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REACTION MECHANISM OF BENZOPHENONE-PHOTOINITIATED CROSSLINKING OF POLYETHYLENE

Chinese Journal of polymer science 2002年第4期20卷 291-307页

作者： bao-jun qu state key laboratory of fire science and department of polymer science and engineering university of science and technology of china hefei 230026 china Univ Sci & Technol china State Key Lab Fire Sci Hefei 230026 Peoples R China Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The radical intermediates, the crosslink microstructures, and the reaction mechanism of benzophenone (BP)-photoinitiated crosslinking of low-density polyethylene (LDPE) and model compounds (MD) have been reviewed in detail. The spin-trapping electron spin resonance (ESR) spectra obtained from the LDPE/BP systems with spin-trap agents show that two kinds of polymer radical intermediates are mainly formed: tertiary carbon and secondary carbon radicals. The spin-trapping ESR studies of MD/BP systems give further evidence that photocrosslinking reactions of PE predominantly take place a sites of tertiary carbon, secondary carbon, and especially allylic carbon when available. The high resolution C-13-NMR spectra obtained from LDPE and MD systems show that the crosslink microstructures have H- and Y-type links and that their concentrations are of the same order. The fluorescence, ESR, C-13 and H-1-NMR spectra from the PE and MD systems demonstrate that the main photoreduction product of BP (PPB) is benzpinacol formed by the recombination of two diphenylhydroxymethyl (K-.) radical intermediates. Two new PPB products: an isomer of benzpinacol with quinoid structure, 1-phenylhydroxymethylene-4-diphenylhydroxymethyl-2,5-cyclobexadiene and three kinds of alpha-alkyl-benzhydrols have been detected and identified. These results provide new experimental evidence for elucidating the reaction mechanism in the BP-photoinitiated crosslinking of polyethylene.

关键词： photocrosslinking mechanism polymer radical intermediates crosslink microstructures photolytic products of benzophenone polyethylene model compound

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A NEW SYNERGIST FOR INTUMESCENT FLAME RETARDANT POLYPROPYLENE

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Chinese Journal of polymer science 2002年第4期20卷 377-380页

作者： Qiang Wu bao-jun qu state key laboratory of fire science and department of polymer science and engineering university of science and technology of china, hefei 230026 china Univ Sci & Technol china State Key Lab Fire Sci Hefei 230026 Peoples R China Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The synergistic effects of silicotungstic acid (SiW12) as a catalyst in the phosphorus-nitrogen compounds AM-based intumescent flame-retardant (IFR) polypropylene (PP) were studied using the limiting oxygen index (LOI), the UL-94 test, thermogravimetric analysis (TGA), real time Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS). The LOI data show that SiW12 added to PP/IFR systems has a synergistic FR effect with an IFR additive named AM. The TGA data show that SiW12 apparently increases the thermal stability of the PP/IFR systems at high temperature (T > 500degreesC). The FTIR results provide the positive evidence that IFR can improve the thermal stability of PP and SiW12 can induce a higher rate of formation of phosphoric acid and its derivatives. The LRS measurements provide useful information on the carbonaceous microstructures. In short, a suitable amount of SiW12 (1.5 wt%) exerts synergistic effects with the IFR by increasing the LOI value and the thermal stability at high temperature and promoting the formation of charred structures on the burning PP surface.

关键词： silicotungistic acid synergistic effect intumescent flame retardant polypropylene

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Recent progress in polymer/layered double hydroxide nanocomposites

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Progress in Natural science:Materials International 2006年第6期16卷 573-579页

作者： DING Peng, CHEN Wei and qu baojun (state key laboratory of fire science and department of polymer science and engineering, university of science and technology of china, hefei 230026, china) [a] state key laboratory of fire science and department of polymer engineering University of Science and Technology of china Hefei China

New developments in the studies of nanocomposites based on polymer matrixes and layered double hydroxides (LDHs) in recent years are reviewed combining our relative research work, among which the synthesis techniques, the physicochemical characterizations, and the improved material properties are especially discussed. The possible application of polymer/LDH nanocomposites is also proposed.

关键词： nanocomposite layered double hydroxide synthesis characterization structure property.

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TRANSESTERIFICATION OF POLY(ETHYLENE TEREPHTHALATE) WITH POLY(ε-CAPROLACTONE)

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Chinese Journal of polymer science 2000年第5期18卷 405-412页

作者： Zheng-ping Zhang Xiao-lie Luo Yu-chen Lu De-zhu Ma department of polymer science and engineering, university of science and technology of china, hefei 230026, china Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

Transesterification of poly（ethylene terephthalate）（PET） with poly（ε-caprolactone）（PCL） was investigated bymeans of NMR spectroscopy, extraction experiments, differential scanning calorimetry （DSC） and phase contrast microscopy（PCM）. The;H-NMR results show that transesterification takes place in the melt blends and leads to the formation of thePET-PCL copolyester with a chemical structure similar to ethylene terephthalate-ε-caprolactonc copolycster （TCL）synthesized directly from monomers. However, even in the blend that has been transesterified for 8 h, the random PET-PCLcopolyester, PET-PCL copolyester with long PET or long PCL segments and the unreacted PET and PCL homopolymersmay coexist. Due to the low mobility of PET and PCL chains and the high viscosity of the two macromolecules, thetransesterification proceeds with difficulty. Furthermore, PET is incompatible with PCL, the transesterification can onlyoccur at the interface or in the interfacial region between two phases, and finally the reaction can only reach a localequilibrium. These results indicate that in fact the transesterification in the melt blend between two incompatiblehomopolymers could not lead to the formation of completely random or typical block copolyesters.

关键词： Transesterification Poly(ethylene terephthalate) Poly(ε-caprolactone) Crystallization Phase structure

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ATOMIC FORCE MICROSCOPY STUDIES OF POLYCAPROLACTONE RINGED SPHERULITES

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Chinese Journal of polymer science 2000年第6期18卷 569-572页

作者： Jian-bin Zhang De-zhu Ma Hua Zhong Xiao-lie Luo department of polymer science and engineering, university of science and technology of china, hefei 230026, china Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The surface morphology of free-surface PCL ringed spherulites was investigated by using atomic force microscopy. The spherulites were obtained by crystallization of PCL/PVC blends of different compositions. It was found that the ringed spherulite exhibited regularly fluctuating rings on its surface. Compared with the bright-dark ring pattern of the spherulite under a polarizing microscope, it was proved that the optical characteristics of the ringed spherulite under polarizing microscope coincided with its surface characteristics. The bright rings in polarizing micrographs of the spherulite coincided with the convex rings on its surface, while the dark rings coincided with the concave rings.

关键词： AFM surface morphology ringed spherulites PCL/PVC blends

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COMPOSITIONAL HETEROGENEITY OF ETHYLENE OXIDE-BUTYLENE TEREPHTHALATE SEGMENTED COpolymer

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Chinese Journal of polymer science 1999年第3期17卷 271-280页

作者： De-zhu Ma Dong-sheng Li Ming-chuan Zhao Mo-zhen Wang Ran Ye Xiao-lie Luo department of polymer science and engineering, university of science and technology of china, hefei 230026, china Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

A series of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with different soft segment length and hard segment content were synthesized. The compositional heterogeneity was studied by solvent extraction. The results show that the compositional heterogeneity increases when soft segment length and hard segment content increase. The compositional heterogeneity is also reflected in the crystallization behavior and morphology of soft and hard segment in EOBT segmented copolymer. The more compositional heterogeneous the EOBT segmented copolymer is, the more different the morphology and the crystallization behavior between separated fractions. Compared with ethylene oxide-ethylene terephthalate (EOET) segmented copolymer, compositional heterogeneity in EOBT segmented copolymer is weaker. But the compositional heterogeneity in EOBT segmented copolymer with long soft segment and high hard segment content is still obvious.

关键词： ethylene oxide-butylene terephthalate segmented copolymer compositional heterogeneity crystallizability morphology

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EFFECT OF PROCESSING METHOD ON THE IMPACT STRENGTH OF POM/TPU/CaCO_3 TERNARY COMPOSITES

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Chinese Journal of polymer science 2005年第5期23卷 531-537页

作者： Xiao-ling Gao Cheng qu Qin Zhang Rong-ni Du and Qiang Fu department of polymer science & Materials,Sichuan university,state key laboratory of polymer Materials engineering,Chengdu 610065,china Sichuan Univ Dept Polymer Sci & Mat State Key Lab Polymer Mat Engn Chengdu 610065 Peoples R China

Polyoxymethylene （POM）/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane （TPU） and inorganic filler, namely, CaCO3, were used to achieve balanced mechanical properties of POM. The dispersion and phase morphology of POM/elastomer/filler composites were found to depend largely on processing method, CaCO3 content in masterbatch and the filler size. Two processing methods were employed to prepare POM/elastomer/filler ternary composites. One is called the one-step method, in which elastomer and the filler directly melt blended with POM matrix. The other is called the two-step method, in which the elastomer and the filler were mixed to get masterbatch first, which was then melt blended with pure POM of different content. The effect of phase morphology and processing method on impact strength was investigated. It was found that the two-step method results in an increase in impact strength but not for the one-step method. Additionally, the impact strength of POM ternary composites decreases with the increase in the size of CaCO3 particles.

关键词： POM/TPU/CaCO3 composites Core-shell structure Impact strength.

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Synthesis and Characterization of Poly (Aryl Ether Ketone) Containing Phthalazinone and Naphthalene Moieties

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Chinese Chemical Letters 2000年第9期11卷 777-778页

作者： Ye GAO Xi Gao JIAN Jin Yan WANG department of polymer science, College of Chemical engineering, Dalian university of technology, Dalian 116012 Dalian Univ Technol Coll Chem Engn Dept Polymer Sci Dalian 116012 Peoples R China

A novel poly (aryl ether ketone) (PPEK) containing phthalazinone and naphthalene moieties was prepared by the nucleophilic displacement reaction of 4-(4-hydroxyphenyl) (2H) phthalazin-1-one with 1-chloro-4-(4-chlorobe... 详细信息

关键词： engineering thermoplastics poly (aryl ether ketone) synthesis

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A critical review on direct catalytic hydrogasification of coal into CH_(4):catalysis process configurations,evaluations,and prospects

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International Journal of Coal science & technology 2024年第3期11卷 51-85页

作者： Shuai Yan jun Feng Shenfu Yuan Zihong Xia Fengshuang Han Xuan qu Jicheng Bi School of Materials and Chemical engineering Ningbo University of TechnologyNingbo315211ZhejiangChina Zhejiang Institute of Tianjin university Ningbo315201ZhejiangChina state key laboratory of Coal Conversion Institute of Coal ChemistryChinese Academy of SciencesTaiyuan030001China School of Chemical science and engineering Key Laboratory of Medicinal Chemistry for Natural ResourceMinistry of EducationNational Center for Experimental Chemistry and Chemical Engineering Education DemonstrationYunnan Provincial Key Laboratory of Carbon Neutral and Green Low-Carbon TechnologyYunnan UniversityKunming650091China department of Energy and Chemical engineering East China University of Science and TechnologyShanghai200237China

Coal catalytic hydrogasification(CCHG)is a straightforward approach for producing CH_(4),which shows advantages over the mature coal-to-CH_(4) technologies from the perspectives of CH_(4) yield,thermal efficiency,and CO_(2) *** core of CCHG is to make carbon in coal convert into CH_(4) efficiently with a *** the past decades,intensive research has been devoted to catalytic hydrogasification of model carbon(pitch coke,activated carbon,coal char).However,the chemical process of CCHG is still not well understood because the coal structure is more complicated,and CCHG is a combination of coal catalytic hydropyrolysis and coal char catalytic *** review seeks to shed light on the catalytic process of raw coal during *** configuration of suitable catalysts,operating conditions,and feedstocks for tailoring CH_(4) formation were identified,and the underlying mechanisms were *** on these results,the CCHG process was evaluated,emphasizing pollutant emissions,energy efficiency,and reactor ***,the opportunities and strategic approaches for CCHG under the restraint of carbon neutrality were highlighted by considering the penetration of“green”H2,biomass,and CO_(2) into *** investigations from our laboratories demonstrated that the integrated CCHG and biomass/CO_(2) hydrogenation process could perform as an emerging pathway for boosting CH_(4) production by consuming fewer fossil fuels,fulfilling the context of green *** work not only provides systematic knowledge of CCHG but also helps to guide the efficient hydrogenation of other carbonaceous resources such as biomass,CO_(2),and coal-derived wastes.

关键词： Coal gasification Catalytic hydrogasification Methane Pressurized fluidized bed

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SMALL ANGLE LIGHT SCATTERING MEASUREMENT OF THE ISOTROPIC TO NEMATIC TRANSITION OF A SIDE CHAIN NEMATIC POLYMETHACRYLATE

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Chinese Journal of polymer science 2002年第5期20卷 431-437页

作者： Zhong-ming Hu Ren-yuan Qian Shou-xi Chen Xiao-fang Chen Qi-feng Zhou Centre for Molecular science, Institute of Chemistry Chinese Academy of sciences, Beijing 100080, china department of polymer science & engineering College of Chemistry & Molecular engineering Peking university Beijing 100871, china Chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China Peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China

The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer shows the transition temperatures K52N79I in degreesC, The H-v scattering intensity T(q,t) during the transition I (at 80.2degreesC)-->N (at 75.8degreesC) shows that T(q) is independent of q for all t, and during the initial stage (in 6 s) T(t) increases exponentially with t. In the later stage of the transition T(t) approaches a saturation value in 2 min. This experimental result indicates that the I-->N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.

关键词： side chain nematic polymer isotropic-nematic transition small angle depolarized light scattering

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