Research On Preparation Of Magnesium Oxysulfate Whiskers And Its Application In Flexible PVC

The Chemical composition of magnesium oxysulfate whiskers is MgSO₄·5Mg(OH)₂·3H₂O,and its morphology is needle or fiber. The characteristics of whisker are high intension, high elasticity coefficient and low density, and as the intensifier applied in composite materials such as plastic, rubber, and resin etc. the mechanical properties including flexural strength and impact strength can be improved. Due to MOS molecule contain crystal water which decomposes until 260℃and the decomposition products are no innocuity, MOS is an environmentally friendly flame retardant.In this paper, the preparation and application in flexible PVC of magnesium oxysulfate whiskers were researched. The effects of two preparation equipment of intermediate product, reactant concentration and rotor speed on the product quality were discussed. Under the same conditions, MOS was also prepared in a pilot test in 100 L autoclave, and the product was characterized by SEM, XRD and TG. In the study of application, the micro-morphology of modified and unmodified MOS in flexible PVC was reviewed by SEM of section. Influence of MOS content on flame retardancy and mechanical properties of the composite system was investigated. Also, MOS and MH were mixed with different proportions, and PVC/MOS/MH composites were prepared. Influence of mixed two inorganic fillers on flame retardancy and mechanical properties of the composite system was investigated.The experimental results showed that the preparation of magnesium oxysulfate whiskers by rotor-stator reactor and hydrothermal method was magnify to pilot. The product had a good quality and the yield of MOS reached 40-50g·L^-1.Surface modification treatment made surface energyreduced, and benefit for dispersion. The best modifier was titanate. The composite system MOS/PVC gets better General performance at the dosage of 60phr MOS. The oxygen index of system rose up to 28.3%, tensile strength and Elongation at break descend to 18.48 and 534.3%, flame retardant and mechanical properties were satisfactory to operation requirement in practice. When modified MOS and MH were added to flexible PVC at the ratio of 1:5, the composite system MOS/MH/PVC get better application effect: The oxygen index of system rose up to 28.8%, tensile strength and Elongation at break descend to 19.86MPa and 506.8%.