Research On Environmentally Friendly Halogen-free Flame Retardant Polyamide Composites

Polyamide is an engineering plastic with many advantages such as good wear resistance and high mechanical strength.PA6 and PA66,as the most widely used varieties of polyamides,are both occupying an important position in various industrial fields due to their excellent comprehensive properties.The main research of this paper is to apply the new organic phosphorus-based halogen-free flame retardant aluminum diethylphosphinate to the preparation of environmentally-friendly halogen-free flame-retardant PA6 and PA66 composite materials.By studying the effects of the combination of ADP flame retardant and other halogen-free flame retardants and their composition on the performance of PA6 and PA66 composite materials,a series of flame retardant compositions used in the preparation of environmentally-friendly flame retardant PA6 and PA66 composite materials have been obtained preparation technology and application technology.The application effect of the series of flame retardant compositions developed in environmentally-friendly halogen-free flame retardant PA6 and PA66 composite materials has reached the corresponding OP series flame retardant level produced by Clariant,Germany.The materials have been tested by the Ningbo Branch of Environmental Quality General Standards Technical Service Co.,Ltd.and have met the requirements of the RoHS and REACH directives issued by the European Union.In this project,the vertical combustion level was measured by the horizontal and vertical combustion instrument,and the limiting oxygen index was measured by the index tester.The flame-retardant properties of environmentally-friendly halogen-free flame-retardant PA6 and PA66 composite materials were studied,and the flame-retardant mechanism was discussed.The universal material testing machine was used to test the tensile strength and flexural strength,the pendulum impact testing machine was used to test the impact strength,and the mechanical properties of environmentally-friendly halogen-free flame-retardant PA6 and PA66 composite materials were studied.The thermal degradation performance of environmentally-friendly halogen-free flame-retardant PA6 and PA66 composites was studied by thermogravimetric analysis technology.The morphology of the carbon residue on the surface of the standard samples after the oxygen index combustion test was analyzed by scanning electron microscope.And the crystalline properties of environmentally-friendly halogen-free flame retardant PA6 and PA66 composite materials were studied by differential scanning calorimeter.The specific research content of this paper is as follows:(1)Research on environmentally-friendly halogen-free flame retardant PA6 composite material.In this study,halogen-free flame-retardant PA6 composites were prepared by melt blending using aluminum diethylphosphinate as the flame-retardant char-forming agent and melamine cyanurate as the flame-retardant synergist.The results showed that the prepared flame-retardant PA6 composite materials could pass the V-0 level of the vertical combustion test;when the amount of ADP added is 18%,the LOI could reach 33.3%;when 14% ADP was added,the LOI of the ADP/MCA compound flame retardant system maintained at about 31%.MCA and ADP had a synergistic flame-retardant effect.The addition of MCA reduced the thermal decomposition temperature,prompted PA6 to rapidly form carbon during combustion,effectively improves the structure of the carbon layer,and kept the flame-retardant PA6 composite material maintaining good mechanics performance.The non-isothermal crystallization kinetics of composite flame retardants composed of aluminum hypophosphite,ADP and MCA and melamine polyphosphate on PA6 composites were studied.The results showed that both Jeziorny method and Mo Zhishen method were suitable for halogen-free flame retardant PA6 composites.In the crystallization process of halogen-free flame-retardant PA6 composites,homogeneous nucleation and heterogeneous nucleation existed simultaneously.Increasing the cooling rate was beneficial to halogen-free flame-retardant PA6 composites to achieve higher crystallinity per unit time.(2)Research on environmentally-friendly halogen-free flame retardant GF-PA6 composite material.The flame retardant effects of ADP and MCA,zinc diethylphosphinate,TAF,zinc borate and other compounds in GF-PA6 material have been studied,and developed a composite flame retardant system XHPFR-2041 with ADP and MCA,zinc diethylphosphinate,TAF,and zinc borate as main materials,which was used as a high-efficiency composite flame retardant for flame retardant GF-PA6.The performance of flame retardant GF-PA6 composites prepared by melt blending of XHPFR-2041 composite flame retardant was studied.The results showed that when the amount of XHPFR-2041 composite flame retardant was 18 parts,the LOI of flame retardant GF-PA6 composite material was basically maintained at about 31%,and all of them passed the V-0 level tested by UL-94.The addition of flame retardants would reduce the thermal stability of flame retardant GF-PA6 composites.The ADP and MCA in the flame retardant XHPFR-2041 had a good synergistic flame retardant effect.The interaction in the flame retardant reinforced PA6 composite material could form a dense and good carbon layer to inhibit further combustion of the material.(3)Research on environmentally-friendly halogen-free flame retardant GF-PA66 composite material.The flame retardant effects of ADP and MPP,zinc diethylphosphinate,TAF,zinc borate and other compounds in GF-PA66 material have been studied,and developed a composite flame retardant system XHPFR-2042 with ADP and MPP,zinc diethylphosphinate,TAF,and zinc borate as main materials,which was used as a high-efficiency composite flame retardant for flame retardant GF-PA66.The performance of the XHPFR-2042 composite flame retardant prepared by melt blending to prepare flame retardant GF-PA66 composites was studied.The results showed that when the amount of XHPFR-2042 composite flame retardant was 14 parts,the flame retardant reinforced PA66 composite materials all passed the V-0 level tested by UL-94.With the increase of the addition of flame retardant XHPFR-2042,the LOI would increase.When the addition was22%,the LOI could reach 35.2%.The synergistic effect of ADP and MPP promoted the char formation of PA66 matrix material.The existence of the residual char could prevent the transfer of internal and external heat to prevent the internal material from further thermal decomposition.Moreover,the contact with the combustible gas was isolated to terminate the combustion process.