Materials and Properties
HUANG Guotao, GUI Yuan, LI Yucai, WU Xin, FENG Xinxing, DENG Jianping, WANG Cao, PAN Kai
Abstract (
1139 )
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In this paper， ethylene?vinyl?acetate copolymer （EVA）/nylon elastomer compounds were prepared through melt extrusion using the most popular commercial product of PEBAXnylon 12. The resultant compounds were foamed to prepare a new type of EVA/nylon 12 microporous foaming materials. The experimental results indicated that the EVA/nylon 12 compounds were foamed successfully through a chemical method， and their foaming materials achieved an improvement in performance in comparison with the traditional EVA ones. The EVA/nylon 12 foaming materials obtained an optimal performance at a nylon 12 content of 5 wt% and a foaming agent content of 1 wt%. This type of nylon elastomer?based foaming materials has superiority in cost and performance， therefore it has a good prospect for the replacement of traditional EVA foamed materials used in shoes.
LU Weixin, LU Chong, WANG Bin, HU Jing, WU Jingjing, ZHOU Qinpeng
Abstract (
913 )
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This work reported an investigation on the effect of different type of epoxy modifiers on the tensile properties， rheological properties， and crystallization properties of PA6/EVOH blends. The reaction mechanism of glycidyl methacrylate （GMA） with blends was also and explored. The blends were characterized with torque test， Fourier?transform infrared spectroscopy （FTIR）， hydrogen nuclear magnetic resonance （NMR）， tensile tests， rotational rheological test and differential scanning calorimetry. The results indicated that the blends showed an increase in blending torque， tensile strength， complex viscosity and storage modulus with an increase in the epoxy value of modifiers increases. Their crystallinity and crystallization temperature was found to present a decrease with the epoxy value， whereas the elongation at break tended to increase at first and then decreased. With polyepoxy groups in the molecules， most of epoxy modifiers can react with amine， carboxyl or hydroxyl groups for chain extension to improve the properties of the blends. Taking into account the fluidity issue in the processing procedure， the GMA?modified blend has the optimal properties with the tensile strength increased by 8.5 % and elongation at break increased by 26.6 %. FTIR and 1H?NMR characterization results indicated that GMA underwent self?polymerization at high temperatures to form polyepoxy oligomers. These oligomers can react with PA6 and EVOH to improve the properties of their blends.
SUN Zhengmeng, ZHANG Mingxu, ZHANG Xinning, LIANG Ce, ZHANG Hailiang, LI Yunhui, MA Yuqin
Abstract (
884 )
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Epoxy?based composites were prepared through compression molding using bisphenol?A?type epoxy resin as a matrix and chopped glass fiber and nano glass powders as fillers. TG and SEM were used to investigate the effect of the loading of nano glass powders on the thermal stability of this type of resin matrix composites. Kissinger method and Flynn?Wall?Ozawa method were adopted to investigate their thermal decomposition kinetics. The results indicated that the maximum thermal decomposition temperature of the epoxy resin increased from 365 °C to 369 °C with the addition of chopped glass fiber， and it was further increased by 5~16 °C with the addition of nano glass powders. The composites presented a residual char yield ranging from 65.41 % to 69.15 %， which were increased by 69.88 %~71.51 % and 22.95 %~27.11 % in comparison with pure bisphenol A epoxy resin and chopped?glass?fiber?reinforced epoxy composites， respectively. Meanwhile， the composites achieved an improvement in thermal decomposition activation energy up to 153.14 kJ/mol due to the introduction of nano glass powders. Such a value is significantly higher than the thermal decomposition activation energy of 135.65 kJ/mol and 137.46 kJ/mol for pure bisphenol?A epoxy resin and chopped?glass?fiber?reinforced epoxy composites， respectively. These results indicated that the addition of nano glass powders could change the internal microstructure of the epoxy composites then improved their thermal stability.
FANG Mei, TAN Kunlun, TAN Yuan, XU Jingwei, HUANG Ming, ZHANG Na
Abstract (
1193 )
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The development of high?performance fiber?reinforced composite materials to replace traditional metal materials is considered as one of the most effective ways to realize the lightweight of automobiles. However， the application safety of automobile has risen an emerging for the high?temperature resistance of composite materials. This work focuses on the influence of high temperature treatment on the mechanical properties of composite materials. Epoxy resin （EP）/carbon fiber （CF） and EP/CF/glass mat （GF） composites were prepared through vacuum assisted resin transfer molding （VARTM）.The relationship between the square of resin flow distance and the flow time in the two fiber layup modes was explored， and the permeability of the two fiber layup systems was investigated comparatively. Two types of composites were treated at high temperatures and their mechanical properties before and after the high temperature treatment were analyzed. The tensile fracture morphology of the composites was observed by scanning electron microscopy. The results indicated that the loose structure of GF felt in the EP/CF/GF composites made the resin flow more easily. The Young's modulus and tensile strain of EP/CF composites decreased by 9.97 % and 11.36 %， respectively. However， the effect of heat treatment on the EP/CF/GF composites was insignificant. The addition of GF felt resulted in a decrease in the flexure properties of the two composites. The fracture surface of the composites without heat treatment was smooth. However， after heat treatment， the fracture surface became rough with significant deformation of the matrix.
ZHANG Dingran, LU Lingang
Abstract (
828 )
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The thermal stability of calixarene and p?tert?butylcalixarene was studied by thermogravimetric analysis （TG） under a nitrogen atmosphere， and their apparent activation energy were calculated using the Kissinger’s and Flynn?wall?Ozawa’s methods. The thermal decomposition kinetic mechanisms and models were determined from the Coats?Redfern method. The apparent activation energy of calixarene was determined to be 166.64 kJ/mol and 175.79 kJ/mol through the Kissinger’s and Flynn?wall?Ozawa’s methods， respectively. The apparent activation energy of 4?tert?butylcalixarene were calculated to be 153.97 kJ/mol and 166.81 kJ/mol through the Kissinger’s and Flynn?wall?Ozawa’s methods， respectively. The results indicated that the thermal properties of two compounds were relatively stable in nitrogen， and their decomposition temperatures had a strong adaptability to polymer materials. The thermal decomposition mechanism function and reaction order of calixarene were determined to be g（α）=［-ln（1-α）］3/2 and n =3/2， respectively. Its non?isothermal thermal decomposition mechanism belongs to the random nucleation and subsequent growth reaction. The thermal decomposition mechanism function and reaction order of 4?tert?butylcalixarene were determined to be g（α）=［-ln（1-α）］2/3 and n=2/3， respectively. Its non?isothermal thermal decomposition mechanism belongs to the random nucleation and subsequent growth reaction. The thermal decomposition mechanism function and reaction order of 4?tert?butylcalixarene for the thermal decomposition process of benzene ring were determined to be g（α）=α2 and n=2， respectively. Its non?isothermal thermal decomposition mechanism belongs to the one?dimensional diffusion reaction.
LIU Lei, YANG Jianjun, WU Qingyun, WU Mingyuan, ZHANG Jianan, LIU Jiuyi
Abstract (
1006 )
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Polyester-type double bond-terminated polyurethane prepolymer （HPU） was synthesized by using a high adhesive and high heat-resistant diol （XC-488）， toluene diisocyanate （TDI） and hydroxyethyl methacrylate （HEMA） as raw materials. The bulk molding plastics （BMC） were prepared through blending HPU with unsaturated polyester resin， short cut glass fiber， calcium carbonate， flame retardant at different loadings. Fourier-transform infrared spectroscopy， differential scanning calorimeter， mechanical property test， water absorption test， melt fluidity test， acid-base resistance test， aging test and scanning electron microscope were used to characterize the structures and properties of the resultant BMC. The results indicated that the composite achieved the optimal comprehensive mechanical properties at an HPU content of 6 wt%. They also achieved tensile strength of （47.24±0.42） MPa， bending strength of （117.76±0.65） MPa and impact strength of （33.8 ± 0.2） kJ/m2.
LEI Zhenkai, ZHANG Xi, GONG Jie, Kamran·POLAT
Abstract (
653 )
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The oxidation induction time （OIT） has been included in the new national standard for the drip tapes with labyrinth on one side. This brings new requirements for resistance to thermal and oxygen aging of the products. Based on the formulation of drip tapes， this article discusses the material?efficiency relationship between the raw materials for products and their OIT. The weight fraction of anti?aging master batch has the greatest impact on the OIT of drip tapes. The OIT of drip tapes can be improved through increasing their ratios. The addition amount of PE?HD can generate a much greater influence on the OIT than those of PE?LLD and PE?LD. The OIT of drip tapes can be improved by increasing the weight fraction PE?HD in the raw materials. Moreover， the reduction of the weight fraction of PE?LLD and PE?LD can lead to an increase in the weight fraction of PE?HD. The weight fraction of PE?LD had the least impact on the OIT. A reasonable weight fraction of PE?HD， PE?LLD， and PE?LD should be adopted through formula design to meet the requirements for good processing and other performance of drip tape. The weight fraction of stabilizer in the anti?aging master batch should not be reduced in spite of its cost. The OIT of drip tapes increases with an increase in the weight fraction of stabilizer. Through the characterizations of melt flow rate （MFR）， carbon black content and OIT of drip belt， it was concluded that there was no obvious relationship between the MFR， the content of carbon black and OIT of drip tapes.
JIA Xianfei, ZHANG Kun, MI Qinghua, ZHU Xingkui, XU Jing
Abstract (
824 )
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Polyethylene （PE）/hydrotalcites （LDH） composite films were prepared through extrusion blow molding using three types of LDH， including the domestic products A and B， and imported product C. The effects of three types of LDH on the structure， heat preservation， mechanical properties， light transmittance， hydrophobicity， moisture retention and thermal properties of the composite films were investigated comparatively. When 8 % LDH were incorporated， the infrared absorbance integral area of the composite films increases by 183 % for the product A， 177 % for the product B and 77.1 % for the product C compared to pristine PE film. Mechanical analysis indicated that the composite films containing the domestic LDH achieved much better tensile strength and elongation at break and tended to be isotropic. All of the composite films presented the light transmittance higher than 89 %， and the haze of the composite films containing the imported LDH was smallest. Furthermore， there are no significant difference between the hydrophobicity and thermal properties of three types of composite films. Performance investigation indicated that the advantages of the imported LDH did not have outstanding comprehensive performance compared to the domestic ones. However， the domestic LDH are more cost?effective.
PENG Fanchang, CHEN Xiaosui, ZHANG Aiqing, ZHOU Hongfu
Abstract (
600 )
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Three types of hyperbranched polyphosphoramide coated carbon nanotubes （CNTs/HBPPA） with different coating thicknesses were prepared through one-step polymerization （A2+B3） using carboxylic CNTs （CNT-COOH） as a core material， phosphorus oxychloride （POCl3） and N， N?diaminodiphenylmethane （DDM） as monomers， and triethylamine as an acid binding and catalytic agent. A series of epoxy （EP） composites with different contents of CNT/HBPPA were then fabricated， and the reinforcing and flame?retarding effects were investigated. It was found that with increasing the mass ratio of CNT to （POCl3+DDM） （1∶1.5~6）， the there is an increase in the coating thickness of CNT/HBPPA but an reduction in T5% （the characteristic temperature at 95 wt.% mass loss） and residual char yield. The CNT/HBPPA cross-linked together when the mass ratio increased to 1：6. Among those composite samples， the CNT/HBPPA-3 exhibited optimum reinforcing and flame-retarding effects on the EP composites. The experimental results indicated that the EP composites containing 2 wt% CNT/HBPPA achieved the largest LOI of 28.2 %， highest tensile of 53.28 MPa， and highest impact strength of 11.19 kJ/m2 as well as a UL 94 V-1 classification. There are a great number of active groups of -NH2 dispersed on surface of CNT/HBPPA， leading to better interfacial compatibility with the EP matrix. Therefore， the additives could be distributed more homogeneously and act as the net-shaped skeleton in the EP composites to achieve better flame retardancy and mechanical properties. During the combustion process， the skeleton of CNT/HBPPA potentially cross-linked together to construct a more compact and continuous char layer， which could protect the underlying materials against the heat and combustible volatiles transmission efficiently.
Processing and Application
WANG Zhigang, YANG Bo, LI Zhi, PENG Guoping, JIANG Zaijia, LI Guanbao
Abstract (
890 )
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An ultrasonic phased array detection technology was proposed to measure the edge width （l） of Heat Affected Zone（HAZ） of polyethylene pipe elector?fusion joints under different welding time （t）. The percentage of brittle peel， composition of functional groups and crystallinity （Xc） were measured by extrusion peel， FTIR and DSC， and then the relationship between （l） and welding performance （Hc） was established to realize the non?destructive testing of the elector?fusion joint. The results indicated that the HAZ was moved to the outer wall in an exponential growth trend with an increase in welding time. The welding performance of the joint was improved first and then tended to decrease. When t=50 s， l=2.21 mm， Xc=53.03 %， thewelding performance reached a maximum value of 96.21 %. When t<40 s， l and Xc were slightly lower， and there were cold welding defects on the joint. In contrast， when t>70 s， there were dislocation and fusion on the metal wire in the melting zone of the joint appears. The over?welding defects also took place on the joints due to a high?temperature oxidation reaction. Both of two defects led to a decrease in the joint welding performance.
WANG Ruohan, BI Chao, LI Ao
Abstract (
679 )
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Based on a response surface method， the influence of fused deposition modeling （FDM） technical parameters on the forming accuracy of preparing acetaminophen （APAP） tablets was explored， and the optimal experiment plan was obtained and verified. The results indicated that the factors affecting the horizontal and vertical dimensional errors of the APAP tablets prepared by FDM technology showed primary and secondary orders as follows： nozzle temperature > platform temperature > printing speed and nozzle temperature > printing speed > platform temperature， respectively. The interaction between the nozzle and platform temperatures had a significant effect on the forming accuracy of APAP tablets. The relative error of the optimized test plan was small and the result was reliable.
SI Xiaochuang, YUAN Duanpeng, LI Kai, HAO Liucheng, CHEN Rui, ZHANG Nana
Abstract (
873 )
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PA66/short glass fiber （SGF） composites with different content of SGF were prepared and their physical properties， mechanical properties and insulation properties were investigated and compared with those of the thermosetting epoxy?based insulating materials. The results indicated that the density of PA66/SGF composites increased with an increase in the SGF content， but it is still lower than the standard of thermosetting epoxy?based insulator material. The composites presented an increase in bending strength， tensile strength and impact strength of when the content of SGF is more than 20 %. The comprehensive mechanical performance of the composite can reach the standard of thermosetting epoxy?based insulator material. Moreover， the dielectric strength and arc resistance time of the composites were improved to be better than the standard of thermosetting epoxy?based insulator material. In conclusion， it is feasible to employ the PA66/GF composites as an insulation material for use in HV switchgear. However， an engineering application research is still necessary for the practical application of the PA66/GF composites.
LUO Fei, LI Cuijuan, LIU Zhuojia, LIU Yuxin, SHI Suyu, DANG Xudan, LIU Chuntai, ZHAO Yongtao
Abstract (
839 )
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Bisphenol?A polycarbonate （PC） plates were prepared through precision injection molding. Based on the relationship between residual flow?induced stresses and molecular orientation， an optical birefringence method was used to investigate the average molecular orientation of the PC plates， and their dynamic mechanical properties were also studied. The experimental results indicated that the plate samples near the gate had a larger molecular orientation than those far from the gate. There is a certain relationship between the orientation and dynamic viscoelasticity. When the loss modulus （tan δ） was selected to be 1， the larger the birefringence， the smaller the dynamic viscosity. This means that the samples with large orientation have small viscosity. When the storage modulus at the end of the glassy platform was selected， the elasticity of the PC plates increased with an increase in orientation， although the dependency was not obvious due to the interference from free volume.
LI Shuai, LONG Chunguang, MIN Jianxin, ZHOU Zhuo
Abstract (
821 )
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The ring?shape and disk-shape samples of modified polyethylene terephthalate （PET） wear-resistant composites were prepared through extrusion granulation and injection molding. The difference between their limit pressure-velocity（PV）values and tribological properties were investigated using the MPV-3 horizontal （ring） and MW?1A vertical pin?disk wear testing machine. The results indicated that when two types of samples reached an ultimate load， the ultimate pressure measured by the horizontal test method was less than that by the vertical test method with minimum values of 0.37 and 2.10 MPa， respectively. With increasing the rotating speed， the ultimate pressure of the former decreased much significantly. The limiting PV value of the former was less than that of the latter， and the fluctuation of its limiting PV value was smaller. The wear mechanism of the former belongs to the adhesive wear， whereas the latter has a large amount of wear debris spilling. The friction coefficient of the former is greater than that of the latter with the maximum values of 0.305 and 0.28， respectively. However， the wear of the former is smaller than that of the latter with the minimum values of 2 mg and 3 mg， respectively. The experimental results obtained from MPV-3 horizontal wear test system and MWW-1A vertical wear test system on the modified PET are different to some degree. However， the friction coefficient trends obtained from these two systems are the same. Under certain conditions， the vertical pin?disk test can replace the horizontal wear test to provide a basis for the rapid selection of sliding bearing materials.
Additive
MENG Xin, FAN Min, TONG Chuangchuang, LI Chao, GAO Jin, XIN Zhong
Abstract (
611 )
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A nucleation system based on the zeolite-loading organic phosphate （MBP） was fabricated through a solution immersion method， the influence of this nucleation system on the crystalline and mechanical properties of isotactic polypropylene （iPP） was investigated. The effect of different types of zeolites on the dispersion of MBP was characterized using scanning electron microscope （SEM） to investigate the reason why the zeolites can improve the nucleation of MBP in iPP. The results indicated that the MBPs loaded with B-zeolite-1 and B?zeolite-2 had little effect on the performance enhancement of iPP. However， both of them improved the properties of iPP significantly. The nucleated iPP achieved an increase in crystallization temperature by 10 and 6.0 °C for he MBPs loaded with B-zeolite-1 and B-zeolite-2， respectively. The stiffness and toughness increased synchronously. The flexural modulus resulting from the MBPs loaded with B?zeolite-1 and B-zeolite-2 increased by 29.9 % and 13.0 %， respectively. The impact strength from the MBPs loaded with B?zeolite-1 and B?zeolite-2 increased by 8 % and 7 %， respectively. SEM observation indicated that the A?zeolite-1 was well dispersed in the MBP， generating a good nucleation effect on the crystallization of iPP. B-zeolite-1 showed serious self-agglomeration and could not be dispersed in the MBP. Therefore， it cannot act as a nucleation agent to promote the nucleation of MBP.
LIANG Mengke, QIU Jie, ZHU Yongchen, TIAN Huafeng, WU Zhipeng, LUO Zhenyang
Abstract (
656 )
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With the second largest reserve in nature， lignin was used as a supporting matrix for intumescent flame retardant. A lignin-based intumescent flame retardant named as Lig-T was successfully synthesized through introducing nitrogenous and phosphorus elements. In this flame retardant， the carbon source， acid source and gas source were integrated to achieve good flame retardancy. Epoxy resin （EP）/Lig-T composites were prepared at different mass fractions， and their thermal stability and flame retardancy were investigated through cone calorimetry， focusing on the heat release and smoke release law to simulate the condition of real fire accident. The results indicated that when the mass fraction of Lig-T was 20 %， the composites obtained a peak heat release rate of 1 960 kW/m2， a total heat release of 60.80 MJ/m2， and a total smoke release of 1 634 m2/m2. All of these data exhibited a downward trend compared to the values of pure epoxy resin. In addition， the residual char yield at the end of combustion was increased from 4.26 to 10.01 wt%. Based on the synergistic flame retardant mechanism of gas phase and condensed phase， lignin can act as a carbon source of intumescent flame retardants to endow the composites with a better carbon-forming effect at high temperature， resulting in the formation of a stable and dense carbon layer structure during the combustion process. This work demonstrated that lignin can reduce the release of toxic gas as well as achieve a high?efficient flame-retardant effect， thus reducing the risk of fire.
Standard and Test
JIN Fujing, HAO Yunan, JIAO Hongwen, ZHAO Hongyu
Abstract (
2227 )
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Rigid extruded polystyrene foam boards are superior to other building insulation materials in many properties. They have excellent thermal insulation performance and a high ratio of performance to price. With an improvement in the fire protection standard for buildings， there a lot of new materials developed and emerged， resulting in a heavy competition of market. The market share of rigid extruded polystyrene foam boards has been occupied and reduced greatly. In order to maintain a market share and cope with the impact of new materials and the improvement of fire protection standard， graphite?modified extruded polystyrene foam boards have been developed by various research institutions and enterprises. Based on the development of JC/T 2627? 2021 “Graphite modified extruded polystyrene （GXPS） foam board for thermal insulation of building”， this paper introduced the main requirements for performance and application directions of GXPS boards and pointed out the product problems. This paper is expected to provide references for the subsequent research as well as the development of relevant standards.
GUO Qi, JIANG Hong, WU Kenan, YANG Jinjie, DUAN Bin, LIU Feng
Abstract (
712 )
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Raman difference spectroscopy is one of the most commonly used testing methods. In this paper， a computer classification and recognition technology were applied for the test of a common disposable plastic cup cover at the scene of the case to obtain the differential Raman spectra of the specimens. According to the obtained spectrum， the specimens can be divided into three categories： PP， PS and pet. The peak positions of functional groups were analyzed and compared. The best clustering number was then determined to be 5 by using the calinski harabash evaluation index， followed by carrying out the K?means clustering. 40 specimens were randomly selected to establish a support vector machine discriminant model. The directional gradient histogram and gray level co?occurrence matrix were extracted and combined into a vector as a row of the feature matrix. The remaining 8 specimens were used as the test set to verify the results. The results indicated that the recognition accuracy reached 100 %. This efficient identification method has the advantages of low inspection cost and fast analysis speed， and it can play a technical reference role for the actual process of handling cases form the public security organs.
Plastic and Environment
LIU Pingping, LU Huan, ZHU Lifang, DING Yongzhi
Abstract (
593 )
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Coating agent is an important part of skin material，which directly affects the mechanical properties of skin materials. In order to understand a change rule in the properties of coating agent in skin materials under the natural environment. Taking the URETEK?5972 material as research object，this material was exposed to the natural environment for 0 to 4 years. The characteristic functional groups and mechanical properties of the URETEK?5972 were characterized using Gas permeameter and infrared spectrometer and mechanical testing machine. The influence of exposure time under the natural environment on the performance of functional layer was analyzed， and the change rule of coating agent was explored. The results indicated that the proportion of free carbonyl group in the coating agent decreased with an increase in natural environment exposure time. The intermolecular force between the coating agent and functional layers decreased， leading to a reduction in the connection fastness between the functional layers.
Machinery and Mould
QIAO Linjun, XIN Chunling, HE Yadong, ZHAI Yujiao, YAN Baorui
Abstract (
684 )
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The gas injector is an important device in the micro?foam injection molding process. This article investigated the gas injection process of a new type of gas injector. The gas injection process was analyzed using a high?speed camera and the pressure curve collected by a computer data acquisition system. The results indicated that the gas entered the visualization device from the gas injector in a dispersed state. This was advantageous to the dispersion and mixing of gas and melt during the micro?foaming process. The gas injection flow rate was calculated by using the pressure data and combined with a high?speed camera image analysis. It was found that the gas injection pressure difference and initial water pressure had a great influence on the gas injection flow rate. Through investigating the gas injection process and the amount of gas injection， the gas injection process of this new type of micro?foaming gas injector was found to be stable and controllable， and it could be used for the micro?foaming injection molding experiments.
Review
WEI Zongchen, XI Yuewei, WENG Yunxuan
Abstract (
1189 )
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This paper reviewed the recent research progress in the poly（lactic acid）?based composite materials used for bone tissue engineering and summarized their compositions， preparation and synthesis technologies， processing methods， and mechanical and biological properties. The relationship between the composition， structure and performance of the composite materials was clarified. The development trend of the composite materials was prospected.
SUN Guohua, ZHANG Xin, WU Dezhen, HOU Lianlong
Abstract (
2248 )
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This paper reviewed the research progress in the high?performance polyimide composites at home and abroad and briefly summarized the development of the polyimide matrix composites based on the bismaleimide resin， PMR polyimide resin， and acetenyl terminated polyimide resins as well as the polyimide-fiber-reinforced composites. In addition， the relationship between the structure and performance and the optimization of material performance were introduced， and the development direction of polyimide composites was proposed.
ZHANG Zhouya, BAI Shijian, ZHANG Yuxia, ZHOU Hongfu, GONG Fangfang, TANG Xueguli, WANG Bin
Abstract (
1273 )
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The paper reviewed the research progress in factors affecting the thermal conductivity of polymeric materials. The paper also emphatically discussed the influences of their structural characteristics including chain structure， molecular interaction， orientation， and crystallinty， the thermal conductivity fillers including type， content， morphology and size， and the preparation technology on the thermal conductivity of polymeric materials.
