Plastics. Hardeners and accelerators for epoxy resins

2008 ◽  
Keyword(s):  
Author(s):  
J. G. Adams ◽  
M. M. Campbell ◽  
H. Thomas ◽  
J. J. Ghldonl

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).


Author(s):  
K. Chien ◽  
R.L. Van de Velde ◽  
R.C. Heusser

Sectioning quality of epoxy resins can be improved by the addition of a 1% silicone 200 fluid (Dow Corning), however this produces a softer block. To compensate, a harder plastic has been used for embedding various tissues encountered in our pathology laboratory. Exact amounts of the plastic mixture can be directly made up for embedding as shown: The chart reveals a Poly/Bed 812 (WPE 145) to anhydride ratio of 1:0.7 and a NMA to DDSA ratio of 7:3. 1% silicone fluid is added to above mixtures.Due to impurities within the DDSA and NMA, the polymerized epoxy blocks vary in darkness and appear to affect sectioning quality. After discussing this problem with Polysciences Inc., they have agreed to purify their anhydrides in an effort to standardize the consistency of the plastic.


Author(s):  
Hilton H. Mollenhauer

Many factors (e.g., resolution of microscope, type of tissue, and preparation of sample) affect electron microscopical images and alter the amount of information that can be retrieved from a specimen. Of interest in this report are those factors associated with the evaluation of epoxy embedded tissues. In this context, informational retrieval is dependant, in part, on the ability to “see” sample detail (e.g., contrast) and, in part, on tue quality of sample preservation. Two aspects of this problem will be discussed: 1) epoxy resins and their effect on image contrast, information retrieval, and sample preservation; and 2) the interaction between some stains commonly used for enhancing contrast and information retrieval.


2019 ◽  
Author(s):  
Frank Palmieri ◽  
Tyler Hudson ◽  
Roberto Cano ◽  
Erik Tastepe ◽  
Dean Rufeisen ◽  
...  

Author(s):  
Georgel MIHU ◽  
Claudia Veronica UNGUREANU ◽  
Vasile BRIA ◽  
Marina BUNEA ◽  
Rodica CHIHAI PEȚU ◽  
...  

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.


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