Cellular cellulose acetate

Fig. 4-11 (a) BT-15 in flight, (b) sandwich wing section using RP skins and cellular cellulose acetate foam, and (c) section of the monocoque fuselage, and (d) example of a design flexibility in RP construction. 

CCA cellular cellulose acetate DGA differential gravimetric analysis... 

Even though most plastics can be made into foamed products, from a practical and market oriented view only a few different types are used. A few of these plastics will be reviewed. As an example limited use has been made using cellular cellulose acetate (CCA). The CCA was one of the first rigid foams produced and was used rather extensively during the 1940s and 1950s mainly in aircraft sandwich constructions. 

Discussions on cross-linked vinyl foams, which are rigid, can be found below under Vinyl Foams, and rigid cellular cellulose acetate (CCA) foams and polysulfone foams are discussed in the section under Miscellaneous Foams. 

Cellular Cellulose Acetate A number of solvents can be used by themselves in cementing cellulose acetate. The following formulations involve mixtures of several solvents, including bodying resins (dope-type cements) (5). 

Cellular Cellulose Acetate Conventional adhesives recommended include polyurethanes, synthetic resins, thermoplastics, resorcinol-formaldehyde, nitrile-phenolic, and rubber-based materials (8). 

MIL-C-18345A Notice 1 Core Material, Cellular Cellulose Acetate, 13 September 1988, 1 p Notice + 3 pp base spec (FSC 9330) (AR)... 

CCA cellular cellulose acetate GFRP carbon fiber reinforced plastics... 

Cellular cellulose acetate is made in a maimer somewhat similar to the one used in the production of expanded polystyrene. It is relatively the same density of expanded polystyrene however, the useful temperature range is extended up to 175°C. It also has somewhat better chemical resistance than polystyrene foam. Thus it is seen in many of the same applications as polystyrene foam where these additional properties are necessary (e.g., aircraft structure cores, flotation devices). Cellulose acetate foam is trademarked Strux (Aircraft Specialties Corp.). 

Cellulose Acetate. The extrusion process has also been used to produce cellular cellulose acetate (93) in the density range of 96-112 kg/m (6-7 Ib/ft ). A hot mixture of polymer, blowing agent, and nucleating agent is forced through an orifice into the atmosphere. It expands, cools, and is carried away on a moving belt. 

Physical Stabilization Process. Cellular polystyrene, cellulose acetate, polyolefins, and poly(vinyl chloride) can be manufactured by this process, Chemical Stabilization Processes. Cellular rubber and ebonite are produced by chemical stabilization processes. 

When applied to suspension cells the acid washing steps may be done by repeated centrifugation but this is tedious and leads to losses of cellular material unless care is taken. Alternatives involve retaining the cells on glass fibre or cellulose acetate filters in a microanalysis filter holder (Millipore Corp. Ltd.) or the cells may... 

Among those plastics which are commercially produced in cellular form are polyurethane, PVC, polystyrene, polyethylene, polypropylene, epoxy, phenol-formaldehyde, urea-formaldehyde, ABS, cellulose acetate, styrene-acrylonitrile, silicone, and ionomers. However, note that it is possible today to produce virtually every thermoplastic and thermoset material in cellular form. In general, the basic properties of the respective polymers are present in the cellular products except, of course, those changed by conversion to the cellular form. 

FIGURE 4.11 Cellular viability of osteoblasts on (a) cellulose acetate scaffolds and (b) cellulose acetate collagen scaffolds. The green cells are viable and the red ones are nonviable (live/Dead staining) [170]. 

The mechanisms of formation and the structural characteristics of cellulose acetate membranes for reverse osmosis have been investigated. Scanning electron microscopy studies showed the membranes to be high molecular weight condensation structures of the cellular type. 

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