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Influence of wet activation of used inorganic binder on cyclically refreshed water glass moulding sands hardened by microwaves

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China Foundry 2016年第6期13卷 427-432页

作者： Mateusz Stachowicz Kazimierz Granat department of Foundry Plastics and Automation Wroc?aw University of Technology

The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermally loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermally treated inorganic binder, each of the examined processes employed the surface phenomenon usually associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclically prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands allo

关键词： moulding sand reclamation water-glass microwave heating refreshing

TRANSAMIDATION IN THE in situ BLENDING OF POLYAMIDE 1212 WITH POLYAMIDE 6 THROUGH ANIONIC POLYMERIZATION OF CAPROLACTAM

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Chinese Journal of Polymer Science 2007年第5期25卷 473-481页

作者：郑强杨桂生 department of Polymer Science and Engineering Zhejiang University Key Laboratory of Engineering plastics Institute of Chemistry Chinese Academy of Sciences

20 wt% polyamide 12 （PA1212） pellets were dissolved in molten caprolactam. The caprolactam was then catalyzed at 180℃ and polymerized by means of anionic ring-opening polymerization to produce in situ blends of the resultant polyamide 6 （PA6） and PA 1212. Mechanical blends with same ingredient were prepared through melt blending on a twin-screw extruder. Scanning electron microscopy （SEM） observation revealed that contrary to the mechanical blends with small spherulites embedded in the matrix, no phase-separation existed in the in situ blends. The results of thermal analysis by differential scanning calorimetry （DSC） showed that single melting peak and crystallization peak existed for the in situ blends, while two melting and crystallization peaks appeared for the mechanical blends. The in situ blend film and the mixed blend film, both cast from a dilute formic acid solution with a concentration of 0.5 g/L, remained similar crystallization and melting behavior as above. It is proved by solution 13C-NMR analysis that transamidation took place during the in situ blending, and it is suggested that the combination of temperature increasing and the basic surrounding derived from NaOH during polymerization resulted in the occurrence of transamidation. Furthermore, it is proposed that the interchange reaction between PA 1212 and PA6 also resulted from the degradative reaction during the anionic polymerization.

关键词： Transamidation Polyamide Anionic ring-opening polymerization NMR.

Preliminary study on the possible new modification of isotactic polypropylene crystallized under high pressure

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Chinese Science Bulletin 1996年第3期41卷 257-261页

作者：黄锐傅强彭少贤张雄伟 department of plastics Engineering Chengdu Univ. of Sci. and Technology Chengdu 610065 China

Isotactic polypropylene (iPP) has complex polymorphic structures. It can crystallize in at least four different modifications, termed α, β, γ and δ, under different crystallization conditions. The modifications of iPP and their transitions have attracted much attention over the years. Studies on the relationships between the modifications and the possibility of formation of new modification are significantly important to investigation on the relationships between structure and properties of iPP. In this note,

关键词： isotactic polypropylene modification high pressure crystallization.

Mechanical characterization of functional graphene nanoplatelets coated natural and synthetic fiber yarns using polymeric binders

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International Journal of Smart and Nano Materials 2020年第1期11卷 78-91页

作者： Velram Balaji Mohan Debes Bhattacharyya plastics Centre of Excellence&Centre for Advanced Composite Materials Department of Mechanical EngineeringThe University of AucklandAucklandNew Zealand

Fabrication of electrically conductive yarns(glass,flax and polypropylene fibers)coated with graphene nanoparticles(GNP)were characterized for their mechanical properties and compared with their electrical *** composites were produced with the use of polymeric binders(epoxy resin and thermoplastic starch)and two different dipcoating methodologies were developed to create the coating ***-1 involved coating of binder and then GNP layer whereas Technique-2 had a mixture of binder and GNP in the predetermined ratio,which was coated on the *** mechanism of adhesion varies or influences on a number of factors such as the nature of the fiber surface,coating method and effective *** properties of the yarns were measured by an appropriate standard,and the highest tensile strength was noticed with epoxy-based glass fiber samples as 222 MPa followed by flax fiber samples as 206 *** composites of starch-based showed poor mechanical performance compared to those of epoxy *** was due to poor adhesion between the surface and starch layer(interphase)where the Van der Wall’s force was quite *** conductivity,glass fiber yarns with epoxy binder were identified to have the highest electrical conductivity of 0.1 ***−1 among other samples.

关键词： Coating fiber yarn composites conductive yarns mechanical properties interfacial bonding microstructure

A new asymmetric anthracene derivative with high mobility

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Science China Chemistry 2019年第2期62卷 251-255页

作者： Xixia Yu Lei Zheng Jinfeng Li Lu Wang Jiangli Han Huayi Chen Xiaotao Zhang Wenping Hu Tianjin Key Laboratory of Molecular Optoelectronic Science Department of Chemistry Tianjin University Shen Ma Engineering plastics Co.Ltd.

An asymmetric anthracene derivative(4-HDPA) was designed and synthesized. With the optimization of proper scenario of fabrication process, top-contact thin film devices based on 4-HDPA exhibit mobility as high as 3.59 cm^2 V^(–1) s^(–1), while its singlecrystal devices exhibit mobility as high as 5.12 cm^2 V^(–1) s^(–1), which is higher than the symmetrical counterpart of 4-HDPA in both single-crystal and thin film devices.

关键词： organic field-effect transistor (OFET) asymmetric anthracene derivative mobility

Thermal conductivity of natural rubber nanocomposites with hybrid fillers

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Chinese Journal of Chemical Engineering 2019年第4期27卷 928-934页

作者： Junping Song Xiteng Li Kaiyan Tian Lianxiang Ma Wei Li Shichune Yao Key Laboratory of Rubber-plastics Ministry of Education Shandong Provincial Key Laboratory of Rubber-plastics Chinese and German School of Science and Technology College of Electromechanical Engineering Qingdao University of Science and Technology Qingdao 266061 China department of Energy Engineering Zhejiang University Hangzhou 310027 China department of Mechanical Engineering Carnegie Mellon University Pittsburgh PA 15213-3890 USA

Natural rubber nanocomposites filled with hybrid fillers of multi-walled carbon nanotubes(CNTs) and carbon black(CB) were prepared. CNTs were ultrasonically modified in mixture of hydrogen peroxide(H2O2) and distilled water(H2O). The functional groups on the surface of CNTs, changes in nanotube structure and morphology were characterized by Fourier transform infrared spectroscopy(FT-IR), Raman Spectroscopy, and transmission electron microscopy(TEM). It shows that hydroxyl(OH·) is successfully introduced. The surface defects of modified CNTs were obviously higher than those of original CNTs, and the degree of agglomeration was greatly reduced. Thermal conductivity of the composites was tested by protection heat flow meter method. Compared with unmodified CNTs/CB filling system, the thermal conductivity of hybrid composites is improved by an average of 5.8% with 1.5 phr(phr is parts per hundred rubber) of hydroxyl CNTs and 40 phr of CB filled. A three-dimensional heat conduction network composed of hydroxyl CNTs and CB, as observed by TEM, contributes to the good properties. Thermal conductivity of the hybrid composites increases as temperature rises. The mechanical properties of hybrid composites are also good with hydroxyl CNTs filled nanocomposites;the tensile strength, 100% and 300% tensile stress are improved by 10.1%, 22.4% and 26.2% respectively.

关键词： Modified carbon nanotube Carbon black Hybrid filler Natural rubber Thermal conductivity

Light weight, mechanically strong and biocompatible α-chitin aerogels from different aqueous alkali hydroxide/urea solutions

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Science China Chemistry 2016年第11期59卷 1405-1414页

作者： Beibei Ding Dan Zhao Jianhui Song Huichang Gao Duoduo Xu Min Xu Xiaodong Cao Lina Zhang Jie Cai College of Chemistry & Molecular Sciences Wuhan University Key Laboratory of Rubber-plastics Ministry of Education Shandong Provincial Key Laboratory of Rubber-PlasticsQingdao University of Science & Technology department of Physics Shanghai Key Laboratory of Magnetic Resonance East China Normal University School of Materials Science and Engineering South China University of Technology

Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide(KOH, Na OH and Li OH)/urea solutions. All of the α-chitin solutions exhibited temperature-induced rapid gelation behavior. 13 C nuclear magnetic resonance(NMR) spectra revealed that the aqueous alkali hydroxide/urea solutions are non-derivatizing solvents for α-chitin. Fourier transform infrared(FT-IR), X-ray diffraction(XRD) and cross-polarization magic angle spinning(CP/MAS) 13 C NMR confirmed that α-chitin has a stable aggregate structure after undergoing dissolution and regeneration. Subsequently, nanostructured α-chitin aerogels were fabricated by regeneration from the chitin solutions in ethanol and then freeze-drying from t-Bu OH. These α-chitin aerogels exhibited high porosity(87% to 94%), low density(0.09 to 0.19 g/cm^3), high specific surface area(419 to 535 m^2/g) and large pore volume(2.7 to 3.8 cm^3/g). Moreover, the α-chitin aerogels exhibited good mechanical properties under compression and tension models. In vitro studies showed that m BMSCs cultured on chitin hydrogels have good biocompatibility. These nanostructured α-chitin aerogels may be useful for various applications, such as catalyst supports, carbon aerogel precursors and biomedical materials.

关键词： chitin aerogels alkali hydroxide/urea aqueous solutions mechanical properties biocompatibility

Damage Studies of Brittle-Ductile Transition in PP EPDM Blends

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Science China Chemistry 1993年第11期36卷 1300-1306页

作者：李强郑文革漆宗能吴选征 State Key Laboratory of Engineering plastics Institute of Chemistry Academia Sinica Beijing 100080 PRC department of Applied Physics Hong Kong Polytechnic Hong Kong

Damage zones of brittle-ductile (B-D) transition in PP/EPDM blends are studied in this paper. The contribution of crazing and shear yielding zones in damage zones to energy dissipation of blends was measured with computer image analysis (CIA) and the transition of shear yielding zone (A_(sh)) with rubber volume fraction (V_f) was also manipulated. Results showed that the B-D transition of impact strength of blends corresponded to the fracture mechanism in PP/EPDM blends, from matrix crazing to matrix shear yielding. In addition, two new parameters, density of energy dissipation for crazing zone (F_(cz)) and for shear yielding zone (F_(sh)), are first obtained in this paper. The value of F_(sh) is about four times larger than that of F_(cz) for PP/EPDM blends, which confirmed that the matrix shear yielding is a more effective way of energy dissipation in blends.

关键词： brittle-ductile transition damage studies pereolation model density of energy dissipation for crazing zone(F_(cz)) density of energy dissipation for shear yielding zone(F_(sb)).

Constructing an efficient deep-blue TADF emitter by host-guest interactions towards solution-processed OLEDs with narrowband emission

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Science China Chemistry 2023年第3期66卷 826-836页

作者： Yanchao Xie Lei Hua Zhi Wang Yuerong Liu Shian Ying Yuchao Liu Zhongjie Ren Shouke Yan department Key Laboratory of Rubber-plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-PlasticsSchool of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao 266042China State Key Laboratory of Chemical Resource Engineering College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China

High-efficiency thermally activated delayed fluorescence(TADF) emitters and corresponding well-designed solution-processed organic light emitting diodes(OLEDs) are presently attractive due to their potential for exploiting large-area flexible displays. In this context, we innovatively integrate 2,12-di-tert-butyl-5,9-dioxa-13b-boronaphtho [3,2,1] anthracene as the acceptor with 3,6-bis(3,6-di-tert-butylcarbazol-N-yl) carbazole as the donor to construct a rigid deep-blue emitter, TB-3t BuCz, which exhibits a narrow emission with full-width-at-half-maximum(FWHM) of 46 nm. TB-3t BuCz itself dispalys no TADF characteristics both in solution or in pure film states. However, the significant TADF behavior can be observed when TB-3t BuCz is doped with 2,6-DCzPPy host due to the formation of exciplex-like species in 2,6-DCzPPy/TB-3t BuCz system. It is also found that the discernible spin-flip of triplet excitons is feasible when the S1/T1states of the formed exciplex stay slightly lower than S1 and T1states of TB-3t BuCz for the other host/TB-3t BuCz systems. Eventually, thanks to the synergetic effect of rigid structure and favorable photophysical properties of TB-3t BuCz, the solution-processed OLEDs based on 2,6-DCzPPy/TB-3t BuCz as emitting layer has achieved the significantly improved external quantum efficiency(EQE) of 14.6% with suppressed efficiency *** CIE1931 coordinate of(0.158, 0.052) is typically in deep-blue region. Note that, this EQE value is among the highest echelon of solution-processed OLEDs with deep-blue emission by utilizing boron-containing TADF emitters.

关键词： thermally activated delayed fluorescence oxygen-bridged cyclized boron host-guest interactions solution-processed OLEDs narrowband deep-blue emission