Synthesis Of Two Allyl Esters And Their Application In Crosslinking Modification Of EVA / LDPE Composites

Triallyl isocyanurate (TAIC) is widely used as cross-linking agent, and often produced through the aqueous phase on industrial, but this method is likely to cause loss of allyl chloride in production process which increased the cost. Furthermore, the demand of TAIC is also increasing on the industry, because the molecular structure has three olefin monomer, and often used for cross-linking modified in the field of polymer materials, especially in modified cross-linking pipe, it can improve the mechanical strength of the material, solvent resistance and heat resistance etc. However the low density polyethylene (LDPE) is a common material in producing pipes, while adding ethylene-vinyl acetate copolymer (EVA) to improve the processing performance. As the pipe is insufficient in mechanical properties and heat resistance which limited its development, and we added the TAIC to modify the material. Also, the synthesis and modification of hexaallylhexaazaisowurtzitane which contains multifunctional olefin monomers have also been studied.Based on this, the research is composed by the following aspects:Firstly, the synthesis study of triallyl isocyanurate; Secondly, the properties study of EVA and LDPE blending, which is aimed to choose the appropriate proportions as the base material; and then by the addition of TAIC to EVA/LDPE composites to modify the material in the method of chemical cross-linking, Finally, the synthesis of hexaallylhexaazaisowurtzitane and its modification is studied, the specific contents are as following:(1) By using the method of cyanuricacid trisodium salt to synthesis the TAIC, while using the unit operations of extraction instead of distillation, to optimize the synthesis process study of TAIC. And FT-IR, NMR, GC-MS, gas chromatography etc were used to characterize the product, which indicated that the synthetic product is triallyl isocyanurate, while the purity is tested by external standard method through standard curve. Finally, the reaction temperature, the molar ratio of allyl chloride and cyanuric acid, reaction time, catalyst, solvent selection and other aspects were explored in the synthesis of triallyl isocyanurate. Through the reaction of glyoxal and propylene amine was to synthesized hexaallylhexaazaisowurtzitane successfully, and characterized by high resolution mass spectrometry, elemental analysis, infrared analysis and NMR.(2) The main study is to research the properties changes of EVA/LDPE binary blend with different proportions. By using the melt flow rate test (MFR) and the hardness test to characterize the physical properties of the material, Differential Scanning Calorimeter (DSC) shows melting point and crystal changes, and TGA studies its thermal stability. Scanning Electron Microscopy (SEM) studies the fracture surface of the material, the tensile testing is used to study the mechanical properties change, and ultimately 40/60 is selected as the matrix ratio of EVA/LDPE.(3) By using the twin screw extruder, the modified ethylene-vinyl acetate copolymer/low density polyethylene (EVA/LDPE) composites were prepared with EVA/LDPE as the matrix, 2,5-dimethyl-2,5 double(tertiary-butyl oxygen radicals) hexane as initiator, and triallyl isocyanurate (TAIC) as cross-linking agent. The effects of TAIC with different content on the properties of the modified EVA/LDPE composites were studied through the gel content and mechanical analysis, differential scanning calorimetry analysis, dynamic mechanical analysis, and dielectric performance test, etc. The results indicate that with the increasing content of TAIC, the gel content of the composites increases significantly (can reach above 70%); and the tensile strength of the composites increases firstly and then decreases, when the content of TAIC reaches 2%, the tensile strength of the composites can be improved from 11.64MPa (unmodified EVA/LDPE) to 19MPa. Moreover, with the increasing content of TAIC, the melting point, crystallization temperature and storage modulus decreases, glass transition temperature, Vicat softening temperature and viscosity increases, and the dielectric constant shows a downward tendency, but the dielectric loss changes little. While the cross-linking temperature, cross-linking time, initiator content are also researched on EVA/LDPE composite as the cross-linking process conditions(4) Added the hexaallyl hexaazaisowurtzitane to the composite material, and by the gel content analysis, dynamic mechanical analysis, dielectric properties and mechanical analysis test to study the different amounts of hexaallylhexaazaisowurtzitane impact on the composites. The results show that:with the amount of hexaallylhexaazaisowurtzitane increased, the gel content of the composite material, the dielectric constant, vicat softening temperature, tensile intensity firstly increased and then decreased, and the dielectric loss upward showing trend. With continue in-depth study in the process, found that the mechanical properties of the test material showing a poor repeatability...