Application of Nanometer Silica in PVC Materials

Because nano-silica has the characteristics of small size, large specific surface area, quantum effect and surface effect, domestic researchers have introduced nano-scale materials to the research of PVC toughening and modification, and found that the modified PVC material has both Excellent toughness, process flow, dimensional stability and thermal stability. In recent years, with the development of nanoparticle surface treatment technology, nanoparticle toughened PVC has become a hot spot of research and development at home and abroad. The toughening mechanism is that the presence of nanoparticles produces a stress concentration effect. Causes micro-cracks in the surrounding resin, attracting a certain amount of deformation work: nanoparticles can also play a role in preventing and passivating cracks in the resin, and finally prevent the cracks from developing into destructive cracks: due to the large contact area between the nanoparticles and the matrix resin , when the material is impacted, more microcracks will be generated and more impact energy will be absorbed.
With the increase of silica content, the tensile, impact strength, elongation at break and yield strength of polyvinyl chloride composites increased gradually, and reached the maximum value when the silica content was 3%. Compared with the polyvinyl chloride composite without added silica, the tensile strength of the composite is increased by about 18.8%. The impact strength increased by 116.7%, the yield strength increased by 21.4%, and the elongation at break increased by 69.5%. From the SEM photos of the PVC/fine SiO composite material, it can be seen that the continuous phase of the PVC material, the interface between SiO and PVC is well bonded, and the existence of many micro-holes and micro-cracks can also be observed, which is easy to absorb impact energy, thus ensuring that The effect of SiO on strengthening and toughening of PVC materials.

In the research on the properties of PVC/Nano-SiO composites, it was found that the tensile strength of the composites gradually increased with the increase of the amount of Nano-SiO, and the tensile strength of the composites reached the maximum when the amount of Nano-SiO was 4%. When the dosage exceeds 4%, the tensile strength of the composite material gradually decreases; with the increase of Nano-SiO: dosage, the impact strength of the composite material first increases and then decreases. When the dosage is 3%, the composite material's impact strength The impact strength reached the maximum value, and then the impact strength of the composites began to gradually decrease: the flexural modulus of the composites showed an obvious trend of increasing with the increase of the amount of Nano-SiO.

Nanoparticles were surface treated by ultrasonic, vibration grinding and other methods. It can promote the uniform dispersion of nanoparticles in the matrix, and greatly improve the strength and toughness of the composite material. When the addition amount of nano-SiO is 3%, the composite material has the best comprehensive mechanical properties, and its tensile strength, impact strength and Young's modulus are greatly improved. The vibration grinding time also has an effect on the improvement of the properties of the composite materials by nanoparticles, and the effect of improving the impact of the composite materials is the best when the treatment is 6h.

In the study of the effect of surface modification on the properties of PVC/Nano-SiO composites, it was found that when the addition amount was less than 3%, the surface modification of Nano-SiO had basically no effect on the impact properties of the composite material: when the addition amount was less than 4%, Whether its surface modification or not has basically no effect on the tensile strength, flexural properties of the composite and its dispersion in the PVC matrix: after the addition of more than 3%, the surface modification of Nano-SiO makes the composite have better impact Performance: After the addition of more than 4%, the surface modification of Nano-SiO makes the composite material have better tensile and bending properties, and its dispersibility in the PVC matrix and its interfacial adhesion with the PVC matrix are also improved. better.