Research On Drying Process Of Recycled Polyester Bottle Flakes Effect To The Fiber Properties

China is the largest pruducer and consumer of plastics in the world,it is convient for us because of the appearance and rapid development of polyester materials.Polyester bottles are widely used in beverage packing materials because of its good performance,such as the light weight,good barrier properties,unbreakable appearance,preservative,low manufacturing costs and its nice security.However,it is a great waste of resources to waste polyester and its products directly.In addition,if the waste polyester was dumped,land filled or burned without any treatment,it will not only caused environmental pollution,but also seriously affected human health.It is a hot research that how to achieve high recovery of the polyester bottle flakes in the whole world.Most of the bottle flakes in our country have been made PET fiber by physical recovery technology.Three-dimensional hollow polyester staple fiber is mainly used in thermal insulation materials and filling fag.This paper studied the influence of drying process on the moisture content,thermal properties,intrinsic viscosity and crystallinity of recycled polyester(PET)bottle flakes The experimental results showed that the moisture content reduced with the increase of the drying temperature and time and that the moisture content could be controlled in 0.08% at 160? for 6h.With the development of the drying process,the glass transition temperature,crystallization temperature,crystallization heat,melting heat,intrinsic viscosity and crystallinity increased,while the melting point had relatively little influence.For the conditions of production cost,the optimum drying process was 160? and 6h.The research on melt rheological properties of recycled PET bottle flakes has great significance for spinning.The melt of PET bottle flakes was studied by RH 7 capillary rheometer.The shear stress,apparent shear viscosity and non-Newtonian index decreased with the increasing of shear rate.Highly water-containing flakes are more susceptible to hydrolysis during high-temperature spinning,the length of the macromolecular segment decreases,molecular chain displacement resistance decreases,the activation energy of viscous flow increases,the apparent viscosity decreases significantly.At the same shear rate,the shear stress reduces with the increasing of the temperature,however,the apparent viscosity and non-Newtonian index increases.Therefore,it is important to control the moisture content of polyester within a certain range.Increasing the temperature favors macromolecular motion and improves the flow properties of the melt.The effects of dry heat treatment on the apparent morphology,heat shrinkage,mechanical properties and elastic properties of three-dimensional hollow polyester staple fibers were studied in this paper.The surface of raw PET fibers is smooth without curl,the curl and fluffy have been improved after the drafting process.The heat shrinkage of PET fibers increase with the increasing of the temperature and time,but the fiber shrinkage rate remained stably after 5 min.The elongation at break increased with the increase of heat treatment temperature,the breaking strength increased slightly and the initial modulus decreased.The elastic recovery rate of polyester fiber increased evidently at the beginning of heating,and remained stable after 5 min.The effect of heat treatment temperature on the elastic recovery of PET fiber was not significant.Setting the heat treatment and process conditions reasonably has an important impact to the performance of three-dimensional hollow polyester fiber.It is necessary to consider the performance of fibers,application and the cost of production to set the process conditions.