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VISCOELASTIC BEHAVIOR OF THE NON-HOOKE DEFORMATION BEFORE YIELDING IN UNIAXIAL DRAWING OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)

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chinese Journal of polymer Science 2001年第4期19卷 399-405页

作者： zhen-hua Yuan De-yan Shen Ren-yuan Qian polymer physics {3. center for molecular Science, Institute of Chemistry chinese academy of sciences, beijing 100080 china chinese Acad Sci Inst Chem Ctr Mol Sci Polymer Phys Lab Beijing 100080 Peoples R China

Viscoelastic behavior of the non-Hooke deformation of amorphous PET film before yield was investigated in the temperature region 74-80.5 degreesC around the glass transition temperature. The film specimen was drawn to yield point followed by unloading to zero stress, then the residual deformation was held constant; while the subsequent evolution of the stress was recorded. An induction period was found in the course of stress evolution followed by a stress step-increase. The induction period decreases with increasing drawing temperature with an activation energy of 1.10 MJ/mol.K, which is attributed to the time needed for the relaxation of rubbery deformation through cooperative internal rotations. At temperatures lower than 74 degreesC, there is no stress increase or the induction period becomes too long to be observed. Thus the nature of anelasticity in the non-Hooke region before yielding is attributed to stress induced rubbery deformation. The experimental results are interpreted in terms of Perez' theological model of a series connected Hooks spring and a Voigt element consisting of a parallel connected elastic spring and a dashpot.

关键词： pre-yield deformation PET uniaxial drawing non-Hooke deformation viscoelasticity stress induced rubbery deformation

RHEOLOGICAL BEHAVIOR OF EPOXY RESIN WATERBORNE DISPERSIONS

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chinese Journal of polymer Science 2001年第5期19卷 471-476页

作者： zhen-zhong yang Yuan-ze Xu De-lu Zhao State Key laboratory of {3. physics & Chemistry, center for molecular Science Institute of Chemistry, chinese academy of sciences, beijing 100080 china chinese Acad Sci Inst Chem State Key Lab Polymer Phys & Chem Ctr Mol Sci Beijing 100080 Peoples R China

The waterborne dispersions of epoxy resin were prepared by the phase inversion emulsification technique. Rheological behavior and its relationship with the structural change of the systems were studied. It was shown that the concentrated dispersions were highly viscoelastic and pseudoplastic, which was attributed to the formation of a physical network among the waterborne particles via hydrogen bond. The dilute dispersions were Newtonian fluids. The discrete clusters composed of small waterborne particles were found in diluted dispersions. With increasing solid content, there existed a structural transition via percolation through a cluster-cluster aggregation mode to form the physical network, which was qualitatively evidenced by the TEM morphologies.

关键词： epoxy resin waterborne dispersion rheological behavior cluster-cluster aggregation percolation transition

molecular SIMULATION STUDY ON THE CHANGE OF polymer STRUCTURE DURING YIELDING

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chinese Journal of polymer Science 2001年第5期19卷 527-529页

作者： Chen-guang Xu Tai-ning Liang Juan Sun xiao-zhen yang State Key {3. of polymer physics and Chemistry center for molecular Science, Institute of Chemistry chinese academy of sciences, beijing 100080 {13. chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Polymer Phys & Chem Beijing 100080 Peoples R China

A better understanding of a recently raised argument on whether there occurs a structure change during yielding has been acquired by using molecular simulation. That is, when monitoring the displacements of all atoms before and after the yield, a structure transition does occur, which is the 'atomic jump' that coordinates the amount of the atoms in the polymer and makes a large step beyond similar to0.05 nm for all those atoms. Results indicate that the complex of polymer chain packing induces the multiple atomic jumps around the yield point. This explains why polymers have a broader yielding peak.

关键词： polymer deformation yield structure transition atomic jump multiple yields

Multiple Melting Endotherms of Syndiotactic Polystyrene in β Crystalline Form

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chinese Chemical Letters 2000年第4期11卷 367-368页

作者： zhen Hua YUAN De Yan SHEN (polymer physics {3., center for molecular Science. Institute of Chemistry. chinese academy of sciences, beijing 100080) chinese Acad Sci Inst Chem Ctr Mol Sci Polymer Phys Lab Beijing 100080 Peoples R China

A series of syndiotactic polystyrene (SPS) samples in β crystalline form were prepared by cooling from the melt at various cooling rates. The effects of cooling rate from the melt, and DSC heating rate on the multiple melting behaviors of β crystals were investigated by differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC), from which the *** the multiple melting behavior was ascribed to the occurring of a recrystallization process.

关键词： Multiple melting behavior syndiotactic polystyrene recrystalliation.

EFFECT OF PARTICLE SIZE ON THE FILMING PROCESS OF POLYSTYRENE LATEX STUDIED BY AFM

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chinese Journal of polymer Science 2002年第6期20卷 509-515页

作者： xiao-zhong Qu Yi Shi Liu-sheng Chen Xi-gao Jin State Key laboratory of polymer {3. & Chemistry, center for molecular Science,Institute of Chemistry, chinese academy of sciences, beijing 100080 china chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Polymer Phys & Chem Beijing 100080 Peoples R China

The film formation process of micro-PS particles (diameter 742 nm) and nano-PS particles (diameter 29 nm) was studied by atomic force microscopy and differential scanning calorimetry. During a step heating process, the particles were annealed for 0.5 h at each selected temperature. It was found that the deformation and interdiffusion temperatures of the micro-PS particles are ca. 120-13.degreesC and 140-150degreesC, that of the nano-PS particles are 90degreesC and 100-110degreesC respectively. The DSC traces of nano-PS particles showed that there was an exothermic peak near T-g after annealing for 0.5 h at the selected temperatures below 90degreesC; otherwise, the exothermic peak disappeared after annealing at 100degreesC or above. Compared with the micro-PS particles, the sintering process of nano-PS particles occurs at much lower temperature determined by the confined state of polymer chains with higher conformational energy in nano-particles, and completes in a much narrower temperature range driven mainly by the larger total surface energy.

关键词： polystyrene latex filming process particle size effect

STRESS-INDUCED CRYSTALLIZATION OF POLYURETHANE/MONTMORILLONITE NANOCOMPOSITE

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chinese Journal of polymer Science 2002年第5期20卷 481-483页

作者： Xin-hua Dai Xiang-dong Luo Qun Gu xiao-li Zhang De-yan Shen Liang-he Shi Jian Xu State Key laboratory of polymer {3. and Chemiscy center for molecular Science, Institute of Chemistry,chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Polymer Phys & Chem Beijing 100080 Peoples R China

Exfoliated polyurethane/montmorillonite nanocomposites with both high elongation at break and high tensilestrength were studied by dynamic-infrared spectroscopy (dynamic-IR). The results show that crystallization indu... 详细信息

关键词： PU/montmorillonite nanocomposite dynamic-IR crystallization

Confined Mn^(2+) enables effective aerobic oxidation catalysis

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Science china Chemistry 2024年第5期67卷 1545-1553页

作者： Desheng Yuan Sicong Ma xiao Kong Chi Zhang Lin Chen Chengsheng yang Lihua Wang zhen Liu Lin Ye Yongmei Liu Rui Ma Zhi-Pan Liu Yifeng Zhu Yong Cao Xinhe Bao Department of Chemical physics University of Science and Technology of ChinaHefei 230026China Department of Chemistry Shanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsCollaborative Innovation Center of Chemistry for Energy MaterialsFudan UniversityShanghai 200438China Key laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China Institute of Advanced Fluorine-Containing Materials Zhejiang Normal UniversityJinhua 321004China State Key laboratory of Catalysis National Laboratory for Clean EnergyCollaborative Innovation Center of Chemistry for Energy MaterialsDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China

Effective and mild activation of O_(2) is essential but challenging for aerobic oxidation. In heterogeneous catalysis, high-valence manganese oxide(e.g., +4) is known to be active for the oxidation, whereas divalent MnO is ineffective due to its limited capacity to supply surface oxygen and its thermodynamically unstable structure when binding O_(2) in reaction conditions. Inspired by natural enzymes that rely on divalent Mn^(2+), we discovered that confining Mn^(2+) onto the Mn_(2)O_(3. surface through a dedicated calcination process creates highly active catalysts for the aerobic oxidation of 5-hydroxymethylfurfural, benzyl alcohol, and *** Mn_(2)O_(3.-confined Mn^(2+) is undercoordinated and efficiently mediates O_(2) activation, resulting in 2–3.orders of magnitude higher activity than Mn_(2)O_(3. alone. Through low-temperature infrared spectroscopy, we distinguished low-content Mn^(2+) sites at Mn_(2)O_(3. surface, which are difficult to be differentiated by X-ray photoelectron spectroscopy. The combination of in-situ energydispersive X-ray absorption spectroscopy and X-ray diffraction further provides insights into the formation of the newly identified active Mn^(2+) sites. By optimizing the calcination step, we were able to increase the catalytic activity threefold *** finding offers promising frontiers for exploring active oxidation catalysts by utilizing the confinement of Mn^(2+)and oftenignored calcination skills.

关键词： confinement catalysis manganese oxide aerobic oxidation divalent Mn^(2+) operando spectroscopies

Topological Confinement in Reversibly Interlocked polymer Networks

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chinese Journal of polymer Science 2024年第2期42卷 133-140,I0004页

作者： Wan-Ting Dai zhen-Hua Xie Yu-Bin Ke yang You Min-Zhi Rong Ming-Qiu Zhang Key laboratory for polymeric Composite and Functional Materials of Ministry of Education GD HPPC LabIGCMESchool of ChemistrySun Yat-sen UniversityGuangzhou510275China Spallation Neutron Source Science center China Spallation Neutron SourceDongguan523803China Institute of High Energy physics Chinese Academy of SciencesBeijing100049China College of Materials and Metallurgy Guizhou UniversityGuiyang550025China

Recently, we reported a series of reversibly interlocked polymer networks(RILNs), whose mechanical robustness and functionalities improvement was believed to be derived from topological interlocking of two sub-networks, although the direct evidence for the deduction is still lacking. Herein, a specially-designed RILNs system, in which the inter-component hydrogen bonds can be shielded as needed, was prepared and used to study the micro-structures of RILNs, aiming to verify the existence of mechanical interlocking in RILNs. By changing the pH of the swelling solvent, the effect exerted by the inter-component non-covalent bonds was eliminated, so detailed information of the networks structure was exposed. The small angle X-ray scattering(SAXS) and small-angle neutron scattering(SANS) results indicated that swelling-induced structural evolution of the two sub-networks mutually affected each other, even when the inter-component hydrogen bonds were absent, proving the presence of topological interlocking. The findings may help to draw a more accurate physical image and reveal the detailed structureproperty relationship of RILNs.

关键词： Reversibly interlocked polymer networks Small angle X-ray scattering Small-angle neutron scattering Topological confinement

Naphthalene diimide-based cathode interlayer material enables 20.2% efficiency in organic photovoltaic cells

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Science china Chemistry 2024年

作者： Yue Yu Jianqiu Wang Zhihao Chen yang xiao zhen Fu Tao Zhang Haoyu Yuan xiao-Tao Hao Long Ye Yong Cui Jianhui Hou State Key laboratory of polymer physics and Chemistry Beijing National Laboratory for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences University of chinese academy of sciences School of physics State Key Laboratory of Crystal Materials Shandong University beijing Advanced Innovation center for Soft Matter Science and Engineering College of Materials Science and Engineering Beijing University of Chemical Technology School of Materials Science and Engineering Tianjin University

Cathode interlayer(CIL) materials play an important role in improving the power conversion efficiency(PCE) of organic photovoltaic(OPV) cells. However, the current understanding of the structure-property relationship in CIL materials is limited, and systematic studies in this regard are scarce. Here, two new CIL materials, NDI-PhC 4 and NDI-PhC 6 were synthesized by varying the alkylamine chain length on the NDI-Ph core. Our investigation reveals a systematic variation in the physical and chemical properties of these materials with increasing alkylamine chain length. Specifically, we observe a sequential decrease in melting point and self-doping effect, accompanied by an enhancement in crystallinity. Among these CIL materials, NDI-PhC 4 has a notable balance across various performance metrics. It also exhibits excellent surface modification capabilities, leading to a low surface roughness. Consequently, OPV cells based on NDI-PhC 4 achieve a PCE of 20.2%, which is one of the highest reported efficiencies for OPV cells. In addition, the appropriate melting point of NDI-PhC 4 contributes to the excellent stability of OPV cells.

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