Microporous PVC separators

4 Microporous PVC Separators A mixture of powdered PVC, cyclohexanone as solvent, silica, and water is extruded and rolled in a calender into a profiled 

5 Comparative Evaluation of the Traction Battery Separators Which separator properties are important for use in traction batteries For this aspect primarily the highly predominant application, namely forklift traction batteries, is to be considered chemical resistance against attacks by acid and oxidation, mechanical stability for problem-free assembly, stiffness to counteract overexpansion of the negative active material, and low acid displacement are particularly desirable. Delay in antimony poisoning, absence or near-absence of oily deposits in the cells, and - last but not least - a low electrical resistance complete the requirement profile. 

In Table 11.11 an attempt is made to include the above criteria in the form of quantitative data or quahtative evaluations. 

Polyethylene separators offer the best balanced property spectrum excellent mechanical and chemical stability as well as good values for acid availability and electrical resistance have estabhshed their breakthrough to be the leading traction battery separator. Rubber separators, phenohc resin-resorcinol separators, and microporous PVC separators are more difficult to handle than polyethylene separators their lack of flexibihty does not allow folding into sleeves or use in a meandering assembly in addition they are more expensive. 

Special applications are often governed by different priorities as already discussed in relation to golf carts, the low water loss and the delay in antimony poisoning in heavy-duty service of a forklift are of eminent importance, with the result that rubber separators remain the preferred product there. Submarine batteries offer a different picture the number of cycles to be reached is far lower ( 500) and, due to the slow ( 100h) but very deep discharge, the acid availability becomes the decisive criterion, which favors, for example, the phenolic resin-resorcinol separator. Such requirements are already similar to the application in open stationary cells. 

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In the second half of the 1960s, at the same time but independently, three basically different plastic separators were developed. One was the polyethylene separator [16] already referred to in starter batteries, used only rarely in stationary batteries, but successful in traction batteries. The others were the microporous phenolic resin separator (DARAK) [18] and a microporous PVC separator [19], both of which became accepted as the standard separation for stationary batteries. They distinguish themselves by high porosity (about 70 percent) and thus very low electrical resistance and very low acid displacement, both important criteria for stationary batteries. 

Polyethylene separators Rubber separators Phenol formaldehyde-resorcinol separators Microporous PVC separators... 

Much of the above also holds true for the application of microporous PVC separators (see Sec. 9.2.3.1) in open stationary batteries. Very high porosity and thus low acid displacement and electrical resistance are also offered by this system. The relevant properties are compiled in Table 12. 

Polyethylene separators Phenol-Formal dehyde-resorcinol Separators Microporous PVC separators Sintered PVC separators Rubber separators... 

Among the separator varieties described, the phenol-formaldehyde-resorcinol separator (DARAK 2000) [60] as well as the microporous PVC separator [86] have proven effective for this construction. For applications without deep discharges, concessions may be made with the respect to porosity and pore sizes of the separator therefore polyethylene separators or a spe-... 

Phenol- formaldehyde- resorclnol separators Microporous PVC separators Class fiber/poly ester fiber separators Rubber separators... 

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