Chemical Degradation of Polymers in Corrosive Liquid Media

Moiseev, Yu. V.; Markin, V. S.; Заиков, Г. Е.

doi:10.1070/rc1976v045n03abeh002632

Cited by 21 publications

(29 citation statements)

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“…However, their understanding is on the sufficiently high level. 24 The situation is different as it is related to physical processes of aging. Structural rearrangements in aged glassy polymers and their relation to changes of important technical properties such as dimensional, mechanical, electric and many others-have no reasonable physical interpretation.…”

Section: Enthalpy and Volume Relaxa-tions Of Polymer Glasses In Isothmentioning

confidence: 99%

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Glassy Polymers as Matrices for Advanced Composites

Олейник

1987

Polym J

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ABSTRACT:This paper is concerned with several fundamental aspects of the glassy polymer structure and properties. One aspect is chemical vitrification, the process whereby the reactants are transformed from the liquid into the glassy state due to chemical reactions. The influence of that transformation on the Young moduli and T• of formed polymers is considered. This is exemplified by the epoxy cure process. Another aspect is the mechanism of plastic deformation of polymeric glasses and the third one is the isothermal enthalpy and volume relaxations in glassy polymers during physical aging. Choice of these topics is connected with their importance for polymer materials and advanced composite science. Some new experimental results for glassy polymers are introduced. The plastic deformation of glassy polymers is interpreted in the terms of two independent deformation modes. Mode I (low deformation temperature mode) is crystal-like and based on the nucleation and growth under stress of defects which have many features of dislocations. The second (high deformation temperature) Mode II is the diffusion motion of vacancies (holes) due to simultaneous action of stress and temperature. In the simultaneous measurement of volume and enthalpy isothermal relaxation a new type of relaxation asymmetry for sample contraction and expansion was found.

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Section: Enthalpy and Volume Relaxa-tions Of Polymer Glasses In Isothmentioning

confidence: 99%

“…There are the necessary conditions for the description of glassy state thermodynamics. 24 Polymer J., Vol. 19, No.…”

Section: Enthalpy and Volume Relaxa-tions Of Polymer Glasses In Isothmentioning

confidence: 99%

Glassy Polymers as Matrices for Advanced Composites

Олейник

1987

Polym J

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“…The carbocation is then quickly stabilized by the free electron pairs of a water molecule, and so the new oligo-or polysaccharide end is formed. 9 Thus, the rate should be proportional to the concentration of protonated bonds and consequently to the proton concentration, although some evidence exists that this is not the case for a thermal hydrolysis. 10 In this study, the proton concentration is kept constant during trials and the apparent hydrolysis rate constant is determined.…”

Section: Introductionmentioning

confidence: 99%

Model for Random Hydrolysis and End Degradation of Linear Polysaccharides: Application to the Thermal Treatment of Mannan in Solution

Nattorp

Graf

Spuehler

et al. 1999

Ind. Eng. Chem. Res.

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The kinetics for homogeneous hydrolysis of mannan is studied in a batch reactor at temperatures from 160 to 220°C. A formate buffer ensures a pH of 3.8-4.0, measured at 25°C. Samples are analyzed for oligosaccharides up to a degree of polymerization of 6 and also for the total amount of mannose after acid hydrolysis. A mathematical model with two reactions (1, random hydrolysis of the glucosidic bonds; 2, degradation of the reducing end of the molecule) describes accurately the time course of oligosaccharides. Optimized rate constants follow closely an Arrhenius relationship, with the degradation having a higher activation energy (140 kJ/mol) than the hydrolysis (113 kJ/mol). The mathematical model has the advantage that production of small molecules is independent of the initial chain-length distribution as long as the average initial chain length is some 5 times longer than the largest species measured. It can be applied to first-order depolymerization of other linear polymers with one link type in order to determine reaction rate constants or make predictions about molecular weight distribution on the base of known reaction rate constants.

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“…Detailed data on the effect of liquid media and vapors on polymeric materials, including PFCM, are reported in [2,10,[192][193][194][195][196][197][198][199]. However, we note that the data on water absorption and water, oil, and gasoline resistance are preliminary and can differ strongly, since the properties of the components of PFCM and their reaction with the active media are very different.…”

Section: Polar Matrices (Binders) And/or Fibres Water Absorption and mentioning

confidence: 99%

“…The effect of active media on composites includes the following fundamental cases [2, 10, [192][193][194][195][196][197][198][199]: wetting of the surface by liquids; sorption of liquids by the material, accompanied by swelling and plasticization of the material; sorption of vapors, accompanied by swelling and plasticization of the material; chemical degradation under the effect of acid and basic media or, in rare cases, formation of additional intermolecular cross-links; biodegradation by microorganisms. As a result of the effect of active media, the properties of the material change: the mechanical properties change in swelling and plasticization without degradation of the components of the composite the strength decreases and the deformability increases (the deformation modulus decreases and the deformation at failure increases); when degradation processes predominate, the strength and deformability simultaneously decrease.…”

Section: Effect Of Active Media On Pfcmmentioning

confidence: 99%

Polymeric fibre composites, basic types, principles of fabrication, and properties. Part 5. Effect of performance effects on polymeric fibre composites; safety/hazardousness characteristics

Perepelkin

2006

Fibre Chem

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The principles of materials science of polymeric fibre composite materials (PFCM) containing different reinforcing fibrous fillers (short-cut fibres, paper, yarn, tow, sliver, fabrics, and nonwoven materials) and different matrices (thermoplasts and thermosets) are examined in an analytical review [Khim. Volokna, No. 4 and 5 (2005); No. 1, 4, and 6 (2006)]. The mutual effect and reaction of the components of PFCM (fibres and matrices) are analyzed. information is reported on the fabrication and properties of different kinds of composites: fibre-filled molding materials, pertinaxes, textolites, unidirectional composites, honeycomb plastics, etc. New types of composites with ultrahigh mechanical and thermal characteristics are examined. Testing methods and the functional properties of PFCM are examined: mechanical, thermophysical, electrophysical, optical. The mechanisms of the changes in the structure and properties of PFCM under external effects: thermal, photochemical, ionizing radiation, active media, and other factors, are analyzed. Performance reliability indexes are examined, including aging and the effect of extreme conditions. Safety/ hazardousness characteristics are very important in selection of PFCM and use of articles made from them: sanitary-hygienic and toxicological, combustibility and toxicity of products of combustion. The following features of polymeric fibre composites in comparison to other materials are summarized below based on the examination: Combination of different kinds of fibre fillers and matrices (binders) allows regulating the properties of PCM in a wide range, selecting the optimum indexes for items with a wide spectrum of applications.Items made of PFCM involve low specific consumption of materials and are easy to manufacture, process, and treat in comparison to many traditional materials, metals and ceramics in particular. Articles made from composites are reliable in use, almost not subject to corrosion, and do not require special protection or periodic painting of the surface. With respect to specific mass characteristics, PFCM can be many times better than items made of metals and other traditional materials. This is important for using them in vehicles, aircraft, rescue craft, and sporting goods. Due to the features of the properties and the positive performance characteristics, PFCM have a great future in the most varied areas of application. BASIC EFFECTS ON PFCM DURING USEPolymer fibre materials and items made from them are constantly exposed to the environment during use: high temperatures, insolation and radiation, atmospheric and microbiological effects, active liquid and gaseous media, and other factors. Usually several of these factors act simultaneously, potentiating each other [2, 10,[171][172][173]. Aging during use of PFCM takes place under the effect of external factors their structure and properties, evaluated by the change in the basic functional characteristics, primarily mechanical and physical, gradually change.St. Petersburg State University of Technology ...

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Chemical Degradation of Polymers in Corrosive Liquid Media

Cited by 21 publications

References 0 publications

Glassy Polymers as Matrices for Advanced Composites

Glassy Polymers as Matrices for Advanced Composites

Model for Random Hydrolysis and End Degradation of Linear Polysaccharides: Application to the Thermal Treatment of Mannan in Solution

Polymeric fibre composites, basic types, principles of fabrication, and properties. Part 5. Effect of performance effects on polymeric fibre composites; safety/hazardousness characteristics

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