Chapter 20 - Polybenzoxazine/Polyimide Alloys

Abstract

This chapter describes the polybenzoxazine-PI alloys prepared by the thermal curing of BA-a in the presence of various PI components, such as poly (amide acid), soluble PI, or poly (imide-siloxane). The thermal and mechanical properties of the polymer alloys were noticeably improved by the introduction of PI components. Polybenzoxazines have not only the characteristics of the traditional phenolic resins, such as excellent thermal properties and flame retardance, but also unique characteristics such as molecular design flexibility, low melt viscosities, near-zero shrinkage upon polymerization, low moisture absorption, and low dielectric constant. Polybenzoxazines overcome the disadvantages of the traditional phenolic resins without sacrificing the advantages of those resins, which leads to a novel and promising candidate for high performance thermosetting resins. However, polybenzoxazines have some shortcomings. It illustrates Polyimide (PI), which is known as one of the most important thermally stable polymers and is widely used as a suitable component of a polymer alloy due to the high thermal and mechanical properties, and the high molecular design flexibility. It describes the preparation and properties of high performance polymer alloys based on polybenzoxazine and PI. PIs are in general not soluble in organic solvents. Therefore, typical polybenzoxazine-PI alloys are prepared by blending BA-a as a benzoxazine monomer with poly (amic acid) (PAA) as a processable precursor of PI, followed by film casting and thermal treatment up to 240 °C for the ring-opening polymerization of the benzoxazine and imidization of PAA.