Aggregative State Structure Effect On Chain Segment Motion And Localized State Distributions In Polyamide 610

Polyamide 610, which has a molecular structure analogous to polyamide 66, is one of the most important polyamide engineering plastics. Polyamide 610 is a typical semicrystalline polymer with different microstructures under various thermal histories. The investigation of the aggregative state structure effect on chain segment motion and localized state sistributions in polyamide 610 is interesting both from the fundamental and technological point of view. Polymers acquire persistent polarization due to the alignment of dipoles and migration of space charges over macroscopic distance. Information on charge storage and transport phenomena in polymer electrets is of great interest for several industrial applications. The corresponding work is an important topic in the field of polymer electronic properties. It helps leading charge storage and transportation properties further in polymer and then has a great meaning on polymer's application in electrics, optics, acoustics, etc.1. The experimental dielectric data were analyzed within the formalisms of complex permittivity and electric modulus. The results were discussed in terms of ac conductivity, MWS polarization, electrode polarization, and dc conductivity. Maxwell-Wagner-Sillars (MWS) polarization in polyamide 610 arising from charge carriers accumulated at the interphase between amorphous and crystalline regions and electrode polarization arising from charge carriers accumulating at the interface between an electrode and polyamide 610 have been investigated by means of dielectric relaxation spectra. In the frequency spectra of polyamide 610, the dielectric permittivity showed high values at low frequencies originating from charge carrier movement. The maximum ofε″MWS andε″eiec of quenched polyamide 610 is smaller than that for annealed polyamide 610 because crystallinity of quenched polyamide 610 increases with increase of the temperature and crystallinity of 180℃annealed polyamide 610 doesn't change. The temperature dependence of relaxation time follows the Vogel-Tammann-Fulcher (VTF) type. The results revealed that there is a transition temperature for the MWS polarization and dc conductivity, located between 110 and 120℃, resulting in the separation of two different charge carrier movement mechanisms. Below and above this transition temperature, the charge carrier transport is governed by the motion of the polymer chains. The change of charge carrier movement mechanisms is due to the onset of polymer chain motion in the interphase. For electrode polarization the motion of the polymeric chains was one of the factors leading to charge-carrier transport at temperatures higher than the glass-transition temperature2. Quenched polyamide 610 polarizing at different temperatures corresponds to annealed polyamide 610 at different temperatures. There are three current peaks (namedα,ρ1 andρ2peak respectively) in TSDC spectra of quenched polyamide 610.αpeak is corresponding to the glass transition,ρ1 peak is attributed to space charge trapped in the bulk of amorphous region and inter-phase between crystalline and amorphous regions, and p2 peak is originated from space charge trapped in crystalline region. By analyzing the characteristic parameters of these peaks, it is found that the increase of polarization temperature induces the decrease of the chain segment mobility and promotes the creation of structural traps in polyamide 610. The decrease of the chain segment mobility in amorphous phase makes intensity of a peak weak and activation energy increscent. The higher of polarization temperature, the higher of degree of crystallinity, the more of charge carriers trapped in crystalline region. So the increase of polarization temperature makes intensity of the p2 peak strong and increases the stability of trapped charge in the crystalline regions, and the increase of polarization temperature makes intensity of the pi peak strong and decreases the stability of trapped charge in the amorphous region and inter-phase.3. There are three current peaks (namedα,ρ1 andρ2 peak respectively) in the TSDC spectra of annealed polyamide 610. The a peak is attributed to a background dipole relaxation by the motion of chain segments over space charge contribution, theρ1 peak is originated from space charge trapped in amorphous phase and the interphase between crystalline and amorphous phases, and the p2 peak is originated from space charge trapped in crystalline phase. By analyzing the characteristic parameters of these peaks, it was found that annealing induced a decrease of the chain segment mobility and promoted the creation of structural traps in polyamide 610. The decrease of the chain segment mobility in amorphous phase made the intensity of the a peak weak and activation energy increased. The higher the annealing temperature, the higher the degree of crystallinity and the more charge carriers trapped in crystalline phase. So the increase of annealing temperature made the intensity of the p2 peak strong and increased the stability of trapped charge in the crystalline phases. The increase of annealing temperature made the intensity of the pi peak strong and decreased the stability of trapped charge in the amorphous phase and interphase,4. There are four current peaks (namedα,ρ1,ρ2 andρ3 peak respectively) in TSDC spectra of solution-cast polyamide 610.αpeak corresponds to the glass transition,ρ1 peak is attributed to space charge trapped in the amorphous phase,ρ2 peak is originated from space charge trapped in the interphase between crystalline and amorphous regions andρ3 peak is originated from space charge trapped in crystalline phase. With the increase of irradiation dose from 1.5MGy to 2MGy,ρ1 peak andρ2 peak gradually merge into a peak. So the superiority of the crosslinking in amorphous phase over the crosslinking in interphase makes trap level of the amorphous phase and that of interphase gradually close. By analyzing the characteristic parameters of these peaks, it is found that gamma irradiation induces the decrease of chain segment mobility and increases structural defects in polyamide 610. Irradiation increases the stability of trapped charge in amorphous phase and interphase, but basically makes the stability of trapped charge in crystalline phase unchanged.