Glass-surface potentials are established and maintained by the passage of electricity through the glass. Glass-surface potential is a linear function of hydrogen-electrode potential only through a limited range of values. Variations in glass-surface potential may be used as the basis of an electrometric titration method in the presence of oxidizing agents which render the hydrogen electrode useless. In such cases the method might give data which could not be obtained in any other way. 4. The presence of certain substances (strong salt solutions or gelatin solutions) other than hydrogen ions affects glass-surface potentials.

Main chain-type elastomeric polybenzoxazines (abbreviated as CA-pdms-fu) with very high char yield have been developed. Seven compositions of elastomeric benzoxazine adhesives are synthesized to find the optimum structure by changing the chain length of the siloxane component. The successful synthesis of CApdms-fu derived from catechol is confirmed with 1 H NMR and FT-IR spectroscopy. Polymerization characteristics, including polymerization temperature, enthalpy of polymerization, and extent of polymerization for all seven compounds, are analyzed from FT-IR and DSC data. The TGA results indicate remarkable superiority of CA-pdms-fu over traditional epoxy and polyurethane adhesives, with 93% higher char yield than polyurethane elastomer. The flammability of the elastomeric polymer was quantified by heat release capacity using microscale combustion calorimetry (MCC). The seven compositions of elastomeric polybenzoxazines exhibit heat release capacities between 48 and 63 J/g•K, which are within the noncombustible material range, without added flame retardants. Adhesive failure strengths are determined by lap shear strength, making a single lap shear joint on aluminum and copper rectangular bars. The lap shear strength for cross-linked poly(CA-pdms(2)-fu) is comparable to polyurethane adhesives, and the low flammability and very high char yield make this polymer suitable for developing fire-resistant elastomeric materials.

The exact acid content of a compound has an important effect on the physical properties secured with it and there is probably a definite state of acidity for each accelerator, and perhaps compound, which gives the best results with the combinations in question. The naturally occurring resin acids in rubber must be considered in figuring the total available acid in any compound. This is especially important where changes are made from one type or grade of rubber to another.