Bis-epoxies

Bis-epoxy compounds that have been used for crosslinking purposes vary mainly in their chain length, ranging from the 4-carbon bridge of l,2 3,4-diepoxybutane (Skold, 1983 Kohn et al., 1966), the 6-carbon spacer of l,2 5,6-diepoxyhexane (Fearnley and Speakman, 1950),... 

Novolac epoxy resins, phenolic or cresol novolacs, are reacted with epichlorohydrin to produce these novolac epoxy resins which cure more rapidly than the epi-bis epoxies and have higher exotherms. These cured novolacs have higher heat-deflection temperatures than the epi-bis resins as shown in Table 2.8. The novolacs also have excellent resistance to solvents and chemicals when compared with that of an epi-bis resin as seen in Table 2.9. 

Aliphatic polyesters are also available by the chemical reaction of carbon monoxide and formaldehyde (Masuda, 1991), carbon dioxide and epox) compounds (Yoshida, 1992), and bis epoxies and bis carboxylic acids (Yamamoto, 1991). 

FIGURE 3.6 Chain-extension reactions of lactic acid based prepolymers nsing bis-epoxies. 

Bis-epoxies have been reported to be useful for chain extending PLA. The epoxy groups can react both with hydroxyl groups and with carboxylic acid groups (Figure 3.6). 

Thermoset epoxies are commonly made by mixing a bis-epoxy component with ... 

The appearance of polymer is a white powder, density is 1.21 1.31 g/cm, and secondary transition point of 65—85°C. Freeze-dried dehydrated PVA that was completely saponified, with repeated freezing and defrosting of PVA solution, chemically reacting with N-methylol compounds, dicarboxylic acid and bis epoxy, adding metals such as steel and copper, or irradiating radiation. 

Stereochemical courses of EH-catalyzed hydrolysis/cyclization cascades of 6,7 9,10-bis (epoxy) pentadecane to yield tetrahydrofurane derivatives. 

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