Fractionation of blends of syndiotacticity-rich and a tactic poly(vinyl alcohol) from its aqueous solution induced by shearing force

Yamaura, Kazuo; Yanagisawa, H.; Matsuzawa, Shuji

doi:10.1007/bf01508045

Cited by 10 publications

(1 citation statement)

References 17 publications

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“…To the extent that liquid phase precursor formation proves to be a general characteristic of flow-induced crystallization, such an inter-400 VRAHOPOULOU AND McHUGH pretation would also apply to other systems where fractionation has been observed. 11- 14 A thermodynamic analysis of flow-induced phase separation for monodisperse systems has been presented by us in a previous paper. Calculations were based on a modification of Flory-Huggins theory in which the effect of conformational changes due to flow-induced stresses was viewed as thermodynamically equivalent to introducing a "degree of rigidity" f to the polymer coils.…”

Section: Introductionmentioning

confidence: 98%

Thermodynamics of flow‐induced phase separation in polymers. II. The effect of molecular weight distribution

Vrahopoulou

McHugh

1986

J of Applied Polymer Sci

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SynopsisA thermodynamic analysis of flow-induced phase transformations in polymers is presented. Calculations are based on the assumption that stresses on the polymer coils lower their effective flexibility. This leads to the possibility of a spontaneous liquid separation in which the more concentrated phase contains chains having a lower flexibility relative to those in the more dilute phase. The effects of molecular weight distribution are included, and calculations demonstrate that reducing the flexibility also enhances fractionation in that the more concentrated phase is preferentially enriched with the higher molecular weight fraction of the original polydisperse system. These results offer a quantitative basis for understanding flow-induced structure formation and phase transformation phenomena in polymers in general and the phenomena of precursor formation and polymer fractionation in flow-induced crystallization in particular. Application to the latter phenomenon is also discussed.

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Section: Introductionmentioning

confidence: 98%

Thermodynamics of flow‐induced phase separation in polymers. II. The effect of molecular weight distribution

Vrahopoulou

McHugh

1986

J of Applied Polymer Sci

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Mechanical denaturation of high polymers in solutions. XXXIX. Flow‐induced crystallization of high molecular weight syndiotactic‐rich poly(vinyl alcohol)

Yamaura

Daimoh

Tanigami

et al. 1988

J of Applied Polymer Sci

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SynopsisThe crystallization of syndiotactic-rich poly(viny1 alcohol) (s-PVA) with a molecular weight of 6.73 X lo5 from aqueous solutions was carried out under Couette flow with or without seed crystals. The crystallization of s-PVA from aqueous solutions occurred below the surface of the solutions even in the presence of seed placed in the solution; whereas, in the case of aqueous s-PVA solutions containing 0.02% octyl alcohol (antifoaming reagent) only the longitudinal growth of seed occurred. The lengths of the fibers obtained were 2.5 to 3.0 cm.

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Mechanisms of flow induced crystallization

McHugh¹

1982

Polymer Engineering & Sci

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This paper presents a review of the field of flow induced crystallization from solution. Experimental facts concerning the nature of fibrous nucleation and the “shishkebob” morphology which results are reviewed. The discussion of growth models emphasizes the details of the nucleation control and flow control calculations which have been presented in the literature. A major problem in the development of quantitative models for the growth mechanisms has been the lack of a reproducible growth rate data base and the reasons for this are discussed. The review emphasizes those areas of the field both experimental and theoretical, where further studies are needed before a unified theory of flow induced crystal growth can emerge.

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Fractionation of blends of syndiotacticity-rich and a tactic poly(vinyl alcohol) from its aqueous solution induced by shearing force

Cited by 10 publications

References 17 publications

Thermodynamics of flow‐induced phase separation in polymers. II. The effect of molecular weight distribution

Thermodynamics of flow‐induced phase separation in polymers. II. The effect of molecular weight distribution

Mechanical denaturation of high polymers in solutions. XXXIX. Flow‐induced crystallization of high molecular weight syndiotactic‐rich poly(vinyl alcohol)

Mechanisms of flow induced crystallization

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