Epon®

Epon Foam Spray 175, yi Eow Temperature Insulation, bulletin. Shell Chemical Co., Houston, Tex., Nov. 1963. 

Blends have also been prepared by dissolving DMPPO in a monomer and then polymerizing the monomer. An example is an epoxy—DMPPO blend prepared by curing a solution of DMPPO in Epon 828 at 85°C with an alurninum—tetramethylguariidine catalyst. Some copolymer formation is observed. The solutions can be appHed to glass cloth before curing to produce prepregs for composites in appHcations such as printed circuit boards (67). 

Fig. 2. Epoxy matrix resius for advanced composites (a) TACTIX 558 (Courtesy of The Dow Chemical Company), (b) EPON HPT Resia 1071 (Courtesy...

Shell Chemical Company has iatroduced a new tetraglycidyl amine and a new stiff backbone diglycidyl ether under the respective trade names EPON HPT Resia 1071 [103490-06-8] and EPON HPT Resia 1079 [47758-37-2] (8,9), which have superior hot—wet performance compared with TGMDA. These two materials are chemically Ai,Ai,A7,A7-tetraglycidyl-a,aTis(4-aminophenyl)-/)-diisopropylben2ene and... 

The carboxylated latexes are formulated to use a reduced amount of a less reactive 2inc complex. Special resin blends provide an optimum balance of film tack and strength, and are coUoidaHy compatible with the carboxylated latexes (158). Epon resins may also be used as an acid acceptor in place of 2inc oxide (160). 

SoHd epoxy resins are sometimes designated as 1-, 4-, 7-, or 9-type resins these approximate the degree of polymerization. Commercial products are designated similarly, eg, Epon 1001, 1004, 1007, and 1009 (SheU Chemical Co.). The relationship between n value, epoxy equivalent weight, and melting point is shown in Table 5. 

In addition to its higher reactivity towards epoxy groups, another advantage provided by the reaction of ethylpiperazine terminated siloxanes with Epon Resin 828 was... 

Fig. 6. Electron microscopy of Ca -ATPase crystals in thin sections. Sarcoplasmic reticulum (2mg of protein/ml) was solubilized in the standard crystallization medium with C12E8 (2mg/mg protein) and incubated under nitrogen at 2°C for 15 days. The crystalline sediment was embedded in Epon-Araldite mixture and processed for electron microscopy. Depending on conditions during fixation, embedding, sectioning and viewing, the observed periodicities in different specimens varied between 103 and 147 A. Magnification, x 207000. From Taylor et al. [156].

Shell s Epon 828, a blend of oligomers of diglycidyl ether of bisphenol A (DGEBA, n=0), was used. 

The initial formulation of Epon 828 and NMA must be such that oxirane equivalents equal the concentration of anhydride groups. A balanced stoichiometric ratio enables the polymerization to develop macromolecules at high extents of reaction (10). Therefore... 

Initially, oligomers of DGEBA are present in Epon 828 at a specific, but low ratio. It is also likely that some residual acid is contained within NMA (less than a few percent). Both contribute to... 

The resin contained 100.00 parts Epon 828, 80.00 parts NMA and 2.00 parts of BDMA. A part is a unit of mass. This formulation yields a resin with good mechanical performance. The formulation was cured in small test tubes that were placed in an electrically-heated, forced-air circulating oven which was controlled within 0.1°C of the set temperature. Specimens were removed with increasing time, thermally quenched and stored at -25°C. 

Roessner14 Epon-embedded AR protocol for test battery... 

III. Transmission electron microscopy of radish seeds Transmission electron microscopy (TEM) of radish seeds was done as listed below For TEM preparations, the specimens after fixation and dehydration, were embedded in Epon 812 resin (Luft, 1961). Thick sections (ca. 1mm each) were stained with 0.1% toluidine blue and observed with a Zeiss light photomicroscope. Thin sections, obtained with a diamond knife on a Supernova microtome, were sequentially stained at room temperature with 2% uranyle acetate (aqueous) for 5 min and by lead citrate for 10 min (Reynolds, 1963). Ultrastructural studies were made using a Philips CM12 transmission electrone microscope (TEM) operated at 80 KV. 

The DIBF OPPI combination has been shown to efficiently cure a wide variety of epoxies including cycloaliphatics. With this photoinitiator it is possible to cure bisphenol A epoxies such as Epon 828 quickly without the need for acrylation of the epoxy. Cycloaliphatic epoxies were of special interest because they were expected to react much faster than bisphenol A type epoxies. Those tested include 3,4-epoxycyclohexylmethyl-3 ,4 -epoxycyclohexyl-carboxylate (UVR 6110), bis(3,4 epoxy-cyclohexylmethyl) adipate (UVR 6128), and 1,2-epoxy-4-vinylcyclohexane (vinyl cyclohexene oxide). It was found that the vinyl cyclohexene oxide reacted rapidly, but work with it was discontinued because it has a fairly high vapor pressure (2 torr at 20 °C), an intense odor, and the photoinitiator does not dissolve in this resin. 

Bisphenol A type epoxies such as Epon 828, were also cured with the DIBF OPPI combination. When a modifier, Heloxy 505 (a low viscosity polyepoxide modifier) was added, viscosity was reduced and adhesion to the metal surface and impact resistance were improved as compared with the bisphenol A only. Surprisingly cure was faster than with the Union Carbide cycloaliphatic resins, but charring of the resin during cure was a problem. 

FIGURE 1-2 TransversesectionofarabbitlumbarspinalcordatL-1. Gray matter is seen as a paler-staining area in an H configuration formed by the dorsal and ventral horns with the central canal in the center ( ). The dorsal horns would meet the incoming dorsal spine nerve roots at the upper arrows. The anterior roots can be seen below (lower arrows), opposite the ventral horns, from which they received their fibers. The white matter occupies a major part of the spinal cord and stains darker. Epon section, 1 pm, stained with toluidine blue. 

FIGURE 4-2 Light micrograph of a 1 pm Epon section of rabbit peripheral nerve (anterior root), stained with toluidine blue. The myelin sheath appears as a thick black ring around the pale axon. (Courtesy of Dr Cedric Raine.)... 

Epon or Spurr s Glass for glass knives Print trays... 

Canet D, Rohr R, Chanel A, Guilliam F. Atomic force microscopy study of isolated ivy leaf cuticles observed directly and other embedding in Epon. New Phytologist 1996 134 571-577. 

Epon 812 (Polybed) Formvar Glutaraldehyde Ilford L-4 emulsion with appropriate safelight Osmium tetroxide Phosphate Dibasic Monobasic Propylene oxide Sodium thiosulfate fixing solution... 

Embed in Vestopal W. More contemporary embedding procedures would include Spurr s or Epon embedding media. The protocols for both Spurr s and Polybed (a recent em formulation) use can be found in a variety of EM books (see Chapter 1). In addition, these protocols accompany the commercially available kits. 

If Epon as Polybed 812 is employed, a graded alcohol series followed by a transitional solvent such as propylene oxide and progressive propylene oxide-Polybed is desired. (Updated from Dashek and Rosen [2].)... 

In many studies it is desirable to gain information from both LM and EM. Methods have been devised for such correlative studies (30-32). Sawada and Esaki s method (33) was designed to address factors that they believed to be important for accurate comparison. These factors are the transparency and thinness of embedded blocks, the flatness of tissue sections, and ease of removal of embedding molds from polymerized Epon blocks. Sawada and Esaki s method is summarized below. 

Fig. 1. Slide with tissue sections. Gray area represents applied Epon. The aclar film (cut to fit) is applied on top of this setup. 

Dehydrate through an ethanol series substituted with propylene oxide and add several drops of Epon before sections dry. 

---