Synthesis Of Layered Double Hydroxide-graphene Hybrids And Its Smoke Suppression And Attenuation On TPU

Graphene oxide was synthesized by Hummers method,and GO/Mg-Al LDHs,GO/Mg-Al-Fe LDHs,and GO/Mg-Fe LDHs were prepared by coprecipitation method.Three different hydrotalcite hybrids were synthesized.Graphene oxide/Hydrotalcite hybrid materials were characterized by TEM,XRD,SEM-EDS and other test methods;these three different graphene oxide/hydrotalcite were melt-blended with TPU to get the composite,and the synergistic effect of APP and graphene oxide/Mg-Fe LDHs were melt-blended to TPU,then the cone calorimeter(CCT),smoke density tester(SDT),TG and GC-MS were used to test the flame retardancy,smoke suppression,and gas generated after pyrolysis of the composite samples.The mechanism of burning and smoke suppression was initially discussed.After all these experimental research finished we found:(1)After the characterization of TEM and XRD,the graphene oxide were proved to be successfully prepared by Hummers method,and the graphene oxide we got has a monolayer structure;After XRD,SEM and SEM-EDS tests,it was confirmed that the three different graphene oxide/hydrotalcite hybrid materials were successfully prepared by co-precipitation method,and they all had the structural features of hydrotalcite.(2)Compared with pure TPU and TGAL0,the heat release rate(HRR)and smoke release rate(SPR)of TPU/GO/Mg-Al LDHs composites were decreased.After adding 37.5%LDHs-2.5%GO to TPU,the peak heat release rate of TPU/GO/Mg-Al LDHs composites dropped from 1075 kW/m~2 to above 200 kW/m~2.In the SDT test(without the application of a pilot fire),the luminous flux of TPU/GO/Mg-Al LDHs composites was higher than that of pure TPU and TGAL0.Compared with pure TPU,the organic products produced after thermal cracking of TPU/GO/Mg-Al LDHs composites were reduced to some extent.(3)Compared with pure TPU and TPU/Mg-Fe LDHs composites,the HRR,SPR,TSR and other related indexes of TPU/GO/Mg-Fe LDHs composites decreased significantly,with the adding component of 37.5%LDHs-2.5%GO to TPUs.What's more,the pHRR was only338.6 kW/m~2,which was 53.08%lower than that of pure TPU.The luminous flux of the composite material with 38%LDHs-2%GO remained at above 60%;Compared with TPU/Mg-Fe LDHs composites,the thermal stability of TPU/GO/Mg-Fe LDHs composites has been significantly improved,and the toxic organics produced by thermal cracking have also been reduced;The pHRR of the samples of 60%of TPU with 33%GO/Mg-Fe LDHs and7%APP was only 285.2 kW/m~2,which was significantly lower than that of composites added with 37.5%LDHs-2.5%GO.(4)Compared with pure TPU and TPU/Mg-Al-Fe LDHs composites,the HRR,SPR and mass loss rate of TPU/GO/Mg-Al-Fe LDHs composites have significantly decreased.After adding 38%LDHs-2%GO,the peak heat release rate of TPU/GO/Mg-Al-Fe LDHs composites was reduced by 72.3%compared with pure TPU;and under the application of a pilot fire conditions,the composite materials containing 37.5%LDHs-2.5%GO has been maintained at more than 40%in terms of the luminous flux;and its thermal cracking products are compared with TPU/Mg-Al-Fe LDHs composites also have some attenuation effects.(5)Hibridize graphene oxide with three different hydrotalcites,the obtained hybrid material can increase the flame-retardant efficiency of the original pure hydrotalcite in some degree,and the addition of graphene oxide can be combined with hydrotalcite.The synergistic effect is to improve the compactness and integrity of the carbon layer which was formed after combustion,and to significantly reduce the flame retardancy,and improve the smoke suppression performance of the polymer.