On the structure and properties of polyamides. XXVI. The effect of end groups in poly-6-caprolactam on the Huggins constant of polymer solutions in tricresol

AbstractThe cross-linked poly(esterurethanes) (PEU) based on unsaturated oligo(alkyleneester)diol (OAE) are presented. OAE was prepared from adipic acid, maleic anhydride and ethylene glycol and then characterized by elemental analysis, FTIR, 1H NMR and 13C NMR spectroscopy in account of double bonds and -COOH end groups. The synthesis of PEU was conducted in two steps. In the first step the prepolymers, containing free NCO or OH groups, were obtained via the reaction of OAE with 4,4`-diphenylmethane diisocyanate (MDI) used in excess. The cross-linking was achieved in the next step, in which the prepolymers were dissolved in methyl methacrylate (MMA) of concentrations in the range of 30 to 50 wt% in the presence of 1 wt% of methyl ethyl peroxide and 0.003 wt% of cobalt (II) 2-ethylhexanoate. It is proved that both chemical structure and MDI content in prepolymer influence the static and dynamic mechanical properties and thermal stability of the poly(esterurethanes).

Download Full-text

On the Huggins constant of dilute polymer solutions

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1969.0022 ◽

1969 ◽

Vol 308 (1495) ◽

pp. 497-515 ◽

Cited By ~ 11

Keyword(s):

Polymer Solutions ◽

Relaxation Spectrum ◽

Order Approximation ◽

Polymer Concentration ◽

Numerical Constant ◽

First Order ◽

Dilute Polymer Solutions ◽

Huggins Constant ◽

First Order Approximation ◽

Good Agreement

As is well known, the stress in a polymer solution can be expressed in terms of the characteristic relaxation spectrum. Here the effect of polymer concentration on the relaxation spectrum is evaluated to the first-order approximation. It is then possible to calculate the Huggins constant k H (in the viscosity equation ɳ sp. / c = [ɳ] + k H [ ɳ ] 2 c ) from this spectrum. It is found that k H is related to its value k Ɵ at the Ɵ-point, thus: k H = k Ɵ α ɳ -4 + C 0 z α ɳ -5 where C 0 is a numerical constant, z is the customary excluded volume parameter, and α ɳ is the expansion coefficient (approximately measured by the intrinsic viscosity). This equation is compared with recent experiments by Nagasawa and by Inagaki, and good agreement is obtained. Thus two different polymer solutions give plots of adequate linearity for α 4 ɳ k H against M 1/2 /α ŋ (since z is proportional to M 1/2 ) with approximately the same intercept ( k Ɵ ~ 0·45).

Download Full-text

Rotary mobility of macromolecular end groups in polymer solutions

Polymer Science U S S R ◽

10.1016/0032-3950(80)90230-0 ◽

1980 ◽

Vol 22 (5) ◽

pp. 1280-1287

Author(s):

A.Yu. Shaulov ◽

V.Ya. Katsobashvili ◽

I.I. Tugov

Keyword(s):

Polymer Solutions ◽

End Groups

Download Full-text

Structure of second phases in TiAl alloys containing Cr and B

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087197 ◽

1991 ◽

Vol 49 ◽

pp. 576-577

Author(s):

Ernest L. Hall ◽

Shyh-Chin Huang

Keyword(s):

Grain Size ◽

Second Phase ◽

Structure And Properties ◽

Tial Alloys ◽

Second Phases ◽

Interstitial Elements

Addition of interstitial elements to γ-TiAl alloys is currently being explored as a method for improving the properties of these alloys. Previous work in which a number of interstitial elements were studied showed that boron was particularly effective in refining the grain size in castings, and led to enhanced strength while maintaining reasonable ductility. Other investigators have shown that B in γ-TiAl alloys tends to promote the formation of TiB2 as a second phase. In this study, the microstructure of Bcontaining TiAl alloys was examined in detail in order to describe the mechanism by which B alters the structure and properties of these alloys.

Download Full-text