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Titolo:
Polymerization of epoxy resins studied by positron annihilation
Autore:
Suzuki, T; Hayashi, T; Ito, Y;
Indirizzi:
High Energy Accelerator Res Org, Radiat Sci Ctr, Tsukuba, Ibaraki 3050801,Japan High Energy Accelerator Res Org Tsukuba Ibaraki Japan 3050801 50801,Japan Sumitomo Chem Co Ltd, Fine Chem Res Lab, Tsukuba, Ibaraki 3003294, Japan Sumitomo Chem Co Ltd Tsukuba Ibaraki Japan 3003294 Ibaraki 3003294, Japan Univ Tokyo, Nucl Sci & Technol Res Ctr, Tokai, Ibaraki 3191106, Japan UnivTokyo Tokai Ibaraki Japan 3191106 Ctr, Tokai, Ibaraki 3191106, Japan
Titolo Testata:
MATERIALS RESEARCH INNOVATIONS
fascicolo: 5-6, volume: 4, anno: 2001,
pagine: 273 - 277
SICI:
1432-8917(200104)4:5-6<273:POERSB>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Keywords:
positron annihilation; epoxy resins; free volume; glass transition; polymerization; positronium; positron lifetime; surface tension; gelation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
14
Recensione:
Indirizzi per estratti:
Indirizzo: Suzuki, T High Energy Accelerator Res Org, Radiat Sci Ctr, Tsukuba, Ibaraki 3050801,Japan High Energy Accelerator Res Org Tsukuba Ibaraki Japan 3050801 n
Citazione:
T. Suzuki et al., "Polymerization of epoxy resins studied by positron annihilation", MAT RES INN, 4(5-6), 2001, pp. 273-277

Abstract

Positron annihilation lifetime spectroscopy (PALS) has been applied to study polymerization of epoxy resins of cresole novolac with a hardener of phenol novolac. PALS uses positrons to probe the microstructure of a nanometer(nm) size. Using PALS polymerization can be followed through three states:powder (monomer), liquid and solid. PALS is a unique method for the detection of intermolecular spaces, hence polymerization was followed from the point of view of free spaces (inter-molecular spaces) between polymer networks. The glass transition temperature (T-g) was determined from the temperature dependence of the positronium (Ps) lifetime. Although Tg determined by PALS is usually lower than that determined by a mechanical analysis (TMA), it was observed that T-g approached the value determined by TMA after long curing. Ps can form bubbles in a liquid, and the surface tension of a mixture of the resin and the hardener was calculated from a simple empirical formula using the Ps lifetime; the resulting value is similar to that of the bisphenol-A epoxy resin. Gelation was observed as an increase in the intensity of Ps and a sharp decrease in the lifetime.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/02/20 alle ore 08:06:08