Expanded polystyrene beads

Other Plastics Uses. The plasticizer range alcohols have a number of other uses in plastics hexanol and 2-ethylhexanol are used as part of the catalyst system in the polymerization of acrylates, ethylene, and propylene (55) the peroxydicarbonate of 2-ethylhexanol is utilized as a polymerization initiator for vinyl chloride various trialkyl phosphites find usage as heat and light stabHizers for plastics organotin derivatives are used as heat stabHizers for PVC octanol improves the compatibHity of calcium carbonate filler in various plastics 2-ethylhexanol is used to make expanded polystyrene beads (56) and acrylate esters serve as pressure sensitive adhesives. 

Economics. Rigid foam systems are typically in the range of 32 kg/m (2 Ibs/fT) and, in 1992, had a foam price of about 3.63/kg ( 1.65 per lb) with hquid foam systems at about 2.75/kg. Unit prices for pour-ia-place polyurethane packaging systems fall between the competitive expandable polystyrene bead foam at 3.30/kg and low density polyethylene foams at 5.80/kg. 

Expanded polystyrene bead mol ding products account for the largest portion of the drinking cup market and are used in fabricating a variety of other products including packaging materials, iasulation board, and ice chests. The iasulation value, the moisture resistance, and physical properties are inferior to extmded boardstock, but the material cost is much less. 

Roofiag panels have been made from polyisocyanurate foams, both foam- and felt-reiaforced with glass fiber. PhenoHc resias are used especially for decorative laminates for paneling. The substrate may be fiberboard or a core of expanded polystyrene beads. In one case the beads are coated with phenoHc resia, then expanded ia a mold to form a stmctural foam panel. 

The approximately round shape and small size of the suspension beads is useful for some applications such as expandable polystyrene or as an intermediate for further compounding with pigments, other polystyrene beads, etc. Being round, however, they tend to roll, not only causing a safety hazard when spilled on floors but more importantly causing difficulties in some fabricating extruders and molding machines. Except for expandable polystyrene, beads are seldom sold as such but are extruded into pellets. 

Suspension Polymerization. Water is the suspending phase. Inorganic salts and vigorous agitation prevent coalescence and agglomeration. The reaction mode is batch. The largest use of suspension polymerization is for the manufacture of expandable polystyrene beads. 

Figure 4.35 Thermal conductivity of expanded polystyrene beads as a function of density. Reprinted, by permission, from The Dow Chemical Company. Copyright 1966.

While unaffected by water, styrofoam is dissolved by many organic solvents and is unsuitable for high-temperature applications because its heat-distortion temperature is around 77°C. Molded styrofoam objects are produced commercially from expandable polystyrene beads, but this process does not appear attractive for laboratory applications because polyurethane foams are much easier to foam in place. However, extruded polystyrene foam is available in slabs and boards which may be sawed, carved, or sanded into desired shapes and may be cemented. It is generally undesirable to join expanded polystyrene parts with cements that contain solvents which will dissolve the plastic and thus cause collapse of the cellular structure. This excludes from use a large number of cements which contain volatile aromatic hydrocarbons, ketones, or esters. Some suitable cements are room-temperature-vulcanizing silicone rubber (see below) and solvent-free epoxy cements. When a strong bond is not necessary, polyvinyl-acetate emulsion (Elmer s Glue-All) will work. 

Foam molding operations are those in which a liquid mixture of foam components is used. It is poured into a mold cavity to form a cellular shaped product. The molded product is later removed after setting or curing. As reviewed in the case of expandable polystyrene beads the preexpanded or virgin beads are poured into a mold and heated to form the desired object. In this case, liquids are not used, although the free-flowing beads might be considered a fluid. 

Low-density polystyrene foam sheet was first produced by the extrusion of expandable polystyrene beads or pellets containing pentane as blowing agent [81,82]. Currently, polystyrene foam is extruded in a single-screw tandem line or in a twin-screw extruder. 

In unconfined pre-expansion the translucent beads grow larger and become white in color. Confined and subjected to heat, the preexpanded beads can produce a smooth-skinned closed-cell foam of controlled density, registering every detail of an intricate mold. To minimize formation of a density gradient and to ensure uniform expansion throughout the molded piece, expandable-polystyrene beads are preexpanded to the approximate required density by control of time and temperature, since the process of molding does not increase the density (6). 

Expansion of anall beads of a thermoplastic resin by heating an internally controlled blowing agent, such as pentane. This technique is used to expand polystyrene beads used in making plastic cups, packaging, and mannequin heads. 

Light bricks are manufactured almost exclusively by the incorporation of expanded polystyrene beads and/or sawdust. 

Expandable polystyrene beads 3 0.1 Single-stage flash... 

Includes prime, off-grade, export, and polymer used for Styrofoam brand plastic foam as well as expandable polystyrene beads plus miscellaneous end uses. 

Major applications for styrene plastics are summarized in Table III (23). The packaging and serviceware (disposables) markets predominate, and account for approximately 50% of the total. One of the most rapidly growing portions of these markets is in low-density (usually 1-10 Ib/ft ) polystyrene foams, either in the form of extruded foam sheet or expanded polystyrene beads (EPS). Projections indicate that production of these foams will be greater than 2000 metric tons (24). 

Tegotens. [Goldschmidt AG] Solubilizers, emulsifers, wetting agents, antistat, surface coating for expanded polystyrene beads containing a ixr Uant... 

Polymeric Beads, Expandable Polystyrene Beads, Expandable Plastics Moulding Compound A moulding material in bead or granular form consisting predominantly of polystyrene, poly(methyl methacrylate) or other polymeric material and containing 5% to 8% of a volatile hydrocarbon which is predominantly pentane. During storage a small proportion of this pentane is released to the atmosphere this proportion increases at elevated temperatures. IMO 9036... 

The expandable polystyrene beads may be used in a tabular blow-extrusion process (Figure 2.59) to produce polystyrene foam sheet, which can subsequently be formed into containers, such as egg cartons and cold-drink cups, by thermoforming techniques. 

Expandable polystyrene beads are often molded in two separate steps (1) Preexpansion or prefoaming of the expandable beads by heat, and (2) further expansion and fusion of the preexpanded beads by heat in the enclosed space of a shaping mold. 

What is the optimum density of expanded polystyrene beads (EPS) for the helmet ... 

B. Chen, J. Liu Mechanical properties of polymer-modified concretes containing expanded polystyrene beads. Construction and Building Materials 21, (2007), p. 7-11. 

Expanded polystyrene beads rated B1 according to DIN 4102 contain this agent in almost every instance. . 

Flame-retardance of expanded polystyrene beads can be brought about by the application of the additive (e.g. pentabromophenyl allyl ether), dispersed in fine quartz flour, to the surface of beads before expansion. For the flame-retardance of extruded foam sheets, the agent should be admixed with the polystyrene granules. 

Koseki H. 1982, Warehouse Fire atYokkaichi City, Shoubou Shuuhou, No.36, 25-29p, 1982 Fire and Disaster Management Agency 1982, Fite Safety Countermeasures for Expandable Polystyrene Beads, etc., Notification, Dec. 14, 1982... 

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