Epoxide networks preparation

The organic phase of the O-I hybrid studied in the present work consists of a stoichiometric epoxide-amine network prepared by curing DGEBA with oligomeric amine D2000 (M=1970). 

Void-free phenolic networks can be prepared by crosslinking novolacs with epoxies instead of HMTA. A variety of difunctional and multifunctional epoxy reagents can be used to generate networks with excellent dielectric properties.2 One example of epoxy reagents used in diis manner is the epoxidized novolac (Fig. 7.34) derived from the reaction of novolac oligomers with an excess of epichlorohydrin. 

Curing Agents for Carboxyl-Terminated Polybutadiene Prepolymers. The types of curing agents used to prepare binders for CTPB propellants are the same as those for PBAN or PBAA. The bifunctionality of CTPB, however, requires that part of the curing agents be polyfunctional to provide for the formation of the tridimensional network. Almost without exception, the polyfunctional aziridines and epoxides used with CTPB undergo side reactions in the presence of ammonium perchlorate, which affects the binder network formation. Kinetic studies conducted with model compounds have established the nature and extent of the cure interference by these side reactions. The types and properties of some of the crosslinkers and chain extenders used to prepare solid propellants are summarized in Table IV. 

P = 1) systems while the apparent activation energy markedly decreases in the same series AEapp for the linear polymer DGER-AN is close to the typical value for many polymers 57 59). The results testify that the fragment (segment) of the network which is responsible for a-transition is in average smaller than that of a linear polymer. The temperature range of the T transition for the networks is markedly narrower than that for linear polymers and epoxides prepared from industrial resins 13,19). This points to a narrower distribution of relaxation times in the considered networks as compared with other crosslinked polymers. 

Lichtenhan et al. [23,24] prepared several monosubstituted POSS epoxides (XIX). The Cs-based chain epoxy (5-9 wt%) was used with 1,4-butanediol diglycidyl ether (EDGE) (XX), diglycidyl ether of Bisphenol A (DGEBA) (XXIII) and polyoxypropylene diamines (XXI) to prepare nano-reinforced epoxy network glasses (Scheme 6) [23]. 

The first part concludes with a discussion of the similarity between the mechanisms of initiation and chain transfer, the appreciation of which led to the inifer concept, which in turn yielded new telechelics, networks, sequential copolymers, etc. The second part of this presentation focuses on practical consequences of understanding details of the mechanism of initiation. The synthesis of a new family of telechelic linear and tri-arm star polyisobutylenes will be described. Among the new prepolymers are telechelic olefins, epoxides, aldehydes, alcohols, and amines. The preparation of new ionomers and polyisobutylene-based polyurethanes will be outlined and some fundamental properties of these new materials will be discussed. 

The strain recovery curves for (a) XPCL-1.2k/ENR, (b) XPCL-2.0k/ENR, and (c) XPCL-3.6k/ ENR blends. (Reproduced from Chang, Y.-W., Eom, J.-P, Kim, J.-G., Kim, H.-T, and Kim, D.-K. 2010. Preparation and characterization of shape memory polymer networks based on carboxylated telechelic poly( -caprolactone)/epoxidized natural rubber blends. Journal of Industrial and Engineering Chemistry 16 256-260 with permission from Elsevier.)... 

Polymer networks derived fi-om the curing of epoxidized LO have also been prepared and characterized [53]. The crosslinking agents were phthalic (PA), tetrahydro phthalic (TEA), tetrahydromethyl phthalic (TMPA), hexahy-dromethyl phthalic (HMPA) and methyl endomethylene tetrahydrophthalic (MTPA) anhydrides and the reaction was catalyzed by different tertiary amines. The effect of the steric hindrance and stiffness of the hardeners was also studied. 

The additive reaction of oxiranes was also utilized for the preparation of SMP networks with covalent crosslinks. The crosslinking of 3-amino-1,2,4-triazole with epoxidized natural rubber catalyzed by bisphenol-A resulted in polymer networks having shape-memory capability with Ti ms = Tg [82]. The Tg could be controlled by the 3-amino-1,2,4-triazole content in the range between 29 and 64 °C. Recently, the crosslinking reaction of oxiranes and amines was systematically investigated in two polymer systems based on the reaction of the diglycidyl ether of bisphenol A epoxy monomer cured with the bifunctional poly(propylene glycol)bis(2-aminopropyl)... 

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