Characteristics of borazine oligomers

Furthermore, we now believe that this kind of intermediate is critical to achieving many of the unique features associated with BN prepared from this precursor. 

In this chapter, the key characteristics of the oligomer necessary for successful processing of composites is described. Specific data confirming the liquid crystalline character of the oligomer are presented. Finally, some of the key advantages of BN formed via this route are described. 

Borazine oligomers are formed by means of condensation reactions of the 6-membered ring compound borazine, B N H. These reactions occur very readily upon heating in a sealed vessel at temperatures between 60 and SO C [21]. Both molecular weight and viscosity increase as a function of polymerization time, allowing the flexibility of tailoring the melt viscosity to meet the needs of the application. 

It is noteworthy that the borazine oligomer does not show a transition enthalpy in differential scanning calorimetry (DSC) measurements. This is also comparable to the carbonaceous mesophase in which a nematic to isotropic transition enthalpy has not been observed [24]. In both the 

Both composition and physical treatments affect the degree of crystallinity in the borazine oligomer melt. For example, the propensity to exhibit anisotropic behavior is enhanced by cooling the oligomer at 5 C for extended periods of time [17]. This allows segregation and molecular orientation at very slow polymerization rates. 

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