scholarly journals Modification of epoxy resins with thermoplastic segmented polycarbonate-based polyurethanes

2014 ◽  
Vol 68 (6) ◽  
pp. 755-765 ◽  
Author(s):  
Jelena Pavlicevic ◽  
Mirjana Jovicic ◽  
Vesna Simendic ◽  
Oskar Bera ◽  
Radmila Radicevic ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Hard Segment ◽  
Crosslinking Agent ◽  
Polyurethane Elastomers ◽  
Hard Segment Content ◽  
Weight Content ◽  
Epoxy Curing ◽  
Hard Segments ◽  
Modified Epoxy

In this work, epoxy hybrid materials were synthesized by addition of thermoplastic segmented aliphatic polyurethanes with good elastic properties. The modified epoxy samples were obtained by curing of previously homogenized mixture of prepared polyurethane melts, epoxy resin and crosslinking agent Jeffamine D-2000. The influence of different weight content of polyurethanes (5, 10 and 15 wt. % compared to pure epoxy resin) as well the influence of different hard segments of elastomers (20, 25 and 30 wt. %) on the curing of modified epoxy systems was studied. The curing was followed by differential scanning calorimetry (DSC), in dynamic regime from 30 to 300?C, at three heating rates (5, 10 and 20?C/min). With the increase of hard segments content of polyurethanes added in higher concentration (10 and 15 wt. %) into epoxy matrix, the temperature of maximum ratio of curing was shifted to lower values (from 205 to 179?C). Obtained DSC data were analyzed using two integral methods (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose) and one differential kinetic model (Friedman). The significant differences were observed in the second part of the epoxy curing (for the reaction degrees higher than 60 %), where the values of activation energies remarkably increase. The addition of polyurethane elastomers retarded the curing process due to decreased mobility of reactant molecules caused by higher viscosity of reaction mixture. By detailed analysis of determined kinetic parameters, it is concluded that the influence of slow diffusion is more pronounced in the presence of thermoplastic polycarbonate-based polyurethanes, which confirmed their effect on the mechanism of epoxy curing. The highest tensile strength and hardness showed the DGEBA modified with the polyurethane with highest hard segment content. Increasing the hard segment content of polyurethane and its concentration in matrix, the tensile strength of modified epoxy was increased. The elongation at break of modified epoxy samples was significantly improved by addition of polycarbonate-based polyurethanes with low hard segment content, due to higher content of flexible soft segment chains.

Synthesis of Polyurethane Elastomers by One-shot Technique and Study of Different Polyol Types and Hard Segment Content After Exposure to γ-Irradiation

2018 ◽  
Vol 12 (4) ◽  
pp. 705-715
Author(s):  
H. M. Abd El-Raheem ◽  
Y. K. Abdel-Monem ◽  
I. M. El-Sherbiny ◽  
K. Lotfy ◽  
M. M. Basuni ◽  
...  
Keyword(s):  
Hard Segment ◽  
Γ Irradiation ◽  
Polyurethane Elastomers ◽  
Hard Segment Content

Investigating the Properties and Structure of Polyurethane Elastomers with Monoethylene Glycol Chain Extender

2020 ◽  
Vol 986 ◽  
pp. 18-23
Author(s):  
Patcharapon Somdee ◽  
Timea Lassu-Kuknyo ◽  
Csaba Konya ◽  
Tamás Szabó ◽  
Kálmán Marossy
Keyword(s):  
Hard Segment ◽  
Chain Extender ◽  
Polypropylene Glycol ◽  
Polyurethane Elastomers ◽  
Elongation At Break ◽  
Peak Intensity ◽  
Hard Segment Content ◽  
Polymeric Chains ◽  
Monoethylene Glycol ◽  
Hardness Values

The effect of monoethylene glycol (mEG) acting as chain extender in polypropylene glycol (PPG-4000) and 4,4ʹ-diphenylmethane diisocyanate (MDI) reaction was investigated. Polyurethane elastomers (PUR) were changed from flexible to rigid materials by varying the mEG content. Results show that Shore A and D hardness values trend to increase with increasing mEG content. It appears that increasing the chain extender content increases the hard segment content in the polyurethane structure. Moreover, increasing the mEG content increases Young’s modulus and the tensile strength of PUR, while elongation at break decreases. The chemical structure of the hard segment of PUR was characterized by Infrared (IR) spectroscopy. IR spectra exhibited the bands typical for PUR consisting of –NH, CH2– and C=O groups. The spectra reveal a few interactions between the polymeric chains that appear to be responsible for the shift of transmittance peak and decrease of some peak intensity. This may be due to the hard segment aggregating more to form domains in the PUR when mEG content was increased.

Aliphatic polycarbonate-based polyurethane elastomers and nanocomposites. I. The influence of hard-segment content and macrodiol-constitution on bottom-up self-assembly

2012 ◽  
Vol 126 (3) ◽  
pp. 1016-1030 ◽  
Author(s):  
Milena Špírková ◽  
Rafał Poręba ◽  
Jelena Pavličević ◽  
Libor Kobera ◽  
Josef Baldrian ◽  
...  
Keyword(s):  
Self Assembly ◽  
Hard Segment ◽  
Polyurethane Elastomers ◽  
Bottom Up ◽  
Hard Segment Content ◽  
Aliphatic Polycarbonate

Influence Factors Study on the Properties of Epoxy Resin Modified by Polyurethane

2012 ◽  
Vol 472-475 ◽  
pp. 1937-1940
Author(s):  
Dong Yan Ren ◽  
Xiao Hong Li ◽  
Zhi Hua Li
Keyword(s):  
Tensile Strength ◽  
Thermal Properties ◽  
Impact Strength ◽  
Epoxy Resin ◽  
Influence Factors ◽  
Mechanical And Thermal Properties ◽  
Thermal Properties Of Materials ◽  
Properties Of Materials ◽  
The Impact ◽  
Modified Epoxy

Polyurethane-modified epoxy resin was prepared with Polyurethane prepolymer(PUP). The effects of the PUP content and epoxy resin type on mechanical and thermal properties of materials were discussed. The results indicate that the tensile strength and impact strength of the material increase to maximum successively, and then decrease with the increasing addition of PUP. When the mass fraction of PUP was 15%, the tensile strength and the impact strength of materials were all the best. There were significant differences in mechanical and thermal properties of material for different epoxy, and the best results were cured epoxy TDE-85.

scholarly journals Influence of Hard Segment Content and Diisocyanate Structure on the Transparency and Mechanical Properties of Poly(dimethylsiloxane)-Based Urea Elastomers for Biomedical Applications

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 212
Author(s):  
Natascha Riehle ◽  
Kiriaki Athanasopulu ◽  
Larysa Kutuzova ◽  
Tobias Götz ◽  
Andreas Kandelbauer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Biomedical Applications ◽  
Hard Segment ◽  
Phenyl Isocyanate ◽  
In Vitro Cytotoxicity ◽  
Chain Extender ◽  
Elongation At Break ◽  
Hard Segment Content ◽  
Hard Segments

The effect of hard segment content and diisocyanate structure on the transparency and mechanical properties of soft poly(dimethylsiloxane) (PDMS)-based urea elastomers (PSUs) was investigated. A series of PSU elastomers were synthesized from an aminopropyl-terminated PDMS (M¯n: 16,300 g·mol−1), which was prepared by ring chain equilibration of the monomers octamethylcyclotetrasiloxane (D4) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). The hard segments (HSs) comprised diisocyanates of different symmetry, i.e., 4,4′-methylenebis(cyclohexyl isocyanate) (H12MDI), 4,4′-methylenebis(phenyl isocyanate) (MDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI). The HS contents of the PSU elastomers based on H12MDI and IPDI were systematically varied between 5% and 20% by increasing the ratio of the diisocyanate and the chain extender APTMDS. PSU copolymers of very low urea HS contents (1.0–1.6%) were prepared without the chain extender. All PSU elastomers and copolymers exhibited good elastomeric properties and displayed elongation at break values between 600% and 1100%. The PSUs with HS contents below 10% were transparent and became increasingly translucent at HS contents of 15% and higher. The Young’s modulus (YM) and ultimate tensile strength values of the elastomers increased linearly with increasing HS content. The YM values differed significantly among the PSU copolymers depending on the symmetry of the diisocyanate. The softest elastomer was that based on the asymmetric IPDI. The elastomers synthesized from H12MDI and MDI both exhibited an intermediate YM, while the stiffest elastomer, i.e., that comprising the symmetric CHDI, had a YM three-times higher than that prepared with IPDI. The PSUs were subjected to load–unload cycles at 100% and 300% strain to study the influence of HS morphology on 10-cycle hysteresis behavior. At 100% strain, the first-cycle hysteresis values of the IPDI- and H12MDI-based elastomers first decreased to a minimum of approximately 9–10% at an HS content of 10% and increased again to 22–28% at an HS content of 20%. A similar, though less pronounced, trend was observed at 300% strain. First-cycle hysteresis among the PSU copolymers at 100% strain was lowest in the case of CHDI and highest in the IPDI-based elastomer. However, this effect was reversed at 300% strain, with CHDI displaying the highest hysteresis in the first cycle. In vitro cytotoxicity tests performed using HaCaT cells did not show any adverse effects, revealing their potential suitability for biomedical applications.

EFFECT OF INCREASING NCO/OH MOLAR RATIO ON THE CHEMICAL AND MECHANICAL PROPERTIES OF ISOCYANATE TERMINATED POLYURETHANE PREPOLYMER DERIVED FROM BIO-MASS

2016 ◽  
Vol 2 (2) ◽  
pp. 78-82
Author(s):  
K. Rathika ◽  
S. Begila David
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Castor Oil ◽  
Hard Segment ◽  
Molar Ratio ◽  
Curing Time ◽  
Percent Elongation ◽  
Hard Segment Content ◽  
Polyurethane Film ◽  
Polyurethane Prepolymer

The study deals the effect of increasing NCO/OH molar ratio on the physico-mechanical properties of isocyanate terminated polyurethane prepolymer. The prepolymer was prepared using castor oil and toluene-2,4-diisocyanate. The NCO/OH molar ratio has been varied from 1.6 to 2.0. The formation of the prepolymer was confirmed by UV and FTIR spectroscopy. The results reveal that the curing time of the prepolymer decreased with increase in NCO/OH molar ratio. When NCO/OH molar ratio increased, the tensile strength of the polyurethane film increased, while percent elongation decreased due to increase in hard segment content.

scholarly journals The influence of bentonite and montmorillonite addition on thermal decomposition of novel polyurethane/organoclay nanocomposites

2013 ◽  
Vol 32 (1) ◽  
pp. 319 ◽  
Author(s):  
Jelena Pavličević ◽  
Milena Špírková ◽  
Oskar Bera ◽  
Mirjana Jovičić ◽  
Katalin Mészáros Szécsényi ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Hard Segment ◽  
Reaction Order ◽  
Hexamethylene Diisocyanate ◽  
Scanning Calorimetry ◽  
Degradation Kinetic ◽  
Polyurethane Elastomers ◽  
Hard Segment Content ◽  
Butane Diol ◽  
Thermal Stability Of

Polycarbonate-based polyurethane (PC-PUs) hybrid materials were obtained by the addition oforganically modified bentonite and montmorillonite (1 w/w %). PC-PUs and their nanocomposites wereprepared using prepolymerization with two polycarbonate diols (both of Mr ca 1000) differing in chainconstitution, hexamethylene-diisocyanate and 1,4-butane diol (chain extender) as starting components. All samples contained the same hard-segment content (30 w/w %). Thermogravimetry coupled with differential scanning calorimetry (TG-DSC) was performed to obtain information about the organoclays addition on the thermal stability of the prepared polyurethane elastomers. The effect of bentonite and montmorillonite nanofillers on the decomposition pattern has been evaluated. By deconvolution of derivative thermogravimetric (DTG) curves, it has been found that the thermal decomposition of polyurethane samples takes place in three overlapping processes. Degradation kinetic parameters (activation energy and reaction order) were calculated on the basis of thermal data obtained at only one heating rate.

Study on epoxy resin with high elongation-at-break using polyamide and polyether amine as a two-component curing agent

e-Polymers ◽  
2018 ◽  
Vol 18 (5) ◽  
pp. 433-439
Author(s):  
Shunsheng Su ◽  
Haiqing Wang ◽  
Chuanjian Zhou ◽  
Yanxiang Wang ◽  
Jianjun Liu
Keyword(s):  
Epoxy Resin ◽  
Tensile Tests ◽  
Curing Agent ◽  
Scanning Calorimetry ◽  
Elongation At Break ◽  
Epoxy Curing ◽  
Two Component ◽  
High Elongation ◽  
Amine Curing ◽  
Modified Epoxy

AbstractThis study aimed to improve the flexibility of E-51 epoxy resin by using polyamide/polyether amine as a two-component curing agent. Through solid state nuclear magnetic resonance (SSNMR), it was found that the cross-linking density of epoxy resin could be effectively reduced by adding the polyamide and polyether amine curing agent. The tensile tests showed that the elongation-at-break was remarkably improved. It was found by differential scanning calorimetry (DSC) that the curing behavior of the polyamide epoxy curing system varied with the addition of different polyether amine. Phase contrast microscope showed that phase separation occurred during the reaction of epoxy resin with the polyamide/polyether amine composite curing agent. In this paper, the modified epoxy resin was endowed with high elongation-at-break (>100%) and appropriate tensile strength (10~20 MPa).

Effects of Hard Segment Contents on Dynamic Mechanical Properties of Gap-Based Polyurethane Elastomers

2013 ◽  
Vol 376 ◽  
pp. 125-129
Author(s):  
Hai Qin Ding ◽  
Le Qin Xiao ◽  
Wei Liang Zhou ◽  
Li Rong He ◽  
Huai Long Zhang
Keyword(s):  
Mechanical Properties ◽  
Hard Segment ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Polyurethane Elastomers ◽  
Elongation At Break ◽  
Dynamic Mechanical ◽  
Soft Segments ◽  
Hard Segments ◽  
Fragility Parameter

Gap-based polyurethane elastomer (GAPE) with different hard segment contents are synthesized with 44-Diphenylmethane diisocyanate (MDI), 1,4 butylene glycol (BDO) as hard segments and GAP as soft segments. Dynamic mechanical analysis (DMA) is applied to investigated the dynamic mechanical properties and the mechanical properties of GAPE are studied by materials laboratorial instrument. The results show that GAPE-2 with 33 wt% hard segment has better mechanical properties, of which the tensile strength is 11.3MPa and elongation at break is 460.5%.As shown in DMA, T g of GAPE-2 is-18.4°C, and the low-temperature fragility parameter and activation energy of GAPE-2 are lower, 55.6 and 271.0 KJ·mol-1 respectively. Elastomer with good stiffness and flexibility is obtained.

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