Natural rubber （NR）/multi-walled carbon nanotube （MWCNTs） composites were prepared by combining self-assembly and latex compounding techniques.The acid-treated MWCNTs （H2SO4：HNO3=3：1,volume ratio） were self-assembled with poly （diallyldimethylammonium chloride） （PDDA） through electrostatic adhesion.In the second assembling,NR/MWCNTs composites were developed by mixing MWCNTs/PDDA solution with NR latex.The results show that MWCNTs are homogenously distributed throughout the NR matrix as single tube and present a great interfacial adhesion with NR phase when MWCNTs contents are less than 3 wt%.Moreover,the addition of the MWCNTs brings about the remarkable enhancement in tensile strength and crosslink density compared with the NR host,and the data peak at 2 wt% MWCNTs loadings.When more MWCNTs are loaded,aggregations of MWCNTs are gradually generated,and the tensile strength and crosslink both decrease to a certain extent.
Rule of similarity and latex compounding techniques were combined for the first time to prepare natural rubber/nanosilica （NR/SiO2） nanocomposite with core-shell nanosilica-poly （methyl methacrylate） （SiO2-PMMA） particles and PMMA-modified natural rubber matrix （NR-PMMA）. The micro- structure of SiO2 and nanocomposites with different SiO2 contents was characterized by fourier transform infrared spectroscopy （FTIR）; the morphology of nanocomposites was investigated with scanning electron microscopy （SEM）; the tensile strength was characterized by tensile testing machine and the thermal stability of composites was studied by thermal gravimetric analysis. Results showed that PMMA chains have successfully grafted onto the surface of SiO2, and the core-shell SiO2-PMMA nanoparticles and NR-PMMA latex have been perfectly incorporated. SiO2-PMMA nanoparticles are evenly distributed over the NR matrix with an average size in the range of 60-100 nm at the low content （SiO2≤ 3 wt%）, while aggregations are apparently observed when 5 wt% SiO2 is loaded. In addition, NP/SiO2 composities possess a considerable improvement in ageing resistance compared with the pure NR. The tensile strength of composite increases from 6.99 to 12.72 MPa, reaching the highest value at a 0.5 wt% SiO2 loading, and then the figure decreases gradually because of the aggregation of SiO2 nanoparticles. It is anticipated that the reported process is to provide a simple and economic way for preparing NR composites.
Natural rubber (NR) was reinforced in situ with nano CaCO3 that had been modified with methacrylic acid (MAA)(M-CaCO3).The structures and properties of the resulting composites were studied using attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR),scanning electron microscopy(SEM),and Mooney viscometer and mechanical tests.The results show that when NR is physically blended with CaCO3 and MAA,(Ca2+)-(–OOC) is formed in situ.When dicumyl peroxide (DCP) is added,the (Ca^2+)-(–OOC) self-homopolymerizes,and during the curing process poly-(Ca^2+)-(–OOC) is formed and grafts to the molecular chains of the NR via carbon-carbon double bonds.The NR/M-CaCO3 composites formed have close interfacial interaction and are well dispersed.Compared with the NR composites reinforced with unmodified nano CaCO3,the NR/M-CaCO3 composites have very different cure characteristics,rheological behavior,and mechanical properties,and these characteristics and properties show a significant relationship with the loading of M-CaCO3.
