| In order to save resources and protect the environment to realize sustainable development,the "green" tires with low-carbon and energy-saving become the theme and direction of tire industry.As common tire reinforcing filler,silica can significantly reduce the rolling resistance,saving fuel,it have the advantages of safety and economic.Styrene-butadiene rubber has low themogenesis and high wear resistance,thus usually used as the tread of green tires.For rubber-based nanocomposites with multi-level and multi-scale complex microstructures,the dispersion of filler particles and the interface of the nanocomposites are the key factor in the preparation of high performance composites.As the link between rubber and inorganic nanoparticles,the interface play an important role in stress transfer,which affect the macro properties of the composites.Thus,the research of interface is very important and necessary.However,the traditional characterization of interface are mostly indirect,qualitative or semi-quantitative,it can not get accurate conclusion,so we still have no definite understanding of the interface microstructure and the formation mechanism.In this paper,we established a method to quantitatively characterize the interface properties of silica/SSBR nanocomposites,using the peak force quantitative nanomechanics(PF-QNM)mode of atomic force microscopy(AFM).The influence of physical and chemical properties of silica on the interfacial interaction and interfacial properties are investigated,we aim to improve the comprehensive performance of nanocomposites.The main four contents are as follows:1.We simultaneously obtained the height,Young's modulus and adhesion maps of Si02/SSBR nanocomposite via PF-QNM mode of AFM.Based on increasing nanoscale mechanical properties of the interface,we established the quantitative nano-identification method to measure the interfacial thickness of SiO2/SSBR nanocomposite.In addition,we observed the interfacial double-layer structure,and statistically investigated the thickness of TBR and LBR layer.The accuracy of this method was verified through direct observation of bound rubber via HR-TEM,the thickness of TBR is about 4 nm.2.We use three kinds of modified silica,KH570-SiO2,Si69-SiO2 and DA-Si69-SiO2 to investigate the influence of modifier type on the interface of Si02/SSBR nanocomposites.The results show that after modification,the interfacial thickness of nanocomposites were all improved,the thickness of interface between Si69 modified silica and SSBR is larger than KH570,and further increased after DA coating.At the same time,we found that it mainly lies in the increase of LBR layer.Furthermore,SEM,DMA,surface energy and static mechanical test were also used to investigate the interfacial interaction,we found that the interface compatibility and interfacial interaction both increased,consistent with the results of AFM.3.The influence of modifier grafting degree on the interfacial property of Si02/SSBR nanocomposites were studied by using different amounts of Si69 to modify silica.The result of AFM show that the interfacial thickness increase from 8.3 nm to 17.2 nm with the increasing of grafting degree,and it mainly lies in LBR layer.At the same time,according to the dispersion of the filler,the change of Tg,the interfacial tension and the tensile strength,we found that with the increase of the grafting degree,the interfacial compatibility between filler and rubber is gradually increased.4.We choose three kinds of silica,the diameter of these are 20 nm,200 nm,1 ?m to study the influence of the silica particle size on the interface between silica and SSBR.The result of AFM show that the thickness of interface layer increase from 8.3 nm to 19.1 nm with the increasing of silica particle size.The total interface volume is gradually reduced from 1.17 × 10 5 m3 to 2.7 × 10-7 m3 due to the difference of the number of filler particles.Meanwhile,the Tg of the nanocomposites gradually decreased,and the tensile strength gradually decreased. |
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