1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% H...1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% HNO3 at 120 ℃ for 12 h to introduce surface functional groups) .The nanoparticles of Pt and Ru are synthesized by reduction of H2PtCl6 and K4Ru(CN)6 with sodium borohydride in a 5.5 buffer solution of sodium citrate,the complexation of citrate with metal ions is beneficial to the formati...展开更多
1 Results Surface oxidized carbon vulcane XC-72 as catalyst support, prepared by chemically anchoring Pt onto the surface modified carbon vulcane XC-72. The nanoparticles of Pt are synthesized by reduction of H2PtCl6 ...1 Results Surface oxidized carbon vulcane XC-72 as catalyst support, prepared by chemically anchoring Pt onto the surface modified carbon vulcane XC-72. The nanoparticles of Pt are synthesized by reduction of H2PtCl6 with sodium borohydride in a 5.5 buffer solution of sodium citrate, the complexation of citrate with metal ions is beneficial to the formation of nanoparticles. For comparison, an electrode is prepared by E-Tek Pt/C 20 Wt% with a typical Pt loading of 50 μg·cm-2, that shows higher specifi...展开更多
This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for t...This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for the manufacture of O-rings has been developed, with properties close to those found on the market. The process includes an experimental methodology of a sulfur vulcanization system choice and the quantification of ingredients, as well as the experimental determination of cure parameters. Mechanical tests on the samples completed the work by providing the mechanical characteristics of both unaged and aged (thermo-oxidative ageing) novel material. This process has a high potential for sustainable development and industrialization, making it a valuable contribution to the recycling of rubber in African developing countries.展开更多
Kinetics of natural rubber （NR） vulcanization by lanthanum O, O＇-diisopropyldithiophosphate [ La（DiPDP）3 ] was studied. La（DiPDP）3 had remarkable accelerating effect on the vulcanization of NR. The rate constan...Kinetics of natural rubber （NR） vulcanization by lanthanum O, O＇-diisopropyldithiophosphate [ La（DiPDP）3 ] was studied. La（DiPDP）3 had remarkable accelerating effect on the vulcanization of NR. The rate constant k6 of the reaction that turned polysulphidic cross-links into the modified main chain was higher than that of desulfuration reaction of polysulfidic cross-links （k3 ）. The activation energies （Ea2, Ea3, and Ea6） of the formation, desulfuration, and decomposition of polysulfidic cross-links were 87.57,102.34, and 95.01 kJ · mol^-1, respectively. Activation energy （Eas） of the reaction that turned the cross-link precursors into the modified main chain was 82.67 kJ · mol^-1. It could be concluded that the proportion of polysulphidic cross-links was higher than mono- and di- sulphidic cross-links during induction and curing periods, mono- and di- sulphidic cross-links increased as curing temperature rose. In the temperature range of 140 - 160 ℃, the amounts of polysulphidic cross-links were similar. However, over 160℃, mono- and di- sulphidic cross-links increased rapidly. Moreover, cross-link density of the vulcanizates was determined from the equilibrium-swelling data. A chemical probe detected the concentration of polysulphidic cross-links of vulcanizates. The change trend of the results predicated from equation corresponded to that of the experimental results.展开更多
The fabrication of magnetorheological （MR） elastomers was studied by two vulcanization methods, including heat vulcanization （HV） and radiation vulcanization （RV）, were employed to fabricate MRE samples. The dyn...The fabrication of magnetorheological （MR） elastomers was studied by two vulcanization methods, including heat vulcanization （HV） and radiation vulcanization （RV）, were employed to fabricate MRE samples. The dynamical mechanical properties were characterized by using a dynamic mechanic analyzer. In particular, both the MR effect and its durability were investigated. The experimental results showed that RV samples have large magnetoinduced modulus, large zero-field modulus, and good durability property of MR effect. To explain these results, cubic deformation and plasticizer migration were analyzed. Large magneto-induced modulus of RV sample results from cubic deformation during vulcanization process. And the plasticizer migration results in better durability of MR effect.展开更多
Eight complexes of rare earth with 2 mercaptobenthiazole, RELCl 2·RE(OH) 3· x H 2O (L=2 mercaptobenthiazole, RE= La～Gd, Y, except for Pm, x =0, 2～4), were synthesized in unhydrous ethanol and char...Eight complexes of rare earth with 2 mercaptobenthiazole, RELCl 2·RE(OH) 3· x H 2O (L=2 mercaptobenthiazole, RE= La～Gd, Y, except for Pm, x =0, 2～4), were synthesized in unhydrous ethanol and characterized by elemental analyses, IR spectra and thermal analyses. The results show that the ligand is coordinated to the RE ion through both the exocyclic sulfur and the thiazole nitrogen. The vulcanizing properties of the La complex as accelerator were studied in the traditional tire rubber, which indicate that the cross linked rubber accelerated by the rare earth complex has good physical and dynamic mechanical properties by comparison.展开更多
By incorporating copper sulfate （CuSO4） particles into acrylonitrile butadiene rubber （NBR） followed by heat pressing, a novel vulcanization method is developed in rubber through the formation of coordination cros...By incorporating copper sulfate （CuSO4） particles into acrylonitrile butadiene rubber （NBR） followed by heat pressing, a novel vulcanization method is developed in rubber through the formation of coordination crosslinking. This method totally differs from traditional covalent or non-covalent vulcanization approaches of rubber. No other vulcanizing agent or additional additive is involved in this process. By analyzing the results of DMA, XPS and FT-IR, it is found that the crosslinking of CuSO4 particles filled NBR was induced by in situ coordination between nitrogen atoms of nitrile groups （-CN） and copper ions （Cu^2＋） from CuSO4. SEM and EDX results revealed the generation of a core （CuSO4 solid particle）- shell （adherent NBR） structure, which leads to a result that the crosslinked rubber has excellent mechanical properties. Moreover, poly（vinyl chloride） （PVC） and liquid acrylonitrile-butadiene rubber （LNBR） were used as mobilizer to improve the coordination crosslinking of CuSO4/NBR. The addition of PVC or LNBR could lead to higher crosslink density and better mechanical properties of coordination vulcanization. In addition, crystal water in CuSO4 played a positive role to coordination crosslinking of rubber because it decreased the metal point of CuSO4 and promoted the metal ionization.展开更多
Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncry...Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region of PP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent of EPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with various compositions.展开更多
Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to dat...Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to date self-propelled jumping phenomenon has only been observed and studied on superhydrophobic surfaces,other than those hydrophobic surfaces with weaker but fairish water-repellency,for instance,vulcanized silicon rubber(RTV) coatings.In this work,from the perspective of thermodynamic-based energy balance aspect,the reason that self-propelled jumping phenomenon does not happen on RTV coatings is studied.The apparent contact angles of droplets on RTV coatings can be less than the theoretical critical values therefore cannot promise energy surplus for the coalesced droplets onside.Besides,on RTV and superhydrophobic surfaces,the droplet-size dependent variation characteristics of the energy leftover from the coalescence process are opposite.For the droplets coalescing on RTV coatings,the magnitudes of energy dissipations are more sensitive to the increase in droplet size,compared to that of released surface energy.While for superhydrophobic coatings,the energy generated during the coalescence process can be more sensitive than the dissipations to the change in droplet size.展开更多
We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a ...We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a crosslinker on HCSR were studied. Thevulcanizates with fine mechanical properties could be obtained with suitable amounts ofTMDPDS. Sol fractions, and crosslinking density of vulcanizates and vulcanizationretardation effect of TMDPDS on hydrosilation curing silicone rubber were also discussed.展开更多
Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin...Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.展开更多
文摘1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% HNO3 at 120 ℃ for 12 h to introduce surface functional groups) .The nanoparticles of Pt and Ru are synthesized by reduction of H2PtCl6 and K4Ru(CN)6 with sodium borohydride in a 5.5 buffer solution of sodium citrate,the complexation of citrate with metal ions is beneficial to the formati...
文摘1 Results Surface oxidized carbon vulcane XC-72 as catalyst support, prepared by chemically anchoring Pt onto the surface modified carbon vulcane XC-72. The nanoparticles of Pt are synthesized by reduction of H2PtCl6 with sodium borohydride in a 5.5 buffer solution of sodium citrate, the complexation of citrate with metal ions is beneficial to the formation of nanoparticles. For comparison, an electrode is prepared by E-Tek Pt/C 20 Wt% with a typical Pt loading of 50 μg·cm-2, that shows higher specifi...
文摘This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for the manufacture of O-rings has been developed, with properties close to those found on the market. The process includes an experimental methodology of a sulfur vulcanization system choice and the quantification of ingredients, as well as the experimental determination of cure parameters. Mechanical tests on the samples completed the work by providing the mechanical characteristics of both unaged and aged (thermo-oxidative ageing) novel material. This process has a high potential for sustainable development and industrialization, making it a valuable contribution to the recycling of rubber in African developing countries.
基金Project supported by the Guangdong Natural Science Foundation (05006563)
文摘Kinetics of natural rubber （NR） vulcanization by lanthanum O, O＇-diisopropyldithiophosphate [ La（DiPDP）3 ] was studied. La（DiPDP）3 had remarkable accelerating effect on the vulcanization of NR. The rate constant k6 of the reaction that turned polysulphidic cross-links into the modified main chain was higher than that of desulfuration reaction of polysulfidic cross-links （k3 ）. The activation energies （Ea2, Ea3, and Ea6） of the formation, desulfuration, and decomposition of polysulfidic cross-links were 87.57,102.34, and 95.01 kJ · mol^-1, respectively. Activation energy （Eas） of the reaction that turned the cross-link precursors into the modified main chain was 82.67 kJ · mol^-1. It could be concluded that the proportion of polysulphidic cross-links was higher than mono- and di- sulphidic cross-links during induction and curing periods, mono- and di- sulphidic cross-links increased as curing temperature rose. In the temperature range of 140 - 160 ℃, the amounts of polysulphidic cross-links were similar. However, over 160℃, mono- and di- sulphidic cross-links increased rapidly. Moreover, cross-link density of the vulcanizates was determined from the equilibrium-swelling data. A chemical probe detected the concentration of polysulphidic cross-links of vulcanizates. The change trend of the results predicated from equation corresponded to that of the experimental results.
基金The work was supported by the National Natural Science Foundation of China （No.10672154）.
文摘The fabrication of magnetorheological （MR） elastomers was studied by two vulcanization methods, including heat vulcanization （HV） and radiation vulcanization （RV）, were employed to fabricate MRE samples. The dynamical mechanical properties were characterized by using a dynamic mechanic analyzer. In particular, both the MR effect and its durability were investigated. The experimental results showed that RV samples have large magnetoinduced modulus, large zero-field modulus, and good durability property of MR effect. To explain these results, cubic deformation and plasticizer migration were analyzed. Large magneto-induced modulus of RV sample results from cubic deformation during vulcanization process. And the plasticizer migration results in better durability of MR effect.
文摘Eight complexes of rare earth with 2 mercaptobenthiazole, RELCl 2·RE(OH) 3· x H 2O (L=2 mercaptobenthiazole, RE= La～Gd, Y, except for Pm, x =0, 2～4), were synthesized in unhydrous ethanol and characterized by elemental analyses, IR spectra and thermal analyses. The results show that the ligand is coordinated to the RE ion through both the exocyclic sulfur and the thiazole nitrogen. The vulcanizing properties of the La complex as accelerator were studied in the traditional tire rubber, which indicate that the cross linked rubber accelerated by the rare earth complex has good physical and dynamic mechanical properties by comparison.
基金This work was financially supported by the Program of National Natural Science Foundation of China(No.50473031).
文摘By incorporating copper sulfate （CuSO4） particles into acrylonitrile butadiene rubber （NBR） followed by heat pressing, a novel vulcanization method is developed in rubber through the formation of coordination crosslinking. This method totally differs from traditional covalent or non-covalent vulcanization approaches of rubber. No other vulcanizing agent or additional additive is involved in this process. By analyzing the results of DMA, XPS and FT-IR, it is found that the crosslinking of CuSO4 particles filled NBR was induced by in situ coordination between nitrogen atoms of nitrile groups （-CN） and copper ions （Cu^2＋） from CuSO4. SEM and EDX results revealed the generation of a core （CuSO4 solid particle）- shell （adherent NBR） structure, which leads to a result that the crosslinked rubber has excellent mechanical properties. Moreover, poly（vinyl chloride） （PVC） and liquid acrylonitrile-butadiene rubber （LNBR） were used as mobilizer to improve the coordination crosslinking of CuSO4/NBR. The addition of PVC or LNBR could lead to higher crosslink density and better mechanical properties of coordination vulcanization. In addition, crystal water in CuSO4 played a positive role to coordination crosslinking of rubber because it decreased the metal point of CuSO4 and promoted the metal ionization.
基金This work was financially supported by 863 Programme of China No.863-715-012-0160
文摘Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region of PP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent of EPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with various compositions.
文摘Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to date self-propelled jumping phenomenon has only been observed and studied on superhydrophobic surfaces,other than those hydrophobic surfaces with weaker but fairish water-repellency,for instance,vulcanized silicon rubber(RTV) coatings.In this work,from the perspective of thermodynamic-based energy balance aspect,the reason that self-propelled jumping phenomenon does not happen on RTV coatings is studied.The apparent contact angles of droplets on RTV coatings can be less than the theoretical critical values therefore cannot promise energy surplus for the coalesced droplets onside.Besides,on RTV and superhydrophobic surfaces,the droplet-size dependent variation characteristics of the energy leftover from the coalescence process are opposite.For the droplets coalescing on RTV coatings,the magnitudes of energy dissipations are more sensitive to the increase in droplet size,compared to that of released surface energy.While for superhydrophobic coatings,the energy generated during the coalescence process can be more sensitive than the dissipations to the change in droplet size.
文摘We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a crosslinker on HCSR were studied. Thevulcanizates with fine mechanical properties could be obtained with suitable amounts ofTMDPDS. Sol fractions, and crosslinking density of vulcanizates and vulcanizationretardation effect of TMDPDS on hydrosilation curing silicone rubber were also discussed.
基金Funded by the National Natural Science Foundation of China(No.21174108)the Science and Technology Project of China Southern Power Grid Co,Ltd(No.GDKJQQ20161197)
文摘Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.
