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001-es BibID:BIBFORM084735
Első szerző:Karger-Kocsis József (vegyészmérnök)
Cím:Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing / Karger-Kocsis József, Kéki Sándor
Dátum:2014
ISSN:1788-618X
Megjegyzések:Shape memory polymers (SMPs) are capable of memorizing one or more temporary shapes and recovering to the permanent shape upon an external stimulus that is usually heat. Biodegradable polymers are an emerging family within the SMPs. This minireview delivers an overlook on actual concepts of molecular and supramolecular architectures which are followed to tailor the shape memory (SM) properties of biodegradable polyesters. Because the underlying switching mechanisms of SM actions is either related to the glass transition (Tg) or melting temperatures (Tm), the related SMPs are classified as Tg- or Tm-activated ones. For fixing of the permanent shape various physical and chemical networks serve, which were also introduced and discussed. Beside of the structure developments in one-way, also those in two-way SM polyesters were considered. Adjustment of the switching temperature to that of the human body, acceleration of the shape recovery, enhancement of the recovery stress, controlled degradation, and recycling aspects were concluded as main targets for the future development of SM systems with biodegradable polyesters.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény hazai lapban
folyóiratcikk
polymer synthesis
molecular engineering
smart polymers
biopolymers
biodegradable polymers
Megjelenés:Express Polymer Letters. - 8 : 6 (2014), p. 397-412. -
További szerzők:Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:OTKA-NK83421
OTKA
TÁMOP-4.2.2.A-11/1/KONV-2012-0036
TÁMOP
TÁMOP-4.2.4.A/2-11/1-2012-0001
TÁMOP
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2.

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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3.

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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