Nanostructure, and molecular dynamics in rodlike polyimide/flexible-chain polyimide molecular composites

Bershtein, VA; Egorova, LM; Yakushev, PN; Meszaros, O; Sysel, P; David, L; Kanapitsas, A; Pissis, P

dc.contributor.author	Bershtein, VA	en
dc.contributor.author	Egorova, LM	en
dc.contributor.author	Yakushev, PN	en
dc.contributor.author	Meszaros, O	en
dc.contributor.author	Sysel, P	en
dc.contributor.author	David, L	en
dc.contributor.author	Kanapitsas, A	en
dc.contributor.author	Pissis, P	en
dc.date.accessioned	2014-03-01T01:18:05Z
dc.date.available	2014-03-01T01:18:05Z
dc.date.issued	2002	en
dc.identifier.issn	0022-2348	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14792
dc.subject	polyimides	en
dc.subject	molecular dynamics	en
dc.subject	molecular reinforcement	en
dc.subject	nanocomposites	en
dc.subject.classification	Polymer Science	en
dc.subject.other	CREEP RATE SPECTROSCOPY	en
dc.subject.other	LASER INTERFEROMETER	en
dc.subject.other	GLASS-TRANSITION	en
dc.subject.other	T-G	en
dc.subject.other	RELAXATIONS	en
dc.subject.other	FILMS	en
dc.subject.other	HETEROGENEITY	en
dc.subject.other	NETWORKS	en
dc.subject.other	ORIGIN	en
dc.subject.other	BLENDS	en
dc.title	Nanostructure, and molecular dynamics in rodlike polyimide/flexible-chain polyimide molecular composites	en
heal.type	journalArticle	en
heal.identifier.primary	10.1081/MB-120004346	en
heal.identifier.secondary	http://dx.doi.org/10.1081/MB-120004346	en
heal.language	English	en
heal.publicationDate	2002	en
heal.abstract	A complete study of structure and molecular dynamics was performed for a series of rigid rodlike polyimide (PIR)/flexible-chain polyimide (PIF) molecular composites, with 0, 20, 40, 50, 60, 80, and 100 wt% of the rigid component. The PIR and PIF were synthesized from 3,3'4,4'-biphenyltetracarboxylic dianhydride and 1,4-phenylenediamine or 4,4'-oxydianiline, respectively. Small-angle x-ray scattering, differential scanning calorimetry, dynamic mechanical analysis, laser-interferometric creep rate spectroscopy, dielectric relaxation spectroscopy, and thermally stimulated depolarization currents techniques were used for overall characterization of nanostructure, glass transition, and sub-T-g relaxations. The experiments were carried out, on the whole, at temperatures ranging from 100 to 660K and frequencies ranging from 10(-2) to 10(6) Hz. All the experiments indicated pronounced deviations from additivity in both nanostructure and dynamics of the molecular composites. Mixing of the PIR and PIF components led, in particular, to a smaller nanostructure, down to formation of the nanoscale-homogeneous 20PI(R)/80PI(F) composite. Changes of the glass transition characteristics in two opposite directions and the arising of large dynamic heterogeneity around T-g were observed. The results were readily treated in terms of nanostructural changes, loosening of molecular packing due to confinement of PIF chains between PIR chains as the "rigid walls," and the constraining influence of the latter on segmental motion in PIF chains adjoining the "rigid walls".	en
heal.publisher	MARCEL DEKKER INC	en
heal.journalName	JOURNAL OF MACROMOLECULAR SCIENCE-PHYSICS	en
dc.identifier.doi	10.1081/MB-120004346	en
dc.identifier.isi	ISI:000176590500002	en
dc.identifier.volume	B41	en
dc.identifier.issue	3	en
dc.identifier.spage	419	en
dc.identifier.epage	450	en