Effect Of Macromolecular Modifier On Relaxation Behavior Of Silicon/SBR Composite

As the world first industrialized rubber,styrene-butadiene rubber has excellent processing properties,good product performance,and a wide range of applications.It is widely used in automobiles,electrical appliances,and water conservancy.In this paper,the silicon powder was modified by modifiers with different molecular weights,and the structural changes and dispersion stability of the silicon powder before and after the modification were compared and the effects on the relaxation behavior of the styrene-butadiene rubber were compared.1.Using a two-step addition method,styrene(St)and?-methacryloxypropyl trimethoxy silane(MAPTMS)were used as reaction monomers to synthesize macromolecular modifier St/MAPTMS by radical copolymerization.The molecular structure was confirmed by FTIR and ~1H-NMR.The mass average molecular weight of the product is about 10000 were calculated by ~1H-NMR spectrum,when the mass ratio of St to MAPTMS is 2:1 at 80?;the DSC analysis shows that the glass transition temperature of St/MAPTMS is in the range of 60-70?,a wider temperature range indicates that it has a larger application advantage in modified powders;TG curve shows St/MAPTMS decomposition temperature in the range of 325-425?,followed by thermal weight loss tends to be stable,indicating St/MAPTMS thermal stability better,and consistent with the decomposition temperature range of most polymer materials2.Using St/MAPTMS and MAPTMS as modifiers,the silicon powder was modified by solvent method.The structure and properties of silicon powder were analyzed by FTIR,XPS,XRD,contact angle and thermal analysis.FTIR results showed that the modifier silicon was dehydrated and condensed onto the silicon powder surface to form an active surface anchor layer;from XPS spectra analysis of C-1s,284.7 eV was found to be C-C and C-Si.The binding energy,about 286.2eV is the electronic binding energy of C=C and C-O,C=O is 288.8eV;the XPS spectrum of Si-2s shows that the electronic binding energy of Si is about 150.6eV,and the electronic binding energy of Si-O is About 154.4eV;the XPS spectrum of Si-2p shows that the electron binding energy of Si is about 99.4 eV,and the electron binding energy of Si-O is about 102.8 eV.From the spectrum,we can see that the silicon powder goes through 10%MAPTMS and 10%St/MAPTMS.After modification,the content of C-1s increased from 8.29%to 25.38%and27.37%,respectively,and the content of Si-2s decreased from 41.28%to 25.99%and 28.99%,respectively.The content of Si-2p was up to that of the original 3.08%increased to 24.43%and 27.25%,indicating that the modifiers chemically grafted onto the silicon powder surface;XRD showed that the addition of modifier did not change the cubic crystal structure of the silicon powder;compared with the sedimentation results,the application of St/MAPTMS reduced the particle agglomeration and further promoted the dispersion stability of the silicon powder,and its application efficiency was far higher.In MAPTMS,the contact angle analysis showed that the contact angles of 10%St/MAPTMS and 15%MAPTMS modified silicon powder were 109.31°and 100.24°respectively,indicating that the modifier reduced the surface energy of the silicon powder and the hydrophilicity weakened.It shows that macromolecule modifiers with a lower amount than MAPTMS can also completely outperform the performance of small molecule modifiers;thermogravimetric analysis shows that the efficiency of 20%St/MAPTMS and MAPTMS grafted silicon powders reaches 44.5%and 16.5%respectively.This shows that the polyfunctional group on the molecular chain of St/MAPTMS has a high attachment efficiency to silicon powder,further inhibits the approach of powder particles and agglomeration,and ensures the improvement of the dispersion stability of the powder.3.SBR composites filled with different modified modifiers were prepared by open milling and molding process.The silicon powder/SBR composites were characterized by rubber processing analyzer RPA8000,SEM and thermal analysis techniques.The results show that the addition of the modifier reduces the scorch time and the cure time;the strain test of the composites with different modifier content shows a typical Payne effect,and the energy storage of 15%St/MAPTMS modified silicon powder filled rubber,The modulus reaches 600kPa,while the storage modulus of 15%MAPTMS modified silicon powder filled rubber reaches 550kPa,the loss modulus shows a more gradual and then a sharply rising trend in the low strain region,which is related to the filler network breaking-rebuilding.The frequency test shows that as the frequency increases,the storage modulus undergoes an ascending-descending process,which indicates that the filler network can resist the shear deformation well,and the 15%St/MAPTMS modified silicon filler rubber is the best for resistance to deformation.The loss modulus first rises slightly,then rises sharply.This indicates that the frequency increases and destroys the filler network.The rubber matrix is directly subjected to shearing.Under the effect of internal friction,the loss modulus rises linearly;the variable temperature test shows that The storage modulus rises first and then decreases with increasing temperature.This may be due to the fact that the internal cross-linked structure of the rubber can resist deformation very well at lower temperatures,but the temperature increased,modifier molecular chain softens,the filler network is destroyed,the storage modulus decreases,and the loss modulus decreases.This may be due to the deformation of the modifier on the surface of the silicon powder and the occurrence of a crack in the vulcanizate at elevated temperatures burning,loss reduction,and the temperature is too high,then the rubber softens,the molecular chain decomposes,the material is finally destroyed;Styrene butadiene rubber filled with St/MAPTMS,MAPTMS modified silicon powder,the tensile strength,tear strength,hardness increased by 63.6%,52.6%,74.1%,13.1%,38.1%,11.8%,wear reduction 53.2%,23.3%.Thermogravimetric analysis showed that after the styrene-butadiene rubber was filled with St/MAPTMS and MAPTMS-modified silicon powder,the Tg increased from the original-44.3? to-40.5? and-41.5?,respectively,indicating the internal crosslinking of the modified rubber.High degree,increased cross-linking density of styrene butadiene rubber compound,improved interface compatibility of styrene butadiene rubber and silicon powder;SEM analysis showed that the addition of coupling agent made the distribution of silicon powder in styrene butadiene rubber more uniform.And the effect of macromolecularmodifier St/MAPTMS modified silicon powder filled rubber is better than MAPTMS modified silicon powder filled rubber.