#I/ t ~ ~ ~ ~ ~ p ~ with m i t iprupertics ws varyiiie Erim those oS Iinrd riitiher to those of a jelled rubber eeinent enilmlying n~odified, snbstantially insnlnlile polymers of vinyl halides. By :iiIaptttt,iom of cumposition and of nictliods or liroctwing, a varict,y of nsefni rubber-like materials has I m n prorodneed, tlic physical and clicirri(:a1 prqirrtic'. of which may bevitried over a wide rrnigi! I,?rwnpi,imndiiig, ytrbienlrtrly by the clioiec of pltirticizer. It is my to distingiiish betwwn plasticizers a Ivcnta, and ivrc stinll arliitrarily t,errri :is pl ers the relatively nom volatilr materials, and as solvents, the readily nilxtile materials. 'I'hosc sohrble or insolubltfi iiintcriala xdiirb are not plasticizers or solvents, but which are added to niodify the processing or t o cliange the appearaneeor properties of tho finished prodnet mill, aceording to the usage cointnon in t.lie riilrber iiiilnstry, be termed "pigments." To a v i d cmiinsiini, all data givcn in t i l e subsequent port.im US this gaper will be based on viiiyl chloride wniponnils containing a single rcpresentat i w pl:t.irerhas been iininersed in the ligiit oil, meiitiulied in the Sorcgoing, Sor 60 days. Conqiarison of the two samples will give soiiie idea OS tile volume cliairge. I
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flanged oil p i p i n g operating a t 150 pounds per aqunre inch pressure where soiiie fifteen UT twenty other materirtis, including paper, asbestos, rubber coriiposit,ions, syntlietic niliber-like product.s, a.nd duck-inserted rubIier, lrad failed; sealing iiiembers on reciproca.ting pistons (Figiirr I-t) where aft,cr 15,000,000 4-inch strokes no leakage coiilil i)c iletret.cd; arid t.rarisforiner gaskets d i e r e service cuiiditioos wc quite severe. Froin the inertness of the base mat,orial, u ~ i einiglit readily :inticipnt,e tile resistatice OS I
