Rigid PVC foams

The Kleber-Colombes rigid PVC foam (253,254) is produced by compression mol ding vinyl plastisol to react and gel the compound, followed by steam expansion. The process involves mixing, mol ding, and expansion. The formulation consists of PVC, isocyanate, vinyl monomers such as styrene, anhydrides such as maleic anhydride, polymerization initiators, FC-11, and nucleators. The ingredients are mixed in a Wemer-Pfleiderer or a Baker Perkins... 

Statistical experimental design was used to study the effects of blowing agents, processing aids and fdlers in rigid PVC foam formulations. This technique provided an alternative approach to the classical experimental method of changing one variable at a time. It provided information about interactions between variables and could be used to help to predict an optimum formulation. 24 refs. 

Journal of Vinyl and Additive Technology 3, No.3, Sept. 1997, p.210-5 EFFECT OF EXTRUSION CONDITIONS ON RIGID PVC FOAM... 

Results are presented of an investigation of the effect of extrusion conditions, such as melt temp., screw speed and draw-down, on process morphology of rigid PVC foams and the properties of the extruded profile, including density, cell structure and surface appearance. The optimum conditions for the best quality profile found in this study were 190 to 196C melt temp, and no greater than 20 rpm screw speed on a 63.5 mm single screw. 15 refs. 

Polyvinyl Chloride (PVQ Foams. Rigid PVC foam is inherently fire retardant because of the high chlorine content (56.7%). Flexible PVC foams present increased fire hazards because of the plasticizers they contain. Flammable plasticizers used include alkyl phthalates, as dioctyl phthalate. Non-burning types include alkyl aryl phosphates (phosphate esters). The latter types should improve resistance to ignition and reduce flame spread when compared to the usual phthalate plasticizers (38) (41). 

A number of methods have been devised for producing cellular products from PVC, either by a mechanical blowing process or by one of several chemical blowing techniques. PVC foams are produced in rigid or flexible forms. The greatest interest in rigid PVC foam is in applications where low-flammability requirements prevail. It has an almost completely closed cell structure and therefore low water absorption. The rigid PVC foam is used as the cellular layer of some sandwich and multi-layer panels. 

Rigid PVC foam. Pata from Decker, R. W.,J. Vinyl Additive Technol, 2,2,121-124,1996.]... 

Uses Filler, mar resist, aid, gloss aid for paints containing soivs., povird. coatings filler for plastics (rigid PVC extrusion, rigid PVC foam extrusion, plasticized PVC, cables, calendered sheet, profiles, moldings, PE/ XPE), rubber, plastics... 

The complete cab consists of a shell, floor, and bulkhead together with various other fittings such as valence panels, doors, windows, desk, seats, and instrument console. The shell and bulkhead are constructed from GRP skins with polyurethane (PU) foam core, the floor consists of GRP skinned rigid PVC foam, and the other fittings are straightforward GRP laminates. 

Whereas the cab shell and bulkhead consisted of outer and inner GRP skins having PU foam cores, the floor had a rigid PVC foam core instead of PU foam. Rigid PVC foam was chosen for the floor section because of its superior strength properties. Slabstock PVC foam was used. 

Typical Use Metal, concrete, asbestos-based, ceramics, wood, plastic laminates, rigid-PVC, foam materials. ... 

PO foams, in contrast to PS or rigid PVC foams, are considered multiimpact materials. This means that the foams can be used for more than one impact. The modulus, collapse stress, and cushioning properties of CPOF changes after preloading. Increase in the amount of strain increases the loss in mechanical properties. The greater the foam stiffness, the larger the reduction in properties. [70,71]. 

Figure 7.42 shows a schematic diagram of an inground liquid nitrogen tank constructed at Hiratsuka, Japan. The successive tank layers going from the inside to the outside of the tank include a stainless steel membrane, plywood panels, rigid PVC foam insulation, plywood, and a concrete outer... 

Other Extruded Rigid PVC Products Rigid PVC Foam... 

However, higher-molecular-weight resins tend to yield compounds with better physical properties. Many rigid PVC foam profiles are nailed or mechanically fastened to another part or surface. Properly fused resins with T-values 65 or higher are sometimes used in these applications because they are less likely to split or incur damage when nailed, cut, or mechanically fastened than the lower-molecular-weight resins typically used in foam applications. ... 

N.H. Abu-Zahra, Neural Network Approach to Density Control of Rigid PVC Foam in Extrusion Process. International Polymer Processing, 18, (122) (2003). 

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