Epoxy resin deterioration

Epon 828 resins, which are based on diglycidyl ether of bisphenol A filled with 40wt.% Si02, were irradiated at 4.9 K and tested at 77 K after being warmed up to room temperature. The flexural and compressive strengths of the filled epoxy resins were found to be little affected by a y-ray dose of 2 x 107 Gy, but to deteriorate significantly after exposure to 1 x 108 Gy [49],... 

Acetylene terminated (AT) resins are being studied as a new technology to form the matrix of high performance structural composites (1). This class of resin cures by an addition reaction mechanism. Because of the absence of volatile by-product during cure, these resins are easy to process to yield void-free components. These resins also have the advantage over epoxy resins in terms of resistance to deterioration of properties at elevated temperature due to exposure to humid environments (2). 

In one further work on epoxy-POSS, comparative studies were conducted on epoxy/ladderlike polyphenylsilsesquioxane (PPSQ) blends and the associated nanocomposites [2]. The work revealed that, although a decrease in the flexural strength and modulus of epoxy/POSS nanocomposites in comparison to the neat epoxy resin was observed, only flexural strength deteriorated in the epoxy/PPSQ blends compared to the neat epoxy resin. Flexural modulus of epoxy/PPSQ blends was reported to be much higher than that of the epoxy resin and also increased with an increase in POSS content. It was... 

Of course, floors in a structure receive the greatest abuse, where deterioration occurs in such areas, epoxy resin systems have been widely used for repairs. Industrial floors are now constructed with initial specifications calling for an epoxy mortar, usually, 1/4 inch in thickness, to provide a diemically and physically resistant surface. Slip-resistant aggregates may be embedded in such epoxy toppings. The same tech-... 

In recent years, epoxy resin systems have been utilized for special applications on the exteriors of buildings. One of these systems involves the use of an epoxy plaster, which is troweled onto the surface of an exposed wall, into which are set stone aggregates. This surfacing resembles a pre-cast concrete panel with an exposed aggregate facing. This method is utilized, not only in new construction, but in re-surfacing deteriorated areas. 

Deteriorated or worn timber floors can be upgraded by bonding new timber to old with epoxy resin. The procedure involves removing all deteriorated timber back to a sound surface prior to the application of a penetrating epoxy sealer. The new timber is then bonded to the old and composite action ensured by drilling and inserting dowel pins set in resin as shown in Fig. 6.25. 

On the other hand, coating techniques do have less influence on the fibre surface. Nevertheless, brittle coatings such as SiC deteriorate mechanical properties of the fibres. As an example, reactive sputtered SiC layers improve the interfacial shear strength of carbon fibre reinforced epoxy resin /3/. Recently, Dagli and Sung 141 reported about the coating of carbon fibres by plasma polymerization of acrylonitrile and styrene using an inductively coupled plasma. 

In general addition of 10-60% glass fibre causes an improvement in the dissipation factor in PC and PA 6,6, and in surface arc resistance in PPO and epoxy resins but causes deterioration of dielectric constant in PA 6,6 and in tracking resistance of PP epoxies and phenylene oxide. Glass fibre caused an improvement in the dielectric strength of epoxies. 

In general, carbon fibres causes a deterioration of volume resistivity in epoxy resins or PTFE, and improves the dielectric strength and dielectric constant in epoxies but causes deterioration of surface arc resistance and tracking resistance in epoxies. PTFE causes deterioration in the dielectric constant and surface resistance in PA 6,6. Mineral fillers also cause deterioration of the dielectric constant and surface arc resistance of PA 6,6. 

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