343results about How to "High limiting oxygen index" patented technology

The invention relates to a preparation method of polyimide fiber. The procedures and conditions of the preparation method are as follows: (1) precursor acid polyamine solution used for spinning is made by fasculating diamine and dianhydride monomer; (2) the preparation of the polyimide fiber adopts dry-wet spinning process; (3) the polyimide fiber is imidized; and (4) the polyimide fiber undergoes the heat drawing under the temperature of 300 to 500 DEG C, and the drawing multiple of the fiber is 1 to 7 times. Imide process adopts a gradient heating-up thermal treatment furnace so as to overcome the defects of the inaccurate temperature control and the non-feasibility of the prior double thermal furnace process. The preparation method has simple process and is easy for continuous production. The prepared polyimide fiber has stronger strength and high modulus and can be used under the temperature of over 300 DEG C. In addition, the polyimide fiber has UV irradiating resistance property, a higher limited oxygen index and corrosion resistance, so the polyimide fiber can be widely applicable for the reinforced fiber of composite materials, a cable sheath, a cable reinforcing core, themooring rope of vehicle and vessel and the filtering materials of high temperature or radioactive substance, etc.