Effect of a heterogeneous network on glass transition dynamics and solvent crack behavior of epoxy resins

Soft Matter ◽  
2020 ◽  
Vol 16 (32) ◽  
pp. 7470-7478 ◽  
Author(s):  
Mika Aoki ◽  
Atsuomi Shundo ◽  
Satoru Yamamoto ◽  
Keiji Tanaka
Keyword(s):  
Glass Transition ◽  
Epoxy Resin ◽  
Network Structure ◽  
Heterogeneous Network ◽  
Epoxy Resins ◽  
Curing Temperature ◽  
Transition Dynamics ◽  
Crack Behavior

Network structure in an epoxy resin, which became more heterogeneous with increasing pre-curing temperature, affected the glass transition dynamics and solvent crack behavior.

Study on the Composites Epoxy Resin/Nano-TiO2/Polyester

2013 ◽  
Vol 787 ◽  
pp. 408-412
Author(s):  
Jiao Yan Ai ◽  
Quan Chen ◽  
Xiao Bo Wang
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Diethylene Glycol ◽  
Epoxy Resins ◽  
Experimental Results ◽  
Hydroxybenzoic Acid ◽  
Suitable Amount

Two kinds of polyester bis (p-hydroxybenzoic acid) butanediolatepolyester (BDPET) and bis (p-hydroxybenzoic acid) diethylene glycol (DGPET) were synthesized through melting transesterification reaction.Then the epoxy resins were modified with BDPET or DGPET,and nanoTiO2. The composites were characterized by DSC and SEM. The experimental results showed that the polyester can act as an effective toughening modifier for the epoxy resin. The mechanical properties of the composites were greatly improved and reached to the maxium at 4wt.%PET. The PET/EP system modified by adding suitable amount of nanoTiO2have better performance.The glass transition temperature (Tg) of PET/EP and nanoTiO2/PET/EP system improved about 20°Cand 27.8°C,respectively.

EFFECT OF CURING TEMPERATURE OF EPOXY RESIN ON THE ELECTRICAL RESPONSE OF CARBON NANOTUBE YARN MONOFILAMENT COMPOSITES

2021 ◽  
Author(s):  
OMAR RODRIGUEZ-UICAB ◽  
JANDRO L. ABOT ◽  
FRANCIS AVILÉS
Keyword(s):  
Carbon Nanotube ◽  
Epoxy Resin ◽  
Electrical Resistance ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Negative Temperature Coefficient ◽  
Electrical Response ◽  
Negative Temperature ◽  
Curing Temperature ◽  
Temperature Coefficient Of Resistance

The cyclic thermoresistive response of individual carbon nanotube yarns (CNTYs) embedded into epoxy resins is investigated. The influence of the temperature at which the epoxy resin cures on the thermoresistive response is investigated by using two epoxy resins, one that cures at room temperature and the other one that cures at 130 °C. Heating-cooling cycles ranging from room temperature (RT, 25 °C) to 80 °C, incremental cycles (RT to 40 °C, RT to 60 °C and RT to 80 °C) and incremental heating-dwell cycles are applied to monofilament composites, while their electrical resistance is simultaneously recorded. The monofilament composites showed a negative temperature coefficient of resistance during the heating-cooling cycles of -7.07x10-4 °C-1 for specimens cured at high temperature, and -5.93x10-4 °C-1 for specimens cured at room temperature. The hysteresis after the different heating-cooling cycles was slightly smaller for specimens cured at 130 °C, in comparison to specimens cured at room temperature. Several factors including the intrinsic thermoresistivity of CNTY, level of infiltration and the effect of curing temperature may explain the thermoresistive sensitivity of the monofilament composites.

scholarly journals Curing of Epoxy Resin DER-331 by Hexakis(4-acetamidophenoxy)cyclotriphosphazene and Properties of the Prepared Composition

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1191 ◽  
Author(s):  
Evgeniy M. Chistyakov ◽  
Ivan V. Terekhov ◽  
Aleksey V. Shapagin ◽  
Sergey N. Filatov ◽  
Vladimir P. Chuev
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ir Spectroscopy ◽  
Epoxy Resin ◽  
Curing Temperature ◽  
Optimum Temperature ◽  
Scanning Calorimetry ◽  
Optical Wedge

The method of optical wedge revealed that the optimum temperature for compatibility of hexakis(4-acetamidophenoxy)cyclotriphosphazene (ACP) and DER-331 epoxy resin is in the range of 220–260 °C. The interdiffusion time of components at these temperatures is about 30 min. The TGA and differential scanning calorimetry (DSC) methods revealed the curing temperature of 280 °С for this composition. IR spectroscopy confirmed that the reaction between the resin and ACP is completed within 10 min. According to the DSC data, a glass transition temperature of 130 °С was estimated for the cured resin. Combustion test UL-94 demonstrated that the obtained material can be assigned to the fireproof category of V-0. Burning droplets were not formed during the burning. The coke formed during the combustion of samples possessed a dense and porous structure. The shape of pores is closed, while their size is in the range of 0.2–200 µm.

Chemical Monitoring of Composite Matrices Using Evanescent Wave Spectroscopy

2008 ◽  
Vol 56 ◽  
pp. 297-302
Author(s):  
Peter B.S. Bailey ◽  
S.A. Hayes ◽  
R.J. Hand ◽  
B. Zhang
Keyword(s):  
Glass Transition ◽  
Epoxy Resin ◽  
Evanescent Wave ◽  
Chalcogenide Glasses ◽  
Curing Temperature ◽  
Chemical Degradation ◽  
Glass Transition Point ◽  
Lead Sulphide ◽  
Sensing Applications ◽  
Arsenic Selenide

The results of an initial investigation into the monitoring of water absorption and chemical degradation in epoxy matrix composites using evanescent wave spectroscopy are presented. While conventional silica glasses have too low a refractive index and too short an IR transmission window to be useful as unclad sensing elements in most resin systems, chalcogenide glasses offer suitable refractive indices and infrared transmission windows. Arsenic selenide compositions with gallium or tellurium additions were initially investigated as they have been successfully demonstrated in other fibre sensing applications. However their glass transition point lies near or below the curing temperature for many commercial epoxy resins and thus germanium-antimony-lead sulphide glasses were also investigated as they display higher glass transition temperatures. The fibres were embedded in a representative matrix resin by casting samples of epoxy resin around sections of fibre. The end faces were prepared to allow an infrared beam to be passed along the fibre and the samples were subjected to hygrothermal aging. Changes in the transmitted spectra were observed, and photoelasticity was used to monitor the occurrence of fibre fragmentation. Both the arsenic selenide based compositions and the germanium-antimony-lead sulphide compositions displayed minimal bonding with the epoxy resin, so a simple silane treatment was used to improve adhesion.

High Temperature Resistance of Polyborosilazane/Epoxy Resin Curing System

2017 ◽  
Vol 898 ◽  
pp. 2294-2301 ◽  
Author(s):  
Chen Yu Zhang ◽  
Yong Liu ◽  
Ke Qing Han ◽  
Xue Feng Chang ◽  
Mu Huo Yu
Keyword(s):  
Thermal Stability ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Curing Temperature ◽  
Temperature Resistance ◽  
Curing Agents ◽  
Resin Curing ◽  
Residual Weight ◽  
Thermal Stability Of ◽  
Better Than

In this paper, Polyborosilazane (PBSZ) was successfully synthesized and used as curing agents for epoxy resin. FTIR, TGA, XRD, SEM were used to analyze the curing mechanism, curing temperature and thermal stability of the curing system. The results indicated that PBSZ could be used as curing agents for bisphenol A epoxy resin when its usage amount was 30-60 wt.% at the temperature between 100 ∼ 150 °C. Additionally, the thermal stability of PBSZ cured epoxy resin samples were better than that of epoxy resin cured with 4, 4-diaminodiphenylsulfone (DDS), showing a higher residual weight at 900°C. As PBSZ content increased, the residual weight of PBSZ cured epoxy resin at 900°C increased. When PBSZ content was 30%, the surface of cured epoxy resins was smooth without obvious defects. However, the surface became coarse when PBSZ content was further increased.

Epoxy Resin Embedment

1968 ◽  
Vol 26 ◽  
pp. 100-101
Author(s):  
J. G. Adams ◽  
M. M. Campbell ◽  
H. Thomas ◽  
J. J. Ghldonl
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Epoxy Resin ◽  
Light Microscope ◽  
Epoxy Resins ◽  
Image Contrast ◽  
Tissue Preservation ◽  
Resin System ◽  
Excellent Quality

Since the introduction of epoxy resins as embedding material for electron microscopy, the list of new formulations and variations of widely accepted mixtures has grown rapidly. Described here is a resin system utilizing Maraglas 655, Dow D.E.R. 732, DDSA, and BDMA, which is a variation of the mixtures of Lockwood and Erlandson. In the development of the mixture, the Maraglas and the Dow resins were tested in 3 different volumetric proportions, 6:4, 7:3, and 8:2. Cutting qualities and characteristics of stability in the electron beam and image contrast were evaluated for these epoxy mixtures with anhydride (DDSA) to epoxy ratios of 0.4, 0.55, and 0.7. Each mixture was polymerized overnight at 60°C with 2% and 3% BDMA.Although the differences among the test resins were slight in terms of cutting ease, general tissue preservation, and stability in the beam, the 7:3 Maraglas to D.E.R. 732 ratio at an anhydride to epoxy ratio of 0.55 polymerized with 3% BDMA proved to be most consistent. The resulting plastic is relatively hard and somewhat brittle which necessitates trimming and facing the block slowly and cautiously to avoid chipping. Sections up to about 2 microns in thickness can be cut and stained with any of several light microscope stains and excellent quality light photomicrographs can be taken of such sections (Fig. 1).

The Mechanical Properties of Organic Modified Epoxy Resin

2020 ◽  
Vol 43 (3) ◽  
pp. 10-14
Author(s):  
Georgel MIHU ◽  
Claudia Veronica UNGUREANU ◽  
Vasile BRIA ◽  
Marina BUNEA ◽  
Rodica CHIHAI PEȚU ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Epoxy Resin ◽  
Epoxy Matrix ◽  
Epoxy Resins ◽  
Mechanical Tests ◽  
Organic Modification ◽  
Three Point Bending ◽  
Modified Epoxy

Epoxy resins have been presenting a lot of scientific and technical interests and organic modified epoxy resins have recently receiving a great deal of attention. For obtaining the composite materials with good mechanical proprieties, a large variety of organic modification agents were used. For this study gluten and gelatin had been used as modifying agents thinking that their dispersion inside the polymer could increase the polymer biocompatibility. Equal amounts of the proteins were milled together and the obtained compound was used to form 1 to 5% weight ratios organic agents modified epoxy materials. To highlight the effect of these proteins in epoxy matrix mechanical tests as three-point bending and compression were performed.

scholarly journals Investigation of the functional network modifier loading on the stoichiometric ratio of epoxy resins and their dielectric properties

2021 ◽  
Author(s):  
Istebreq A. Saeedi ◽  
Sunny Chaudhary ◽  
Thomas Andritsch ◽  
Alun S. Vaughan
Keyword(s):  
Glass Transition ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Epoxy Resins ◽  
Functional Network ◽  
Cross Linking ◽  
Network Modifier ◽  
Epoxy Resin System ◽  
The Cross ◽  
The Impact

AbstractReactive molecular additives have often been employed to tailor the mechanical properties of epoxy resins. In addition, several studies have reported improved electrical properties in such systems, where the network architecture and included function groups have been modified through the use of so-called functional network modifier (FNM) molecules. The study reported here set out to investigate the effect of a glycidyl polyhedral oligomeric silsesquioxane (GPOSS) FNM on the cross-linking reactions, glass transition, breakdown strength and dielectric properties of an amine-cured epoxy resin system. Since many previous studies have considered POSS to act as an inorganic filler, a key aim was to consider the impact of GPOSS addition on the stoichiometry of curing. Fourier transform infrared spectroscopy revealed significant changes in the cross-linking reactions that occur if appropriate stoichiometric compensation is not made for the additional epoxide groups present on the GPOSS. These changes, in concert with the direct effect of the GPOSS itself, influence the glass transition temperature, dielectric breakdown behaviour and dielectric response of the system. Specifically, the work shows that the inclusion of GPOSS can result in beneficial changes in electrical properties, but that these gains are easily lost if consequential changes in the matrix polymer are not appropriately counteracted. Nevertheless, if the system is appropriately optimized, materials with pronounced improvements in technologically important characteristics can be designed.

scholarly journals Studies on the Modification of Commercial Bisphenol-A-Based Epoxy Resin Using Different Multifunctional Epoxy Systems

2021 ◽  
Vol 2 (2) ◽  
pp. 419-430
Author(s):  
Ankur Bajpai ◽  
James R. Davidson ◽  
Colin Robert
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Bisphenol A ◽  
Epoxy Resin ◽  
Tensile Fracture ◽  
Chemical Structures ◽  
Amino Phenol ◽  
Epoxy Systems

The tensile fracture mechanics and thermo-mechanical properties of mixtures composed of two kinds of epoxy resins of different chemical structures and functional groups were studied. The base resin was a bi-functional epoxy resin based on diglycidyl ether of bisphenol-A (DGEBA) and the other resins were (a) distilled triglycidylether of meta-amino phenol (b) 1, 6–naphthalene di epoxy and (c) fluorene di epoxy. This research shows that a small number of multifunctional epoxy systems, both di- and tri-functional, can significantly increase tensile strength (14%) over neat DGEBA while having no negative impact on other mechanical properties including glass transition temperature and elastic modulus. In fact, when compared to unmodified DGEBA, the tri-functional epoxy shows a slight increase (5%) in glass transition temperature at 10 wt.% concentration. The enhanced crosslinking of DGEBA (90 wt.%)/distilled triglycidylether of meta-amino phenol (10 wt.%) blends may be the possible reason for the improved glass transition. Finally, the influence of strain rate, temperature and moisture were investigated for both the neat DGEBA and the best performing modified system. The neat DGEBA was steadily outperformed by its modified counterpart in every condition.

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