Zum abbau von polymerlösungen durch kapillarscherung. Einfluß der kapillarlänge und strömungsform auf den abbau

Müller, H. G.

doi:10.1002/apmc.1977.050570108

Angew. Makromol. Chem.

1977

DOI: 10.1002/apmc.1977.050570108

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Zum abbau von polymerlösungen durch kapillarscherung. Einfluß der kapillarlänge und strömungsform auf den abbau

H. G. Müller

Abstract: ZUSAMMENFASSUNG:I>er EinfluD der Kapillarlange auf den Abbau von Polymerlosungen bei konstanter SlJMMARY:The dependence of shear degradation of polymer solutions on capillary length at constant shear stress is investigated with solutions of poly(isobuty1ene) (Mvis= 6,l . lo6) in toluene. We examined concentrations of 0.1,0.25, 1 and 4% and found the degradation to increase with capillary length. In 0,l x, solution we found a decreased efficiency of degradation, due to a change in the structure of solution. Fl… Show more

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Cited by 5 publications

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On the mathematical modeling of mechanochemical degradation of acrylonitrile–α‐methyl styrene–vinyl acetate terpolymer in conditions simulating the wet‐spinning

Oprea¹,

Popa²,

Petrovan³

1986

J of Applied Polymer Sci

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SynopsisThis article aims to carry out mathematical modeling of the mechanochemical degradation process of acrylonitrile-a-methyl styrene-vinyl acetate ternary copolymer in conditions that simulate its wet-spinning from dimethyl formamide solution. The influence of some factors on the mechanochemical degradation process is studied. Based on a great number of experiments a regression equation is determined, which correlates the intrinsic viscosity of the copolymer solution with the mechanical process variables (the length and length/diameter ratio, solution concentration, and pressure).

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On the mathematical modeling of mechanochemical degradation of acrylonitrile–α‐methyl styrene–vinyl acetate terpolymer in conditions simulating the wet‐spinning

Oprea¹,

Popa²,

Petrovan³

1986

J of Applied Polymer Sci

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Mechanischer Scherabbau von Polymeren in Lösung mittels turbulenter Strömung, 1. Kinetik, Molekulargewichtsabhängigkeit und Frage des Bruchmechanismus

Müller

Klein

1981

Makromol. Chem.

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The mechanical shear degradation of poly(decy1 methacrylate) with webht average molecular weights 1 ,O . lo6 Q M , Q 1,7 . lo6, and molecular polydispersity ratio M,,,/M,, = 5 in dilute solutions is studied in turbulent flow as a function of molecular weight using a special apparatus consisting of two vessels connected by a capillary. Shear stress and shear rate remained constant during degradation. The rate of degradation was followed up by molecular weight distribution curves using gel permeation chromatography and described by -dci/dt = ki. c:, i being a high molecular weight species of the distribution. The reaction was found to be of the first order (n = I ) independent of solvent and of capillary length. Rate constants ki in the molecular weight range from 3,2. lo6 to 1 3 J . lo6 proved to be proportional to the hydrodynamic volume of the polymer molecules expressed in terms of the product of intrinsic viscosity and molecular weight [qli . Mi. This corresponds to a linear relationship between ki and M:*75. Additional experiments show that this type of dependence on molecular weight holds only for turbulent flow; in laminar flow the result of the literature could be confirmed that there is a linear relation between ki andMi'. Both results are independent of capillary length. As to the mechanism of breakage in turbulent flow it seems that in one step each macromolecule is broken simultaneously into several smaller parts.

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Mechanischer Scherabbau von Polymeren in Lösung mittels turbulenter Strömung, 2. Die Abhängigkeit der Abbaugeschwindigkeit von der Polymergesamtkonzentration in guten Lösungsmitteln

1981

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Mechanical shear degradation of poly(decyl methacrylate), (viscosity average molecular weight in tetrahydrofuran M,, = 1,3 . 1 06, M,/M, = 5) in the thermodynamically good solventtetrahydrofuran has been studied in turbulent flow through a capillary as a function of polymer concentration in the range from 0,22 to 8,9 g/100 cm3. Due to turbulent flow conditions the shear stress, shear rate and shear energy proved to be the same for all concentrations and remained constant during degradation, giving a general insight into mechanism of degradation. The rate of degradation has been followed using molecular weight distribution curves obtained by gel permeation chromatography. The reaction was found to be of first order. Rate constants determined for molecular weights from 3,2 -9,5 . 106 decreased with increasing concentration following a law of the type ki = (K + b -c ) -' , K and b being constants for each molecular weight. Hydrodynamic volumes of polymer molecules have been calculated according to models of Rudin as function of molecular weight and concentration. It can be shown that rate constants of degradation and calculated hydrodynamic volumes are proportional for the whole range of molecular weight and concentrations up to 3,6 g/100 cm3. There is also a rather good proportionality between these rate constants and the volumes of polymer coils predicted by de Gennes. This result is an additional confirmation of the concept that hydrodynamic volume governs shear degradation of polymer solutions. Additional experiments show that this type of concentration dependence is also to be found for other polymers in other solvents.

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Zum abbau von polymerlösungen durch kapillarscherung. Einfluß der kapillarlänge und strömungsform auf den abbau

Cited by 5 publications

References 22 publications

On the mathematical modeling of mechanochemical degradation of acrylonitrile–α‐methyl styrene–vinyl acetate terpolymer in conditions simulating the wet‐spinning

On the mathematical modeling of mechanochemical degradation of acrylonitrile–α‐methyl styrene–vinyl acetate terpolymer in conditions simulating the wet‐spinning

Mechanischer Scherabbau von Polymeren in Lösung mittels turbulenter Strömung, 1. Kinetik, Molekulargewichtsabhängigkeit und Frage des Bruchmechanismus

Mechanischer Scherabbau von Polymeren in Lösung mittels turbulenter Strömung, 2. Die Abhängigkeit der Abbaugeschwindigkeit von der Polymergesamtkonzentration in guten Lösungsmitteln

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