Studies On Preparations And Properties Of Upr/inorganic Nano-particles Composites

Unsaturated polyester resins(UPR) is a kind of the most important thermosetting resins, which are widely used in many fields such as automobile industry, building, household appliances, aerospace industry and so on, due to their superior properties including lower price, easy processing, low densities and high hardness. However, impact resistance and ageing resistance of UPR is poor, especially ultraviolet can make the properties poorer, which also limits their applications. The added elastomer can improve toughness of UPR, however, the addition of elastomer in UPR generally results in a decrease in tensile strength and thermal stability. With the development of nano technology and nano material applied technology, it has important theory and practical value to improve the ultraviolet aging property and mechanical properties of UPR using inorganic nano particles.The common UPR was used as the matrix and rutile nano-TiO₂ and nano-CeO₂ were used as reinforcing material in this thesis. The dispersion of nanoparticles in the unsaturated polyester resin(UPR) solution were improved by means of solution blending, and the series of UPR composites specimens were prepared by casting technology and hand lay-up molding techniques. The dispersion behavior of nanoparticles in the UPR matrix was characterized by field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectrometer(EDS). The mechanical properties, thermal properties and ultraviolet aging property were systematic studied. The aim of this work is to gain UPR composite with good performance. The work and results are as follows:(1) TiO₂ nanoparticles were dispersed in UPR solution using mechanical agitation and milling respectively. Subsequently, the viscosity of mixture with different experimental conditions was measured, and then the TiO₂/UPR composites specimens were prepared by casting technology. The dispersion behavior of TiO₂ nanoparticles in the UPR matrix was characterized by SEM and EDS. The results showed that the perfect dispersion was markedly impacted by milling. Contrast with mechanical agitation, the dispersion effect is prominent. Fracture surfaces of UPR and its composites were investigated by SEM, the images of composites show a heterogeneous fracture surface having cracks with good distribution. The viscosity test showed that dispersion behavior of TiO₂/UPR mixture was perfect after milling 2h in room temperature, viscosity test of mixture can use as the important token means for the dispersion of nano TiO₂ in UPR matrix. The mechanical properties of milled composites were tested. The results showed that when the UPR was with 3.0wt% content nanometer TiO₂ its tensile strength and bending strength were higher than the pure UPR. The tensile strength and bending strength were improved more than 63.0% and 17.0% respectively. It was also found that when mass fraction of nano-TiO₂ is 1.0wt%, the impact strength was reinforced more than 6.1%. Thermogravimetric Analysis (TGA) indicated that TiO₂/UPR composites have better thermal stability than UPR.(2) First, TiO₂ nanoparticles were dispersed in UPR solution by milling, and then UPR/nano TiO₂/glass fiber composites were prepared by hand lay-up molding techniques. Images of composites showed that a good combination was observed between UPR and CeO₂ nanoparticles or glass fiber. The mechanical properties and FT-IR of composites which exposed and unexposed were studied, the result showed the addition of TiO₂ nanoparticles component to UPR leads to improvements in ultraviolet aging property, combined with test result, aging mechanism were putted forward.(3) UPR solution and CeO₂ nanoparticles were mixed by means of milling, the UPR/nano CeO₂ composites specimens comprising different CeO₂ content were prepared by casting technology. Different experimental techniques including SEM and EDS have been applied for the analysis dispersion of CeO₂ nanoparticles in the UPR matrix. We found that the dispersion was markedly impacted by milling time. The break surface was characterized by SEM, the test result showed the composites with 2.0 wt% nano CeO₂ content milling for 2 h, its impact fracture surface formed lots of tenacity rupture avulsion strip. The tensile strength, impact strength and bending strength of the composites were reinforced with the addition of CeO₂ nanoparticles. The tensile strength, impact strength and bending strength reach a maximum respectively at 2.0wt%, which is 69.5%, 87.8% and 17.8% higher than that of the pure UPR.