Effects of Self-Diffusion and Inter-Diffusion in Polymer Systems

Voyutskii, S.S.; Vakula, V. L.

doi:10.5254/1.3540397

Cited by 29 publications

(14 citation statements)

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“…The activation energies were found to be 38 and 64 kca1.l mole of repeat unit for Penton and PET, respectively. Although these activation energies are on the same order of magnitude as those reported for other polymers using different detection techniques, 39 the PET value is slightly higher than previous reported values which range up to 50 kcal./ mole of repeat unit. 41 Since the activation energies of self-diffusion have been determined for very few polymers, a more valid comparison may be r e ported activation energies for viscous flow.…”

Section: Crystallization Kineticsmentioning

confidence: 42%

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Crystallization from the glassy state

Collier¹,

Baer²

1966

J of Applied Polymer Sci

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SynopsisIsothermal crystallization of poly[3,3-bis(chloromethyl)oxacyclob~tane] and poly-(ethylene terephthalate) from the quenched glassy state gave small lamellae approsimately 1000-2000 A. in lateral dimension with a constant thickness of about 100 A. The maximum primary nuclei density for crystallization slightly above the glass transition temperature, T,, was 1010 greater than frequently observed dnring spherulitic growth from the melt. Since the lamellae grow a t a linear rate, the crystallization process could be described by the Avrami theory for two-dimensional growth with a constant nuclei density. By assuming that crystallization near T, is diffusion-controlled, bnlk crystallization rate data were analyzed to obtain self-diffusion coefficients whose activation energies were similar to reported values for other polymers.

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Section: Crystallization Kineticsmentioning

confidence: 42%

“…PET has a high cohesive energy density43 and would be expected to have a high activation energy because of its helical rather rigid chain and the polar groups. 39 …”

Section: Crystallization Kineticsmentioning

confidence: 99%

Crystallization from the glassy state

Collier¹,

Baer²

1966

J of Applied Polymer Sci

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“…It has previously been reported (23) that PBMA films cast for 3 hr at 353 Κ undergo an aging process in which permeability decreases as a function of storage time -presumed to be due to further gradual coalescence, as described by Bradford and Vanderhoff (24,25,26), or the process of autohesion as described by Voyutskii (27,28,29). Such films showed a greater level of structure (by FFTEM) than those films shown here.…”

Section: Polymer Latex Films Containing Leachable Additives 365mentioning

confidence: 94%

“…Gas permeability measurements proved to be a more sensitive probe of film permeability than solute permeability measurements. For example, gas permeability measurements were able to detect film aging (5) (due to, for example, the effects of further gradual coalescence (24,25,26) or autohesion (27,28,29)) which could not be detected by solute permeability measurements (due to the effects being hidden by the experimental uncertainty).…”

Section: Et Almentioning

confidence: 98%

Permeation and Morphology in Polymer Latex Films Containing Leachable Additives

Steward¹,

Hearn

Wilkinson³

et al. 1996

ACS Symposium Series

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This paper reviews recent research, performed at The Nottingham Trent University, into the enhancement of the permeability properties of polymer latex films. Both leachate-free model colloid latices, made by surfactant-free emulsion polymerisation, and commercially available latices, containing surfactants and often requiring plasticiser addition to achieve good film formation, have been studied. Water soluble leachable additives such as sucrose, HPMC and a soluble polymer latex, have been employed to deliberately enhance solute permeant flux, and the transport properties of the films are discussed with reference to film morphology. The use of increasing levels of leachable additive allows the solute transport mechanism to be systematically changed from one in which permeation occurs predominantly by solution-diffusion to a mechanism in which convective diffusion predominates and solute permeation tends to become independent of penetrant solubility in the polymer. The results are discussed in terms of the increased hydration of the polymer resulting from additive leaching.Whenever polymer latex films are used as coatings, then their permeabilities to gases, water vapour and solutes are likely to be of significance. In the case of barrier coatings for substrate protection, a minimisation of the flux would often be desirable, but where coatings are used to aid sustained or controlled release of an active ingredient then an ability to modify the flux is needed. In the latter application, water soluble leachates play an important role.This paper utilises free polymer latex films to investigate the transport properties of such films to a range of permeants, and the effects on film permeability of leachable additives ranging from endogenous surfactants, essential plasticisers and molecular sized

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“…Consequently, the welding time at a given temperature, which gives the value G,, is linked to (1;) by a relation similar to eq. (5): (8) This analysis corresponds to a welding process a t constant temperature. For the present study, we propose the calculation given in the Appendix, which deals with welding under dynamic thermal conditions.…”

Section: Optimal Conditions For Fusion Welding Process Theoretical Amentioning

confidence: 99%

Test methodology for the determination of optimum fusion welding conditions of polyethylene

Saint-Royre

Gueugnaut

Reveret

1989

J of Applied Polymer Sci

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SynopsisThe fusion welding behavior of a medium density polyethylene resin has been studied for a wide range of heating rates using a recently developed test methodology. With this method, the thermal and physical phenomena occurring at the interface of two thin polyethylene pieces assembled by fusion can be studied. It consists of a thermal welding phase and a phase of mechanical separation of the welded assembly. For the mechanical phase, an adaptation of the T-peel test was used. These conditions make it possible to determine the thermal welding parameters (temperature, time) for optimal mechanical quality of the joint, according to a criterion established by optimization of the peel test used. The variations in minimum temperature required for an optimum weld, as a function of heating rate, can be simulated with a numerical model based on the concept of macromolecular interdiffusion. Consistent with the experimental behavior, the numerical model involves two parameters characteristic of the diffusion behavior of the polyethylene resin. Thus, these parameters characterize the weldability of the polyethylene resin under study.

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Effects of Self-Diffusion and Inter-Diffusion in Polymer Systems

Cited by 29 publications

References 0 publications

Crystallization from the glassy state

Crystallization from the glassy state

Permeation and Morphology in Polymer Latex Films Containing Leachable Additives

Test methodology for the determination of optimum fusion welding conditions of polyethylene

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