Expandable beads

ANTTBIOTTCS - BETA-LACTAMS - PENICILLINS AND OTTiERS] (Vol 3) Expanded bead molding... 

There are five basic types of polystyrene foams produced in a wide range of densities and employed in a wide variety of apphcations (/) extmded polystyrene board (2) extmded polystyrene sheet (2) expanded bead mol ding (4) injection molded stmctural foam and (5) expanded polystyrene loose-fiU packaging. 

Thermal Insulation. Foamed plastics (qv) are used as thermal insulation for aU types of constmction because of their low heat- and moisture-transmission values. Polystyrene is used either as foamed board or expandable beads. The foam may be faced with a stmctural surfacing material, eg, a kraft liner-board, to form a panel for insulating mobile homes. These foams can dupHcate the appearance of wood and be used as trim. Foams can also be used as backing, for example, on aluminum siding, to provide heat and sound insulation. Foamed beads can be incorporated in concrete to reduce its density and provide some thermal insulation. 

Foamed polystyrene - which is also known as expanded polystyrene - is used extensively in a variety of applications, ranging from packaging peanuts to insulation board and single-use cups and plates. We produce it by two processes foam extrusion and bead expansion. Both types of expanded polystyrene consist of closed cells, i.e., bubbles with continuous walls. We can visually distinguish the two types of foam by the fact that products made by the expanded bead process consist of discrete beads that are welded together... 

The expanded polystyrene can be made by impregnating small porous beads of the polymer with pentane and heating in steam. The volume increases many a times. Expanded beads are kept in warm air for 24-36 hours and moulded with steam into blocks. 

Raising of ships by filling with pre-expanded beads. 

The moulding of expandable beads is commonly used for EPS packaging by some manufacturers. 

Final moulding the pre-expanded beads are poured into a mould fitted into a press, are reheated with steam and expand to take the shape of the mould. According to the mould shape, the final product can be a finished part or large blocks. Blocks can be cut into panels, boards, etc. 

Patent Number US 6077875 A1 20000620 FOAMED AND EXPANDED BEADS OF POLYPROPYLENE RESIN FOR MOLDING... 

Patent Number EP 963827 A2 19991215 MOULDED ARTICLE OF FOAMED AND EXPANDED BEADS OF PROPYLENE RESIN... 

Expandable beads made in water suspensions must be dried at relatively low temperatures (e.g., 50°-60°C. maximum) to avoid excessive evaporation of n-pentane (b.p., 36°C.). The loss of n-pentane in one hour is related to temperature and n-pentane content of the beads as shown in Table I (63). 

Table I. Loss of a-Pentane in 1 Hour from Expandable Beads at Varying Temperature...

To reduce pentane losses in shipping, expandable beads are ordinarily transported in 50-gallon drums constructed from fiberboard with an inner liner of aluminum foil. In these containers the beads meet most expansion requirements for a few months, depending on storage conditions. When expandable beads (screened through a 10-mesh sieve and retained on a 25-mesh sieve) were exposed in open containers at 23°C., their n-pentane content decreased from 7.0 to 6.0% in 6-7 days. 

Tihis chapter describes the manufacture of expandable beads in the copolymer 1-butene-sulfur dioxide by suspension polymerization. The processing and properties of expandable beads and of molded articles are examined briefly. 

Suspension copolymerization of 1-butene and sulfur dioxide can lead to expandable beads. The cellular material obtained has improved properties with respect to expanded polystyrene. The manufacture of expandable beads by suspension copolymerization is covered by a patent... 

Degussa AG Polystyrene, expandable beads Styrene Expanding agent is fed into the reactor during batch-polymerization 2 1990... 

A low concentration of branched macromolecules should result in a higher melt flow rate during the pre-foaming step of the expandable beads [12,13]. In the literature, the procedure of earlier addition of blowing agent is described to reduce the viscosity of the droplets. Hamielec and co-workers [16] pointed to the fact that temperature increase and, simultaneously, earlier addition of... 

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