Experimental studies on comparison of microwave curing and thermal curing of epoxy resins used for alternative mould materials

2004 ◽  
Vol 155-156 ◽  
pp. 1532-1538 ◽  
Author(s):  
K.D.V.Prasad Yarlagadda ◽  
Shu-Hau Hsu
Keyword(s):  
Epoxy Resins ◽  
Experimental Studies ◽  
Thermal Curing ◽  
Microwave Curing

scholarly journals CHEMICALLY RESISTANT FLAME RETARDING COATINGS BASED ON EPOXY-AMINE COMPOSITES MODIFIED WITH COPPER(II) CARBONATE

Fire Safety ◽  
2019 ◽  
pp. 66-71
Author(s):  
P. V. Pastuhov ◽  
V. V. Kochubei ◽  
O. I. Lavrenyuk ◽  
B. M. Mykhalichko
Keyword(s):  
Flame Propagation ◽  
Epoxy Resins ◽  
Experimental Studies ◽  
Gravimetric Method ◽  
Fire Retardant ◽  
Propagation Rate ◽  
Binding Agent ◽  
Corrosive Media ◽  
Epoxy Amine ◽  
Effect Of Copper

Introduction. The development of modern technologies and the elaboration of new materials facilitates the wide use of epoxy resins for instance in industries. Particular attention deserves the various fire retardant coatings making. These coatings are increasingly used to increase fire resistance of details and designs made of metals, plastics, wood in various industrial and civil constructions, and in transport. The very perspective mode producing the effective fire retardant coatings is the direct introduction into the polymeric matrix of epoxy resins of reactive fire retardant agents. Purpose. The aim of this work is to study the effect of the elaborated fire retardant on the ability of epoxy-amine composites modified with copper(II) carbonate to resist the spread of the flame, as well as the effects of water and chemicals. Metods. The flame propagation rate on the surface of horizontally located experimental samples was determined according to all-State Standard 28157-89. Water and chemical resistance were evaluated by a gravimetric method on the polymer mass film change after exposure to distilled water and corrosive media for a certain period of time. Results. The results of experimental studies have shown that samples of the epoxy-amine composites containing 20, 40 and 80 mass parts of CuCO3 per 100 mass part of the binding agent do not propagate the flame horizontally at all. At that, duration of free combustion of these polymer samples did not exceed 2 min. It has been found too that the penetrability of water and chemicals through films based on epoxy-amine composites modified with CuCO3 is reduced due to the formation of chemical bonds between copper(II) carbonate and polyethylenepolyamine. The lowest level of the equilibrium absorption in water and 10% aqueous solutions of H2SO4 and NaOH was watched for samples of those composites that contained 20 mass parts of CuCO3 per 100 mass parts of binder. Conclusion. When studying the effect of copper(II) carbonate on the flame propagation rate, it was found that the epoxy-amine composites containing >20 mass parts of CuCO3 per 100 mass parts of the binding agent, do not propagate the flame and so these are self-extinguishing. The copper(II) carbonate addition to epoxy polymers reduces their sorption capacity in water and solutions of alkalis and acids. These data are the basis to future develop the chemically resistant fire retarding coatings based on epoxy-amine composites modified with copper(II) carbonate. Keywords

Variations of the dielectric properties of epoxy resins during microwave curing

1991 ◽  
Vol 27 (4-5) ◽  
pp. 371-376 ◽  
Author(s):  
Michel Delmotte ◽  
Henri Jullien ◽  
Michel Ollivon
Keyword(s):  
Dielectric Properties ◽  
Epoxy Resins ◽  
Microwave Curing

Analysis of the effect and mechanism of microwave curing on the chemical shrinkage of epoxy resins

2016 ◽  
Vol 29 (10) ◽  
pp. 1165-1174 ◽  
Author(s):  
Xiaochun Wu ◽  
Yingguang Li ◽  
Nanya Li ◽  
Jing Zhou ◽  
Xiaozhong Hao
Keyword(s):  
Epoxy Resins ◽  
Diglycidyl Ether ◽  
Heating Process ◽  
Hydroxyl Groups ◽  
Chemical Shrinkage ◽  
Positron Annihilation Lifetime ◽  
Microwave Curing ◽  
Diaminodiphenyl Sulfone ◽  
Influencing Mechanism ◽  
Lower Tensile Strength

The microwave cure–induced chemical shrinkage of epoxy resins in composite materials was researched in this article. Four kinds of epoxy resins were cured using the microwave and thermal heating process. An improved device containing fiber Bragg grating sensors was applied to accurately measure the chemical shrinkage–induced linear strains in those samples. Experimental results indicated that the chemical shrinkage of diglycidyl ether of bisphenol A (DGEBA)/polyetheramine (PEA) and tetraglycidyl diaminodiphenylmethane/4,4′-diaminodiphenyl sulfone epoxy resins was significantly reduced by microwave curing, and the reductions about 37.1 and 38.4% were achieved compared with the thermal-cured counterparts. However, the chemical shrinkage of the thermal- and microwave-cured samples was almost the same for DGEBA/methyl tetrahydrophthalic anhydride and DGEBA/dicyandiamide epoxies. In order to analyze the influencing mechanism of microwaves on the chemical shrinkage, the chemical structure of various samples was characterized by using Fourier-transform infrared spectroscopy, and the free volume was measured by positron annihilation lifetime spectrometer. It was found that microwaves can greatly decrease the contents of hydroxyl groups in epoxy resins, leading to the reduction of the chemical shrinkage. Furthermore, the mechanical properties of both microwave- and thermal-cured DGEBA/PEA epoxies were studied, and the results showed that the microwave-cured specimens have a higher impact strength but a lower tensile strength.

scholarly journals Enhancing Toughness and Impact Strength of Epoxy Resins by Using Hyperbranched Polymers

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hangyu Park ◽  
Youngson Choe
Keyword(s):  
Molecular Weight ◽  
Impact Strength ◽  
Epoxy Resins ◽  
Impact Resistance ◽  
Experimental Studies ◽  
Molecular Size ◽  
Hyperbranched Polymers ◽  
Phase Separations ◽  
Hyperbranched Poly ◽  
The Impact

Toughened epoxy has been widely used in industrial areas such as automotive and electronics. In this study, nanosized hyperbranched polymers (HBPs) as a flexibilizer are synthesized and embedded into epoxy resin to enhance the toughness and flexibility. Two different HBPs, hyperbranched poly(methylacrylate-diethanolamine) (poly(MA-DEA)) and poly(methylacrylate- ethanolamine) (poly(MA-EA)), were prepared and blended with both epoxy and polyetheramine, a curing agent. The molecular size of HBPs was estimated to be 6 ~ 14 nm in diameter. The molecular weight of HBPs ranges from 1500(1.5 K) to 7000(7.0 K) g/mol. In cured epoxy/HBP blends, no phase separations are occurred, indicating that HBPs possess sufficient miscibility with epoxy. The tensile toughness of the blends increased with changing the molecular weight of HBPs without sacrificing tensile strengths. The impact strength of the blends increases stiffly until the loading % of HBPs in the blends reaches 10 wt%. In addition, the experimental studies showed that impact resistance also increased with an increase in molecular weight of HBPs. The obtained impact resistance of the epoxy/HBP blends with 10 wt% was 270% more effective compared to that of cured neat epoxy.

Effects of Rapid Microwave-Curing on Mechanical and Piezoresistive Sensing Properties of Elastomeric Nanocomposites

2020 ◽  
Author(s):  
Blake Herren ◽  
Mrinal C. Saha ◽  
M. Cengiz Altan ◽  
Yingtao Liu
Keyword(s):  
Electrical Conductivity ◽  
Compressive Modulus ◽  
Microwave Oven ◽  
Thermal Curing ◽  
Microwave Curing ◽  
Convection Oven ◽  
Curing Methods ◽  
One Step ◽  
The One ◽  
Curing Procedure

Abstract Carbon nanotubes (CNTs) have the unique ability to absorb microwave radiation and efficiently transfer the energy into substantial heat. When adequately dispersed in a thermoset polymer, such as polydimethylsiloxane (PDMS), the nanocomposite can be fully cured in seconds in a microwave oven rather than in hours in a convection oven. In this paper, cylindrical PDMS nanocomposites containing well-dispersed CNTs are fabricated by either microwave-curing or conventional thermal-curing. The mechanical, electrical, and piezoresistive properties of the fabricated samples are compared to understand the effects of different curing methods. Microwave-cured nanocomposites exhibit a significantly reduced compressive modulus for different CNT loadings. In addition, the electrical conductivity of microwave-cured nanocomposites is significantly enhanced over the thermally-cured counterparts. Experimental results demonstrate that the one-step microwave-curing procedure can improve the electrical conductivity of 1 wt% nanocomposites by almost 150 % over thermal-curing. However, their piezoresistive sensitivity remains remarkably similar, showing the potential for microwave-curing to replace thermal-curing for the manufacturing of highly flexible CNT-based nanocomposites.

Microwave curing of epoxy resins with diaminodiphenylmethane II. Crosslinking under continuous or pulsed waves

1988 ◽  
Vol 24 (1) ◽  
pp. 49-52 ◽  
Author(s):  
Nadir Beldjoudi ◽  
Abdelaziz Bouazizi ◽  
Driss Douibi ◽  
Albert Gourdenne
Keyword(s):  
Epoxy Resins ◽  
Microwave Curing

Automation of Microwave Processing of Graphite / Epoxy Composite Materials using an Expert Systems Technique

1992 ◽  
Vol 269 ◽  
Author(s):  
Valerie Adegbite ◽  
Martin Hawley ◽  
Dave Decker ◽  
Jon Sticklen
Keyword(s):  
Composite Materials ◽  
Expert Systems ◽  
Major Elements ◽  
Process Models ◽  
Thermal Curing ◽  
Monitoring And Control ◽  
Microwave Curing ◽  
Selective Heating ◽  
Cure Monitoring ◽  
And Control

ABSTRACTMicrowave curing of composite materials is a novel technology which can be an alternative to conventional thermal curing and has many advantages over thermal curing, i.e, fast and direct heating, selective heating, and controllability. Currently, the existing technology is more empirical and cannot be easily described by traditional process models. One key enabling step for realizing the advantages of the microwave curing technology is a capability for utilizing all the available existing knowledge in a concise manner. The major elements of a control system which utilizes traditional control techniques and (non-traditional) expert systems techniques in a real time microwave cure monitoring and control is discussed.

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