Foams reinforced plastic

Elastomers are flexible. Plastics can provide flexible to rigid foams. Reinforced plastics or composites are plastics (polymers or resins) with reinforcing additives, such as fibers and whiskers, added, basically, to increase the product s mechanical properties. Throughout this book these terms are used precisely according to their respective areas of interest. 

Many cellular plastic products are available with different types of protective faces, including composite metal and plastic foils, fiber-reinforced plastic skins, and other coatings. These reduce but do not eliminate the rate of aging. For optimum performance, such membranes must be totally adhered to the foam, and other imperfections such as wrinkles, cuts, holes, and unprotected edges should be avoided because they all contribute to accelerated aging. 

Conventional machining operations are used preferably from the same plastic to be used in the product (Chapter 8, SECONDARY EQUIPMENT). Different casting techniques are used that provide low cost even though they are usually labor intensive. The casting of unfilled or filled/reinforced plastic used include TS polyurethane, epoxy, structural foam, and RTV silicone. Also used are die cast metals. 

Plastic also refers to a material that has a physical characteristic such as plasticity and toughness. The general term commodity plastic, engineering plastic, advanced plastic, advanced reinforced plastic, or advanced plastic composite is used to indicate different performance materials. These terms and others will be reviewed latter in this chapter. Plastics are made into specialty products that have developed into major markets. An example is plastic foams that can provide flexibility to rigidity as well as other desired properties (heat and electrical insulation, toughness, filtration, etc.). 

In order for such an extensive project to remain manageable, certain requirements were necessary. Initially the data were confined to TPs, TSs, TPEs, and casting plastics. To be included in this group were the TSEs, reinforced plastics, foams, semifinished products, and others. Polymat completed its initial work in 1989. New plastics products on the market and updated additional information on existing products are continually added. Data no longer available are still accessible to the user in a memory file. 

SCRIMP process This Seeman Composites Resin Infusion Process (SCRIMP) is described as a gas-assist resin transfer molding process. As an example glass fiber fabrics/ thermoset vinyl ester polyester plastic and polyurethane foam panels (for insulation) are placed in a segmented tool. A vacuum is pulled with a bag so that a huge amount of plastic can be drawn into the mold (Marco process approach). Its curved roof is made separately and bonded to the box with mechanical and adhesive fastening. It is similar to various reinforced plastics molding processes. 

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. 

Epoxy resins find a large number of uses because of their remarkable chemical resistance and good adhesion. Epoxy resins are excellent structural adhesives. When properly cured, epoxy resins can yield very tough materials. They are used in industrial floorings, foams, potting materials for electrical insulations, etc. One of the principal constituents in many of the Fibre-reinforced plastics (FRP) is an epoxy polymer. 

Inserts are often dedicated to specific plastic materials neat thermoplastics, neat and filled thermosets, reinforced plastics, composites, structural foams. .. 

Common uses for polyester resins are reinforced plastics automotive parts boat hulls foams encapsulation of electrical equipment protective coatings ducts flues and other structural applications low pressure laminates magnetic tapes piping bottles non-woven disposable filters and low-temperature mortars. 

The methods used to increase the water resistance of a glass microsphere foam are basically those applied to glass-reinforced plastics, filled thermoplasts, and elastomers, viz. hydrophobic adhesion compounds are added to binder and microsphere dressing 147). The compounds added are alkyl alkoxysilane derivatives, amino or epoxy alkoxysilanes for epoxy and phenolic resins, vinyl or methacryloxy alkoxysilanes for polyester resins. The dressing agents used are aminoethoxysilanes (y-aminopropyl-... 

Sheets of hard foam can be covered at both sides by a thin skin, e.g. by metal or glass-reinforced plastic, to form light and stiff sandwich panels, to be used as building panels. 

Chlorinated paraffins, which contain up to 60-70% chlorine, are low in cost and are used as secondary plasticizer in PVC wire and cable insulations. Perchlorobicyclopentadiene has little plasticizing action and is used in polyethylene. Some of the more expensive bromine-containing fire retardants which have been used in the ratio of 5 p.p.h. in polystyrene foam, may be reduced to 0.5 p.p.h. by adding synergists such as peroxides or nitroso compounds. The reaction-type retardants, such as chlorendic acid and anhydride, hydroxy-terminated phosphonated esters, and specific brominated aliphatic esters, are admixed to rigid and flexible polyurethane foams, reinforced polyesters, phenolics, and epoxy resins. 

Another important distinction is based on (1) filled and reinforced plastics, and (2) foams. (1) When any family of polymers is combined with particulate inorganic fillers, this produces major increase in density, modulus, dimensional stability, heat transfer, dielectric constant, and opacity, and frequently a decrease in cost. When the fillers are reinforcing fibers, they can further produce a great increase in strength, impact resistance, and dimensional stability. Thus, these properties may depend more upon the use of fillers and fibers, than upon the choice of the particular polymer in which they are used. 

In the last decade several novel types of gas-filled polymers appeared which belong to the second generation integral (structural) plastic foams syntactic foams reinforced polymer foams multilayer foams (foamed laminates), metallized plastic foams mineral and metallic foamed materials obtained on the basis of foamed polymers laminated constructions on the basis of foamed polymers and monolithic (unfoamed) plastics, metals, paper, leather, etc. 

Figure 17-2 Foamed borosilicate glass block and urethane asphalt adhesive/membrane over fiberglass reinforced plastic.

The most widely used applications reported in 1973 included rib structures in the fabrication of lightweight reinforced-plastic parts and as a core material in sandwich construction, bonded to metal, wood, or glass. Other applications are as reinforcements for aircraft-control surfaces, radome housings, fUler blocks under fuel cells, tank floats for indicating devices, and ribs, posts, and framing in houses and shelters. Due to its buoyancy characteristics cellulose acetate foam has been used in lifeboats, buoys, and other flotation devices (21). 

This particular manufacturer created a composite panel consisting of a glass-fiber reinforced plastic outer shell backed with a rigid polyurethane foam. The product looks like a cluster of hand split wood shakes. When installed, the panels interlock and look exactly like a shake shingle roof to the casual observer. These panels have been tested and qualify as a Class A built-up roof covering. In addition, they provide a much greater resistance to the transmission of heat than wood shake shingles. The panels are fast and easy to install and quite durable. 

Small houses (6x8 ft) are often built with 2-in thick walls filled foam inserted between reinforced plastic panels —similarly to modern refriger ators. The plastic material used should be non-flammable and non-toxic if is to be exposed to fire. In addition, the construction should withstand wih s of up to 200 km/h. 

Instan-set [Devdopment Assoc.] Polyurethane elastomer protective coating over fiberglass-reinforced plastics, metal, PS foam i ods., other substrates. 

---