The Crystallization And Properties Stuy Of Polyaryleneeither Nitriles

Semicrystalline Polyaryleneether nitriles(PEN) have better heat resistance and mechanical properties than the amorphous PEN, but withlittle research at present.In this paper, we researched the isothermal crystallization behavior of Polyaryleneether nitrilessyntheticed from monomers resorcinol(RS-PEN), Shear induced crystallization in one-dimensional space, MWNTs filled with RS-PEN and used asnucleating agent for Polyaryleneether nitrilessyntheticed from monomers biphenol(BP-PEN).First, we studied the crystallization temperature, isothermal melt and cold crystallization and melting behaviors of RS-PEN by DSC. The ideal melt crystallization temperature isbetween 245 oC to 260 oC, and the cold crystallization temperature isbetween 220 oC to 235 oC. The melting point(Tm) of RS-PEN not increased obvious with the increasing of isothermal melt and cold crystallization temperature, indicatingthe thickness of crystal depending not on the crystallization temperature.Thesecondary crystallization occurred in crystallization process of melt and cold crystallization, and secondary crystallization becomes more and more obvious with the increase of melt crystallization temperature, but for cold crystallization, secondary crystallization only obvioued at low temperature. The values of Avramiexponent n are close to 2, indicating the primary crystallizationstage of both the melt and cold crystallization processes correspond to one dimensional acicular aggregate. For melt and cold crystallization, the crystallization activation energy(ΔE) are concluded to be 18.223 kJ/mol and 18.127 kJ/mol, meanwhile theequilibrium melting temperature derivedfrom Hoffman andWeeks’ relationship are 337.4 oC and 338.3 oC respectively, the results are surprisingly similar. The SEM micrograph of the crystals of PEN are presented as elongated ?brils, the diameter of the ?brils is about 20 ~ 30 nm and the length is range from 1 to 10 μm, that is well conform to the Avrami analysis.Second, we opened the MWNTs, RS-PEN is dissolved in N-methylpyrrolidone(NMP), filled the opened MWNTs with Poly(arylene ether nitrile)(PEN) though capillary action.DSC and constituency of electron diffraction show that the molecular chains of PEN were constrainted bythe wall of MWNTs, PEN couldn’t crystallizationas in the open environment. The rheological experiments suggested shear stress on the surface of MWNTs do can transmit to inner, accelerated the crystallization of PEN in the one-dimensional environment and the crystallization caused the volume shrinkage of PEN lead to the G’ performed decrease in a period, this result is also confirmed by DSC. The TEM image showed one-dimensional lattice of PEN formed in the MWNTs during the shear, the lattice spacing is about 0.244 nm, and latticeplane paralleled to the wall of MWNTs due to the joint actions of one-dimensionalconstrain and the transverse vibration of walls.Finally, we used F-MWNTs as nucleating agent for Polyaryleneether nitriles syntheticed from monomers biphenol(BP-PEN), and compared with MWNTs/PEN. F-MWNTs have better effect on PEN than MWNTs, it increased the crystallinity of PENat a lower concentration, at the content of 0.5% crystallinity was increased 2.7 times. π bonded of the MWNTs interact strongly with the aromatic structure of RS-PEN, and the effect externaled, cased BP-PEN interact with MWNTs. SEM showed that the spherulite is disappeared, PEN crystal alongthe outer surface of F-MWNTs, the thickness crystal is about 330 ~ 555 nm. Due to the increase of crystallinity, F-MWNTs/PEN improved the dielectric constant but the dielectric loss didn’t change obviously. In addition, due to the effect of the toughening of the MWNTs, although crystallinity of F-MWNTs/PEN increased significantly, but the strength becomes better, making the material well performance bellow and above the glass transition temperature.