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Start Over Topic glass transition temperature
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1. Ultrasonic welding of 100% lignocellulosic papers.

Author

Regazzi, Arnaud, Viguié, Jérémie, Harthong, Barthélémy, Dumont, Pierre J. J., Imbault, Didier, Peyroux, Robert, Rueff, Martine, Charlier, Quentin, Guérin, David, Leroy, Laurence, Krouit, Mohammed, and Petit-Conil, Michel

Subjects
*ULTRASONIC welding, *THERMOPLASTICS, *X-ray computed microtomography, *GLASS transition temperature, *PAPER, *MINERAL oils
Abstract

Paper-based packaging materials are generally assembled using adhesives formulated with oil-based polymers. These adhesives make the recyclability of the materials more complex and may be the source of material contamination by mineral oil. In view of developing an adhesive-free process, the potential of ultrasonic compression was investigated in this study. 100% lignocellulosic papers were assembled using an ultrasonic welder dedicated to thermoplastic polymers. For papers containing lignin, the measured peeling strengths were equivalent to those achieved by hot-melt gluing, provided that the water content of papers was well adjusted. At the interface between bonded papers, the fiber network was dense and rather continuous. SEM examinations, 3D X-ray microtomography images, and temperature measurements suggested that the development of adhesion originated to a large extent from a thermoplastic welding mechanism: wood fiber polymers passed their glass transition temperatures, creeped and formed a matrix that coated fibers. Thus, ultrasonic welding appears as an efficient adhesive-free technique for assembling papers that are used in a broad range of packaging applications. [ABSTRACT FROM AUTHOR]

Published
2019
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2. THERMAL RESISTANCE OF ORGANIC NANOPARTICLE COATINGS FOR HYDROPHOBICITY AND WATER REPELLENCE OF PAPER SUBSTRATES.

Author

Samyn, Pieter, Schoukens, Gustaaf, Kiekens, Paul, Mast, Peter, Van den Abbeele, Henk, Stanssens, Dirk, and Vonck, Leo

Subjects
SPECTRUM analysis, GLASS transition temperature, NANOPARTICLES, SURFACE chemistry, COATING processes, THERMOPHYSICAL properties
Abstract

The modification of paper substrates by organic nanoparticle coatings offers an attractive alternative for creating hydrophobic and water-repellent surfaces without fluorinated chemicals. The nanoparticles were synthesized by imidization of poly(styrene-maleic anhydride) and applied to a standard paper grade by means of a laboratory bar-coating process. The effects of supplementary heat treatments of the coated papers were investigated in terms of coating morphology and hydrophobicity: a unique coating structure is formed with a combination of microdomains that are internally structured at the nanoscale. The relatively high glass transition temperature of the nanoparticles allows for good thermal stability of the coating with almost no morphological changes at heating up to 180°C. The changes in chemical composition were investigated by diffuse reflectance infrared spectroscopy (DRIFT) and UV/VIS spectroscopy. The latter techniques qualitatively describe the effects of thermal treatments on the imide and styrene moieties. Contact angle measurements indicate that there is an optimum curing temperature in order to obtain a maximum advancing contact angle of 133° to 150°. [ABSTRACT FROM AUTHOR]

Published
2010
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3. Moisture and Temperature Triggered Release of a Volatile Active Agent from Soy Protein Coated Paper: Effect of Glass Transition Phenomena on Carvacrol Diffusion Coefficient

Author

Nathalie Gontard, Pascale Chalier, Afef Ben Arfa, Valérie Guillard, Université de Montpellier (UM), Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)

Subjects
Paper, 0106 biological sciences, Manufactured Materials, Diffusion, Kinetics, Analytical chemistry, Thermal diffusivity, relative humidity, 01 natural sciences, chemistry.chemical_compound, 0404 agricultural biotechnology, 010608 biotechnology, Product Packaging, Relative humidity, Carvacrol, glass transition temperature, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Chromatography, Chemistry, carvacrol diffusivity, Temperature, Humidity, 04 agricultural and veterinary sciences, General Chemistry, Models, Theoretical, 040401 food science, Controlled release, Monoterpenes, Soybean Proteins, Cymenes, Volatilization, Antimicrobial packaging, General Agricultural and Biological Sciences, Glass transition, controlled release
Abstract

Carvacrol release from SPI-coated papers was evaluated at different relative humidities (RH; 60, 80, and 100%) and storage temperatures (5, 20, and 30 degrees C). Effective carvacrol diffusivities were determined from experimental release kinetics and by using a mathematical model based on Fick's second law. Increasing storage temperature and RH lead to an increase of carvacrol diffusivity. Depending on the relative humidity, the carvacrol effective diffusivity varied from 1.71 x 10(-16) to 138 x 10(-16) m(2)/s at 30 degrees C, from 0.85 x 10(-16) to 8.78 x 10(-16) m(2)/s at 20 degrees C, and from 0.11 x 10(-16) to 7.50 x 10(-16) m(2)/s at 5 degrees C. The combined effect of relative humidity and temperature on diffusivity was particularly marked at 30 degrees C and 100% RH. The temperature and relative humidity dependence of carvacrol release was related to the glass transition phenomenon and its effect on chain protein mobility and carvacrol diffusivity.

Published
2009