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Preparation of Nylon 6 with High Viscosity by Chain-extension during Melting Extrusion

Author: LiWeiNa
Tutor: HuGuoSheng
School: University of North
Course: Materials Science
Keywords: Nylon 6 Chain extender Intrinsic viscosity Rheological behavior Crystallization Behavior
CLC: TQ323.6
Type: Master's thesis
Year: 2009
Downloads: 161
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Abstract


Nylon 6 (PA6) is a better overall performance of engineering plastics, but generally obtained by polymerizing a low molecular weight nylon resin, and as engineering plastics is their higher molecular weight requirements; addition, as the nylon has excellent barrier properties and is widely used prepare a hollow vessel, but the low the PA melt viscosity obtained by the general polymerization is difficult to direct blow molding. This thesis molten expanding chain reaction method to prepare high viscosity nylon 6, and Ubbelohde viscometer, melt flow indexer, capillary rheometer, differential scanning calorimetry (DSC) and polarized optical microscopy (POM) of PA6 and the intrinsic viscosity of the chain extender products, end group content, melt index, morphology, mechanical properties, rheological properties and crystallization properties. The intrinsic viscosity, end group content, melt index, and mechanical properties of the study results show that the choice of epoxy (EP) and oxazoline (BO) as the chain extender, EP expanding chain effect is better, with the EP dosage increases, the content of the terminal group has been reduced, the intrinsic viscosity of PA6 significantly improved, 2.5 wt% of the EP allows a PA6 maximum intrinsic viscosity reaches 1.35 dl / g, a melt index of 5.66 g/10min, and when the the EP amount exceeds 2.5 wt%, PA6 extrusion difficulties; BO when the chain extender, the optimum value exists Bo in an amount 1.5 wt% of the BO allows PA6 the maximum intrinsic viscosity reached 1.17dL / g, with the increase in the amount of BO, PA6 end amino group content is essentially the same, the carboxyl end group content has been reduced; PA6 BO and EP chain extender notched impact strength significantly improved its mechanical properties, tensile strength change. The rheological behavior PA6/EP blends PA6 chain extender product are the pseudoplastic fluid showed shear thinning phenomenon. Significantly improved by the the PA6 melt viscosity after the EP chain extender, the consistency (K) increases with the increase of the amount of EP, and the non-Newtonian index (n) is gradually reduced, i.e. the melt flow behavior deviates from the Newtonian fluid increases the degree of . The viscous flow activation energy of the system as the EP content increase the overall downward trend in decreased sensitivity to temperature. Using differential scanning calorimetry to study the crystallization kinetics and melting behavior of of PA6 and PA6/EP blends. Isothermal crystallization kinetics study results show that: Avrami equation to describe the isothermal crystallization process, the addition of the EP reduces the crystallization rate of PA6, hinder the growth of the nuclei. Hoffman-Weeks theory to draw PA6/EP blends of equilibrium melting point lower than the the pure PA6 equilibrium melting point, the EP is added to reduce the degree of perfection of the crystallization of PA6. The non-isothermal crystallization study results show that: the the Avrami equation Jeziorny correction and Mo are suitable for processing PA6 and PA6/EP for blends of non-isothermal crystallization process. PA6 the crystallization rate constant Z C1 pure PA6, after the chain extender is reduced compared to the same cooling rate, in order to achieve the same degree of crystallinity, after chain extension, PA6 the cooling rate must be greater than the cooling rate of the pure PA6 described EP added reduces the growth rate of the crystal, to hinder the growth of the nuclei.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > Polycondensation resin and plastic > Polyamide resin and plastic
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