Preparation And Study Of Polyarylene Ether Nitrile Blends

Poly(arylene ether nitrile)(PEN) is the main polymer of interest since it is a high performance thermoplastic for special uses such as aerospace, military and electronic areas. PEN exhibits excellent mechanical strength, high radiation resistance and strong chemical inertia. However, with different structures the PEN polymers may take different properties. Thus it is the good polymer matrix which can be used to prepare advanced materials, we chose the crystallization and amorphous PEN as the main polymer matrix to study. This dissertation is composed of three parts as follows:1. Poly(arylene ether nitrile)(PEN) blends with different mass ratios of PEN(BP) to PEN(BPA) were prepared by solution-casting method. The morphological, rheological, thermal, dielectric and mechanical properties of the resulted blends were systematically studied. Rheological studies show that the addition of PEN(BPA) could improve the flowability of blends except that of 90/10(BP/BPA). Meanwhile, the crystallization degree of blends also decreases except that of 90/10(BP/BPA). Mechanical measurement results indicate that the PEN blend(PEN(BP) : PEN(BPA) of 90:10) possesses highest tensile strength of 119.7 MPa, increased by 28.6% than PEN blends(PEN(BP) : PEN(BPA) of 50:50). Besides, the scanning electron microscope images show that there exists phase separation in the PEN blends(PEN(BP) : PEN(BPA) of 50:50). Moreover, the phenomenon of phase separation will lead to interfacial polarization between the two different phases, which is a significant factor to induce the transformation of dielectric constant. Furthermore, all blends possess high thermal stability(initial decomposition temperature over 470 oC) and high mechanical property(tensile strength over 93 MPa).2. Polyarylene ether nitrile copolymers were synthesized by nucleophilic substitution reaction of 2, 6-dichlorobenzonitrile(DCBN) with the ratio 9:1 of bisphenol(BP) and bisphenol A(BPA). The molecular chain is completely disrupted by the copolymerization, and the crystallization disappear. Meanwhile, the random copolymer has a quite higher Tg but with a lower mechanical properties. The blend has a quite higher dielectric properties due to the interfacial polarization between the two different PEN. Furthermore, from the rheological anslysis we could know that the storage modulus of pure PEN always has higher value compared with the loss modulus. Which means the elastic deformation of the pure PEN is better than the viscous deformation. It indicates that the PEN matrix presents some rigidity.3. we choose the copolymer as fillers to explore various advantages of PEN blends. From the study, we could know that with the addition of copolymer would obvious increase the properties of the blend. When the copolymer came to 2.5%, it could enhance the crystallization of the blend, the mechanical properties of the blends had a slight increase, and the dielectric loss had a slight decrease. Furthermore, from the rheological anslysis we could know that the viscosity of the blends decreased with the addition of copolymer, which are basement of the future processes and application in special engineering plastics.