Binder hydrolytic stability

Many papers have shown that the water absorption of a syntactic foam is proportional to that of its binder. Polyester syntactic foams, for example, absorb more water, even with dressing additives (silanes, vide infra) than do epoxy syntactic foams (Fig. 11)1. The hydrolytic stability of epoxy foams is increased when the glass microspheres are replaced by carbon ones (Table 19)40). 

The hydrolytical stability of binder no. U was not very good and our next task was to improve this aspect. 

In 1962, Bowman showed that this polymer could be used as a binder for solid propellants [23]. Poly(glycolic acid) (PGA)was found easily thermally degraded [24] and its poor thermal and hydrolytic stabilities were problematic for any permanent appUcation. Choju et al. [25] mentioned that this PGA homopolymer is an unstabiUzed polymer and weight loss under heating begins at 240 °C [25]. 

Some binder systems have used MAPO as the only curing system for carboxy-terminated polybutadiene polymers. Again a problem in long term stability of physical properties is sometimes encountered since MAPO is hydrolytically unstable. The following reaction is possible ... 

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