Thermal Properties Of Epoxy Resin Research Articles

The effect of POSS on the thermal properties of epoxy

The thermal properties of a series of inorganic-organic diglycidyl ether of bisphenol A/octa(aminpropyl)silsesquioxane (EP/POSS-NH2) composites of were systematically investigated. These thermal properties included dynamic mechanical properties, glass transition temperature and thermal degradation temperature. Dynamic mechanical analysis (DMA) and Thermogravimetric analysis (TGA) were adopted. Results showed that the incorporation of POSS into epoxy resin could improve the thermal stabilities of epoxy significantly.

Glass transition and thermal decomposition of epoxy resins from the carboxylic acid system consisting of ester-carboxylic acid derivatives of alcoholysis lignin and ethylene glycol with various dicarboxylic acids

Alcoholysis lignin (AL) was dissolved in ethylene glycol and the obtained mixture was reacted with succinic anhydride to form a mixture of ester-carboxylic acid derivatives of AL and ethylene glycol (AL-poly(ester-carboxylic acid), ALEGPA). The obtained ALEGPA was mixed with dicarboxylic acids with different alkylene chain length such as succinic acid (alkylene chain, C 2), adipic (C 4) acid and sebacic acid (C 8). The obtained mixture of ALEGPA and dicarboxylic acid was reacted with ethylene glycol diglycidyl ether in the presence of a catalytic amount of dimethylbenzylamine to form ester-epoxy resins. The curing reaction was carried out at 130 °C for 5 h. The molar ratio of epoxy groups to carboxylic acid groups ([EPOXY]/[AA] ratios, mol/mol) was 1.0. The ALEGPA content in the above mixture was varied from 0 to 100%. Thermal properties of epoxy resins were studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). Glass transition temperatures ( T g's) increased with increasing ALEGPA contents, suggesting that lignin acts as a hard segment in epoxy resin networks. The values of T g's of epoxy resins with dicarboxylic acids increased in the following order; epoxy resins with succinic acid (alkylene chain, C 2), adipic acid (C 4) and sebacic acid (C 8). Thermal degradation temperatures ( T d's) of epoxy resins slightly decreased with increasing ALEGPA contents. The values of mass residue at 500 °C (MR 500) increased with increasing AL contents in epoxy resins and also with decreasing chain lengths of dicarboxylic acids.

Curing and Glass Transition of Epoxy Resins from Ester‐Carboxylic Acid Derivatives of Mono‐ and Disaccharides, and Alcoholysis Lignin

AbstractMono‐ and disaccharides (SAC) such as glucose (Glc), fructose (Frc) and sucrose (Suc), and also alcoholysis lignin (AL) were dissolved in ethylene glycol and each of the obtained mixtures was reacted with succinic anhydride to form a mixture of ester‐carboxylic acid derivatives such as SAC‐polyacid, SACPA, and AL‐polyacid, ALPA. Ethylene glycol‐polyacid (EGPA) was also prepared from ethylene glycol. Each of the obtained mixtures of ester carboxylic acid derivatives was reacted with ethylene glycol diglycidyl ether in the presence of a catalytic amount of dimethylbenzylamine to form ester‐epoxy resins. The molar ratios of epoxy groups to carboxylic acid groups ([EPOXY]/[ACID] ratios, mol mol−1) was maintained at 1.0. The contents of SACPA and ALPA in the mixtures of SACPA/EGPA, and ALPA/EGPA, respectively, were also varied from 0 to 100 %. The curing reaction of SucPA and ALPA was studied by differential scanning calorimetry (DSC). Activation energy of the curing reaction for the SucPA system was 80.5 kJ/mol. Thermal properties of epoxy resins were studied by DSC. Glass transition temperatures (Tg) decreased with increasing numbers of repeating units in ester chains between cross‐linking points, suggesting that ester chain lengths between cross‐linking points mainly affect the mobility of ester chains in epoxy resin networks.

Synthesis and thermal properties of epoxy resins from ester‐carboxylic acid derivative of alcoholysis lignin

AbstractAlcoholysis lignin (AL) was dissolved in ethylene glycol and the obtained mixture was reacted with succinic anhydride to form a mixture of ester‐carboxylic acid derivatives (AL‐polyacid, ALPA). Ethylene glycol‐polyacid (EGPA) was also prepared from ethylene glycol. The obtained mixture of ester carboxylic acid derivatives was treated with ethylene glycol diglycidyl ether in the presence of catalytic amount of dimethylbenzylamine to form ester‐epoxy resins. The curing reaction was analyzed by Ozawa's method using differential scanning calorimetry. The activation energy of curing reaction in the initial step was found to be ca. 84 kJ mol−1. The molar ratios of epoxy groups to carboxylic acid groups ([EPOXY]/[AA] ratios) were varied from 0.8 to 1.3. The contents of ALPA in the mixture of ALPA and EGPA were also varied from 0 to 100%. Thermal properties of epoxy resins were studied by DSC and thermogravimetry. Glass transition temperatures of epoxy resins showed a maximum value of −11.5 °C when [EPOXY]/[AA] ratio was 1.1. Tg increased with increasing ALPA contents suggesting that lignin acts as a hard segment in epoxy resin networks. Thermal degradation temperatures of epoxy resins slightly decreased with increasing ALPA contents.

Erratum to : Thermal Properties of Epoxy Resins from Ester-Carboxylic Acid Derivatives of Mono- and Disaccharides

Erratum to : Thermal Properties of Epoxy Resins from Ester-Carboxylic Acid Derivatives of Mono- and Disaccharides

Rheological and thermal properties of epoxy resins obtained from epichlorohydrin and m- or p-aminophenol, cured with triethylenetetraamine

Synthesis of triglycidyl derivatives of m- or p-aminophenol and their crosslinking with triethyltetraamine (TETA) has been described. The obtained products have been characterized by IR and l H NMR methods and rheologicalproperties. The curing reaction with TETA has been investigated by differential scanning calorimetry (DSC). Thermal stability of the cured products has been studied by thermogravimetric analysis (TGA).

Thermal stability of epoxy resins containing flame retardant components: an evaluation with thermogravimetric analysis

The thermal properties of epoxy resins containing flame retardants based on silicon, phosphorus, and melamine, were investigated with thermogravimetric analysis (TGA). The weight loss behaviour (including the weight loss temperatures, weight loss rates, and the activation energy for each weight loss stage) and the thermal stability (including the initial decomposition temperature and integral procedure decomposition temperature) were characterized. Phosphorus groups lowered the epoxy resins' initial decomposition temperature, and silicon and melamine groups did not. The integral procedure decomposition temperatures of the epoxy resins were significantly increased with simultaneous incorporation of phosphorus and silicon, owing to the formation of highly anti-oxidant and thermally stable char. Incorporating melamine groups into the silicon-containing epoxy resins did not seriously alter the resins' thermal stability and degradation characteristics.

1205 電熱ヒータへの適用に対する導電性エポキシカーボンブラック複合材の電気的・熱的特性(G.S.11 材料工学)

Studies on the effect of carbon black on the electrical and thermal properties of epoxy are presented in this paper. The analysis covered the network structure, electrical and thermal properties on the content of carbon black in epoxy. The conductivity of epoxy carbon black composites was recorded during one cycle between room temperature and high temperature (depend on CB content). The conductivity of epoxy depends on the content of CB and reached values of between 2×1^<-9> (Ωcm)^<-1> to 3×10^<-4> (Ωcm)^<-1>. The values of Activation Energy (E_a) and Negative Temperature Coefficient of Conductivity (NTCC) of epoxy composites were calculated.

Curing behaviour and thermal properties of Epon 828 resin cured with diimide-diacid and phthalic anhydride

A diimide-diacid (DIDA) curing agent of N,N′-(4,4′-diphenylsulfone) bis(trimellitimide) was synthesized. Through the spectral characterization of infrared (i.r.), 1H n.m.r., 13C n.m.r., and of elemental analysis (EA), the DIDA structure was confirmed. The curing behaviour and resultant thermal properties of epoxy resin (Epon 828) with DIDA were studied by differential scanning calorimetry (d.s.c.) and thermogravimetric analysis (t.g.a.), respectively. In order to improve the processing ability, DIDA was partially replaced by phthalic anhydride (PA) in the formulations carried. The thermal resistance depended on the relative proportions of curing agents in the formulations.

Mechanical and thermal properties of epoxy resins with reversible crosslinks

AbstractThe tensile properties: Young's modulus, ultimate tensile strength, ultimate elongation, the glass transition temperature, and the dynamic mechanical properties (dynamic shear modulus (G'), loss tangent (Tan δ)), of three epoxy resins (Epon 828, Epon 836, Epon HPT 1071) cured with the disulfide‐containing crosslinking agent—4.4‐dithiodianilme (DTDA) have been characterized. The results show that DTDA is a satisfactory crosslinking agent for the epoxide resins that have been studied as compared to the well‐known curing agent methylene dianiline (MDA). There are no significant differences between the properties of Epon 828 cured with DTDA at stoichiometric ratio (2:1) and Epon 828 cured with DTDA at small amine excess ratio (1.75:1). The glass transition temperature of the cured tetrafunctional epoxy resin Epon HPT 1971 (235°C) is significantly higher than that of difunctional epoxy resins such as Epon 828 (Tg–175°C), but the product is too brittle to be used without plasticizer.

Thermal properties of epoxy resin cured with imidazole

Thermal properties of epoxy resin cured with imidazole

Percolation in the effective-medium approximation: Crossover between phonon and fracton excitations

The $d$-dimensional bond-percolating network has been examined with the use of the effective-medium approximation (EMA) of Odagaki and Lax and of Webman. We have found that the fracton dimensionality $\stackrel{-}{\stackrel{-}{d}}=1$ for $2ldl4$, and have obtained explicit values for $\stackrel{-}{\stackrel{-}{d}}$ between $1ldl2$. We have calculated the vibrational density of states, $N(\ensuremath{\omega})$, for percolating networks within the EMA for $d$ in these ranges. We find at $2ldl4$ that a steep change in $N(\ensuremath{\omega})$ takes place between phonon, ${N}_{\mathrm{ph}}(\ensuremath{\omega})$, and fracton, ${N}_{\mathrm{fr}}(\ensuremath{\omega})$, excitation regimes at a critical frequency ${\ensuremath{\omega}}_{c}$ which scales as $p\ensuremath{-}{p}_{c}$. The ratio $\frac{{N}_{\mathrm{fr}}({\ensuremath{\omega}}_{c})}{{N}_{\mathrm{ph}}({\ensuremath{\omega}}_{c})}$ is found to scale as ${(p\ensuremath{-}{p}_{c})}^{1\ensuremath{-}\frac{d}{2}}$. These results provide substantial support for the fracton interpretation of the thermal properties of epoxy resin, glasses, and neutron-irradiated quartz as hypothesized by Alexander, Laermans, Orbach, and Rosenberg. At $d=2$, the transition between the two regimes is smoother (logarithmic), but a clearly defined phonon and fracton regime can be ascertained. The velocity of sound in the phonon regime scales as ${(p\ensuremath{-}{p}_{c})}^{\frac{1}{2}}$, independent of $d$ for $2ldl4$. Finally, we have obtained within the EMA a closed expression for the mean-square diffusion length $〈{R}^{2}(t)〉$ for all times of order ${(p\ensuremath{-}{p}_{c})}^{\ensuremath{-}2}$. It is found to be a smooth function of time between the fractal and homogeneous diffusion regimes.

The effects of cross-link length on the thermal properties of epoxy-resins from 1.5 to 80 K

The thermal conductivity and diffusivity of epoxy-resins with cross-links of varying lengths have been measured from 1.5 to 80 K. The longer the cross-links, the higher is the conductivity in the liquid helium range, but this behaviour is inverted at 80 K. The specific heat is not dependent on the length of the cross-links. The results are discussed in the light of current ideas on the thermal properties of glasses.