Differential scanning calorimetry of the epoxy cure reaction

Prime, R. Bruce

doi:10.1002/pen.760130508

Cited by 265 publications

(105 citation statements)

References 16 publications

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“…As it can be seen in Table 1, the amount of heat generated per unit of mass is independent of b. A similar result has been found in other works [42][43][44][45][46]. An average value of 355 J/g was assigned to the heat of polymerization of the UP resin.…”

Section: Resultssupporting

confidence: 84%

Kinetic analysis of two DSC peaks in the curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate

Martin

2006

Polymer Engineering & Sci

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The curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate as promoter is studied by DSC at different heating rates. A high promoter/peroxide ratio is used. The DSC curves show two exothermic peaks. It has been assumed that they represent two independent cure reactions. A set of kinetic parameters for each DSC peak has been obtained. They describe the overall cure process using an empirical kinetic model. Nth order and autocatalytic kinetic functions have been employed. A computer program was developed to calculate the degrees of conversion associated with each peak, and to evaluate the kinetic parameters. The calculation algorithm uses the Runge-Kutta numerical integration and the ' 'downhill simplex method.' ' This methodology permits to find all kinetic parameters simultaneously. DSC experimental data are very well fitted. The simulated first peak occurs always before the second one, and the fraction of reaction heat associated with the first peak over the overall reaction heat decreases with heating rate. Moreover, activation energies are in good agreement with the tabulated values for typical free radical polymerization induced by thermal and redox decomposition of the peroxides. POLYM. ENG. SCI., 47:62-70, 2007.

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Section: Resultssupporting

confidence: 84%

Kinetic analysis of two DSC peaks in the curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate

Martin

2006

Polymer Engineering & Sci

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“…[30][31][32] The above two methods assume that the exotherm peak temperature p was constant and was independent of the heating rate. 33,34 This made the nth order and the autocatalytic reactions equally effective. For the Kissinger method, the maximum reaction rate occurs at peak temperatures, where d 2 =dt 2 ¼ 0, in this way, it can be expressed as where T p is the exotherm peak temperature, is the linear heating rate, A is the frequency factor, E a is the activation energy and R is the universal gas constant.…”

Section: Effect Of the Structure Of Epoxy Resins On Thermal Curing Rementioning

confidence: 99%

Effect of Structure of Bridging Group on Curing and Properties of Bisphenol-A Based Novolac Epoxy Resins

Pan

Zhang

et al. 2007

Polym J

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ABSTRACT:Three bisphenol-A based novolac epoxy resins with different bridging groups: methylene, methinephenyl and methine-naphthyl, respectively, between bisphenol-A phenyl rings were prepared to study the effect of structure of bridging group on curing and properties of the epoxy resins. The structures of the obtained epoxy resins were characterized using FT-IR and 1 H NMR spectra, the molecular weight and polydispersity index were determined using GPC. The effect of bridging groups on the curing kinetics, thermal mechanical properties, thermal stability, and moisture resistance of the synthesized epoxy resins cured with 4,4 0 -diaminodiphenyl sulphone (DDS) were investigated by dynamic differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, X-ray diffraction and moisture absorption measurement. It was concluded that the methylene-bridged epoxy resin possessed the highest curing reaction reactivity toward DDS and the methine-naphthyl-bridged epoxy network possessed the highest storage modulus, glass transition temperatures, thermal stability, and moisture resistance. Epoxy resin has been utilized in many applications such as surface coatings, structural adhesives, printed circuit board, insulation materials for electronic devices, and advanced composites matrices due to its good thermal and dimensional stability, excellent chemical and corrosion resistance, and superior mechanical and electrical properties, in addition to ease of handling and processabilities. However, in hightech applications lower thermal expansion, higher toughness, better heat and moisture resistance were required.1 For this reason, much work has been continuously directed toward improving their thermal and physical properties by modifications of epoxy resins, in both backbone and pendant groups. 2-5Several approaches were adopted to enhance the heat resistance of epoxy resins with increasing crosslink density or introducing bulky structures such as biphenyl or naphthalene.6-8 The introduction of naphthalene moiety is expected to greatly improve the thermal property and moisture resistance owing to its excellent rigidity, facile packing of molecules and significant degree of hydrophobicity.9-14 Many studies reported that epoxy resin showed remarkably higher glass transition temperature (T g ), higher thermal stability, higher flexural modulus, better moisture resistance, lower coefficient of thermal expansion when stiff naphthalene was inserted or appended by chemical modification. [15][16][17][18] In order to design and develop more novel epoxy resins with higher thermal and mechanical properties to meet the application need, the deeply understanding the effect of the molecular structure of materials on curing behavior, chemical and physical properties of epoxy resin was increasingly more important, because it can predict the end product properties of the new materials and provide a guide for the development process and speed up the development cycle. Varley et al. utilized the relationship between the ...

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“…The toughness of ceramics containing dispersions of zirconia particles can be increased significantly (by up to a factor of 4 or 5) through a dilatational phase transformation in the zirconia, providing crack-tip shielding [28,29]. In alumina/zirconia composites, the zirconia particles additionally present regions of superior toughness to cracks probing through the more brittle alumina.…”

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confidence: 99%

Experimental investigations of crack trapping in brittle heterogeneous solids

Mower

Argon

1995

Mechanics of Materials

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Over the past two decades many mechanisms of toughening have been considered for brittle solids. Some of the most prominent ones applicable to either monolithic materials or fiberreinforced composites include deformation-induced local transformations, micro-cracking, crack trapping, crack bridging, and fiber pull-out. Few if any of these have been studied in the past in a manner which permitted evaluation of the effects of individual mechanisms in the absence of other interacting mechanisms. Here we present the development, analysis and results of an experimental study of toughening by the process of crack trapping by second-phase particles (spheres and fibers) of such toughness that make them impenetrable by probing cracks, forcing the cracks to bow around the obstacles with increasing applied load.The model fracture specimens employed here were wedge-loaded double cantilever beams cast of a brittle epoxy, containing macroscopic (3mm-diameter) inclusions of Nylon or polycarbonate having similar elastic properties to the matrix. The tests were performed at -60*C to achieve controlled, stable crack propagation. Images of the crack fronts advancing at velocities of about 10-4 M/s were recorded with good resolution, providing a continuous record of crack-front shapes during the evolution of the crack-trapping process from the initial pinning configuration through the transition to crack-flank bridging. Remarkable agreement between these images and crack-front shapes predicted by the numerical simulation of Bower & Ortiz is demonstrated. A parametric approach was adopted to study the influence of obstacle spacing, surface adhesion and thermally-induced residual stresses upon the observed crack-front behavior and enhanced stress intensity required to propagate the cracks past these obstacles. Analysis of the quantitative data has demonstrated that, in brittle matrices containing particle volume fractions of approximately 0.2, toughness enhancement by over a factor of two, relative to neat matrix values, may be achieved through the crack-trapping mechanism alone, provided that a high level of adhesion can be maintained between the matrix and the tough reinforcing particles.

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Differential scanning calorimetry of the epoxy cure reaction

Cited by 265 publications

References 16 publications

Kinetic analysis of two DSC peaks in the curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate

Kinetic analysis of two DSC peaks in the curing of an unsaturated polyester resin catalyzed with methylethylketone peroxide and cobalt octoate

Effect of Structure of Bridging Group on Curing and Properties of Bisphenol-A Based Novolac Epoxy Resins

Experimental investigations of crack trapping in brittle heterogeneous solids

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