Materials and Properties
CUI Xiaofeng, FANG Mei, DU Songlin, ZHANG Na, HUANG Ming, GAO Guoli, XU Jingwei
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A series of CFRP with different laminating modes was prepared through VARTM， which included the EP/CF and EP/CF/GF composites. Their mechanical properties before and after electrophoretic baking were compared， and their failure mechanism was explored. The results indicated that the ［±45 °］ laminating method and the addition of GF mat increased the permeability of the composite system significantly. After electrophoretic baking， the tensile strength of the CF［0/90 °］， CF［±45 °］， and CF/GF［±45 °］ composites decreased by 15.65 %， 12.05 %， and 6.77 %， respectively， and their modulus decreased by 9.08 %， 16.39 %， and 10.04 %， respectively. The tensile strength and modulus of the CF/GF［0/90 °］ composite increased by 7.74 % and 6.95 %， respectively. According to the flexural performance after electrophoretic baking， the flexural strength of the CF［0/90 °］， CF/GF［0/90 °］， CF［±45 °］， and CF/GF［±45 °］ composites decreased by 7.62 %， 8.23 %， 15.89 %， and 48.39 %， respectively， and their modulus decreased by 9.23 %， 3.69 %， 17.85 %， and 34.38 %， respectively. There was little effect of electrophoretic baking on the compression performance of these four composite systems. After electrophoretic baking， the energy storage modulus and loss modulus of the CF［0/90 °］ and CF［±45 °］ composites increased， whereas the CF/GF［0/90 °］ and CF/GF［±45 °］ composites showed a decrease in these two moduli.
JI Jianchao, YAN Yue, CHEN Yuhong, HA Enhua, HAO Changshan, LEI Pei
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TiO2 thin films were deposited on low temperature on poly（methylmethacrylate） （PMMA） by DC pulse magnetron sputtering. The effects of oxygen ratio， vacuum degree and other parameters on the structure and optical properties of TiO2 thin films were studied. With the help of elliptic polarizing light tester， X⁃ray diffraction （XRD） tester， spectrophotometer and atomic force microscope （AFM）， the optical properties， element composition， crystallization properties and microstructure of the thin films were analyzed. The experimental result shows that with the increases of oxygen ratio， the deposition rate of the film decreases， the particle size of the film becomes larger， and the film tend to be looser. In term of optical properties， the refractive index deceases with the increase of oxygen proportion，but visible light transmittance increases，the reflectance appears redshift. The films packing densities calculated according to the refractive index are 0.95，0.93，0.87，0.88 and 0.78 respectively， changes inversely with the proportion of oxygen. The band gap of the films calculated according to the spectrum is between 3.12~3.14 eV， changes inversely with the proportion of oxygen. With the decreases of vacuum， the deposition speed of the film first increased and then decreased. The films tend to be looser， and the refractive index decreased. The packing density of the film calculated according to the refractive index are 0.96，0.95，0.89，0.88，0.88，0.87， the vacuum degree has an positive effect on the visible light transmittance of the film， and has an negative effect on the band gap width of the film， which is between 3.13~3.16 eV， The TiO2 thin films deposited in this paper are amorphous，and the oxygen tatio and vacuum degree has little effect on their crystallinity.
ZHOU Ziyu, SANG Xiaoming, DI Xu, XIAO Xiaohong, HUANG Xiaoxiang, CHEN Xinggang
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43 )
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The surface of short⁃cut p⁃aramid fibers was modified with chlorosulfonic acid to introduce —SO2Cl groups. An optimal modification effect was achieved at a chlorosulfonic acid concentration of 40 mmol/L. The fibers were modified by using phenyltriethoxysilane as a coupling agent， and the coupling agent was successfully grafted onto the fiber surface. The polyacrylonitrile/p⁃aramid fiber composites were prepared through in⁃situ polymerization of modified p⁃aramid fiber with benzonitrile monomer. The effect of fiber content on the mechanical properties of the composites was investigated. The composite obtained optimal mechanical properties at a fiber content of 0.5 wt%， and its storage modulus， glass transition temperature， and bending modulus reached 4，137 MPa， 350 ℃， and 4，467 MPa， respectively.
SUN Jishu, PU Xiatian, YANG Kai, JIN Canzhang
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Using the Box⁃Behnken’s response surface method and taking the dosages of silane⁃coupling⁃agent⁃modified montmorillonite， SBS， and high viscosity agent （HVA） as influence factors for asphalt， a model was established to determine the optimal dosages of three types of raw materials in the asphalt based on the Brinell viscosity at 170 ℃ as an evaluation criterion. The results indicated that the high⁃viscosity⁃modified asphalt containing 5 wt% SBS， 9 wt% HVA， and 8 wt% modified montmorillonite exhibited the best performance， and its penetration， ductility， softening point， and Brinell's viscosity at 170 ℃ were determined to be 4.52 mm， 42.9 cm， 86.1 ℃， and 2.371 Pa·s， respectively. Dynamic shear and Brinell's viscosity tests show that， compared to the pristine asphalt and the high⁃viscosity⁃modified asphalt TPS， the addition of modified montmorillonite greatly improved the high⁃temperature performance and rutting resistance of asphalt， resulting in a significant improvement in the viscosity. The functional groups were analyzed by Fourier⁃transmission infrared spectroscopy. The disappearance of the vibration peaks indicated that the silane coupling agent involved a chemical reaction with montmorillonite in the modification process.
CHEN Chisheng, YANG Shuai, ZHANG Jianjun, GUO Qitai, CAI Yuan, MA Sude
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In this paper， a series of polypropylene （PP）⁃based composites were prepared through melt blending using titanium removal tailings as an inorganic filler and KH⁃570 （γ⁃methylacryloxy propyl trimethoxysilane） as a coupling agent. The properties of the composites were characterized by using universal testing machine， scanning electron microscope， and differential scanning calorimeter （DSC）， and the influencing factors were analyzed. The results indicated that the tensile strength of the composites was inversely proportional to the addition amount of titanium tailings. The tensile strength of the composites was effectively improved by washing titanium tailings. The modified slag has better dispersibility in the matrix， the composite samples prepared by using the modified slag exhibited higher tensile strength than the unmodified sample. Meanwhile， their lipophilicity was enhanced， but their hydrophilicity was deteriorated. After screening and grading， the titanium tailings exhibited a more uniform particle⁃size distribution， and the composites presented higher tensile strength than the unscreened system at titanium tailing loadings of 10 and 30 wt%.
ZHANG Jun, XI Wang, QIAN Lijun, ZHOU Fengshuai, QIU Yong, WANG Jingyu, ZHANG Zhipeng
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A series of flame⁃retardant and heat conductive polycarbonate （PC） composites with boron nitride （BN） and phosphafetriazine compound （TAD） was prepared， and its flame retardancy and thermal conductance were investigated. Combustion experimental results indicated that the incorporation of BN and TAD improved the flame⁃retardant performance of PC effectively. The PC composite containing 20 wt% BN and 3 wt% TAD reached a UL 94 V⁃0 level in the vertical burning test， and its limiting oxygen index was 35.1 vol%. Cone calorimetric experimental results indicated that the BN/TAD flame⁃retardant and thermal conductive system effectively reduced the peak heat release rate， total heat release， effective heat of combustion， and other performance parameters， and it could generate an excellent synergistic char⁃forming effect in the condensed phase， resulting in excellent flame⁃retardant performance for PC. Moreover， the PC/BN/TAD composite system obtained an increased in the thermal conductivity by 320 % compared to pure PC， indicating high thermal conductance along with excellent flame⁃retardant performance of the PC⁃matrix composites.
XU Jinjia, HUANG Teng, BAI Zhicheng, SHEN Jiahao, XIE Qingyi, ZHU Junhui, DAI Jinfeng, LIU Yuanqiang, ZHAN Xianxu
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In this paper， a bio⁃based flame⁃retardant coating with different chitosan⁃sulfonated graphene layers was constructed on the surface of a RPUF by using a water⁃based layer⁃by⁃layer self⁃assembly method （LBL）. The influence of different layers on the flame retardancy and smoke suppression of the RPUF was intensively investigated. The results indicated that the RPUF coated with the flame⁃retardant coating exhibited excellent flame⁃retardant performance， high thermal stability， and good smoke suppression， which were also affecting by the numbers of coating layers. The 5⁃layer⁃self⁃assembly coated RPUF （RPU⁃5BL） reached a UL 94 V⁃0 rating in the vertical burning test along with a limiting oxygen index of 35.1 vol% and a char yield of 34.9 wt% at 800 ℃， which were increased by 78.2 % and 85.6 %， respectively， compared to the untreated RPUF. Moreover， the RPU⁃5BL exhibited a peak heat release rate of 163.9 kW/m2， a total smoke production of 9.1 m2， a maximum smoke density of 22.9 %， and a smoke density grade of 14.9， which decreased by 30.6%， 14.2%， 61.9%， and 120.1%， respectively， compared to the controlled sample.
GUO Jiang, XU Mengyi, LI Hui, HUANG Xiang, LIN Hao, JIANG Shengbao, CHEN Shang, CHEN Cheng
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The surface modification of zirconium oxide （ZrO2） powders was performed through emulsion coating to improve their dispersion in the polypropylene （PP） matrix. The dielectric， thermal， and mechanical properties of the modified ZrO2/PP （PP/g⁃ZrO2） composites were investigated. The results indicated that the dielectric constant of the PP/g⁃ZrO2 composites increased to 4.28， and their dielectric loss increased from 0.007 1 to 0.068 at a frequency of 1 kH at a ZrO2 content of 50 wt%. In addition， the thermal stability of the PP/g⁃ZrO2 composites was significantly improved， and their tensile strength reached 38.33 MPa at a ZrO2 content of 20 wt%. Through analyzing the agglomeration state of ZrO2 in the PP matrix before and after modification， the composites achieved optimal overall performance at a ZrO2 content of 30 wt%.
JIANG Shuaihua, LI Zhuolun, LU Haofan, SUN Yibo, WANG Xiangdong, CHEN Shihong, WU Lili
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Polystyrene （PS）/polyphenyl ether （PPO） blends were prepared by melt blending method. By controlling the processing temperature， PPO exists in the blend in the form of rigid particles， forming a stable “island” structure. By using supercritical carbon dioxide as blowing agent， the PS open cell foam with high porosity was obtained. The effect of PPO contents on the rheological properties and thermodynamic behavior of PS， and the effect of stable “island” structure on the formation of PS/PPO foam were studied. The cell size， foaming rate， opening rate and foam compression properties of PS/PPO foam products were analyzed. The results showed that when the foaming temperature was 158 ℃， the pressure was 20 MPa and the PPO content was 10 %， the PS open⁃cell foam with foaming ratio of 37.5 times and opening ratio of 96.9 % could be prepared.
Processing and Application
WANG Peng, YAO Cheng, LIU Gang, CAI Xipeng, JIA Lei, WANG Kai, CHEN Long
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In this work， simultaneous biaxial drawing and sequential biaxial drawing were chosen as two stretching modes to adjust the thickness， extended chain crystal content， fibrillar morphology， and orientation texture of BOPP films， and the working rules of these structural issues on their electrical insulating properties were investigated. The results indicated that a thick lamellar structure with a good thermal stability and an isotropous fibrillated network facilitated an improvement in the breakdown strength and a reduction in the dielectric loss. These results are advantageous to a good understanding on the processing⁃structure⁃property relation of polymer film dielectric.
ZHAO Chuantao, JIA Zhixin, LIU Lijun, LI Jiqiang, ZHANG Chenchen, RONG Di, GAO Lizhen, YAO Jier
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This article addressed the issue of warping deformation in epoxy resin/carbon fiber sheet⁃molded composite flat panel products.， the flatness of the panel products was measured to characterize the extent of warping deformation by using a three⁃coordinate measurement device. The results indicated that the warping deformation varied from 0.302 to 1.29 mm. Through an orthogonal experimental variance analysis， the significance of various molding process parameters on warping deformation was determined with molding pressure having the most significant impact， followed by demolding speed， holding pressure time， and molding temperature. Furthermore， a Duncan's multiple comparison method was used to assess the differences in the significance levels among these factors， the trends in the influence of each process parameter on warping deformation in the products was further analyzed. The mechanism of influence factors for the warping of the products was analyzed， and these factors include fiber distribution， pore characteristics， upper and lower mold temperatures， and cavity pressure distribution.
PU Qiang, HE Xia, WANG Guorong, HU Gang
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The elasticity and yield parameters of PE were determined through a uniaxial tensile experiment. A pipe⁃soil finite element model under a point load was established to study the point⁃loading mechanical response of buried PE gas pipes， and the effects of point⁃loading dimension， pipe internal pressure， and pipe diameter were analyzed. Based on the DFDI （ductile failure damage indicator） model and combined with the finite element simulation results， quantitative damage calculations were carried out for PE pipes under a point load. The results indicated that the point load increased the pipe damage when compared to the damage results of the pipe without a point load. The pipe damage shows a great change with a variation of the internal pressure of the pipe. There is little effect on the PE pipe damage with a small change in the pipe diameter， and the damage values under each pipe diameter are relatively close to each other.
Additive
LIU Meng'en, TANG Qianyi, ZHANG Mingyao, LIU Baijun
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In this study， a core⁃shell structured ASA grafted copolymer latex with a core⁃shell ratio of 6/4 was prepared through two⁃stage emulsion polymerization， and the effects of the composition and content of aqueous antioxidants on the thermo⁃oxidative aging， mechanical， and apparent performance of the ASA grafted copolymers were systematically investigated. The results indicated that the ASA grafted copolymer exhibited the optimal thermo⁃oxidative aging performance at a waterborne antioxidant CPL/DLTP mass ratio of 2/3. The oxidation induction period of the ASA grafted copolymer increased significantly with an increase in the content of water⁃based antioxidants； however， the growth of the oxidation induction period seemed not to be significant with the addition of more than 1 wt% of water⁃based antioxidants. The oxidation induction period for the ASA grafted copolymer containing 1 wt% water⁃based antioxidant reached 73.1 min at 230 ℃ in air， and its resistance to thermo⁃oxidative aging was better than that without an antioxidant under the same condition. Its thermo⁃oxidative aging ability was more than 80 times that of the ASA grafted copolymer without any aqueous antioxidants under the same condition. There is no obvious effect of the composition and content of waterborne antioxidants on the mechanical properties of the ASA resin but an obvious effect on its apparent properties such as whiteness.
Plastic and Environment
LI Guohua, FANG Xuezhen, SHEN Zhu, ZHANG Xinyu, WANG Jingxian
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The polyurethane coating waste was chemically degraded using mono⁃diethylene glycol （DEG） as an alcohololytic agent to recover low molecular weight polyol， and the recovered polyol was mixed with commercial polyol as a raw material to prepare recycled polyurethane foam. The optimum parameters were determined as follows： reaction reagent ratio of 1∶2， reactiontemperature of 180 ℃， reaction time of 2 h， catalyst addition of 1.3 %， under which the extraction rate of the alcoholysis product was 36.8 %， hydroxyl value of 384.6 mgKOH/g， and viscosity of 476 mPa·s. The results were obtained by Fourier transform infrared spectroscopy， gel permeation chromatography， thermogravimetric analysis， and scanning electron microscopy. The recovered polyol and recycled polyurethane foam were characterized and analyzed by FTIR， GPC， TG and SEM. The results showed that the recovered polyol and polyether polyol were consistent in molecular structure and met the performance requirements for the preparation of polyurethane foam. When the recycled polyol was mixed with the commercial polyol， and the proportion of recycled polyol in the total polyol was 33 %， the prepared polyurethane had good pore structure and thermal stability.
LUO Guanqun, ZHAO Le, PAN Yaqi
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The cap （PE） and body （PET） of the discarded 550 mL mineral water bottle of Nongfu Spring were used as raw materials. The laboratory⁃scale fixed⁃bed reactor and thermogravimetric analyzer were used to conduct pyrolysis experiments to explore the synergistic effects of co⁃pyrolysis of waste PE and PET plastics and the kinetic behaviors in which co⁃pyrolysis process was separated into two degradation stages. The results showed that co⁃pyrolysis of PE and PET plastics promoted the production of liquid pyrolysis oil and improving the selectivity of hydrocarbons in pyrolysis oil. When the mixing ratio of PE and PET was 2∶1， the highest pyrolysis oil yield of 84.72 % was achieved. The increment of pyrolysis temperature promoted the occurrence of secondary reactions like Diels⁃Alder and aromatization reactions， generating more aromatic products. The average apparent activation energies of the two degradation stages of co⁃pyrolysis process were 191.05 kJ/mol and 215.22 kJ/mol. The reaction mechanisms of these two stages were aligned with order⁃based model and contracting volume （R3） model， respectively.
Standard and Test
GUO Zhihao, FENG Tao, LI Ziyi, WANG Jing, WANG Bing, WANG Yihan, CAO Bowei
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Through comparing the measurement methods of humidity for each component of plastic mixtures， a humidity testing scheme of plastic mixtures was designed based on a drying weighing method combined with the test method of GB/T 19277.1—2011. This method does not destroy plastic mixtures to obtain relatively accurate measurement results. The results indicated that the difference between the measured mass humidity of the plastic mixture obtained from the conventional drying weighing method was 3 %~5 %. It is difficult to make rapid changes in the mass humidity when the difference reached around 9 %. There is a three⁃stage humidity change process for plastic mixtures as follows： constant rate， deceleration rate， and residue. The Boltzmann function could fit the trend of constant rate and deceleration rate better in the humidity change stage of plastic mixtures. The on⁃demand water replenishment is more advantageous to the aerobic biodegradation activity， which is in better agreement with the requirements of the national standard for the aerobic biodegradation test of plastics. According to the change curves of moisture mass dissipation of plastic mixtures at three gas⁃flow rates， the calculation method of the change curves of moisture mass dissipation at arbitrary gas flow rates was obtained.
Machinery and Mould
CHEN Hao, YANG Weimin, XUN Shanglun, ZHANG Haitao, JIAO Zhiwei
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A geometric model was first established based on the current twin⁃screw barrel and coil distribution， and then the barrel flux variation and temperature uniformity of the electromagnetic heating process were studied using the COMSOL finite element software. Furthermore， a mathematical model was established according to the theoretical basis of electromagnetic heat and heat conduction. A specific experiment was conducted under the guidance of numerical simulation to verify and compare the temperature uniformity on the internal wall and flange of the twin⁃screw barrel， electricity consumption， and electromagnetic radiation safety under electromagnetic and cast copper heating. The results indicated that the temperature uniformity， electricity consumption， and electromagnetic radiation safety were not affected at the same heating time. In the same period of heating time， electromagnetic heating could realize simultaneous barrel and flange heating， resulting in faster barrel heating to the set temperature and reducing the screw torque and host current. This leads to a 40 % saving in the preheating time as well as a higher temperature control accuracy， ensuring temperature uniformity within ± 1 ℃. This is consistent with the simulation results and improves the extrusion performance of molten raw materials. Compared to cast copper heating， electromagnetic heating has less heat loss and heat stress and a lower surface temperature of equipment. Such a new heating mode improves the workshop environment， gains energy saving more than 50 %， and improves the product quality and production efficiency. In addition， electromagnetic radiation conforms to the national safety standard GB 8702—2014， ensuring the personal safety of workers in workshop.
DAI Rui, PAN Wei, HUANG Shizheng, ZHU Jiawei, ZENG Xiankui, YANG Weimin, JIAN Ranran
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The thermal transport characteristics of the innovatively proposed field⁃coordinated torsion screw at different rotational speeds were simulated and analyzed through numerical simulation using the Polyflow software， and their thermal transport performance was systematically investigated through combining parameters such as temperature distribution， convective heat transfer coefficient， viscosity， pressure， etc. and compared with conventional screws as well. The results indicated that the temperature uniformity of the field⁃coordinated torsion screw with a torsion structure was improved alone with an increase in the convective heat transfer coefficient. The heat transfer effect of the entire system was also strengthened， in which the screw B exhibited the optimal heat transfer performance. Taking EPDM as a raw material， an experimental investigation was performed for the heat transfer performance of the conventional screw and field⁃coordinated torsional screw using a torsional extrusion technology combined with the parameters such as radial temperature difference and heat transfer coefficient of the machine head. The obtained results were consistent with the simulation， proving that the field⁃coordinated torsion screw can strengthen heat transfer and improve plasticization uniformity.
Review
HAO Jinling, CHEN Yajun, QIAN Lijun
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This paper reviewed the research progress in the application of silicone⁃aerogels， organic aerogels， and carbon aerogels in the flame⁃retardant field. The characteristics of aerogels and corresponding flame⁃retardant modification technologies as well as their effects on the flame retardancy of materials were summarized. The advantages， disadvantages， and future development trend of various aerogels are discussed.
