Integral foam

Intalox saddle Integral foam Integrated circuits... 

Not only are these reactions of importance in the development of the cross-linked polyurethane networks which are involved in the manufacture of most polyurethane products but many are now also being used to produce modified isocycuiates. For example, modified TDI types containing allophanate, urethane and urea groups are now being used in flexible foam manufacture. For flexible integral foams and for reaction injection moulding, modified MDIs and carbodi-imide MDI modifications cU"e employed. 

THERMAL STABILITY OF THIN-WALLED INTEGRAL FOAM PRODUCTS... 

A study was made of the effect of density of injection moulded, thin-walled, integral foam products made of propylene copolymers, containing 20% PE, on their low-temperature properties. Results are discussed and evaluated. 5 refs. 

Structural foam (or integral foam) is a foam where the walls are solid. Advantages ... 

During synthesis of a polymer, particularly of polyurethane, gaseous products can appear. Therefore, a complete model of the process must take into account (at least in some cases) the possibility of local evaporation and condensation of a solvent or other low-molecular-weight products. Such a complex model is discussed for chemical processing of polyurethane that results in formation of integral foams in a stationary mold.50 In essence, the model is an analysis of the effects of temperature in a closed cell containing a solvent and a monomer. An increase in temperature leads to an increase in pressure which influences the boiling temperature of the solvent and results in an increase in cell volume. The kinetics of polymerization is described by a simple second-order equation. The... 

Figure 3.72 [27] presents the various types of foams and their corresponding characteristic density distributions. In integral foam, the unfoamed skin surrounds the foamed inner core. This type of foam can be produced by injection molding and extrusion and it replaces the sandwiched structure also shown in Fig. 3.72. 

Foams can be made from thermoplastics, thermosets and rubbers. Densities can be obtained from nearly solid down to 200 times diluted. Structural (or integral) foams have a solid skin. The best known foam materials are polystyrene foam, polyurethane foam and polyether foam. 

It is noteworthy that the development of the technology of second-generation foams (early 1960 s) followed this direction. For example, various methods for preparing integral foams were conceived and realized as methods of direct preparation (in one cycle only) of high-precision fini ed products ... 

The glass transition temperature lies considerably above the temperature of use with rigid foams and considerably below the temperature of use with flexible foams. The cellular structure may be open, closed, or mixed. All cells are open to each other with open cellular structures. In contrast, each cell is sealed off or encapsulated from the other cells by a plastic wall in closed-cell structures. Structural foams are foams with a dense outer skin and an interior of lower density they are also called integral foams or self-skinning foams. In contrast to normal foams syntactic foams do not directly enclose the gas but contain small hollow bodies of glass, ceramics, or plastics which are under vacuum or are filled with a gas. 

Many open cell foams such as PU, PIR, PS and integral foams based on polyphenylene oxide are used in construction for acoustic insulation [61-63]. UF and PF foam are used for interior soimd absorbing floors [31]. 

The term structural foam has been defined as flexible or rigid foams produced at greater than about 320 kg/m density having holes in a foamed core rather than a typical lower density structure of pentagonal dodecahedron type (21). Integral foams are also structural foams having a foamed core that gradually decreases in void content to solid skins (22). 

Molding. The reaction mixture can be discharged into a mold to flow out and fill the cavity. High density (about 320 kg/m or 20 Ib/ft ) moldings can be used for decorative furniture items such as drawer fronts or clock frames. The formulation can be adjusted to produce integral foams. 

Of the BTMs skin grafted at Day 11 (four subjects), delayed skin grafts took completely in two pigs, and failed completely in one. Although one other graft failed, enough viable keratinocytes had seeded the integrated foam to then proliferate to reepithelialization. 

Lotus, producers of composite cars since 1957, took a big step forward in 1974 with its new Elite (see Fig. 5.2). This was manufactured by the new VARI process (Vacuum Assisted Resin Injection), in which the two halves of the body are moulded in matched tools, and subsequently bonded together (see Fig. 5.3). The only chassis is a backbone top-hat section in steel otherwise the stability of the body is ensured by integral foam beams (see Fig. 5.4). These foam beams are used to locate and support uni-directional glass rovings, before the polyester resin is injected. The result is an extremely strong body, of which the present Esprit is the latest example. The Lotus system is extremely effective, but no claims are made that it will ever meet the cost and production needs of the mass market. The De Lorean... 

Integralschaumstoff integral foam molding SchaumspritzgieBen integral skin... 

Strukturanalyse structural foam/ integral foam Strukturschaum,... 

Table 2.36 Test of PUR integral foams according to service requirements [513]...

Due to their particular sandwich-like structure formed by high density or even solid skins and a low-density foamed core (PU foams with this type of structure are also known as integral foams), molded flexible PU foams are commonly used in automobile interior parts, furniture cushions, or mattresses. 

Several kinds of polyurethanes are of commercial significance and are conveniently classified into the following major types-flexible foams rigid foams integral foams elastomers surface coatings and adhesives. These various types of material are considered separately in this chapter after an account of the development of polyurethanes, the raw materials involved and the general reactions of isocyanates. 

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