Materials and Properties
DONG Bingting, ZANG Meng, YIN Kai, XIN Chunling, HE Yadong
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728 )
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Hyperbranched polyamide （HyPer） was introduced into thermoplastic polyurethane （TPU）， and the effect of HyPer on the intermolecular hydrogen bond of TPU was investigated by Fourier?transform infrared spectroscopy. The effect of HyPer on the crystallization and rheological properties of TPU were evaluated using rotational rheometer and differential scanning calorimeter. The results indicated that HyPer could form intermolecular hydrogen bonds with carbamates in TPU， resulting in a significantly improvement in the degree of hydrogen bonding of carbonyl peak in TPU. In addition， the addition of HyPer generated a significant plasticizing effect on TPU， reducing its intrinsic viscosity， increa?sing its intermolecular mobility， and improving its crystallization rate and crystallinity. The batch?foaming experimental results demonstrated that the addition of 0.25 wt % HyPer reduced the melt viscoelasticity of TPU. This is beneficial to the cell growth and leads to an increase in foaming ratio by 30 %. The increase of hyper content enhanced the crystallinity of TPU. The existence of microcrystalline not only promoted the cell nucleation but also inhibited the cell growth. This facilitates the increase of cell density and the decrease of cell size.
GU Lin, ZHU Yuting, HE Jialong, ZHU Huihao, MA Yulu, XIE Linsheng
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888 )
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Poly（lactic acid） （PLA）/polycaprolactone （PCL） biodegradable multilayered films were prepared through a micro-nano layer multiplier coextrusion equipment， and their microstructure， mechanical properties and thermal stability were characterized by scanning electron microscopy， tensile and impact measurements， differential scanning calorimetry， and thermogravimetric analysis. The results indicated that the multilayered films exhibited better thermal stability and mechanical properties than the PLA/PCL blend films. PCL showed a significant toughening effect on the multilayered films， improving their crystallinity and thermal stability. When the PLA/PCL ratio was set as 40/60， 50/50 or 60/40， the multilayered films achieved good comprehensive properties with tensile strength of over 51.2 MPa， elongation at break of over 568.6 %， impact strength of over 100.7 J/m， PLA crystallinity of over 43.28 %， and thermal degradation peak temperature of over 373.22 ℃.
YANG Zhitao, FANG Xinglei, LAI Shaochuan, XIONG Daoying, WANG Yao, ZHANG Chen, HE Hezhi, ZHANG He
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687 )
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In light of the microencapsulated epoxy-amine self?healing system with high healing performance， good compati-bility， and relatively good thermal stability， this paper developed a self?healing commercial epoxy resin cured with anhydride at middle and high temperatures ranging from 100 to 170 ℃. The thermal stabilities of the epoxy and amine as healants were extensively evaluated before and after microencapsulating them in the resin matrix. The compatibility of the cured healants with the anhydride?cured epoxy was quantitatively characterized through in?situ injecting the pre-mixed healants into the cracked pure epoxy resin. The self?healing anhydride-cured epoxy using dual?component microcapsule system containing the selected healants was formulated， and the effects of the ratio and concentration of the dual?component microcapsules and the curing procedure of the host matrix on its healing performance was systematically. The results indicated that the selected healants exhibited good thermal stability， especially after microencapsulated and embedded into the host matrix. Owing to the good compatibility between the selected healants and resin matrix as confirmed by the manually injection healing， the self?healing showed good healing performance when epoxy cured with anhydride at middle and high temperatures through the microencapsulated epoxy?amine system. Healing efficiency of over 80 % could be achieved after the parametric optimization.
XU Yunfei, ZHAO Zaisheng, XING Yajing, JIANG Jing
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1323 )
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A series of poly（lactic acid） （PLA）/polyurethane （TPU） blends with different phase morphologies were prepared through melt blending using PLA as a matrix and then foamed through a supercritical carbon dioxide （scCO2） microcellular foaming process. The effects of cell structure， expansion ratio， and open?cell content on the oil absorption performance of the porous composite material at different foaming temperatures were investigated. The results indicated that with an increase in TPU content from 10 wt % to 50 wt %， there was a phase morphology from a typical “sea?island” phase morphology to the partially co?continuous one occurring in the porous composite material. Meanwhile， the viscoelasticity of the PLA matrix increased， but its crystallization ability decreased. The porous composite material containing 70 wt % PLA exhibited a more uniform cell structure. The cell size and expansion ratio increased at first and then tended to decrease with an increase in foaming temperature. The expansion ratio reached 29.1 times at the foaming temperature of 94 ℃ and the maximum open?cell content was 75 %. The addition of TPU significantly increased the elastic recovery ability of the PLA matrix. The porous composite material showed the largest compressive strength and the smallest permanent deformation at a foaming temperature of 94 °C. The oil absorption test results indicated that porous composite material exhibited a greater oil absorption rate for silicone oil than for cyclohexane. Its oil absorption rate was proportional to the product of the expansion ratio and the open?cell content， giving a maximum oil absorption rate of 10.4 g/g for silicone oil.
HE Fenfen, LIN Qingwen, LIU Ling, YUE Hailing
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726 )
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To explore the change of co?pyrolysis characteristics of paint thinner and plastics under different pyrolysis atmosphere. According to the pre?experiment results， the variations of mass loss in TG and enthalpy in DSC during the co?pyrolysis of paint thinner and plastics were measured under different pyrolysis atmosphere （air and nitrogen） at a heating rate of 10 ℃/min using a synchronous thermal analyzer. The thermal dynamics of the samples were analyzed using a Coats?Redfern method. The results indicated that the pyrolysis process of the sample in nitrogen atmosphere showed an obvious lag phenomenon， and its mass loss rate was as low as 82.2 wt %. The air atmosphere was more advantageous to the detection of paint thinner and PET plastic co?pyrolysis reaction intermediate products. The average activation energy of PET plastic and its combustion residues in the air was lower than that in nitrogen. However， the activation energy of the mixture in the air was lower at 400~475 ℃. The mixture reached a secondary combustion condition at 500 ℃.
WEN Zewei, LIU Fuya, CUI Xiaojie, ZHANG Ge, MENG Weihua, XIE Jixing, XU Jianzhong
Abstract (
582 )
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The phosphorylation modification for reed fiber （RF） was conducted through mechanical force chemistry， and the modified reed fiber （PRF） was blended with poly（lactic acid） （PLA） to prepare a series of PLA/PRF composites. The effects of PRF on the thermal stability， flame retardancy， combustion properties， and mechanical properties of the composites were investigated. Infrared spectroscopy and thermogravimetric analysis results indicated that phosphorus was successfully grafted onto RF， resulting in an increase in residual char. The flame?retardant properties of the compo?sites were improved gradually with an increase in PRF content. When 40 wt % of PRF was added， the composite showed flexural strength of 266.9 MPa and tensile strength of 44.7 MPa， and an ultimate oxygen index of 24.6 %. Its maximum heat release peak decreased to 366.9 kW/m2 by 39.3% compared to pure PLA.
BI Weifeng, LIU Jiaoshi, CHEN Shaojun, YUAN Hao, ZHANG Yanxia
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813 )
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The tensile strain and tensile strength of PC/ABS alloy was tested after exposed to alkylbenzene using a universal tensile testing machine. The influence of alkylbenzene on mechanical properties of PC/ABS alloy was investigated. The results indicated that after 30 days of alkylbenzene impregnation at 60 ℃， PC/ABS alloys containing PE?G?MAH， ABS?G?MAH and POE?g?GMA showed a decrease in the rate of tensile strain at fracture by 58.8 %， 25.4 %， and 41.3 %， respectively. Compared to ABS， PC component is a key factor for the decrease of tensile strain at fracture. The effective compatibilizer can prolong the time for the PC/ABS alloy to maintain its mechanical property stability in alkylbenzene solvent. When the flame retardant was dispersed in PC/ABS matrix， a ductile?brittle transformation behavior is more likely to occur due to the osmosis effect of alkylbenzene.
LIU Wei, WU Xian, ZHANG Chun
Abstract (
588 )
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Poly（lactic acid） （PLA）/red mud （RM） composites were prepared by melt?mixing method， and their crystallization， mechanical and foaming behaviors were investigated. The results indicated that RM improved the crystallization of PLA， resulting in an increase in crystallinity from 5.34 wt % to 13.89 wt %. The PLA/RM composites were foamed using a solid?state foaming method with supercritical CO2 as a blowing agent. The foaming behavior showed that the cellular parameters could be controlled by the RM content. With the addition of 5 wt % RM， the cellular density and expansion ratio of the composites decreased down to 1.82×107 cell/cm3 and 2.25 times， respectively. However， the cellular density and expansion ratio increased up to 12.46×107 and 12.40 fold with the addition of MDI. A combination of RM and MDI could improve the foaming behavior and mechanical property of PLA foams.
LI Meilan, HE Jiao, GONG Wei, HE Xiaoni, LAI Qian, LIU Bailing
Abstract (
582 )
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Carboxyl terminated hyperbranched polyester as a phosphorus?free green scale inhibitor was successfully prepared through esterification with itaconic acid， triethanolamine and succinic acid as reaction monomers， and its scale inhibition and dispersion ability under different influence factors was studied by a static scale inhibition experiment. The biodegradability and ecological effects of the scale inhibitor were also determined. The results indicated that the scale inhibitor not only had good dispersibility for Fe2O3 but also had good scale inhibiting effect for CaCO3 and CaSO4 under wide temperature and pH ranges. When the dosage of scale inhibitor was 20 and 12 mg/L， the scale inhibition efficiency for CaCO3 and CaSO4 reached 93.8 % and 96.2 %， respectively. The XRD and SEM analysis showed that the scale inhibitor not only effectively destroyed the regularity of calcium scale crystal but also reduced the crystallinity of calcium scale. This can effectively inhibit the growth of calcium scale， achieving the purpose of scale inhibition and dispersion. In addition， the scale inhibitor had excellent biodegradability with a biodegradation rate of 67.2 % after 28 days. Moreover， the scale inhibitor does not affect the growth of microorganisms of water.
ZENG Zequn, WU Jinyu, XIANG Hui, LIU Weijie, YIN Jun
Abstract (
1444 )
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The effects of density， pore size and thickness of PMI foam on its hygroscopic behavior under different conditions were studied， and the effect of hygroscopicity on its mechanical properties， drying reversibility and adhesive performance were evaluated. The results indicated that an increase in the density of PMI foam led to a decrease in the rate of moisture absorption， whereas the pore size presented an opposite variation trend. The rise of thickness reduced not only the rate of moisture absorption but also the saturated moisture absorptivity. The PMI foam exhibits a decrease in rigidity and an increase in toughness after moisture absorption， which caused defects more easily during adhesion. In the short period of time for high humidity or immersion， the PMI foam shows reversible performance. After a long period of treatment， the performance of PMI foam decreased irreversibly.
Processing and Application
ZHANG Liyan, GAO Lijie, MA Haopeng, MA Jubiao, YANG Weimin, JIAO Zhiwei, YU Yuan
Abstract (
709 )
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Based on the principle of non-solvent induced phase separation， a self-made controllable humidity and gas-assisted 3D printer was used to conduct the 3D printing of high-temperature-resistant special engineering plastics with a high precision and a low cost at ordinary temperatures. Taking polyetherimide as a special engineering plastic example， the effects of extrusion pressure， nozzle diameter， printing speed， relative humidity of printing environment， and printing layer on the forming quality were investigated. The results indicated that the width of extruded wire was related to the printing speed and relative humidity of the printing environment， and it decreased with an increase in printing speed and relative humidity. The printing layer height was related to the wire height of extrusion slurry. When the printing layer height was about equal to the wire height of extrusion slurry， the forming quality was optimal. The optimal printing parameters were obtained from a multilayer deposition experiment， achieving the green body with a good surface quality and a precision.
YUAN Zhihuan, KUANG Tangqing, LAI Jiamei, LIU Hesheng, XU Pan
Abstract (
623 )
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Based on the custom-designed experimental platform of water-assisted co?injection molding， a series of injection-molded pipes were obtained from an orthogonal experiment. The influence of processing parameters on the wall thickness， tensile properties and crystallization of each layer of the pipes were investigate. The results indicated that the outer wall thickness of the pipes decreased with an increase in the outer melt temperature， water injection pressure， inner melt injection pressure， and mold temperature but increased with an increases in melt injection delay time and water injection delay time. Their inner wall thickness increased with an increase in water injection delay time and inner melt injection pressure but decreased with an increase in water injection pressure and mold temperature. The pipes also presented a decrease in tensile strength of decreases with an increase in outer melt temperature， and however， their tensile strength increased with an increase in melt injection delay time and water injection delay time. The processing parameters generated direct influences on the residual wall thickness and the cooling process of the pipes， affecting the crystallinity of each phase and pipe performance accordingly.
SUN Jin, ZHE Dongmei, HU Yanlei, CHENG Debao, XU Haiyun
Abstract (
1004 )
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This paper summarized and compared test principles， data requirements and extrapolation calculation of two test methods， ISO 9080 and ASTM D 2837， for PE-HD pipes. The calculation process of maximum operating pressure of PE-HD pipes under these two standard systems was further analyzed， which can provide a theoretical reference of design for pipeline in different applicable areas.
LI Maodong, LI Yan, YANG Bo, WANG Zhigang, LUO Wenbo
Abstract (
584 )
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Polyethylene （PE） has been widely used in pressure pipeline engineering due to its excellent corrosion resistance. Long-term service behavior of a pipe is predominated by the creep property of its raw material. It is of great significance to study the creep behavior of PE at room temperature for the safety and integrity evaluation of PE pressure pipelines. In this paper， the room temperature creep tests of PE100 grade gas pipe material were conducted under various stresses ranging from 2.4 MPa to 9.6 MPa. The results indicated that there was a stress independency of creep comp?liance of the material when the stress does not exceed 5.4 MPa， indicating linear viscoelastic behavior. However， a stress dependency occurred and showed nonlinear viscoelastic creep when the applied stress was higher than 5.4 MPa. Based on the single integral nonlinear viscoelastic constitutive theory， the Findley model was used to analyze the creep behavior of PE100 grade gas pipe material by comparison with the Struik empirical model. It was found that both the Findley model and the Struik model well described the creep behavior of the pipe material， but the Findley model was more accurate than the Struik one for modeling the nonlinear creep behavior under high stresses.
ZHANG Yi, QIAO Liang, FAN Junming, WEN Jiongming, SUN Lei, CAO Yuguang, LYU Shiwei
Abstract (
601 )
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A systematic experimental study was conducted to investigate the effects of squeeze?off parameters， including squeezing speed， release speed， squeezing ratio， environment temperature， and pipe diameter on the mechanical response of PE pipes. The results indicated that the load in PE pipes increased with an increase in squeezing speed， squee?zing ratio， pipe diameter but a decrease in environment temperature. In addition， the residual deformation of PE pipes increased with an increase in unloading speed. Furthermore， the load decay during the stress relation stage increased with an increase in squeezing speed but a decrease in squeezing ratio， pipe diameter， and environmental temperature.
Additive
ZHANG Dingran, LU Lingang
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671 )
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The pyrolysis characteristics of calixarene and 4?tert?butylcalixarene were investigated by thermogravimetric analysis under a nitrogen atmosphere. Their activation energy and optimal mechanism function equation of the reaction process were studied using a thermal decomposition kinetic analysis method. The results indicated that 4?tert?butylcali?xarene exhibited the same initial thermal decomposition temperature as calixarene due to the instability of tert butyl groups. Hydrocarbons presented a decomposition temperature of about 160 ℃ earlier than calixarene. Their subsequent decomposition process was almost the same with calixarene （namely the bridged methylene cleavage occurs and the thermal cracking of the parent benzene ring）. The residual char of 4?tert?butylcalixarene was slightly higher than calixarene by 10 %. The pyrolysis kinetic analysis demonstrated that the calixarene exhibited activation energy of 387.87 and 376.28 kJ/mol according to the Kissinger and Flynn?wall?Ozawa methods， respectively. According to the Coats?Redfern method， the pyrolysis mecha?nism function of calixarene was determined to be g（α）=［-ln（1-α）］2/5， and the reaction order n was 2/5. Based on this result， the non?isothermal pyrolysis mechanism was determined as a random nucleation and subsequent growth reaction. The pyrolysis mechanism function of 4?tert?butylcalixarene was deterined to be g（α）=［-ln（1-α）］1/2， and the reaction order n was 1/2， assigned to the non?isothermal pyrolysis mechanism as a result of the random nucleation and subsequent growth reaction.
TANG Qiaolin, ZHAO Yu, ZHANG Kaixin, YU Yanli, LI Nianling, ZHANG Yuheng, HU Jialing, ZHONG Liu, CHEN Mingjun, LIU Zhiguo
Abstract (
674 )
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Highly efficient flame-retarded epoxy resin （EPM） was prepared by using a self?made flame retardant bis｛4-［4-（4-aminobenzyl）phenylamino］ ［（6-oxydibenzo［c，e］［1，2］oxophenanthrene?6?yl） methyl］ phenyl｝ phenyl phosphonate （DOP?DDM） compounding with metal oxide. The flame retardant performance of the resultant EPM was evaluated using limiting oxygen index （LOI）， vertical combustion （UL 94） and cone calorimetric combustion test， and its thermal performance was investigated through thermogravimetry and dynamic thermal mechanical analyses. The flame retardant mechanism was analyzed by combining thermogravimetry analysis with infrared spectroscopy， scanning electron microscopy and Raman spectroscopy. The results indicated that the introduction of DOP?DDM reduced the initial degradation temperature of the EPM without any effect on glass transition temperature and increased the residual char yield， storage modulus， loss modulus， and flame retardant properties. When 4.7 wt % of DOP-DDM was incorporated， the resultant EPM achieved a phosphorus content of only 0.37 wt % but a high LOI of 33.5 % with a UL 94 classification of V?0. Its peak heat release rate， total heat release and total smoke release decreased by 23.2 %， 17.8 % and 12.4 %，respectively.When 3.7 wt % DOP-DDM was combined with 1.0 wt % Al2O3， the EPM exhibited a reduction not only in peak heat release rate and total smoke emission but also in CO and CO2 toxic gases by 7.7 % and 17.2 %， respectively.
Standard and Test
HU Huilian, SHI Jialiang, LANG Lei, SHI Chaoou, YAO Jianlei
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2284 )
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Pyrolysis gas chromatography-mass spectrometry （Py-GC/MS） was conducted to identify polyamide 56， polyamide 66， polyamide 6 and their blends. The 100 % relative abundances of polyamide 56 and polyamide 66 were cyclopentanone at a pyrolysis temperature of 550 ℃， which were differentiated with the characteristic pyrolytic products of 1，8?diazabicyclotridecane-2，7-dione and 1，8?diazabicyclotetradecane-2， 7-dione. Meanwhile， polyamide 6 obtained 100 % relative strength of caprolactam. This made it possible to quickly identify industrial primary products of polyamide 56， polyamide 66 and polyamide 6. With this method， polyamide 6/56 blends， modified polyamide 6/66 blends and modified polyamide 66 can be detected successfully.
Machinery and Mould
ZHANG Junwei, DONG Liqun, MA Yun, ZHANG Jun, XUE Ping
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652 )
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Taking the extrusion section， transition body， and extruder head of a conical twin?screw extruder as an research object， the non?isothermal steady?state and transient finite element simulation of Polyflow was conducted to analyze the distributions and change curves of each field in the flow field， their safe mixing issues of energetic materials in the flow channel were studied. Considering both safety performance and mixing effect， a comprehensive evaluation method was established， and the radial clearance was optimized. The results indicated that the maximum shear rate， highest shear stress， and highest viscous heat dissipation of the channel all took place near the entrance of the extruding segment. The highest pressure and temperature were located at the exits of the extruding section flow channel and extruder head， respectively. The mixing effect of the conical twin screw increased with an increase in radial clearance. When the radial gap was 0.5mm， the safety performance of flow channel was the worst. However， the screw exhibited the best safety performance at a radial gap of 1 mm.
ZHOU Jianan
Abstract (
843 )
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The technical requirements and structure characters of the face cover of a type of driving recorder were introduced， and a type of injection mould with two cavities and three different core?pulling mechanisms was designed for the face cover. The first mechanism is a tunnel mode core?pulling mechanism with a pushing block fixed on the top plate. The second mechanism is a titling angular core?pulling mechanism. In the middle of this mechanism， a double T?blocks core?pulling mechanism as the third mechanism is fixed， and the other two mechanisms are linked with it. The fourth mechanism is a common lifter. The computing formulas of core?pulling distance for the titling angular core?pulling mechanism and the double T?blocks core?pulling mechanism were given. The runner system for the mould is open hot nozzles turning to round runners and then to fan?shaped gates. Ejection pins and sleeves were used for the ejector system of the mould.
Review
SONG Renda, WU Gaojian, CHEN Junxiang, ZHU Jinbai, ZHANG Youchen, YANG Weimin, XIE Pengcheng
Abstract (
2811 )
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This paper introduced the principle of electromagnetic shielding and the character of conductive polymer composites and discussed their physical features such as flexibility， hardness and coating in different applications. Moreover， the recent development in the types of conductive fillers， including metal， carbon-based， metal carbide， and nitride MXene， and the processing method for electromagnetic shielding materials were summarized and analyzed. Finally， their development direction in future was prospected.
FENG Chuang, ZHAO Guanghui
Abstract (
875 )
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This paper reviewed the latest research progress in the mechanical properties of adhesive joints in composites over the past decades. The qualitative influence trend and quantitative influence degree of various factors on the mechanical properties of the joint were summarized on the basis the aspects of the lapped structure， adhesives， adherend， environmental conditions and the joint defects. This paper provides a basis for design of the connection between the composite components.
DENG Yafeng, ZHOU Hongfu, LI Quanlai, LI Jian
Abstract (
2071 )
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To solve the problems of high cost and low energy conversion efficiency of dielectroelastic actuator， the basic principle of dielectroelastic power generation and the research progress in its stretching mode were briefly introduced. The research progress in different configurations based on dielectroelastic actuator at home and abroad was also reviewed. The characteristics and application occasions of different types of actuators were analyzed， and their performance characteristics， mechanical properties and application modes were discused. Their processing technology and potential applications were introduced. Finally， the problems in the field of dielectroelastic actuators were described， and some suggestions on the solutions of these problems were proposed.
