The Study On Radiation Grafting Polymerization On PET And Toughening Modification Through In-situ Compatibilization

Poly(ethylene terephthalate) (PET) has been widely used in films, textile fiber, packaging materials, and biomaterials due to its good mechanical strength, good heat and chemical stability, and excellent electrical property. But the inert surface and strong notch sensitivity restrict its wide applications in some fields,γ-ray induced graft copolymerization has been used for many years as a versatile approach to develop new functional materials. Therefore, in this thesis, we introduced y-ray induced graft copolymerization into grafting modification of PET material to improve its surface properties. A concept ofγ-ray irradiation induced in situ compatibilization of PET blend was proposed, i.e., preparing a in-situ compatiblizer through y-ray induced graft copolymerization to construct new toughened system of PET blend. The main achievements are as follows:1. Poly(2-hydroxyethyl acrylate) (HEA) and Poly(glycidyl methacrylate)(GMA) can be successfully grafted onto poly(ethylene terephthalate) (PET) film using y-ray induced graft copolymerization. Compared with other methods, such as plasma treatment and UV radiation grafting copolymerization, it is a simple and feasible strategy with a higher grafting yield. After the graft polymerization of HEA on PET film, the contact angle of PET film decreased from 69.5°to 37.1°. As for the graft polymerization of GMA on PET film, the maximum grafting yield can approach to 418%. Surface property of PET film is improved due to introduction of hydrophilic hydroxyl and high active epoxy groups. This strategy shows great potential application in the preparation of functionalized PET materials.2. To study y-ray irradiation induced in situ compatibilization of PET, we first start the graft polymerization of n-Butyl acrylate (BA) onto PET film iniated by y-ray. The maximum value of DG can reach to 22.1% with methanol as the solvent,25 wt% BA concentration, a dose rate of 0.83 kGy/h, and an absorbed dose of 35 kGy. Microphase separation occurs between grafted PBA side chains and PET backbone. So the Tg of PET and PBA in PET-g-PBA films are nearly the same with those of the corresponding homopolymer. Since PET-g-PBA has the identical chain structure with both PET and PBA, it can act as an internal compatibilizer for immiscible PET/elastomers (e.g., acrylate rubber) blends to improve the toughness of PET based engineering plastic; (2) The radiation grafting copolymerization of BA and styrene comonomer on PET films was investigated next. The composition and the DG o grafted copolymer depend on the comonomer composition and the absorbed dose Under the condition of a BA/St ratio of 4/1(mol%), a dose rate of 1.46 kGy/h, and ai absorbed dose of 35 kGy, the total grafting yield is 37.4%, and the grafting yield o PBA and PS were 21.8% and 15.6%, respectively. Because of the good compatibilit between the grafted P(BA-co-St) side chains and PET backbone, the Tg of PE decreases with the composition of grafted copolymer. Since the composition an flexibility of grafted P(BA-co-St) side chains can be easily adjusted througl controlling the feed ratio and absorbed dose, the prepared PET-g-P(BA-co-St copolymer can act as in-situ compatibilizer to enhance the toughness o PET/elastomers blends.3. The influence of the prepared compatibilizer PET-g-PAA on the mechanica properties of PET/ethylene-methyl acrylate-glycidyl methacrylate (ST2000) blen was studied. The SEM images of the PET/ST-2000/PET-g-PAA blends show a bette interfacial adhesion between the PET matrix and the elastomer. At the same time, th impact strength of PET/ST-2000 has also been improved from 12.28 kJ/m2 to 29.0 kJ/m2 after PET-g-PAA (6 wt%) was added.4. Poly(acrylic acid) (PAA) was facilely grafted onto PET film throughγ-ray induced graft polymerization. Silver nanoparticles produced by the chemica reduction of silver ions were then immobilized by carboxylic anions and embeddec on the surface of PET-g-PAA film. According to the TGA analysis, the content o loaded silver nanoparticles were about 20-36 wt%. It means the amount of loade silver nanoparticles has a positive relationship with the content of grafted PAA. Th PET-g-PAA/Ag hybrid film possesses excellent and stable bactericidal activity (cai kill all E. coli after 1 hour). This technique provides a facile strategy for th preparation of the antibacterial PET film.5. A facile and feasible approach to preparation of multi-walled carboi nanotubes (MWNTs) grafted with epoxy groups has been developed via y-ray induced graft copolymerization. The key factor in this grafting reaction is selecting the appropriate solvent. The prepared PET/MWNTs-g-PGMA composite has highe mechanical strength due to the improved dispersibility and compatibility ofth wall-modified MWNTs.