Epoxy aging

Moisture is a well-known plasticizer for macromolecules (14). Specifically, water penetrates into an epoxy network and can lower the glass temperature of the resin (15). In this report, moisture has for the first time been utilized as a probe to characterize denslfIcatlon process during epoxy aging. Also, using the same rationale, heavy water diffused Into the epoxy resin Is used to study the Interactions of moisture with the aging polymer by hydrogen-2 (deuterium) NMR spectroscopy. 

In an earlier communication ( 5), we reported enthalpy relaxation studies at 140°C aging. In this paper, both 110°C and 80 C sub-Tg annealing data are presented for neat-epoxy aging. Figure 12 shows the DSC scans of fully-cured epoxy samples that were quenched from above T and then subjected to aging at 110°C. The full line Is the first scan, and the dotted line represents a second scan taken Immediately after cooling from the Initial scan. The following observations were made ... 

Nickel dialkyldithiocarbamates stabili2e vulcani2ates of epichlorhydrinethylene oxide against heat aging (178). Nickel dibutyldithiocarbamate [56377-13-0] is used as an oxidation inhibitor in synthetic elastomers. Nickel chelates of substituted acetylacetonates are flame retardants for epoxy resins (179). Nickel dicycloalkyldithiophosphinates have been proposed as flame-retardant additives for polystyrene (180—182) (see Flame retardants Heat stabilizers). 

Allyl Glycidyl Ether. This ether is used mainly as a raw material for silane coupling agents and epichlorohydrin mbber. Epichlorohydrin mbber is synthesized by polymerizing the epoxy group of epichlorohydrin, ethylene oxide, propylene oxide, and aHyl glycidyl ether, AGE, with an aluminum alkyl catalyst (36). This mbber has high cold-resistance. 

In the synthesis of AGE with an acid as the catalyst, aHyl alcohol is added to the epoxy group of epichlorohydrin, yielding 3-aHyloxy-l-chloro-2-propanol [4638-03-3], which then undergoes cyclization with alkaU to yield AGE. Catalysts such as H2SO4, SnCl, BE (C2H )20 (33), heteropolyacids, HQO, andy -CH CgH SO H (34) are used. 

The demands on insulating materials in soil and fresh water are relatively low. Anodically evolved oxygen makes the use of aging-resistant insulating materials necessary. These consist of special types of rubber (neoprene) and stabilized plastics of polyethylene, and polyvinylchloride, as well as cast resins such as acrylate, epoxy, polyester resin and many others. 

Siebeif, A.R., Tolle, L.L. and Drake, R.S., CTBN-modified epoxies work in poor bonding conditions. Adhes. Age, 29, 19 (1986). 

Laminating resins. CNSL resins are added to laminates based on phenol-formaldehyde, epoxy, etc. to reduce brittleness and to improve flexibility of the product. The resins also exhibit better age hardening and improved bonding to the substrate [133,134,137,168]. 

Dimensional stability There is plastics with very good dimensional stability, and they are suitable where some age and environmental dimensional changes are permissible. These materials include polyphenylene oxide, polysulfone, phenoxy, mineral-filled phenolic, diallyl phthalate, epoxy, rigid vinyl, styrene, and various RPs. Such products will gain from an after-bake for dimensional stabilization. Glass fillers will improve the dimensional stability of all plastics. 

Due to the chemical structure, fimctionality and composition of their constituents, ordinary variations of the processing conditions as well as the quality of the raw materials have been observed to lead to changes of the fine structure which are often responsible of lower ageing resistence of the polymer. The data reported here correlate the morphology of some widely utilized epoxy matrices to the informations that can be obtained from the study of the sorption behaviours. 

Apicella, A., Nicolais, L., Carfagna, C., de Notaristefani, C., Voto, C. 27th National SAMPE Meet., San Diego, 1982, The Effect of the Prepolymer Composition on The Environmental Ageing of Epoxy Based Resins ... 

Figure 9. UV-visible absorption spectra of a stabilized PVC plate, with or without a 70 yin UV cured epoxy-acrylate coating, before and after QUV aging at 40°C...

It is also well known that during ageing, new compounds are formed by oxidation reactions. In fact, the presence of 20,24-epoxy-25-hydroxy-dammaren-3-one and 3-oxo-trisnor-... 

Epoxy resins 1936 Adhesives, especially for glass repair Resistant to acid, alkali and organic solvents. Tendency to yellowing with ageing... 

Figure 12.3 GC/MS (a) and THM GC/MS (b) curves of aged dammar. Peak assignments 2, a cubebene 3, copaene 4, ft bourbonene 8,10 12, cadinane type pyrolysis fragments 14 16, cadinene type pyrolysis fragments 17, calamanene type pyrolysis fragments 18 21, unidentified sesquiterpenoids 22, dammaradienone 23, dammaradienol 24, nor a amyrone 25, 28 nor olean 17 en 3 one 26, dammarenolic acid methyl ester 27, oleanonic acid 28, hydroxydammarenone 29, oleanonic aldehyde 30, ursonic acid methyl ester 31, ursonic aldehyde 32, nor (3 amyrone 34, 20,24 epoxy 25 hydroxy 3,4 seco 4(28) dammaren 3 oic acid methyl ester 35, 20,24 epoxy 25 hydroxy dammaren 3 one 36, dammaradienol...

Synonyms AGE AI3-37791 AllyE2,3-epoxypropyl ether l-Allyloxy-2,3-epoxypropane BRN 0105871 CCRIS 2375 EINECS 203-442-4 l,2-Epoxy-3-allyloxypropane Glycidyl allyl ether M 560 NC1-C56666 NSC 18596 [(2-Propenyloxy)methyl]oxirane UN 2219. 

Figure 1. The assignments of FTIR-RA spectra of unaged epoxy free and coated films on steel have been given previously ( ). It should be noted that this aged specimen exhibited extensive filiform corrosion after 7 months exposure. Figures 2 show the spectral changes at different exposure periods. These spectra have been normalized for the baseline shift resulting from the reflection change of the steel substrate due to exposure and corrosion.

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