The Preparation, Structure And Properties Of Evoh/nano-sio₂ Packaging Composites With High-barriers

Products will suffer from damages and impacts of unfavorable factors in the storage, distribution and transportation process, but we can use the reasonable packaging to protect the products, so that the products will be safe from these impacts. High-barrier packaging materials can control the gas composition and content, thereby extending the product shelf-life, so that, high-barrier materials have become one of the most important functional packaging materials.This paper studied the preparation,structure and performance of the EVOH / nano-SiO₂ composites high-barrier packaging. The main content of the thesis is listed as follow: nano-SiO₂ was prepared by chemical precipitation method under multiple shear force field and characterized; EVOH / nano-SiO₂ composite materials were prepared by different blending methods, and we analyzed the impact of processing technique (blending technique and blown technique) on the structure and properties of high barrier packaging film through characterizing the composites. Nano-SiO₂ graft-modified by coupling agent and polymer was used to prepare EVOH / nano-SiO₂ composite materials, and the interface structure of composite materials and the relationship of the interface structure and the composites properties were studied; The EVOH / nano-SiO₂ composite membrane and plate were prepared under good processing technic,nano-SiO₂ modification methods, and the membranes and plates were characterized systematically. We also analyzed the impact of UV irradiation treatment on the composite membrane. EVOH / nano-SiO₂ composite films were compared under vibration force field, and the effect of processing under vibration force field on the barrier materials' structure and properties were analized.The results showed that: the SiO₂ particles are spherical approximately, the average diameter of the particles is around 19.5 nm, the particles had narrow particle size distribution and sound dispersion after modification. The reasonable processing technic improved the degree of film structure order and crystal morphology,so that film properties have been markedly improved; The nano-SiO₂ prepared by solution blending has better dispersion than that prepared by melt blending; Nano-SiO₂ has better dispersion,compatibility and interface interaction after being modified by coupling agent and polymer and the properties of the composite film have been improved greatly. KH550 is the best modifier of this system. Nano-SiO₂ can improve the crystallization properties of composite materials, thereby improving the properties of the membranes and plates; Reasonable UV radiation treatment can improve the properties of the composite film. Processing under vibration force field can improve nano-SiO₂ dispersion, change crystal form and orientation, so that the properties of the composites were improved.