines, as well as extruded, foam molded, and blow molded. Melt temperatures range from 600 to 680°F (316 to 360°C). Mold temperatures should he maintained between 200 and 300°F (93 and 149°C). 

Packaging applications are the most extensive. Meat, poultry, and egg containers arc thermoformed from extruded foamed polystyrene sheet. The fast-food market also accounts for a substantial amount of polystyrene for takeout containers where the insulation value of a foamed container is an advantage. Containers, tubs, and trays formed from extruded impact polystyrene sheets are used for packaging a large variety of food. Biaxially oriented polystyrene film is thermoformed into blister packs, meat trays, container lids, and cookie, candy, pastiy, and other food packages where clarity is required. 

In an effort to make homes and other buildings more energy efficient, the use of polystyrenes in extruded foam board with flame-retardant additives for walls and under slabs has experienced exceptional growth in recent years. Used as a sheeting material, extruded foam board complies with the requirements of the major building codes as well as federal and military spedfiea lions,... 

Foamed plastics (qv) were developed in Europe and the United States in the mid-to-late 1930s. In the mid-1940s, extruded foamed polystyrene (XEPS) was produced commercially, followed by polyurethanes and expanded (molded) polystyrene (EPS) which were manufactured from beads (1,2). In response to the requirement for more fire-resistant cellular plastics, polyisocyanurate foams and modified urethanes containing additives were developed in the late 1960s urea—formaldehyde, phenolic, and other foams were also used in Europe at this time. 

Another possibility is to extrude foam into sheets the pressure within the extruder prevents foam formation only after leaving the die the pentane evaporates to form the foam. In most cases the extrusion process is carried out with normal PS granules in the cylinder pentane or another blowing agent is injected, where it mixes into the polymer and brings about foam formation after leaving the die. 

Certain grades of ETFE are used for extruded foams with void contents from 20 to 50%. The closed foam cells are 0.001 to 0.003 in. (0.02 to 0.08 mm) in diameter. Special grades of ETFE processed in gas-injection foaming process may have void contents up to 70%. Foamed ETFE is used in electrical applications, mainly in cables, because it exhibits lower apparent dielectric constant and dissipation factor and reduces cable weight. 

Two principal PS foams that are fabricated are extruded foam and expanded for molded foams. PS foams are light, closed-cell foams with low thermal conductivities and excellent water resistance. They provide for low-temperature insulation and buoyancy media. The extruded PS foam is fabricated as billets and boards. They are made by extruding molten PS containing a blowing agent, under elevated temperature and pressure, into the atmosphere, where the mass expands. Billets and boards can be used directly or can be cut into many different forms.254... 

Figure 8.1 Example of tandem extruder foam sheet line (courtesy of Battenfeld Gloucester)...

The use of the particular product may dictate an optimum molecular weight distribution. If the product is used to make an extruded foam, a relatively narrow distribution may be desirable to retain orientation and strength in the... 

Very few studies have been performed investigating the effect of branching on the extensional rheological properties of polystyrenes. Such investigations can be valuable because many of the fabrication operations associated with commercial applications of polystyrene include operations in which the polystyrene melt undergoes an extensional deformation. Some examples are extruded foam sheet, blown film, oriented (tentered) sheet, and thermoforming. The types of deformations associated with these processing operations are best described as... 

These films seldom lasted more than 5-20 seconds. The dramatic difference in behavior of the two polymers in the above test undoubtedly helps to explain their considerable difference in ability to stabilize an extruded foam. This is obviously due to hydrophobic groups in the new polymer. 

Polystyrene (PS) is another resin widely used in food packaging and other cushion packaging applications. These include extruded foam sheets such as meat trays. 

Fire-Protective Coating for Extruded Foam Polystyrene... 

---