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Research On Preparation Of Nano-SiO2 And Its Modification Of Polyethylene Terephthalate(pet)

Posted on:2011-12-08Degree:MasterType:Thesis
Country:ChinaCandidate:F ShenFull Text:PDF
GTID:2131330338976441Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
In order to improve the mechanical properties of polyethylene terephthalate (PET) and expand its scope of application, nano-SiO2 sol was prepared by tetraethyl orthosilicate in glycol water, and was used to synthesize nano-SiO2/PET composite materials through in-situ polymerization method.The state of nano-SiO2 particles in sol and its dispersion properties in PET matrix were characterized by dynamic light scattering analyzer (DLS) and transmission electron microscopy (TEM). The relationships between the weight fraction of nano-SiO2 and the thermal properties and crystalline properties were analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD), respectively. The effects of the weight fraction of nano-SiO2 on the intrinsic viscosity, impact toughness and tensile strength of nano-SiO2/PET composite materials were studied by viscosity testing and mechanical testing. The micro-fracture morphology of nano-SiO2/PET composite materials was observed by scanning electron microscopy (SEM).The results showed that in acidic condition, the size of nano-SiO2 particles distribution showed strong polydispersity, while its distribution was very uniform in alkaline condition. Nano-SiO2 particles could hinder the polymerization process of PET to some extent, which resulted in a decline in intrinsic viscosity. They played a role of heterogeneous nucleation in PET matrix, and could significantly promote the crystallization process of PET when the weight fraction was 0.6%. They could raise the thermal crystallization temperature and lower the cold crystallization temperature of PET. When the weight fraction of nano-SiO2 was 1.0%, both of the impact toughness and tensile strength of the composite materials reached maximum, increased by 65% and 32% compared with neat PET, and the impact fracture characteristic obviously appeared a tendency toward toughness. However, both of the impact toughness and tensile strength of the composite materials decreased when the weight fraction continued to increase.
Keywords/Search Tags:polyethylene terephthalate, nano-SiO2, composite, sol, in-situ polymerization
PDF Full Text Request
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