Study On Functionalised Polyolefins Toughing Recycled PET

The reactive extrusion grafting of Maleic anhydride onto High density polyethylene (HDPE) and Polypropylene random copolymer (PPR) was carried out with grafting reactive extruder. The effects of Dicuumyl peroxide (DCP) content and MAH content on the grafting degree and melt flow rate of the product were studied in this paper.The grafting product HDPE-g-MAH and PPR-g-MAH products were used to blend with recycled PET flakes (r-PET) as toughening agents. With the measures of SEM, DSC and mechanics methods the effects of the content and grafting degree of the toughening agents on the morphology structure, mechanical performance and thermal properties of the blends were studied.The results showed, compared with the effect of toughening agent HDPE-g-MAH, PPR-g-MAH had a much better toughening effect. SEM showed PPR-g-MAH was dispersed evenly throughout the r-PET matrix and the fracture surface appeared the feature of toughness fracture. Crystallization performance of r-PET was greatly influenced by the grafting degree of PPR-g-MAH, the r-PET crystallization properties improves when the grafting degree of PPR-g-MAH increasing. The results showed that the blends owns the best mechanical properties with the 4.2mmolMAH/100g grafting degree PPR-g-MAH which content is 10%, the tensile strength is 50 MPa, the elongation at break is 44% and the unnotched izod impact strength is 92 kJ/m2.The effects of two kinds of compatibilizer LDPE-g-MAH and HDPE-g-MAH content on the properties of r-PET/PC blends were studied with the use of condensation reactive extruder. Compared compatibilizing effect of HDPE-g-MAH, the results showed that LDPE-g-MAH performs better and the mechanical properties of r-PET/PC blends improves greatly.The brittle to ductile transition took place when the content of LDPE-g-MAH increased according to the SEM pictures. When the content of LDPE-g-MAH was 6%, the tensile strength of r-PET/PC blends was up to 59MPa, which was increased 32% than that of r-PET/PC blends without compatibilizer, elongation at break was 78% and the unnotched izod impact strength was 117.5 kJ/m2 which was increased 290%.DSC results showed that the crystallization behavior of r-PET was not greatly influenced by the addition of LDPE-g-MAH. DMA results showed that the Tg of r-PET and the Tg of PC got closer which indicate that the compatibility between r-PET and PC was much better with the addition of compatibilizer LDPE-g-MAH. The tanδof blends was getting small when the content of LDPE-g-MAH increasing. The r-PET/PC/LDPE-g-MAH blends got the highest storage modulus when the content of LDPE-g-MAH was 6%.