Pa1212 And Pa1212-b-of Ptmg Melt Viscoelastic Behavior And Pa1212 Molecular Weight Determination

The effects of temperature, molecular weight and the structure of polymers on the viscoelastic behavior of nylonl212(PA1212) bulk homopolymers and the block copolymers nylon and poly(tetramethylene glycol)(PA12l2-b-PTMG) were investigated using the dynamic rheology, creep and recovery test. The information about the viscoelastic characters of PA1212 and the microphase separation of the PA1212-b-PTMG were obtained. Meanwhile the method of measuring the molecular weight for nylon 1212 were explored and some results were obtained. The main conclusions of the dissertation as following: .1. PA1212 presents a wide linear visicoelastic region that is independent the molecular weight. The dynamic storage moduli(G' ) of the PA 1212 increase with the molecular weight increasing, and increases lentamente in the low frequency range for the small molecular weight of PA1212. The loss moduli (G" ) depart from the linear relationship with the frequency in the high frequency range. And the dynamic viscoelastic behavior of PA1212 could not be well desctibed with the Maxwell model. The results show that the PA1212 melt is pseudoplastic fluid and its non-Newton index n reduces with the molecular weight increasing. The creep and recovery of the PA 1212 was tested in the non-linear range. The creep strain becomes smaller and the ratio of its recovery strain increase as the molecular weight increasing. The time-temperature superposition (TTS) deal with the viscoelastic characters of the PA1212 at different temperatures. The relation between shift factor and temperature is fit for Arrhenius function and the shift active energy is equivalent to the flow active energy. The peak of relaxation spectrum shifts to the short time region with temperature increasing.2. The linear viscoelastic range of the PA1212-b-PTMG is narrower than...