Research On TPU/SEBS Halogen-free Flame Retardant Cable Materials

Thermoplastic polyurethane elastomer(TPU)was widely usedas a coating material in the field of the wire and cable because of its good mechanical properties and excellent wear resistance,however,lots of applications were limited due to its higher hardness,bad flame retardant property,weak water resistance and poor flexibility.Hydrogenated styrene-butadiene-styrene block copolymer(SEBS)is excellent in electrical insulation,water resistance and smoothness whilepoor in processing and flame retardant performance.The TPU was modified with SEBS to prepare the TPU and SEBS blendswhich not only overcomes their shortcomings,but also improves the comprehensive properties of the materials to meet the needs of high-grade wire and cable.In this paper,the compatibility of TPU with SEBS was studied by infrared spectroscopy.The influence of three kinds of compatibilizers(PP-g-MAH,EBS and self-made compatibilizer)on the red shift of amino characteristic peaks in the TPU/SEBSblend as well as theircompatibilizing effect were investigated by infrared spectroscopy technique combined with SEM and TG analysis.The results were as follows: self-made compatibilizer showed the best compatibilizing effect among three kinds of compatibilizers.When the content of self-made compatibilizer is 6wt%,the aminocharacteristic peak has the largest red shift,which is from 3322cm-1to3294 cm-1,with the difference of 28 cm-1,it implied that the hydrogen bonding ability was very strong and the compatibilization effect is the best.The results of SEM show that the particle dispersionof TPU/SEBS added with self-made compatibilizerwas the most uniformly,but the interface was fuzzy,and the interface layer was thick.The results of TG showed that the decomposition temperatures of SEBS increased from 438.81℃to 447.03℃when the self-made compatibilizer were added into TPU/SEBS.In this paper,MPP/PER was chosenas the main flame retardants,ADP and gasphase Si O2 were used as the synergistic flame retardants to modify the TPU/SEBS composite materials.The results showed that: 1.When the ratio between the MPP and PER is 3:1,adding amount is 30 wt%,the oxygen index of TPU/SEBS composite materials reached 28 %,which reached V-1 level of flame retardant,meanwhile,the melt dripping phenomenon was obvious,the dielectric properties was improved;2.The flame retardant performancecanbeimprovedobviouslywith adding 4wt% of ADP into TPU/SEBS composite material,the oxygen index was 30%,which reached V-0levelof flame retardant,and without melting drop phenomenon;3.The addition of gas phase Si O2 improved the mechanical properties of TPU/SEBS composite materials,when the gas content of Si O2 is 6 wt%,the tensile strength of TPU/SEBS composite material is 7.8 MPa,and the rupture elongation reached 403%;the flame retardant performance is improved,oxygen index was 29 %,reached V-0level of flame retardant,thewater resistance was also improved,the oxygen index canstill reached to 29%after flooding.TPU and PP-g-MAH were used as modifier to modify MPP/PERrespectively,and which effect on the flame retardant TPU/SEBS composite was researched.The results show thatwhen adding modified MPP/PER,the mechanics performance,flame retardant,resistance to water and electric properties of TPU/SEBS compound are improved;The effect of TPU modification is superior to that of PP-g-MAH,the comprehensive performance is the best when 10 wt% of TPU modified flame retardant was mixed with TPU/SEBS,and itsoxygen index is 33%,reached V-0 level of flame retardant,meanwhile,the tensile strength is 9.3 MPa,the elongation at break is 387%,the volume resistivity is9.31×1012 Ω·m,the breakdown strength is28.41 k V/mm and the oxygen index is 32%after flooding,which also reached V-0level ofthe flame retardant.