Solid-state foaming

On the other hand, at saturation temperatures lower than the Tg f of the polymer (ie, the polymer is in the glassy state at the end of the saturation stage), the foaming process will be triggered in a second stage by heating the sample over its Tg ef (Fig. 9.5). This process is usually called two-step or solid-state foaming [19]. 

Quadrini F, Santo L, Squeo EA (2012) Solid-state foaming of nano-clay-filled thermoset foams with shape memory properties. Polym Plast Technol Eng 51(6) 560-567... 

Zhou, C., Ma, L., Li, W., Yao, D., 2011. Fabrication of tissue engineering scaffolds through solid-state foaming of immiscible polymer blends. Biofabrication 3, 045003. 

Synthesis of Foamed Nanopolymer Blends by Solid-State Foaming... 

Indukuri K K and Lesser A J (2003) Controlled solid-state foaming of elastomeric systems, Polym Mater Sci Eng 89 767-768. 

Microcellular thermoplastic panels with an integral skin of desired thickness can be used in various load bearing applications especially in the construction industry. To achieve flat surfaces the foaming should be constrained in thickness direction, which would then force the sample to grow in plane. This has been successfully demonstrated using two manufacturing processes - extrasion [3, 4] and constrained solid-state foaming process [5],... 

We most often encounter polystyrene in one of three forms, each of which displays characteristic properties. In its pure solid state, polystyrene is a hard, brittle material. When toughened with rubber particles, it can absorb significant mechanical energy prior to failure. Lastly, in its foamed state, it is versatile, light weight thermal insulator. 

Results are presented of experiments undertaken by Gaiker in the manufacture of sandwich panels containing foam cores based on PETP recycled by a solid state polyaddition process developed by M G Ricerche. Panels were produced with glass fibre-reinforced unsaturated polyester and epoxy resin skins, and allthermoplastic panels with PE, PP, PS and glass fibre-reinforced PETP skins were also produced. EVA hot melt adhesives and thermoset adhesives were evaluated in bonding glass fibre-reinforced PETP skins to the foam cores. Data are presented for the mechanical properties of the structures studied. 

Block copolymers are widely used industrially. In the solid and rubbery states they are used as thermoplastic elastomers, with applications such as impact modification, compatibilization and pressure-sensitive adhesion. In solution, their surfactant properties are exploited in foams, oil additives, solubilizers, thickeners and dispersion agents to name a few. Particularly useful reviews of applications of block copolymers in the solid state are contained in the two books edited by Goodman (1982,1985) and the review article by Riess etal. (1985). The applications of block copolymers in solution have been summarized by Schmolka (1991) and Nace (1996). This book is concerned with the physics underlying the practical applications of block copolymers. Both structural and dynamical properties are considered for melts, solids, dilute solutions and concentrated solutions. The book is organized such that each of these states is considered in a separate chapter. 

It should further be noted that the onset of continuity of the dispersed blend phase not only deteriorates the overall mobility of the SAN to form cellular structures, but also increases the average phase size of PPE and, thus, sterically hinders the incorporation into the cell walls. In particular, for the PPE/SAN 60/40 blend, showing some co-continuous features and solid-state characteristics at 180°C, the foamability is limited to such an extent that only local and less defined cell growth proceeds, leading to the highly inhomogeneous foam morphologies. 

By way of an early example, the effect of calcium carbonate, ATH, and MH fillers on smoke production from styrene butadiene (SBR) foams has been reported.47 It was evident that all the fillers reduced soot formation relative to unfilled foam with the hydrated fillers being more effective than the calcium carbonate, which was considered to act merely as matrix diluent. ATH and MH were found to give enhanced char formation with the promotion of solid-state cross-linking as opposed to pyrolytic degradation. An afterglow effect, occurring after the extinction of the flame, was noted with MH and attributed to the slow combustion of carbon residues. 

Step-Grouch Polymerization Synthesis of a Polyurethane Foam Studies of Solutions and Gels Polymer Precipitation Gels from Alginic Acid Salts Solid State Properties... 

An alternative process for the production of PVC foam using microcellular foam technology, not requiring impact modifier, for thin wall profile (280) has been reported. Proof of concept experiments confirm the satisfactory solid state extrusion of PVC pellets, prefoamed in a batch solid state microcellular process (109). 

Just as the products of polycondensation are greatly varied, so are the reaction conditions used in their production. Some are produced in the melt (many polyamides and polyesters), some initially in the melt but with extensive polymerization continuing in the solid state (polyurethane foams and elastomers), in solution (some polyurethane fibres) or in non-homogeneous liquid systems (some polycarbonates, very high melting polyamides). 

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