摘要:

AbstractCalf thymus and salmon sperm deoxyribouncleie acid were degraded by high‐shear stirring to molecular weightsMin the range of 1.3–3.2 × 106and purified by chromatography on methylated bovine serum albumin. Dynamic viscoelastic properties of the fragmented products, in aqueous glycerol solutions in the concentration range ofc= 0.003–0.01 g./ml., were investigated with the apparatus of Birnboim and Ferry. At values of the productcMhigher than 4 × 103, the frequency dependence of the components of the complex shear modulus,G′ andG″, displayed a plateau region in whichG′>G″ – ων1ηS, similar to that observed in concentrated solutions of coiling polymers where it is attributed to an entanglement network (ω is radian frequency, ν1volume fraction of solvent, and η8, solvent viscosity). The width of this plateau region on the logarithmic frequency scale is given by Δ = 3.8 (logcM– 3.56). At lower values ofcM, the frequency dependence is intermediate between those predicted by the theory of Zimm for flexible coiled macromolecules and by the theory of Kirkwood and Auer for rods. Fitting to the Zimm theory gives highly discrepant values for molecular weights, while fitting the low‐frequency end of the dispersion to the Kirkwood‐Auer theory gives reasonable agreement for both molecular weight and rotary diffusion coefficient. It is concluded that the helical fragments appear as nearly rigid rods in their behavior at very low frequencies, but at higher frequencies reveal s

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY