Curing agents for epoxides

The epoxide/cyanate compositions contain catalysts of cyanate cyclotrimerization and oxazoline ring formation. Curing agents for epoxide resin are mentioned in... 

Reguiatory FDA 21 CFR 178.2010 4,4 -Methylenebis 2,6-diethylaniline Toxicoiogy LD50 (oral, rat) 1901 mg/kg nonirritating to skin nonmutagenic Uses Chain extender for elastomeric PU curing agent for epoxides precursor for... 

Aliphatic, low molecular weight, branched polyamides of dimer fatty acids with di- and triethylenediamine are among the most widely used curing agents for epoxide resins. The chemistry of their formation is similar to that observed for the aforementioned crystalline linear polyamides. 

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. 

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,... 

Effects of Curing Agent Type. Epoxide-Cured Propellant. Carboxyl-terminated polybutadiene is a linear, difunctional molecule that requires the use of a polyfunctional crosslinker to achieve a gel. The crosslinkers used in most epoxide-cured propellants are summarized in Table IV and consist of Epon X-801, ERLA-0510, or Epotuf. DER-332, a high-purity diepoxide that exhibits a minimum of side reactions in the presence of the ammonium perchlorate oxidizer, can be used to provide chain extension for further modification of the mechanical properties. A typical study to adjust and optimize the crosslinker level and compensate for side reactions and achieve the best balance of uniaxial tensile properties for a CTPB propellant is shown in Table V. These results are characteristic of epoxide-cured propellants at this solids level and show the effects of curing agent type and plasticizer level on the mechanical properties of propellants. 

Molar excess of epoxynovolak resin was reacted with DDS highly branched aminoepoxide resin was thus obtained. The resin was then mixed with a non-modified epoxide resin, BPA/DC-BMI copolymer, benzoyl peroxide and /V-(3,4-dichloro-phenyI)-Ar, Ar -dimethyIurea (curing agent for the epoxy component) [116]. 

Most of the commerically available high-performance moulding materials use epoxidized cresol-novolak/novolak (especially phenolic novolak) as a base. Systems with amine curing agents, for instance 4,4 -diaminodiphenyl-sulfone (2) or 4,4 -diaminodiphenylmethane, do provide high-quality moulding substances with a thermo-mechanical performance comparable to our system. They are, however even less stable under storage. 

Primary amines and carboxylic acids are commonly used as curing agents for epoxy resins owing to the reaction of amino and carboxylic groups with the epoxide ring according to Eqs. (1)—(3) ... 

Cured epoxy-anhydride systems exhibit excellent thermal, mechanical, and electrical properties, and are used in filament-wound epoxy pipe, PCB laminates, mineral-filled composites, and electrical casting and encapsidation applications. Anhydride-cin-ed epoxies also have better aqueous acid resistance than similar amine-cured systems. Anhydrides are the principal curing agents for cycloaliphatic and epoxidized olefin resins in electrical casting and potting. Some... 

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