Study On Preparation And Properties Of PET Fibrid From Recycled Polyester Bottles

China is the largest producer of polyester,the consumption of polyester bottles rapidly increased with the increasing of the scope of its applications.There exists the waste of resources and environmental pollution caused by the waste of PET bottles,which have been paid much attention.At present,recycled polyester chips have been widely used in nonwoven fabric and polyester cut fibers.however,there are few studies on the preparation of fibrids with high value.In this work,PET fibrids were prepared using recycled polyester chips by precipitation method,and the forming mechanism,structure and surface morphology of PET were analyzed.At the same time,the hydrophilicity of PET was analyzed by physical blending method to prepare the PET / PA66 composite fibrids with a better hydrophilicity.This work firstly discussed the dissolution mechanism of recycled polyester chips in phenol/tetrachloroethane mixture,measuring the viscosity of polymer solution and molecular weight.Meanwhile,crystallization degree and thermal stability of PET particles were investigated.Results showed that the intrinsic viscosity of the recycled PET bottles was reduced,the intrinsic viscosity of 0.61-0.89 dL/g and the molecular weight of 16723-26508,which may meet the requirements of fiber forming conditions.The structure and thermal properties of regenerated particles were characterized by FTIR,TGA.Results showed that the recycled polyester chips and PA66 chips have a high purity and the melting temperature are respectively 432.8°C,455.3°C which suggests that the thermal performance of chips is better.Secondly,the forming mechanism of PET fibrids was studied.It was found that the forming process of PET fibrids including diffusion,solidification and phase separation,and the surface morphology of fibrids was greatly influenced by the diffusion coefficient of solvent and coagulant.The effects of shear rates on the size,surface morphology,structural characteristics,crystallization characteristics and thermal stability of PET fibrids were studied at the same time.The results showed that the weighted length of PET fibrids is normal distribution with the increasing of shear rates,and the length is 0.15-0.55 mm,the fibrids are ribbon-like in shape and flexible.The crystallization and thermal stability of fibrids increaseed with the increase of shear rates,when the shear rate reaches 5000 r/min,the thermal stability is basically unchanged,which indicates that high shear rate is favorable to the heat stability of the fibrids.Due to the poor hydrophilicity of PET fibrids,its applications in papermaking industry are limited.In this study,PA66 chips were used with active groups to prepare PET/PA66 composite fibrids.The fibrids was analysed about the beating degree,contact angle,surface morphology and structural characteristics.The experimental results show that the peaks of PET/PA66 blend fibrids at 3305 cm-1,1636 cm-1,1539 cm-1,which belong to the absorption peaks of-NH stretching vibration and amide I and amide II bands.With the increasing of PA66 in quantity,the length of fibrids mainly focused on 0.15 mm,and the fibrids in R100-R200 accounted for 62.1%-81.5%.Blending fibrids are ribbon-like in shape and the width of fibrids is narrow.With the increasing of the amount of PA66,the beating degree of fibrids and the contact angle decreased,and the dispersibility in the aqueous medium is better in turn,but the initial decomposition temperature of PET fibrids gradually decreased,indicating that the addition of PA66 will affect the thermal stability of fibrids.In addition,XRD and DSC datas showed that the diffraction peaks of PET and PA66 at 22.3° are superimposed,and there is only one melting peak after blending,which shows that the compatibility of PET/PA66 mixture is better.The properties of self-made PET fibrids were analyzed compared with PET pulp prepared by refined from chopped fibers by fiber quality analyzer,SEM,AFM,FTIR and other means.The experimental results show that PET fibrids were uniformly dispersed in the aqueous medium,while PET pulp was flocculated on the water surface.The weighted length of PET fibrids is smaller than that of PET pulp,mainly between 0.1 and 1.0 mm,and the fiber content is respectively 70.4% and 57.6%.SEM and AFM results showed that the surface roughness of PET fibrids were larger than that of PET pulp,fibrids were ribbon-like in shape,wrinkled surface,but PET pulp was cylinder-like in shape,smooth surface.Meanwhile,the results showed that the degree of crystallization of PET fibrids were slightly higher than those of PET pulp,the crystallinity was 37.88% and 33.26%,respectively.The initial decomposition temperature and maximum decomposition temperature of PET fibrids were higher than that of PET pulp,indicating PET fibrids have a better thermal stability compared to commercial PET pulp.