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Curing Behavior (curing + behavior)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Curing Behavior of Epoxy Resin Using Controllable Curing Agents Based on Nickel Complexes

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2006
Abdollah Omrani
Abstract Summary: The curing reaction kinetics and mechanism of the diglycidyl ether of bisphenol A (DGEBA) with three complexes of Ni(II) with diethylentriamine (Dien), Pyrazole (Pz) and Pyridine (Py) as ligands have been studied using differential scanning calorimetry (DSC). The curing reaction was characterized by high cure onset and peak maximum temperatures. The kinetics of the curing reaction were evaluated using the Ozawa method. The average values of activation energy for the three nickel complexes increased in the order: Dien-based curing agent,>,Pz-based curing agent,>,Py-based curing agent. Three main curing mechanisms (catalytic, complex cation and free ligand polymerization path) have been proposed depending on the cure temperature. It was also shown that the cure kinetics of DGEBA with Dien- and Py-based complexes could be described by the Sestak-Berggren equation. The water absorption, chemical resistance and thermal stability of the thermosets were also studied. The results showed that the thermoset obtained with the Py-based complex was more thermally stable than those obtained with the other two curing agents. Activation energy versus conversion plots for the epoxy systems studied. [source]

Curing behavior and mechanical properties of hollow glass microsphere/bisphenol a dicyanate ester composites

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010
Jinhe Wang
Abstract Hollow glass microsphere (HGS)/bisphenol A dicyanate ester (BADCy) composites have been prepared by mechanical mixing, followed by a stepped curing process. The effect of HGS on the curing behavior of BADCy was studied using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the composites were examined by mechanical tests, and the improvements of the mechanical properties were investigated by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). The results show that HGS is catalytic for the polycyclomerization of the BADCy, which is advantageous to reduce the maximal processing temperature. The impact strength, flexural strength, flexural modulus and storage modulus of BADCy are improved. The improvements of the mechanical properties without sacrificing thermal properties, the ability of lowing processing temperature and the low cost make HGS good filler for cyanate ester resin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Curing behavior of a novel polytriazole resin

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007
Liqiang Wan
Abstract The curing behavior of a novel low temperature curing polytriazole resin, prepared from p -xylylene diazide and N,N,N,,N, -tetrapropargyl- p,p, -diaminodiphenylmethane, was investigated by DSC and rheological analyses. The kinetics of the curing of the resin was studied by nonisothermal and isothermal DSC measurements and the kinetics parameters were obtained. The values of apparent activation energy Ea of the curing reaction obtained by nonisothermal and isothermal DSC are 80.7 and 75.3 kJ/mol, respectively. The curing of the resin was traced by the isothermal rheological analysis. The gelation times of the resin at 70, 75, 80, and 85°C are about 200, 150, 110, and 75 min, respectively. The viscosity equation for the resin was found as follows: © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Benzoxazine containing polyester thermosets with improved adhesion and flexibility

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2010
Alev Tuzun
Abstract High molecular weight polyesters containing thermally curable benzoxazine units in the main chain have been synthesized. For this purpose, first the diol functional monomer is synthesized through the Mannich and subsequent ring closure reactions of bisphenol-A, paraformaldehyde, and 5-amino-1-pentanol. Polycondensation of the resulting benzoxazine and pyromellitic dianhydride or 4-4,-(hexafluoroisopropylidene) diphatalic anhydride with or without dibutyltin laurate yielded the corresponding polyesters with the molecular weights between 5800 and 7000 Da. The structures of the precursor diol monomer and the resulting polyesters are confirmed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy analysis. Curing behavior of both the monomer and polymers has also been studied by differential scanning calorimetry. Flexible films of the polyesters were obtained by solvent casting on tin plates and crosslinked by heating in the absence of any catalyst. The cured films exhibited high flexibility and adhesion on the tin plates as determined by ASTM and DIN tests. Thermal properties of the cured polymers were also investigated by thermogravimetric analysis (TGA). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4279,4284, 2010 [source]

Synthesis, characterization, and thermal properties of ladderlike polyepoxysiloxanes

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2001
Yuhui Lin
Abstract Starting from trichlorosilanes and using 1,4-phenylenediamine as a template, we have synthesized some ladderlike poly(glycidyl- co -alkyl/aryl)siloxanes (polyepoxysiloxanes or polyepoxies for short). The structures of copolymers were confirmed through IR, 1H NMR, elemental analyses, and gel permeation chromatography. Curing behaviors of these polyepoxies in the absence and presence of a curing agent have been studied with DSC. It was shown that these epoxies could be cured without any curing agent. Copolymers having aromatic groups showed higher curing reactivity than those having alkyl groups. The experimental results also demonstrate that the curing reaction occurred solely via epoxy functionality, not via the condensation reaction of the hydroxy groups located at the end of polymer main chains. The thermal stability of the cured polymers was examined by thermogravimetric analysis. The results confirm that polyepoxies with aromatic groups had better thermal stability than those with alkyl groups. It was also found that polyepoxies cured with a diamine have a higher thermal stability than those cured in the absence of a curing agent. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2215,2222, 2001 [source]

Curing behavior and mechanical properties of hollow glass microsphere/bisphenol a dicyanate ester composites

The partial replacement of silica or calcium carbonate by halloysite nanotubes as fillers in ethylene propylene diene monomer composites

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009
Pooria Pasbakhsh
Abstract The effect of partial replacement of silica or calcium carbonate (CaCO3) by halloysite nanotubes (HNTs) on the curing behavior, tensile properties, dynamic mechanical properties, and morphological characteristics of ethylene propylene diene monomer (EPDM) composites was studied. Five different compositions of EPDM/Silica/HNT and EPDM/CaCO3/HNT compounds (i.e. 100/30/0, 100/25/5, 100/15/15, 100/5/25, and 100/0/30 parts per hundred rubber (phr)) were prepared on a two-roll mill. The results indicated that the replacement of CaCO3 by HNTs increased the tensile strength, elongation at break (Eb), and tensile modulus of composites from 0 to 30 phr of HNTs whereas for silica, the maximum tensile strength and Eb occurred at 5 phr loading of HNTs with an enhanced stress at 300% elongation (M300). The curing results show that, with replacement of silica or CaCO3 by HNTs, the cure time (t90) and cure rate (CRI) were decreased and increased, respectively. Scanning electron microscopy investigation confirmed that co-incorporation of 5 phr of HNTs with silica would improve the dispersion of silica and enhanced the interactions between fillers and EPDM matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

Formation of new thermosets by the reaction of cyanates with thiophenols

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Monika Bauer
Abstract Sulfur-containing aromatic thermosets, mainly consisting of aryloxy- and arylthio-substituted 1,3,5-triazines, have been prepared through the reaction of difunctional cyanates with mono- and difunctional aromatic thiols. A straightforward three-step reaction scheme is proposed and verified by the identification of key substances: (1) the addition of thiol and cyanate groups, (2) the stepwise addition of (thio)imino carbonic esters with one another, and (3) the ring closure of chain-extended (thio)imino carbonic esters to form 1,3,5-triazines. Reactions of types 2 and 3 are associated with an abstraction of phenol or thiophenol, which can enter into reaction 1 again. Characterization of the curing behavior of dicyanate of bisphenol A with thiophenol as well as dimercaptodiphenyl sulfide by differential scanning calorimetry shows that the reaction rates are significantly enhanced by the admixture of thiols to the cyanate. Dynamic mechanical analysis of resulting thermosets showed that large amounts of comonomers can be incorporated into the network resulting in a decrease of glass temperature but increase of fracture toughness. Finally, the fully cured thermosets resulting from the reaction of dicyanate of bisphenol A with different admixtures of dimercaptodiphenyl sulfide were characterized by cone calorimetry to get information about flame retardancy. The flame retardancy is influenced by incorporation of dimercaptodiphenyl sulfide into the triazine network only slightly. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Rheological and curing behavior of aqueous ambient self-crosslinkable polyacrylate emulsion

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007
Xiaohua Liu
Abstract An aqueous ambient crosslinkable polymer acrylic (AACPA) emulsion was obtained by adding adipic acid dihydrazide (ADH) to the polyacrylate emulsion incorporating diacetone acrylamide (DAAM), and this emulsion was synthesized by two feeding materials methods. The AACPA emulsion and its paint film were characterized with rheological measurements, laser light scattering, Fourier transform infrared, torsional braid analysis (TBA), DTA, and so on. The results showed that AACPA emulsion was pseudoplastic fluid and pseudoplasticity increased with increasing of DAAM content. The results also showed that water resistance, solvent resistance, and thermotacky temperature of AACPA paint film increased with increasing of the content of DAAM. The results dealing with curing behavior of the paint film showed that adding organic swelling solvent and organic acid to the AACPA emulsion can accelerate the curing speed of the paint film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Synthesis of fully lower-rim, carbonate-bridged calix[8]arenes and their curing behavior

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2001
Takuo Sugioka
Abstract Novel fully lower-rim, carbonate-bridged calix[8]arene derivatives were successfully synthesized in high yield by the condensation of p -alkyl substituted calix[8]arenes with triphosgene. Different bases and catalysts were used for the preparation depending on the p -alkyl substituted groups of the calix[8]arenes. The conformational features of the derivatives were examined by 1H NMR analysis. Thermosetting formulations were prepared from a mixture of bisphenol A polycarbonate with calix[8]arene carbonate derivatives using sodium benzoate as a catalyst. Their crosslinking behaviors were studied using differential thermal/thermogravimetric analysis. No glass-transition temperatures were observed after annealing at 280,300 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1149,1155, 2001 [source]

The unidirectional glass fiber reinforced furfuryl alcohol for pultrusion.

POLYMER COMPOSITES, Issue 6 2008

The development of unidirectional glass fiber reinforced furfuryl alcohol (FA) composites has been conducted using an in situ polymerization method. The FA prepolymer synthesized in this study was prepared from blends of FA monomer and catalyst (p -toluene sulfonic acid). The process feasibility, and kinetic analysis of the unidirectional glass fiber reinforced FA composites by pultrusion has been investigated. From the investigations of the long pot life of FA prepolymer, the high reactivity of FA and FA/glass fiber, and excellent fiber wet-out of FA resin and glass fiber, it was found that the FA resin showed excellent process feasibility for pultrusion. A kinetic autocatalytic model, d,/dt = A exp(,E/RT),m(1,,)n, was proposed to describe the curing behavior of FA/glass fiber composites. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans using a multiple regression technique. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source]

The effects of alumina and silica nanoparticles on the cure kinetics of bisphenol E cyanate ester

POLYMER ENGINEERING & SCIENCE, Issue 6 2010
Xia Sheng
Nanoparticles can be used as fillers to reinforce polymers, forming nanocomposites with better thermomechanical properties than composites with macrosized fillers. Furthermore, the addition of nanoparticles may influence the curing behavior of the polymer matrix during processing. In this study, the effect of various loadings of alumina or silica nanoparticles on the cure kinetics of bisphenol E cyanate ester (BECy) is investigated by differential scanning calorimetry (DSC). Alumina nanoparticles are shown to have a catalytic effect on the cure of BECy. The greater catalytic effect of alumina nanoparticles, compared with silica, is attributed to the increased number of hydroxyl groups on the surface and the Lewis acidity of ,-phase alumina. Kinetic parameters were obtained from dynamic DSC experiments. For an autocatalytic model of the cure process, the kinetic parameters obtained from the model suggest that the addition of alumina nanoparticles changed the cure reaction mechanism of BECy. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers [source]

Modification of bisphenol A dicyanate ester by carboxyl-terminated liquid butadiene-acrylonitrile and its composites

POLYMER ENGINEERING & SCIENCE, Issue 5 2006
Jieliang Wang
Cyanate esters with excellent high-temperature properties and easy processing are well known as good resin materials used in aerospace and electrical industries, but the drawback of brittleness limits their usage. In this study, carboxyl-terminated liquid butadiene-acrylonitrile (CTBN) was introduced to improve the toughness of bisphenol A dicyanate resin (BADCy), a typical kind of the cyanate esters. Fourier transform infrared spectroscopy and differential scanning calorimetry were employed to investigate the effects of CTBN on the curing behavior of BADCy; the results indicate that the addition of CTBN has a great influence on the curing behavior of BADCy at lower temperatures, but little at higher temperatures. Data from the thermogravimetric analysis and heat deflection temperature analysis showed that the thermal properties of the modified systems were poorer than that of pristine BADCy resin. On the basis of the scanning electron micrographs of the modified systems, toughening mechanism of the systems was discussed. Mechanical and dielectric properties of the cured resins and glass fiber-reinforced composites were also studied. Modified systems exhibit attractive properties for the future applications in aerospace industries. POLYM. ENG. SCI. 46:581,587, 2006. © 2006 Society of Plastics Engineers. [source]

UV curing behaviors and hydrophilic characteristics of UV curable waterborne hyperbranched aliphatic polyesters,

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2003
Anila Asif
Abstract A series of waterborne hyperbranched polyesters (WBHPs) endcapped with methacrylic and salt-like groups in different ratios have been investigated as UV curable resins. The kinetic studies of the drying step and UV curing were carried out by FT-IR measurements. The drying of the film of 100,,m thickness was completed in less than 6,hr at 70°C or within 10,hr at 50°C in an oven. The influence of different photoinitiators and their concentrations, extent of unsaturation and acid content of WBHP on final unsaturation conversion was studied. The surface free energy is a critical character, which affects the surface properties of a cured film. So one method based on the measurement of contact angle of a pure liquid on a solid surface was applied to determine the polar and dispersive components of the surface energy of UV cured films. The investigations of surface energy of WBHPs illustrated that those with more acid content and thus higher polar component are more sensitive to water, while those containing less acid content and thus lower polar term are less water sensitive. Moreover, the UV cured films of WBHPs and their blends with commercial waterborne resins (trade name EB 210, EB 2002, EB 11 and IRR 160) have acceptable pendulum hardness varying from 55 to 180,sec. Copyright © 2003 John Wiley & Sons, Ltd. [source]