Dependence of mechanical shear degradation of polymers in solution on rate of energy application and on concentration

Goodman, P.

doi:10.1002/pol.1957.1202511006

Cited by 15 publications

(2 citation statements)

References 5 publications

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“…For example, a solution of 3 wt% polyisobutene flowing through a capillary only degraded once a critical flow rate was reached. [106] Similarly, dilute poly(vinyl acetate) in toluene was found to undergo minimal scission at 5000 RPM in a homogeniser. [98] This suggests that there is a minimum critical force required for chain scission to occur.…”

Section: Mechanical Degradation Of Polymers -18 -mentioning

confidence: 99%

“…It has been observed experimentally that increasing deformation rate increases the rate of chain scission; while a minimum deformation rate exists, below which no chain scission is observed to occur. For example, a solution of 3 wt% polyisobutene flowing through a capillary only degraded once a critical flow rate was reached . Similarly, dilute poly(vinyl acetate) in toluene was found to undergo minimal scission at 5000 RPM in a homogeniser .…”

Section: Mechanical Degradation Of Polymersmentioning

confidence: 99%

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Polymeric Drift Control Adjuvants for Agricultural Spraying

Lewis

Evans

Malic

et al. 2016

Macro Chemistry & Physics

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---------The movement of a pesticide or herbicide to an off-target site during agricultural spraying can cause injury to wildlife, plants and contamination of surface water. This phenomenon is known as spray drift and can be controlled by spraying during favorable environmental conditions, and by using low drift nozzles and drift control adjuvants (DCAs). Polymeric DCAs are the most common type of DCA and function by increasing the droplet size produced during spraying. There are, however, two main drawbacks of polymeric DCAs; they are prone to mechanical degradation during spraying which reduces their performance and they can produce oversized drops which reduces the efficacy of the spray. In this review, existing DCA technology is reviewed including the mechanism through which they function.This then provides a platform for the discussion of novel polymeric architectures which have currently not been applied in DCA formulations.-2 -

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Section: Mechanical Degradation Of Polymers -18 -mentioning

confidence: 99%

Section: Mechanical Degradation Of Polymersmentioning

confidence: 99%

Polymeric Drift Control Adjuvants for Agricultural Spraying

Lewis

Evans

Malic

et al. 2016

Macro Chemistry & Physics

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

Müller

1977

Angew. Makromol. Chem.

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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. Flow instabilities, which appear above a critical shear rate D in polymer solutions and pretend a loss in viscosity, are not caused by shear degradation. This result supports our interpretation of unstable flow of polymer solutions as slip flow (spurt).

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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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Dependence of mechanical shear degradation of polymers in solution on rate of energy application and on concentration

Cited by 15 publications

References 5 publications

Polymeric Drift Control Adjuvants for Agricultural Spraying

Polymeric Drift Control Adjuvants for Agricultural Spraying

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

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

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