INDUSTRIAL AND ENGINEERING
September 1947
of the plastic niade using it. This criterion should not be overlooked iii tlie preliminary evaluation of plasticizers for this purpose, particularly since (in the case of ethylcelluiose) certain ne11 known plasticizers such a3 mineral oil, which promote lorvteinpcmture inipact strength, fall out of line if coefficient of viscosity chnngc, i i the only criterion applied. It wail founti that the use of a cellulose acetate a t a high level opity will produce a definite iniprovemerir in tlie lox tcmpc~rntureimpact strength of the resulting plastic; this is also pardlri - ( I other experience in the field of high polymers. that thc. brittlenesj temperature of hat is, its mechanical properties d-as the degree of polymerization or thP iriri I I I P I C Yiscosity of this polymer increaqed. Since%.among (itlirr facliii~~ Tiie . low teniper:tture iriipact strength of d l u l o v :ti'c,t:ite pl:irti,.>1i:i.s b w n coti.~iileredtoo lon- for wcli uiei: a; trail
