Measurements oflsqb;eegr;rsqb;were made for seven fractions of polychloroprene (PCP) in methyl ethyl ketone,nhyphen;butyl acetate, and carbon tetrachloride at 25deg;C and for three fractions of PCP intranshyphen;decalin at a number of temperatures ranging from 0.05deg; to 65deg;C. On a logndash;log graph paper, the values ofagr;eegr;3lpar;thinsp;equals;thinsp;lsqb;eegr;rsqb;sol;lsqb;eegr;rsqb;thgr;rpar;calculated from these data formed a composite curve when plotted againstagr;s3lpar;thinsp;equals;thinsp;lang;S2rang;3sol;2sol;lang;S2rang;03sol;2rpar;obtained from lighthyphen;scattering experiments under the same conditions. This curve is characterized by a relatively marked upward curvature in the vicinity of the origin, followed by a linear portion of unit slope. Its initial tangent has a slope of 0.65, which is much smaller than 0.81 predicted theoretically by Kurata and Yamakawa. Plots ofagr;eegr;3vs the interaction parameterzwere prepared by evaluatingzfor eachagr;sby use of the Yamakawa equation. They were fitted by a single curve having a slight downward curvature, suggesting that no drainage effect manifests itself in the viscosity behavior of the systems studied. This curve explains why the familiar Stockmayerndash;Fixman method to treatlsqb;eegr;rsqb;in nonhyphen;thgr;solvent systems works, despite the fact that, as shown previously, data foragr;sas a function of molecular weight, solvent species, and temperature can be reasonably well described by the modified Flory or by the Yamakawa equation. Recent viscosity data of Berry on polystyrene were rehyphen;examined in terms of the present method, and it was found that his demonstration of the drainage effect onlsqb;eegr;rsqb;is not yet conclusive.
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