Study On Properties Of Nano-Al₂O₃ And Carbon Fiber Reinforced PET Composite

Polyethylene terephthalate?PET?has excellent thermal stability,chemical resistance,electrical properties,and easy recycling properties.However as application in engineering plastics,it has the defects of poor toughness,high molding shrinkage,and processing temperature.Therefore,modification of PET to meet the need of engineering field has broad prospect.This paper aims to modify the defects of neat PET materials through compounding with nano Al₂O₃ and/or carbon fiber?CF?,and investigates the relation between the structure and property of composite,thus provides some data for the processing and application of polymer material.The results are following:Firstly,we choose nano-Al₂O₃ to compare with traditional modifier nano-SiO₂,which dispersed in ethanol and coated with KH570 to prepare a series of composites by melting blending to improve the strength and processability of PET.The crystallization kinetics,crystal structure,and mechanical properties of resultant PET composites were also studied by DSC,TQ and other test methods.Results show that nano-Al₂O₃ and nano-SiO₂ can be uniformly dispersed in the composite and improve the tensile strength and impact strength of the PET material to a certain extent.Crystallization kinetics study showed that MoZhishen method according with the actual process of the non-isothermal crystallization process of composite materials.Nano-Al₂O₃ and nano-SiO₂ both can act as nucleating agent to improve the crystallization ability of PET material,in addition,the well-dispersed nano inorganic particles as nucleating agents in the composite can improve the crystallization ability of PET material,increase the crystallization rate and shorten the time in crystallization.But modification effect was little difference at 1 wt%nano-A12O3 compared with 3wt%nano-SiO₂ and the performance of PET/nano-Al₂O₃ were more stable in the experimental dosage.Therefore,compared with the traditional modifier nano-SiO₂,nano-Al₂O₃ has certain advantages and development prospects.Secondly,the excellent propertie of carbon fiber?CF?which make it as another alternative to the PET modifier,but the inertness surface of the CF is a short board for the performance of PET/CF composite materials.Physical coating and chemical grafting had been used to choose to surface modified.As for physical coating of CF,the KH570 had been chosen as a surface modifier.Results show that the mechanical properties and heat distortion temperature of the resultant composites can be improved to a great extent.With regard to chemical grafting,the functional groups were chemically grafted onto the surface of carbon fiber to improve the compatibility with PET.In order to obtain better results,the CF was pretreated by mixed acid:the maleic anhydride grafting CF had been prepared by solid-phase grafting method as benzoyl peroxide for an initiator,and the property characterizations show that the MAH was successfully expressed in the carbon fiber surface;Meanwhile,free radical polymerization in water solution was used to the chemical grafting of MMA onto the surface of CF,and the infrared spectrum,TG analysis,XPS and SEM showed that MMA was successful grafted on the surface of carbon fiber.Moreover,the PMMA-g-CF and MAH-g-CF were melted blending with PET,the results show that the tensile strength,impact strength and thermal deformation temperature of the composite had further improved than the untreated CF.Dynamic rheological analysis also expressed that PMMA has smaller heterogeneity with PET resin matrix compared with MAH,which indicated PMMA-g-CF can be further improved the properties of the composite than MAH-g-CF.Meanwhile,the crystallization behavior of PET/carbon fiber showed that CF can act as nucleating agent to improve the crystallization ability of PET material and speed up the crystallization rate.Moreover,crystallization kinetic studies show that the Mo method is better to analyze the non-isothermal crystallization process of PET composites,and the FWO method can calculate the non-isothermal crystallization activation energy of several composite in different degree of crystallization,which were consistent with the macro mechanical and rheological data.Among the three kinds of materials of inorganic nano-particles,carbon fiber and the chemically grafted carbon fiber with PMMA?PMMA-g-CF?,PMMA-g-CF showed the best modification effect on PET.