Multifunctional epoxides

Carboxylic acids with multifunctional epoxides or epoxy functional monomers... 

Despite the popularity of the chlorination-Hercosett route, it is clear that AOX problems will often enforce the adoption of alternatives, many of which have already been developed. Non-AOX polymers include polyethers, polyurethanes, polysiloxanes, polyquaternary compounds and multifunctional epoxides. 

The results of model compound studies with three different types of epoxides, obtained in the presence and absence of ammonium perchlorate are shown in Figures 4, 5, and 6. The epoxide DER-332 shows a uniform rate of disappearance for the acid and epoxide species in this reaction. In the presence of ammonium perchlorate, the rate is increased, and a minimum of side reactions occur. Similar data but faster reaction rates are obtained with Epon X-801, but the consumption of epoxide species by side reactions is increased, particularly in the presence of ammonium perchlorate. On the other hand, the epoxide ERLA-0510 (Table IV), which contains a basic nitrogen, shows a reaction rate which is an order of magnitude greater than that for DER-332, accompanied by a substantial increase in side reactions. In the presence of ammonium perchlorate, the side reactions of ERLA-0510 predominate. In all probability, the side reactions of the multifunctional epoxides studied are homopolymerization. 

The problems associated with the multifunctional curing agents for CTPB and the resultant aging behavior of the cured polymers have led to a practical solution for curing binders and propellants—i.e., using mixed aziridines or a mixture of an aziridine and an epoxide. Such mixtures, when appropriately balanced, usually provide satisfactory mechanical behavior and high temperature stability. In dual curing systems such as MAPO and BITA or MAPO and a suitable multifunctional epoxide,... 

Mixed aziridine or mixed epoxide-MAPO cures have been the practical solution to problems encountered with single curing agents. The mechanical properties of mixed aziridine or mixed epoxide—aziridine-cured propellants show less change on aging than those of propellants cured with MAPO or BITA alone. It appears that the BITA or the multifunctional epoxide (ERLA-0510 or Epon X-801) in the mixed curing systems provides stable crosslinks and a slight amount of postcure, which results... 

Multifunctional epoxides have been used predominantly as cross-linkers because of their electrophilic nature. Pentaerythritol tetraglycidyl ether, a tetrafunctional epoxide, was used originally by Alpert and Regnier (37). Pearson and Regnier (38) compared two difunctional epoxides, ethylene glycol diglycidyl ether and 1,4-butanediol diglycidyl ether. These multifunctional cross-linkers increased the hydrophilic nature of the support. 

Table 12.1 gives typical values of the diffusion constant for a series of thermosetting matrices where the effect of polarity of the resin on the equilibrium on moisture concentration is illustrated. Epoxy resins are the network product of the reaction of a multifunctional epoxide monomer with a hardener. One of the important aspects of composite materials which needs to be recognised is that the material is synthesised at the same time as the component is manufactured. The precise chemistry of the final network can be uncertain but is a function of the chemical stmctures of the epoxide and hardener and/or catalyst, which determine the mechanism of cure. In this way, the cured resins can have differing polarities. 

PA-6/PET/multifunctional epoxide resin (0-10 wt%) SEM/WAXD/polarizing microscopy/ DMTA/mechanical properties/DSC/FTIR Huang et al. 1998... 

PA-66 (70-50)/PBT (30-50)/multifunctional epoxide resin (0-5 phr) TSE at 275 °C/SEM/TEM/extrudate swell/DSC/torque rheometry/capillary rheometry/effects of PA PBT ratio and epoxy content on mechanical properties/ blends optionally -l- core-shell elastomer Huang and Chang 1997a, b (see also Chiou and Chang 2000)... 

An alternative type of cross-linking mechanism is based on epoxy resins. A large field of research depends on this type of ehemistry, which proceeds via polymerization of multifunctional epoxide moieties in combination with a photoinitiator. The applicability of such a system led to the production of a commercially available photoresist - SU-8 - developed by IBM in 1989 [GEL 89]. Fiuthermore, SU-8 is involved in himdreds of patents and thousands of journal articles about photohthography iu general or micro-electromeehanieal systems (MEMS). A detailed overview concerning the... 

The area receiving the most intense investigation has been the photoinitiated cationic ring opening polymerization of multifunctional epoxides. This field has been reviewed in several current articles gy ject of a great... 

Commercially-available diaryliodonium (CD-1012, Sartomer) and triaryl-sulfonium (CD-1010, Sartomer) salts were found to initiate polymerization of multifunctional epoxide and vinyl ether monomers [24]. Figure 17a shows a line structure achieved by polymerization of a mixture of poly(bisphenol A-co-epichlorohydrin) glycidyl end-capped and 3,4-epoxycyclohexylmethyl 3,4-epoxylcyclohexanecarboxylate (K126, Sartomer) initiated by CD-1012. To check the potential spatial resolution, we focused the laser using high-NA optics to polymerize commercial resin SCR701 (JSR) and a lateral spatial resolution of 100 nm was obtained (Fig. 17b). 

Figure 30 Addition of a multifunctional epoxide with a polymer resin containing carboxylic acid or acid anhydride (as shown) groups with a PAG can be used to create a negative-tone photoresist that functions via cross-linking. This type of approach has been investigated extensively for use in designing negative-tone 193-nm photoresists.

Figure 31 Nominal structure of the multifunctional epoxide oligomer used in the commercial negative-tone SU-8 photoresist. SU-8 is a popular resist in the fabrication of MEMS and similar devices.

Branched PBT could be produced by reactive extrusion with multifunctional epoxide in a conventional extrusion system, after some initial experiments with an intensive batch mixer. The rheology of the reactive extrusion product could be controlled by material (amount of modifier) and operational (screw rpm and feed rate) conditions. Improved foamability could be attained by the reactive modification under the optimized extrusion conditions. 

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