Preparation And Properties Of Whisker/Silicone Rubber Composites

China's Qinghai Salt Lake has abundant resources,therefore efficient development and utilization of Salt Lake's resources is of great significance.Qinghai Institute of Salt Lake,CAS,has successfully achieved large scale production in manufacturing various types of whisker,such as magnesium borate whisker which is abbreviated to MBO in this thesis and Magnesium Oxysulfate Whisker which is abbreviated to MSO.Previous research has shown that whisker,as a functional additive,could remarkably functionalize on facilitating to reinforce mechanical strength and the flame retardant of liquid silicone rubber and plastic,such as polyethylene and polypropylene.However,there is not sufficient research results had been achieved about whisker-polymer functional composite materials,which largely constrains its application in the polymer field.This thesis studies the whisker/silicone rubber production process and the properties of the products,which uses MBO and MSO as the functional additive and apply various manufacturing technologies,mixing through kneader reactor,open milling through two roll mill,press vulcanization,etc are included.The study finds that whisker increases the tensile strength of the high-temperature vulcanized silicone rubber(HTV),which has an obvious advantage in comparison with other inorganic fire-retardant.Whisker can improve the silicone rubber's heat resistance performance and significantly increase its Limit Oxygen Index.Compare MSO with MBO,MSO has a big length-diameter ratio and provides superior effect of reinforcements to silicone rubber;MBO has better flame retardant performance since its low thermal decomposition.The cross-linking density of silicone rubber have a vital influence on its mechanical property and flame retardant efficiency,high cross-linking density restrain whisker's dispersion and distribution in HTV.When the ratio of two different vinyls content of polysiloxane,the proportion of the two polysiloxane with vinyls of 0.23% and 0.04%,is 2 to 3,it reaches the optimized integrated performance of mechanical and flame retardant function.Compared with untreated whisker,the MBO and MSO treated with HMDS,thus,the surface of the two kinds of whiskers isgrafted by –Si Me3,meanwhile the silicone rubber has better mechanical strength and flame retardant performance.These results provide a new method in producing silicone rubber with high strength,flame retardant,heat resistant properties,besides,it also produced a series of flame retardant and high strength whisker/silicone rubber composites in which the LOI is beyond29% and the tensile strength is beyond 5 MPa.Which makes MBO and MSO have broad application prospects,as functional additive can be uses as flame retardant silicone rubber wire and cable compound packing.