The boroxine-linked organic aluminum compound LAl[OB（3-C4H3O）]2（μ-O） was accomplished by reacting LAl H2 {L =（Z）-4-[（2,6-diisopropylphenyl）amino]pent-3-en-2-ylidene-2,6-diisopropylaniline} with furan-3-ylboro...The boroxine-linked organic aluminum compound LAl[OB（3-C4H3O）]2（μ-O） was accomplished by reacting LAl H2 {L =（Z）-4-[（2,6-diisopropylphenyl）amino]pent-3-en-2-ylidene-2,6-diisopropylaniline} with furan-3-ylboronic acid in good yield.The title compound belongs to the orthorhombic system,space group Pnma with a = 10.9774（15）,b = 19.369（3）,c = 17.362（3） A,V = 3691.5（9） A^3,C37H47 Al B2N2O5,Mr = 648.37,Z = 4,Dc = 1.167 Mg/m^3,μ（Mo Kα） = 0.097 mm^–1,F（000） = 1384,S = 1.000,the final R = 0.0589 and w R = 0.1445 for 9138 observed reflections（I 〉 2σ（I）） and R = 0.0683 and w R = 0.1517 for all data.This compound is an unique example of a spiro-centered aluminum atom,showing the inorganic Al O3B2 ring fused to the organic C3N2 part.It was characterized by 1H NMR,IR,elemental analysis,and single-crystal X-ray structural analysis.Furthermore,the compound was studied by TG analysis as well as DSC.展开更多
Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysila...Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysilane （VTES）, vinyl trimethoxysilane （VTMS） and γ-methacryloylpropyl trimethoxysilane （MPS）. The treated glass fibers were analyzed by fourier transform infrared spectroscopy （FTIR）. Dynamic mechanical thermal analysis （DMTA） and thermo-gravimetric analysis （TGA） were employed to investigate the effect of glass fibers surface modification on viscoelastic behavior and thermal properties. The morphology of fracture surfaces of various composites was observed by scanning electron microscopy （SEM）. The results revealed that these coupling agents were connected to the surfaces of the fibers by chemical bonding. Dynamic mechanical properties as well as thermal stability of the composites were improved considerablely, but to varying degrees depending on the fiber modification. The diversities of improvement of properties were attributed to the different interfacial adhesion between CLPS matrix and the glass fibers.展开更多
The comparison between physical properties and chemical structures of several polysiloxanes was studied at initial state and upon ageings. Techniques such as densimetry, gel permeation chromatography, FTIR spectroscop...The comparison between physical properties and chemical structures of several polysiloxanes was studied at initial state and upon ageings. Techniques such as densimetry, gel permeation chromatography, FTIR spectroscopy, thermogravim- etric analysis coupled with IR spectroscopy and the new tool photo-DSC were used to give assessments of average mo- lecular weight, chemical evolution, cristallinity and thermal stability. Different types of ageing such as thermal ageing (60?C and 100?C), photo-ageing and acid vapour ageing were performed. After ageing we observed an evolution of chemical structures and physical properties for all samples. The main pathway of degradation is given for each sample. It results in oxidation, chain scission or cross-linking. Cross-linking levels are dependant on the type of ageing, the chemical structure and the initial rate of cristallinity. Cross-linking reactions are favoured after photo-ageing. Oxidation is higher for polysiloxane with aliphatic carbon chain.展开更多
A novel cross-linking process using two high molecular weight aromatic poly（thioether）s, which were synthesized by the reactions of 4,4＇-thiobisbenzenethiol with 4,4＇-difluorobenzophenone and 4,4＇-difluorodipheny...A novel cross-linking process using two high molecular weight aromatic poly（thioether）s, which were synthesized by the reactions of 4,4＇-thiobisbenzenethiol with 4,4＇-difluorobenzophenone and 4,4＇-difluorodiphenylsulfone, respectively, and commercially available lower molecular weight poly（p-phenylene sulfide） was investigated. These reactions were carried out in bulk by the addition of silver tetrafluroborate and α,α＇-dibromo-p-xylene at 190℃ over a period of 45 min. Furthermore, the same procedure could be modified to cross-link compression-molded films of these three polymers. The thermal and solubility behaviors of these polymers before and after cross-linking reactions, are presented.展开更多
Commercial poly(p-phenylene sulfide) (PPS) was thermally cured, which resulted in an increase of molecular weight due to cross-linking. Non-isothermal crystallization studies of samples cured for up to 7 days at 250?C...Commercial poly(p-phenylene sulfide) (PPS) was thermally cured, which resulted in an increase of molecular weight due to cross-linking. Non-isothermal crystallization studies of samples cured for up to 7 days at 250?C showed a monotonous increase of crystallization temperature compared to pure PPS. However, a further increase of curing time decreased the crystallization temperature. The change in the half-crystallization time (t1/2) was similar to the crystallization temperature. Thus, the cross-linking of PPS affected crystallization behaviors significantly. To a certain extent, crosslinks acted as nucleation agents, but excessive cross-linking hindered the crystallization. Morphologies observed by polarized optical microscopy suggested that thermal curing for as little as 1 day contributed to the spherulitic structure having a smaller size, that was not observed with pure PPS.展开更多
Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with μ gas chromatography-mass spectrometry (μGC-MS) ...Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with μ gas chromatography-mass spectrometry (μGC-MS) with other analytical techniques (thermogravimetry analysis and in situ X-ray diffraction). Non-isothermal kinetic was examined in air and Ar. A complete analysis of the evolution of infrared spectra matched with crystalline phase transition data during the course of reaction allows access to significant and accurate information about molecular dynamics. While thermogravimetry gives broad conclusion about two steps reaction (dehydration and decarboxylation), in line approach (in situ X-ray and in situ DRIFT coupled to μGC-MS) is proposed as an example of a new robust and forward-looking analysis. While decomposition mechanism of copper acetate monohydrate is still not well elucidated yet previously, the present in-line characterization results lead to accurate data making the corresponding mechanism explicit.展开更多
基金supported by the National Natural Science Foundation of China(No.21001016)the Beijing Natural Science Foundation(No.2132044)Beijing High School Youth Talent Project(YETP1191)
文摘The boroxine-linked organic aluminum compound LAl[OB（3-C4H3O）]2（μ-O） was accomplished by reacting LAl H2 {L =（Z）-4-[（2,6-diisopropylphenyl）amino]pent-3-en-2-ylidene-2,6-diisopropylaniline} with furan-3-ylboronic acid in good yield.The title compound belongs to the orthorhombic system,space group Pnma with a = 10.9774（15）,b = 19.369（3）,c = 17.362（3） A,V = 3691.5（9） A^3,C37H47 Al B2N2O5,Mr = 648.37,Z = 4,Dc = 1.167 Mg/m^3,μ（Mo Kα） = 0.097 mm^–1,F（000） = 1384,S = 1.000,the final R = 0.0589 and w R = 0.1445 for 9138 observed reflections（I 〉 2σ（I）） and R = 0.0683 and w R = 0.1517 for all data.This compound is an unique example of a spiro-centered aluminum atom,showing the inorganic Al O3B2 ring fused to the organic C3N2 part.It was characterized by 1H NMR,IR,elemental analysis,and single-crystal X-ray structural analysis.Furthermore,the compound was studied by TG analysis as well as DSC.
基金Supported by National Natural Science Foundation of China (No.50872101,A3 Foresight Program-50821140308)National Basic Research Program of China (No.2009CB939704)a joint project of National Nature Science Foundation of China and Russian Foundation for Basic Research(No.NSFC-RFBR 51011120252)
文摘Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysilane （VTES）, vinyl trimethoxysilane （VTMS） and γ-methacryloylpropyl trimethoxysilane （MPS）. The treated glass fibers were analyzed by fourier transform infrared spectroscopy （FTIR）. Dynamic mechanical thermal analysis （DMTA） and thermo-gravimetric analysis （TGA） were employed to investigate the effect of glass fibers surface modification on viscoelastic behavior and thermal properties. The morphology of fracture surfaces of various composites was observed by scanning electron microscopy （SEM）. The results revealed that these coupling agents were connected to the surfaces of the fibers by chemical bonding. Dynamic mechanical properties as well as thermal stability of the composites were improved considerablely, but to varying degrees depending on the fiber modification. The diversities of improvement of properties were attributed to the different interfacial adhesion between CLPS matrix and the glass fibers.
文摘The comparison between physical properties and chemical structures of several polysiloxanes was studied at initial state and upon ageings. Techniques such as densimetry, gel permeation chromatography, FTIR spectroscopy, thermogravim- etric analysis coupled with IR spectroscopy and the new tool photo-DSC were used to give assessments of average mo- lecular weight, chemical evolution, cristallinity and thermal stability. Different types of ageing such as thermal ageing (60?C and 100?C), photo-ageing and acid vapour ageing were performed. After ageing we observed an evolution of chemical structures and physical properties for all samples. The main pathway of degradation is given for each sample. It results in oxidation, chain scission or cross-linking. Cross-linking levels are dependant on the type of ageing, the chemical structure and the initial rate of cristallinity. Cross-linking reactions are favoured after photo-ageing. Oxidation is higher for polysiloxane with aliphatic carbon chain.
文摘A novel cross-linking process using two high molecular weight aromatic poly（thioether）s, which were synthesized by the reactions of 4,4＇-thiobisbenzenethiol with 4,4＇-difluorobenzophenone and 4,4＇-difluorodiphenylsulfone, respectively, and commercially available lower molecular weight poly（p-phenylene sulfide） was investigated. These reactions were carried out in bulk by the addition of silver tetrafluroborate and α,α＇-dibromo-p-xylene at 190℃ over a period of 45 min. Furthermore, the same procedure could be modified to cross-link compression-molded films of these three polymers. The thermal and solubility behaviors of these polymers before and after cross-linking reactions, are presented.
文摘Commercial poly(p-phenylene sulfide) (PPS) was thermally cured, which resulted in an increase of molecular weight due to cross-linking. Non-isothermal crystallization studies of samples cured for up to 7 days at 250?C showed a monotonous increase of crystallization temperature compared to pure PPS. However, a further increase of curing time decreased the crystallization temperature. The change in the half-crystallization time (t1/2) was similar to the crystallization temperature. Thus, the cross-linking of PPS affected crystallization behaviors significantly. To a certain extent, crosslinks acted as nucleation agents, but excessive cross-linking hindered the crystallization. Morphologies observed by polarized optical microscopy suggested that thermal curing for as little as 1 day contributed to the spherulitic structure having a smaller size, that was not observed with pure PPS.
文摘Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with μ gas chromatography-mass spectrometry (μGC-MS) with other analytical techniques (thermogravimetry analysis and in situ X-ray diffraction). Non-isothermal kinetic was examined in air and Ar. A complete analysis of the evolution of infrared spectra matched with crystalline phase transition data during the course of reaction allows access to significant and accurate information about molecular dynamics. While thermogravimetry gives broad conclusion about two steps reaction (dehydration and decarboxylation), in line approach (in situ X-ray and in situ DRIFT coupled to μGC-MS) is proposed as an example of a new robust and forward-looking analysis. While decomposition mechanism of copper acetate monohydrate is still not well elucidated yet previously, the present in-line characterization results lead to accurate data making the corresponding mechanism explicit.
