| Polymer and their products such as plastic, rubber and synthetic fiber have been vastly used in the areas of industry, agriculture, military and other economic process. Most high polymers are inflammable and combustible so they are regarded as potential threat to human health. Nowadays, flame-resistance of polymer has drawn great attention in most countries on the world. The modification of the flame-resistance of synthetic and natural polymer is an urgent task globally.In this study, ultra-fine inorganic flame-retardant was surface coated and modified by flame-resisting surfactant. After blending with organic flame-retardant, inorganic particles were dispersed completely in the polymer. The achieved complex intumescent flame-retardant which contained acid source, carbon source and gas source, showed the synergetic effects of all flame retardant components. The effects of single flame-retardant and complex flame-retardant on the flame-resistance and physical properties of HDPE were studied using the method of blending modification. Optimal components and prepare processing of modified halogen-free flame-resisting materials were found out. Ultra-fine flame-retardant/PE materials were made in this way. The work provided a theoretic direction to the manufacture of materials for steel frame-plastic complex pipe. From huge amount of experiments and tests, the following conclusions were drawn:Results:1. High density polyethylene (HDPE) with Magnesium Hydroxide (MH) alone: to achieve the ideal flame-resistance, the minimum amount of MH had to be 60%. At this situation, the mechanic properties of this complex system were severely damaged.2. Surface modifier could improve the rupture extension ratio of the HDPE/MH system, reduced the tensile intensity and flame-resisting ability of the system simultaneously.3. Halogen-free flame retardant such as red phosphor, ammonium polyphosphate (APP) and zinc borate (ZB) could improve the flame-resisting properties of HDPE/MH system slightly. Because of the less amount of halogen-free additive, the mechanic properties of the system could be improved.4. Intumescent flame retardant APP/PER/ZEO system had good flame-resisting effect on HDPE resin. When the amount of APP/PER/ZEO additive was 30% (wt), the oxygen index of intumescent flame retardant polyethylene was 28.8, at relative higher level of the materials of same kind. The flame-resisting performance met the standard for flame retardant materials. The efficiency of flame-resistance was much better than hydroxide. According to thermal degradation and flame-resistance experiment results, the flame-resisting performance depends on the quality of intumescent carbon layer formed by combustion. Aluminosilicate ZEO could improve the quality of intumescent carbon layer of HDPE/APP/PER system.5. According to the pilot-scale test, the optimal components of the special flame retardant were P, APP, ZB, BP and MH. As to HDPE pipe, the components were flame retardant mentioned above 25%, EVA 10%, low-molecular wax 1%, PE (2480) 64% and enough Z200 processing modifier. The processing technology of this special materials was described as below. ZB was dispersed by enough ethanol, and then mixed with MH. After stirred and mixed uniformly, ethanol was evaporated. Added red phosphorus and APP and mixed for 5 minutes in mixer. Added all other raw materials and mixed in mixer for 10 minutes. In the end, materials were extruded and granulated by double-screw extruder (screw ratio >20:1). The parameter of extruder were: input temperature at 130-150℃,extrudate temperature at 190~210℃, die temperature at 190~200℃, screw rotary speed at 60-100 r/min.。...
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