| Colemanite (Ca2·BeO11·H2O) is one important natural borate mine and chemical materials, which is widely used in many industrial fields. It is the main raw material to manufacture boric acid and borax, plastic enhancer and boron alloy. Besides, colemanite could be used as slagging agent in the steel industry and flame retardant in the plastic industry. But added in polymer as a flame retardant, colemanite can not be well compatible with polymer because of its surface polarity. Therefore, to improve its compatibility with organic polymer and invent one high-quality halogen-free flame retardants with lower cost, colemanite should be modified by organic modification agents. In this paper, the physical and chemical characteristics of colemanite are investigated. Based on that, the affinity and compatibility of colemanite with organic polymer minerals would be improved by modification agents and the mechanical properties of mixed polymer materials would also be enhanced. Besides, the application field of colemanite can be widened and its industrial value and economic value is expected to rise.In this paper, components in the colemanite were investigated. Besides, colemanite was characterized by XRD, IR, TG/DTG, SEM and particle size distribution analysis to confirm its physical and chemical characteristics, such as temperature of weight loss and distribution of particles size. These were provided for selecting a proper flame retardant.Based on the above process, in order to make colemanite with a good compatibility with polymer materials, surfactants were used to modify it by a wet chemical process. Stearic acid and oleic acid were selected as modification reagents, respectively, and anhydrous ethanol was used as solvent. The influences of modification temperature, modification time, the ratio of liquid to solid and the dosage of modification agents were discussed. Besides, the modified colemanite was evaluated by XRD, FT-IR, activation index, contact angle and SEM, etc. The results showed that when the temperature is75℃, time is75min, the ratio is1:2and the dosage of stearic acid is5%, the activation index of products is99.45%and contact angle is131.5°. In the condition of60℃for50min with1:1liquid-solid ratio and5%oleic acid, the the activation index of products is68.30%and contact angle was not found. So the hydrophobic is not improved.The modified colemanites were filled into Ethylene-vinyl acetate (EVA). Then, mechanical properties of EVA blending with colemanite modified by different modification reagents were investigated; mechanical properties of EVA blending with different amount of stearic acid modified colemanite were also investigated. The mixed materials were tested by electronic tensile testing machine, SEM, TG-DTG and XRD. The results showed that the properties of EVA blending with stearic acid modified colemanite by the2:3ratio(200g total weight) were better than EVA blending with oleic acid modified colemanite; when EVA blended with stearic acid modified colemanite by the1:4.2:3and3:7ratios, the40%addition had a higher flame retardant property than others, which could extinguish within40s. The result of TG-DTG shows that the modified colemanite could function as fire retardant to hinder the decomposition of mixture plastics. At last, this paper discusses the burned composite materials and its residue morphologies were observed by XRD and SEM.Calcium metaborate hexahydrate was prepared by synthesis and modification method. The resulting product was drying to form calcium metaborate dihydrate. The mechanics performance testing, flammability properties testing, TG-DTG, SEM, and XRD tests were carried on the mixture plastics. The results are the following:(1) the modifier agent, oleic acid, is superior to sodium stearate.(2) the mechanical property of calcium metaborate hexahydrate/EVA is better than calcium metaborate dihydrate/EVA.(3) As the addition of modified product increases, the mechanical property of mixture plastics become lower but flame retardancy is higher. At last, this paper discusses the burned composite materials and its residue morphologies were observed by SEM. |
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