Influence of the structural characteristic of pyrolysis products on thermal stability of styrene-butadiene rubber composites reinforced by different particle sized kaolinites

A series of rubber composites were prepared by blending styrene-butadiene rubber (SBR) latex and the different particle sized kaolinites. The thermal stabilities of the rubber composites were characterized using thermogravimetry, digital photography, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Kaolinite SBR composites showed much greater thermal stability when compared with that of the pure SBR. With the increase of kaolinite particle size, the pyrolysis products became much looser; the char layer and crystalline carbon content gradually decreased in the pyrolysis residues. The pyrolysis residues of the SBR composites filled with the different particle sized kaolinites showed some remarkable changes in structural characteristics. The increase of kaolinite particle size was not beneficial to form the compact and stable crystalline carbon in the pyrolysis process, and resulted in a negative influence in improving the thermal stability of kaolinite/SBR composites.     

功能化石墨烯/聚苯胺复合电极材料的制备和电化学性能

利用水合肼还原十八胺（ODA）接枝的氧化石墨烯（GO）,得到了十八胺功能化石墨烯（ODA-G）,将ODAG与聚苯胺（PANI）通过溶液共混法,制备了功能化石墨烯和聚苯胺纳米复合材料（ODA-G/PANI）. 采用傅里叶变换红外（FTIR）光谱、X射线衍射（XRD）、热重分析（TGA）、拉曼（Raman）光谱及透射电镜（TEM）,对复合材料的结构和形貌进行了表征;利用循环伏安、恒流充放电及交流阻抗谱等,对复合材料的电化学性能进行了测试. 结果显示,少量ODA-G的引入为PANI 的电化学氧化还原反应提供了更多的电子通道和活性位置,有利于提高PANI 的赝电容. 在电流密度1.0 A·g^-1下,2%（w）ODA-G/PANI 的比电容达到787 F·g^-1,而相应的PANI 仅有426 F·g^-1. 此外,ODA-G/PANI的循环稳定性也远高于纯PANI.     

Surface‐modified hydroxyapatite linked by L‐lactic acid oligomer in the absence of catalyst

A new surface modification method of hydroxyapatite nanoparticles (n‐HA) by surface grafting reaction of L ‐lactic acid oligomer with carboxyl terminal (LAc oligomer) in the absence of any catalyst was developed. The LAc oligomer with a certain molecular weight was directly synthesized by condensation of L ‐lactic acid. Surface‐modified HA nanoparticles (p‐HA) were attested by Fourier transformation infrared spectroscopy, ³¹P MAS‐NMR, and thermal gravimetric analysis (TGA). The results showed that LAc oligomer could be grafted onto the n‐HA surface by forming a Ca carboxylate bond. The grafting amount of LAc oligomer was about 13.3 wt %. The p‐HA/PLLA composites showed good mechanical properties and uniform microstructure. The tensile strength and modulus of the p‐HA/PLLA composite containing 15 wt % of p‐HA were 68.7 MPa and 2.1 GPa, respectively, while those of the n‐HA/PLLA composites were 43 MPa and 1.6 GPa, respectively. The p‐HA/PLLA composites had better thermal stability than n‐HA/PLLA composites and neat PLLA had, as determined by isothermal TGA. The hydrolytic degradation behavior of the composites in phosphate buffered saline (PBS, pH 7.4) was investigated. The p‐HA/PLLA composites lost their mechanical properties more slowly than did n‐HA/PLLA composites in PBS because of their reinforced adhesion between the HA filler and PLLA matrix. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5177–5185, 2005     

Mechanical,acoustical and flammability properties of SBR and SBR-PU foam layered structure

In this work a layer structure from styrene butadiene rubber (SBR) composites and PU foam with improved flame retardancy property and high sound absorption coefficient at frequency range (200–500 Hz). Different types of flame retardants; iron (acrylic-co-acrylamide) as metal chelate (MC), magnesium hydroxide (MOH) and sodium tripolyphosphate (STP) were blended with SBR. The type and loading level of flame retardant had a great effect on filler dispersion and consequently on mechanical properties of SBR. MOH exhibited the best dispersion as indicated from scanning electron microscope (SEM), and SBR/MOH samples had almost the highest crosslink density (16.04*10⁻⁵ g⁻¹ mol) and the best mechanical properties where the tensile strength was improved by 32.7% at 40 phr MOH. Horizontal burning rate of SBR composites indicated that MC and MOH reduced the rate of burning of SBR at all loading levels. TGA data presented that the addition of flame retardants to SBR increased the maximum decomposition temperature in all composites. A double and triple layer structures of SBR composite and PU foam was designed. The effect of 2.5 cm air cavity on the sound absorption coefficient of SBR-PU foam layered structure was studied. The presence of air cavity behind the layered structure improved the sound absorption in the range of (200–500 Hz) better than the existence of it between the layers. The triple-layer structure gave higher sound absorption coefficient at lower frequencies than that obtained with the double-layer structure where it reached to ≥0.98 at 315 Hz.     

Effects of Sericite Modified by Macromolecular Dispersant on the Thermal,Mechanical and Electrical Properties of the NR/SBR Composites

A new hydrosoluble macromolecular dispersant and modifier, poly(ethylene glycol)-maleic anhydride-acrylic acid (PEG-MA-AA) terpolymer was synthesized via ring-opening reaction and free radical polymerization. The chemical structure of the PEG-MA-AA terpolymer was confirmed by Fourier transform infrared (FTIR) spectra and nuclear magnetic resonance spectroscopy (NMR), and its average molecular weight was determined by gel permeation chromatography (GPC). Modified sericite (MSE) was synthesized from sericite (SE) by the surface modification with PEG-MA-AA. The NR/SBR/MSE composites were prepared via the blending of the modified sericite and NR/SBR rubber. The thermal, mechanical and electrical properties of the composites were investigated by TGA, tensile test machine and high-insulation resistance meter. The results showed that the thermal stability and the mechanical and electrical insulation properties of NR/SBR/MSE composites were improved significantly. SEM also revealed that modified sericite possessed good dispersibility.     

高填充量碳纳米管/丁苯粉末橡胶机械混炼的物理化学机制

将用喷雾干燥法制备的碳纳米管(CNTs)/丁苯粉末橡胶复合材料在开炼机上机械混炼, 考察机械混炼对复合材料常规力学性能的影响, 并对机械混炼对CNTs增强丁苯橡胶复合材料力学性能的影响进行相应的理论研究和机理分析. 结果表明, 与混炼前的复合材料相比, 机械混炼有效地提高了CNTs/丁苯橡胶复合材料的力学性能, 特别是当CNTs加入量较大时, 提高幅度更为显著, 与填充传统补强剂CB复合材料相比, 具有较大的优势. 这是因为机械混炼一方面使CNTs在橡胶基体中获得了更为充分均匀的分散; 另一方面, 混炼过程中产生的自由基以及巨大的剪切力, 使得CNTs与橡胶基体间界面结合如物理吸附、氢键作用、化学结合等得到了进一步增强, 提高了CNTs/丁苯橡胶复合材料的结合橡胶含量, 更好地发挥了CNTs对丁苯橡胶的补强效应, 从而提高了复合材料的拉伸强度和撕裂强度等力学性能. CNTs补强丁苯橡胶复合材料力学性能的机理符合“强键和弱键学说”.     

A facile and green preparation of nanosilica-supported antioxidant and its reinforcement and antioxidation effect on styrene-butadiene rubber

A novel solid-phase method has been proposed to prepare a nanosilica-supported antioxidant by the reaction of nanosilica with 2-mercaptobenzimidazole (MB) and silane coupling agent γ-chloropropyltriethoxysilane. Fourier transform-infrared spectroscopy and other characterization methods confirmed that MB was chemically bonded onto the surface of nanosilica. Silica-s-MB was homogeneously dispersed in a styrene-butadiene rubber (SBR) matrix with strong filler-rubber interaction, leading to enhanced mechanical performance of SBR/silica-s-MB composites compared with SBR/m-silica composites. Based on the results of thermo-oxidation testing of SBR/silica-s-MB and SBR/m-silica/MB composites containing equivalent antioxidant component, silica-s-MB showed better antioxidative efficiency than the corresponding low-molecular-weight MB owing to its lower migration and volatility at high temperature.     

Dual-Phase structure of polymer electrolytes comprised of NBR/SBR latex films swollen with lithium salt solution

Dual-phase polymer electrolytes (DPE) that have high ionic conductivity (> 10^?3 S/cm) and good mechanical strength were prepared by mixing NBR and SBR latices and casting films. The latex films absorbed large quantities of lithium salt solution (e.g., 1M lithium perchlorate in γ-butyrolactone) to obtain DPE films but did not dissolve with swelling. The NBR phase is polar and was impregnated selectively with the polar lithium salt solution, whereas the SBR phase is nonpolar and formed a mechanically-supportive matrix. Transmission electron microscopic (TEM), electron energy loss spectral (EELS), and energy-dispersive x-ray (EDX) analyses showed microscopically the dual-phase structure. Evidence for swelling by lithium salt solution was found only in the NBR phase and not in the SBR phase by EDX microanalysis. Ionic conductivity as a function of NBR content or swelling degree showed clearly that a percolation threshold for ionic conductivity exists. © 1994 John Wiley & Sons, Inc.     

Effect of halloysite nanotube on microstructure,rheological and mechanical properties of dynamically vulcanized PA6/NBR thermoplastic vulcanizates

Dynamically vulcanized thermoplastic vulcanizate (TPV) nanocomposites based on polyamide-6 (PA6) and acrylonitrile butadiene rubber (NBR) reinforced by halloysite nanotubes (HNT) were prepared via a direct melt mixing process. The effects of HNT on the physical, mechanical, and rheological properties of nanocomposites were investigated. The prepared PA6/NBR/HNT nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning colorimeter (DSC), dynamic mechanical thermal analysis (DMTA), and rheological measurements. The morphology study of prepared nanocomposites shows that the introduction of HNT into the PA6 phase causes a decrease in the size of NBR droplets. The mechanical measurements revealed that Young’s modulus of TPV nanocomposites increased with the HNT loading up to 54%. DMTA results show that the introduction of 10 wt% of HNT into the PA6/NBR TPV leads to a 30% increase in storage modulus. The rheological measurements revealed that the storage modulus of nanocomposites has an increase of more than 200% in the presence of 7 wt% of HNT loading. Analytical stiffness modeling of Young’s modulus of the TPV nanocomposites was investigated using Hui–Shia and Wu models. Both models have some deviations from experimental results and been modified to predict Young’s modulus of the nanocomposites containing HNT with more precisions. The viscosity behavior of TPV nanocomposites was studied using a Carruea–Yasuda model and showed that the yield stress of nanocomposites increases with higher HNT loadings, indicating the formation of a nanotube network along with NBR phase network.     

Cellulose–halloysite nanotube composite hydrogels for curcumin delivery

Halloysite nanotubes (HNTs) were added to cellulose NaOH/urea solution to prepare composite hydrogels using epichlorhydrine crosslinking at an elevated temperature. The shear viscosity, mechanical properties, microstructure, swelling properties, cytocompatibility, and drug delivery behavior of the cellulose/HNT composite hydrogels were investigated. The viscosity of the composite solution increases with the addition of HNT. The compressive mechanical properties of composite hydrogels are significantly improved compared with pure cellulose hydrogel. The compressive strength of the composite hydrogels with 66.7% HNTs is 128 kPa, while that of pure cellulose hydrogel is only 29.8 kPa in compressive strength. Rheological measurement suggests the resistance to deformation is improved for composite hydrogels. X-ray diffraction and Fourier transform infrared spectroscopy show that the crystal structure and chemical structure of HNT are not changed in the composite hydrogels. Hydrogen bonding interactions between HNT and cellulose exist in the composites. A porous structure of the composite hydrogels with pore size of 200–400 μm was found by scanning electron microscopy. The addition of HNT leads to decreased swelling ratios in NaCl solution and pure water for the composite hydrogels. Cytotoxicity assays show that the cellulose/HNT composite hydrogels have a good biocompatibility with MC3T3-E1 cells and MCF-7 cells. Curcumin is further loaded into the composite hydrogel via physical adsorption. The curcumin-loaded composite hydrogels show a strong inhibition effect on the cancer cells. All the results illustrate that the cellulose/HNT composite hydrogels have promising applications such as anticancer drug delivery systems and anti-inflammatory wound dressings.     

Optical Properties of Swift Heavy Ion Beam Irradiated Polycarbonate/Polystyrene Composites Films

Polycarbonate/polystyrene composites films were irradiated by 55 MeV Carbon ion beam with fluence ranging from 1 × 10¹¹ to 1 × 10¹³ ions/cm². The polymer composites films were prepared by solution mixing method. The effects of ion beam on structural, optical and surface morphology of PC/PS composites films were investigated by X-ray diffraction (XRD), UV-visible spectroscopy (UV-vis), Fourier Transform Infrared Spectroscopy (FT-IR) and Optical Microscope. The XRD pattern shows the average crystallite size, percentage of crystallinity and inter-chain separation, which decreases with increase in ion fluences. UV-vis spectra show that the energy band gap and transmittance decreases while number of carbon atoms increases with fluences. The FT-IR spectra evidenced very small change in cross linking and chain scissoring at high ion fluences, while the optical microscopy shows a color change with ion fluence.     

Influence of maleic anhydride grafted ethylene propylene diene monomer (MAH-g-EPDM) on the properties of EPDM nanocomposites reinforced by halloysite nanotubes

Ethylene propylene diene monomer grafted with maleic ahydride (MAH-g-EPDM) was prepared by peroxide-initiated melt grafting of MAH onto EPDM using a HAAKE internal mixer at 180 °C and 60 rpm for 5 min. The effect of MAH-g-EPDM compatibilizer on the interactions, and tensile and morphological properties of halloysite nanotubes (HNTs) filled EPDM nanocomposites was investigated. The tensile properties of the nanocomposites were influenced by two major factors. The hydrogen bonding between MAH-g-EPDM and HNTs, which was confirmed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), as well as the formation of EPDM-rich and HNT-rich areas, are the dominant effects on the tensile strength of the nanocomposites at low and high HNT loading, respectively. It was found that the cure time (t₉₀), maximum torque (M_H) and minimum torque (M_L) of the compatibilized nanocomposites were increased after adding MAH-g-EPDM. The reinforcement mechanism of the compatibilized and un-compatibilized EPDM/HNT nanocomposites was also investigated based on morphological observations of the nanocomposites.     

Enhanced properties of poly(lactic acid) with silica nanoparticles

The objective of this article is to fabricate poly(lactic acid) (PLA) and nano silica (SiO₂) composites and investigate effect of SiO₂ on the properties of PLA composites. Surface‐grafting modification was used in this study by grafting 3‐Glycidoxypropyltrimethoxysilane (KH‐560) onto the surface of silica nanoparticles. The surface‐grafting reaction was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Then the hydrophilic silica nanoparticles became hydrophobic and dispersed homogeneously in PLA matrix. Scanning electron microscope and Dynamic thermomechanical analysis (DMA) results revealed that the compatibility between PLA and SiO₂ was improved. Differential scanning calorimetry and polarized optical microscope tests showed that nano‐silica had a good effect on crystallization of PLA. The transparency analysis showed an increase in transparency of PLA, which had great benefit for the application of PLA. The thermal stability, fire resistance, and mechanical properties were also enhanced because of the addition of nano silica particles. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal stability of styrene butadiene rubber (SBR) composites filled with kaolinite/silica hybrid filler

Styrene butadiene rubber (SBR) composites filled with fillers, such as modified kaolinite (MK), precipitated silica (PS), and the hybrid fillers containing MK and PS, were prepared by melt blending. The kaolinite sheets were finely dispersed in the SBR matrix around 20–80 nm in thickness and reached the nano-scale. The SBR composites with fillers exhibited excellent thermal stability compared to the pure SBR. The thermal stability of SBR composites was improved with the increasing of MK mass fraction. When MK hybridized with PS, kaolinite sheets were covered by the fine silica particles and the interface between filler particles and rubber matrix became more indistinct. SBR composite filled by hybrid fillers containing 40 phr MK and 10 phr PS became more difficult in decomposition and was better than that of 50 phr PS/SBR and 50 phr MK/SBR in thermal stability. Therefore, the hybridization of the fine silica particles with the kaolinite particles can effectively improve the thermal stability of SBR composites.     

Interaction between 3-aminopropyltrimethoxysilane and oil palm ash in styrene butadiene rubber compounds using response surface methodology

Oil palm ash (OPA) is available in abundance and is renewable. The effects of a combination of OPA and 3-aminopropyltrimethoxysilane on the properties of styrene butadiene rubber (SBR) compounds based on their mixing ratios were studied using response surface methodology. The cure characteristics and tensile properties were selected as the responses. The significance of these factors and their interactions were analysed using ANOVA. The results showed that the presence of OPA and AMPTES had a significant effect on the properties of SBR compounds, whereby all the responses had R² of above 0.9. This indicates that the regression model is accurate in describing and predicting the pattern of significance for each factor studied. In addition, with the highest level of AMPTES (6 phr) and OPA (80 phr) in the SBR, the tensile strength of the mixture was significantly improved by 151.6% compared to that of gum SBR compound. These findings were further supported by scanning electron microscopy.     

Study on combustion property and synergistic effect of intumescent flame retardant styrene butadiene rubber with metallic oxides

Effect of metallic oxides on flame retardancy and the thermal stability of styrene butadiene rubber (SBR) composites based on ammonium polyphosphate (APP) and pentaerythritol (PER) was studied by the limiting oxygen index (LOI), UL 94, the cone calorimeter tests, and thermogravimetry analysis (TGA), respectively. Scanning electron microscopy (SEM) and wide‐angle X‐ray diffraction (WAXD) were used to analyze the morphological structure and the component of the residue chars formed from the SBR composites accordingly. The addition of zirconium dioxide (ZrO₂) at a loading of 3.4 phr could improve the UL 94 test rating of the composite to V‐0. The TGA data illustrated that the metallic oxides could enhance the thermal stability of the SBR/Intumescent flame retardant additives (IFRs) composites at high temperature and increase the residue. Cone calorimeter test gave much clear evidence that the incorporation of ZrO₂ into SBR/IFRs composites resulted in the significant deduction of the heat release rate (HRR) values, and the SEM images showed that the char layers of the composites containing the metallic oxides became more compact. From the WAXD pattern, zirconium phosphate (ZrP₂O₇) may be formed by the reaction between ZrO₂ and APP. Due to the addition of ZrO₂ and the formation of ZrP₂O₇, the flame retardancy of the composite was improved. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of polystyrene-grafted multi-walled carbon nanotubes on the viscoelastic behavior and electrical properties of polypropylene-based nanocomposites

In this work, a free-radical grafting method was used to modify multi-walled carbon nanotubes (MWNT) to improve their dispersion in a polymer matrix by use of a compounding technique. By free-radical grafting for in-situ polymerization, MWNT agglomerates are turned into a networked micro-structure, which in turn builds up a strong interfacial interaction with the polymeric matrix during the mixing procedure. Polystyrene (PS)-MWNT with a hairy rod nanostructure were synthesized by in-situ free-radical polymerization of styrene monomer on the surface of MWNT. PS-MWNT/polypropylene (PP) nanocomposites were prepared by melt mixing. The effect of polystyrene-grafted multi-walled carbon nanotube (PS-MWNT) content on the rheological properties of the polypropylene (PP)-based nanocomposites was investigated. Surface characteristics of PS-MWNT were investigated by infrared spectroscopy, Raman spectroscopy (FT-Raman), thermogravimetric analysis, and transmission electron microscopy. The rheological properties of the PS-MWNT/PP composites were confirmed by rheometry. The complex viscosity of the PS-MWNT/polypropylene (PP) nanocomposites increased with increasing PS-MWNT content, primarily because of an increase in the storage modulus G??. In-situ-polymerized PS-MWNT were uniformly distributed in the PP matrix. In addition, the PS-MWNT were interconnected in the PP matrix and then formed PS-MWNT networks, resulting in the formation of a conducting network. Therefore, compared with samples with pristine MWNT, PS-MWNT-reinforced samples have lower conductivity as a resulting of PS grafting on the surface of MWNT.     

Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag@MFe₂O₄ (M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag@C microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe³⁺ and M²⁺ on the surface of the Ag@C spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core.     

Enhanced removal efficiency of methyl red via the modification of halloysite nanotubes by copper oxide

Halloysite nanotubes (HNTs) were modified with CuO to form CuO-HNT composites. Results revealed that the CuO particles deposited on the HNT have higher specific surface area (S_BET) and pore volume compared to unmodified HNT. Application of the composites for the removal of methyl red (MR) dye was investigated. The composites have better removal efficiency than HNT. The data fitted the Freundlich adsorption isotherms. Kinetics of adsorption favored the pseudo-second-order model. Removal efficiency was faster and higher in alkaline conditions. Reusability experiments show that the low-cost composites were effective up to seven cycles.     

Thermal transformations of a polymeric composite consisting of poly(methyl methacrylate) and phosphorus-containing nanodispersed aluminum oxide

Thermal-oxidative properties of polymeric composites based on poly(methyl methacrylate), containing surface-modified nanosized aluminum oxide as filler, were examined. The possibility of chemical grafting to the Al₂O₃ surface of phosphorus-containing groups to decrease the combustibility of filled polymeric composites was examined by IR spectroscopy.