Characterization of polymers using the thermally stimulated current technique

Galop, Marc

doi:10.1007/bf01987427

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…As reported for a semicrystalline polymer, when the amorphous phase is not at equilibrium, the glass transition relaxation event can be related to two peaks T gl and T gu (lower and upper T g ). 12,13 The non-equilibrium state can be induced by drawing the polymer, 14 changing the crystallinity of the polymer 15 or by stretched blow moulding. 16,17 T gl corresponds to the`true' amorphous state of the polymer.…”

Section: Resultsmentioning

confidence: 99%

Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

Satoto¹,

Morikawa²,

Hashimoto³

1999

Polym. Int.

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The thermally stimulated current (TSC) technique has been used to investigate molecular relaxation in poly(ethylene terephthalate) (PET) films unstretched and biaxially stretched at 90 and 95 °C. Unstretched PET films show two peaks at 77 and 90 °C corresponding to α and ρ relaxation processes, respectively. The α relaxation is associated with the main glass transition of the material. The ρ peak with lower intensity is attributable to permanent dipoles. Both biaxially stretched samples show one TSC peak at 95 °C, supposed to correspond to ρ relaxation. The disappearance of the α peak, accompanied by the displacement of the ρ peak to higher temperature, is the result of the higher thermal stability of the permanent dipoles, which is strongly influenced by the stiffening of amorphous parts and the crystallization by stretching. In both stretched samples, the continuous distribution of pre‐exponential factors over activation energies observed might correspond to a single relaxation mode. The kinematics of stretching PET has been discussed in terms of activation energy and temperature dependence of relaxation time. © 1999 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

Satoto¹,

Morikawa²,

Hashimoto³

1999

Polym. Int.

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“…Since then, the technique has evolved into a tool for studying the dynamics and molecular motions/relaxations in semicrystalline and amorphous polymers as well as pharmaceutical powders [45,52,69,73,119,175,176,196].…”

Section: Thermally Stimulated Depolarization Currentmentioning

confidence: 99%

A Review on Methods and Theories to Describe the Glass Transition Phenomenon: Applications in Food and Pharmaceutical Products

2009

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Given the complexity in composition and the various environmental conditions to which foods and pharmaceuticals are exposed during processing and storage, stability, functionality, and quality are key attributes that deserve careful attention. Quality and stability of foods and pharmaceuticals are mainly affected by environmental conditions such as temperature, humidity, and time, and for processing conditions (e.g., shear, pressure) under which they may undergo physical and chemical transformations. Glass transition is a key phenomenon which is useful to understand how external conditions affect physical changes on materials. Consequently, theories that predict and describe the glass transition phenomenon are of a great interest not only for the food industry but also it extends to the pharmaceutical and polymer industries. It is important to emphasize that the materials of relevance in these industries are interchangeably sharing similar issues on functionality and their association with the glass transition phenomenon. Development of new materials and understanding the physicochemical behavior of existing ones require a scientific foundation that translates into safe and high-quality foods, improved quality of pharmaceuticals and nutraceuticals with lower risk to patients, and functional efficacy of polymers used in food and medicinal products. This review addresses the glass transition phenomenon from a kinetics and thermodynamics standpoint by presenting existing models that are able to estimate the glass transition temperature. It also explores traditional and novel methods used for the characterization of the glass transition phenomenon.

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“…Despite of the high polarity of the -C-Cl bond, few references can be found on the low-temperature peak of chlorine-containing polymers. Galop [2] used short-circuit TSD for testing polymers and stated that the frozen-in stresses also produce depolarization current. Interestingly, a low-temperature peak was found in polypropylene at − 50 °C and explained as "relaxation of lateral groups."…”

Section: Introductionmentioning

confidence: 99%

Thermally stimulated discharge (TSD) study of low-temperature transitions in chlorine-containing polymers

Marossy

2023

J Therm Anal Calorim

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Thermally stimulated discharge current (TSD) tests on PVC, chlorinated polyethylene, chlorinated PVC, and chlorinated paraffins always show a relatively low-intensity transition in the − 100 to − 80 °C range. Several chlorine-containing polymers and one chlorinated paraffin were tested up to 70% chlorine content by short-circuited TSD method. The intensities of these transitions show a maximum at about 40% chlorine content except for PVC. Knowing the random nature of chlorination, it is assumed that this transition origins from the rotational movement of neighboring –CH2–CHCl– monomeric units.

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Characterization of polymers using the thermally stimulated current technique

Cited by 7 publications

References 7 publications

Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

A Review on Methods and Theories to Describe the Glass Transition Phenomenon: Applications in Food and Pharmaceutical Products

Thermally stimulated discharge (TSD) study of low-temperature transitions in chlorine-containing polymers

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