| With the development of science and technology and the improvement of people's health awareness,personal impact-resistant protective materials have received more and more attention.Personal impact protection materials refer to a class of materials that can prevent or reduce personnel from being injured by impact.In daily life,people will encounter many low-speed impacts of blunt objects,such as traffic accidents,falling objects from high altitudes,sports impacts,etc.Although the impact speed is not high,this type of impact can damage the muscles and bones and even endanger the life,therefore,anti-low-velocity impact materials should attract enough attention.This article selects hollow glass microspheres(HGMs)as the impact-resistant material filler,water-based polyurethane(WPU)as the binder,and adopts the dipping-coating preparation method to combine with the three-dimensional trapezoidal glass fiber fabric matrix to prepare a lightweight and soft,low-speed impact-resistant textile composite materials that can withstand multiple impacts,and HGMs with four particle sizes of 30?m,40?m,50?m,and 60?m are selected to study the impact of the particle size of the microspheres on the impact strength and compressive strength.After testing,it is found that when the impregnated layer and the coating layer are filled with HGMs with a particle size of 30?m,the impact strength and compressive strength reach the highest,the impact strength reaches 23.08 KJ/m~2,and the compressive strength reaches 47.23 MPa,compared with the pure resin composite material(9.87 KJ/m~2,13.60 MPa)without filling the microspheres,an increase of 2.33 times and 3.47 times,respectively.From the perspective of shock stress wave theory,under the same volume fraction,the smaller the particle size,the higher the packing density of the microspheres,and the more microspheres per unit area are impacted.In addition,it is also found that the impact strength of the impregnated samples is higher than that of the coated samples.Reinforcing the interlayer structure of the fabric can significantly enhance the impact resistance of the fabric,and coating on the impregnated samples is equivalent to adding the impact buffer layer to the composite material,which can not only protect the interlayer structure,but also improve the overall impact resistance.The high temperature and flame retardant properties of the fabric after impregnation-coating treatment with WPU are reduced,therefore,flame retardant filling method was adopted in this paper to improve the flame retardant performance of the composite fabric.In the first step,in order to solve the problems of high-water solubility and poor compatibility with the polymer matrix of ammonium polyphosphate(APP),this article utilizes the precipitation method to synthesize in situ aluminum hydroxide(ATH)on the surface of APP,by changing the reaction temperature,reaction time and the dosage of hydroaluminum chloride,combined with specific surface area and water solubility tests,initially shows that the reaction temperature is 60?,the reaction time is 2 h,and the dosage of anhydrous aluminum chloride is 2 g as the optimal reaction conditions;then combining with flammable waterborne epoxy resin,with morphology characterization and flame retardant test,it is determined that the compatibility of APP@ATH with the matrix are improved under the above-mentioned optimal reaction conditions,and the introduction of ATH particles also improves the flame retardancy.The flame retardant efficiency of the agent can be used as a good polymer-based flame retardant filler.In this paper,the modified flame retardant is added to the HGMs-filled impact-resistant three-dimensional fabric material in the form of filler to explore the flame-retardant performance and impact resistance of the composite fabric material under different mass fractions.With the increase in the amount of flame retardant,the limit oxygen index(LOI)gradually increases.When the mass fraction reaches 15%,the LOI of APP-15 is 25.6%,and the oxygen index of APP#7-15(APP#7 is the best modified product)reaches 27.9%,which means with the same mass fraction of 15%,APP#7-15 meets the standard for flame-retardant materials.Through the vertical combustion test,it is found that APP-20 fails to reach the V-0 level,and APP#7-15 has reached V-0 burning grade which proves that the modified flame retardant can improve the flame retardant efficiency of composite materials.The surface modified flame retardant APP#7 forms a stress buffer at the interface between the resin and the flame retardant,which effectively improves the impact resistance of the composite material.When the mass fraction is 10%,the impact strength reaches47.60 KJ/m~2,which is twice of the impact strength of 30/30 sample.Due to the good compatibility of APP#7 with the matrix,the thermal insulation performance of the composite material has also been improved,reaching the best when the mass fraction is 10%.Based on the above research results,this article proves that under the same volume fraction,HGMs with a smaller particle size can achieve better impact resistance.APP@ATH flame retardant obtained by in-situ polymerization improves the water solubility and compatibility of APP,at the same time,it can also improve the flame retardant efficiency.Combining the appropriate amount of APP@ATH with the composite material filled with HGMs can prepare a textile composite material with both impact resistance and flame retardancy,which further improves the protective function of the composite material. |
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