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001-es BibID:	BIBFORM062341
Első szerző:	Lakatos Csilla (környezetmérnök)
Cím:	Segmented linear shape memory polyurethanes with thermoreversible Diels-Alder coupling: Effects of polycaprolactone molecular weight and diisocyanate type / Cs. Lakatos, K. Czifrák, R. Papp, J. Karger-Kocsis, M. Zsuga, S. Kéki
Dátum:	2016
ISSN:	1788-618X
Megjegyzések:	Segmented linear polyurethanes (PUs) containing Diels-Alder (DA) adduct were synthesized in toluene solutionfrom poly("-caprolactone) (PCL, Mn = 10, 25 and 50 kg/mol), diisocyanate (methylene diphenyl diisocyanate (MDI), 2,4-toluene diisocyanate (TDI), 1,6-hexamethylenediisocyanate, (HDI)), furfurylamine (FA) and bismaleimide (BMI). Theorder of the segments in the PUs was -PCL-MDI-FA-BMI-. The PUs were characterized by size-exclusion chromatography(SEC), different spectroscopic (1H-NMR, attenuated total reflectance Fourier-transform infrared, AT-FTIR), thermal andmechanical analysis (differential scanning calorimetry, DSC, dynamical mechanical analysis, DMA). The DA and retro-DAreactions were identified by 1H-NMR for both the synthesized PU and the coupling components (i.e. FA and BMI). Tensilemechanical and shape memory (SM) properties of the PUs were also determined. The DA coupling in the PU was improvedby heat treatment above the melting temperature (Tm) of PCL. DMA traces showed a plateau-like region above Tm of PCLconfirming the presence of a physical network the netpoints of which are given by the hard segments including the DA couplers.This feature suggested good SM behavior that was confirmed both qualitatively and quantitatively.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény hazai lapban smart polymers polyurethanes Diels-Alder adduct mechanical properties thermal properties
Megjelenés:	Express Polymer Letters. - 10 : 4 (2016), p. 324-336. -
További szerzők:	Czifrák Katalin (1978-) (vegyész) Papp R. Karger-Kocsis József (1950-) (vegyészmérnök) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
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001-es BibID:	BIBFORM103478
035-os BibID:	(WOS)000511115100004 (Scopus)85079341961
Első szerző:	Nagy Lajos (vegyész)
Cím:	Uncatalyzed urethane forming reaction of 1,3-xylylene diisocyanate with aliphatic alcohols of varying chain lengths and polyols / L. Nagy, A. Juhász, M. Zsuga, S. Kéki
Dátum:	2020
ISSN:	1788-618X
Megjegyzések:	In this article, we report a detailed study on the kinetics of the reaction of 1,3-xylylene diisocyanate (1,3-XDI) with alcohols of varying alkyl chain lengths and with low molecular weight polyols such as monomethoxylated polyethylene glycol (mPEG) and polytetrahydrofuran (PTHF) in toluene, in the absence of a catalyst. It was found that the pseudo-first-order rate coefficient increased with the increasing alkyl chain length (k(1,app) was found to be 0.0166 and 0.0341 min(-1) for 1-propanol and 1-hexanol, respectively) and the reactivities of the 1,3-xylyene diisocyanate towards the alcohols and polyols are between those of the aromatic and alkyl isocyanates. The activation energies were also determined and were found to vary from 25.6 to 38.6 kJ/mol (from 1-propanol to 1-hexanol). According to further kinetic studies, the rate coefficients k(1,app) and k(2,app) for the reaction of 1,3-XDI with PTHF were determined to be (1.13 +/- 0.01).10(-2) and (1.28 +/- 0.01).10(-2) min(-1), respectively. It was also found that the rate constants did not depend significantly on the length of the polymer chain. However, significantly lower rate coefficients were obtained for the 1,3-XDI-mPEG reaction (k(1,app) = (2.64 +/- 0.03).10(-3) min(-1) and k(2,app) = (2.45 +/- 0.03).10(-3) min(-1)). Besides, the dependence of the pseudo-first-order rate coefficient on the concentration of the alcohols was also studied, and based on these findings a reaction mechanism is proposed.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény hazai lapban folyóiratcikk polymer synthesis molecular engineering xylylene diisocyanate kinetics aliphatic alcohols
Megjelenés:	Express Polymer Letters. - 14 : 4 (2020), p. 336-347. -
További szerzők:	Juhász A. Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:	NKFIH-FK-128783 Egyéb GINOP-2.3.2-15-2016-00041 GINOP
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