Materials and Properties
SONG Kunpeng, WANG Yinjie, FANG Zhuqing, LIU Jiping, RUAN Fang
Abstract (
1135 )
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794
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In this study， a new type of ZIF-67/polyphosphazene composite microspheres （ZIF-67@PZS） was designed and prepared by an insitu self-assembly method using poly（cyclotriphosphazene-co-4，4'-dihydroxydiphenylsulfone） microspheres （PZS） as a growth substrate for the ZIF-67 crystals. The optimum structural morphology of ZIF-67@PZS was determined by adjusting the mass ratio of raw materials. Scanning electron microscopy （SEM） characterizations indicated that the prepared ZIF-67@PZS presented a higher quality under a cobalt nitrate hexahydrate/2-methylimidazole/triethylamine molar ratio of 1/4/4 and a PZS/cobalt nitrate hexahydrate mass ratio of 5/1. The thermogravimetric analysis results showed that the initial decomposition temperature of ZIF?67@PZS increased by 119 and 20 °C and its residual char yield at 800 °C increased by 25.4 % and 4.7 % compared to pure ZIF-67 and PZS， respectively， indicating an excellent thermal stability. According to the SEM observation under the gradient time， the possible formation mechanism of ZIF-67@PZS was further deduced.
ZHAN Jin, MA Jingjing, GAO Dali, LI Haoyi, YANG Weimin
Abstract (
1021 )
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810
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15 )
The plasticization and crystallization behaviors of three types of melt blown PP plastics and four types of PP melt blown fibers for mask filter layer were investigated by DSC and hot stage polarizing microscopy. In the DSC thermograms， the sample 3# showed a single melting peak， whereas the sample 1#， sample 2#， sample 4#， sample 6# and sample 7# revealed a bimodal melting behavior. Moreover， the sample 5# showed three peaks in its DSC thermogram. Compared to the PP melt blown plastic samples， the crystal plasticization of the PP melt blown fabric samples for mask filter layer started at a lower initial temperature with a wider temperature range for completing the plasticizing process. The presence of such a temperature range also shifted to a lower temperature zone. The initial crystallization temperature of the PP melt blown plastic samples was higher than that of the PP melt blown fabric ones. These results are consistent with their crystal plasticization temperatures and plasticization completion temperatures. This may due to the fact that the PP melt blown fabric samples for the mask filter layer have higher number average molecular weights， resulting in higher crystallization and plasticization temperatures. The crystallization temperature range of the PP melt blown plastic samples is narrower than that of the PP melt blown cloth ones for the mask filter layer， indicating different evolution mechanisms in their crystalline morphology.
WANG Fan, MA Zongli, DU Bin, LI Wen, WANG Duopeng, CHEN Shangtao, WANG Yanfang
Abstract (
935 )
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1621
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The rheological properties of three types of polyethylene resins with different molecular chain structures were investigated by using a rotary rheometer （sentmanat extensional rheometer） and a melt tensile rheometer. These rheological properties include melt transient tensile viscosity， melt tensile strength and tensile viscosity. The results indicated that the growth of the transient tensile viscosity of PE-HD-100N melt tended to slow down gradually with an increase in the Hencky deformation. There was an obvious transient tensile hardening phenomenon appearing in PE-LD-2420F， and the tensile viscosity of its melt increased sharply. The tensile viscosity of the melt of PE-LLD-7050 was low， and it began to decrease after the rapid formation of the platform. The test result of melt tensile indicated that the melt strength and tensile viscosity of PE-HD-100N were higher than those of PE-LD-2420F and PE-LLD-7050. PE-LLD-7050 presented the lowest melt strength and tensile viscosity.
YI Xin, ZHANG Yong, WU Changbo, ZHOU Hualong, XU Hongji, DING Chao
Abstract (
938 )
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645
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22 )
The warpage of brominated flame-retardant PA66 composites was investigated in terms of the compositions without glass fiber and with the circular and flat glass fibers. The warpage of the composites was analyzed on the basis of their mechanical properties， crystallization properties， shrinkage rate and transverse/longitudinal shrinkage ratio. The results indicated that the composites without glass fiber had the highest crystallinity， transverse shrinkage and longitudinal shrinkage， but the lowest transverse/longitudinal shrinkage ratio and warpage. At the same content of glass fibers， the warpage of the composites with the flat glass fiber was obviously better than that of the composite with the circular glass fiber due to a lower ratio of transverse/longitudinal shrinkage. In the case of mechanical properties， the tensile strength and bending strength of the composites with flat glass fibers were lower than that of the composites with the circular glass fiber. The different types of glass fibers had little effect on the crystallization of the composites， and their crystallinity and crystallization peak temperature were very close to each other. At the same content of flame retardant， both the transverse shrinkage and the longitudinal shrinkage of the composites decreased with an increase in the content of the flat glass fiber. However， their transverse/longitudinal shrinkage ratio increased， leading to an increase in the warpage of the composites.
ZHU Mingxin, LIU Zhiying
Abstract (
683 )
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658
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5 )
An oil absorption resin was synthesized through initiation with a gamma ray using 2-ethylhexyl acrylate as a monomer， divinylbenzene （DVB） as a chemical crosslinker， and cyclohexane as a solvent， and its thermal stability and typical functional groups were analyzed by thermogravimetric analysis and Fourier-infrared spectroscopy. Furthermore， its absorbency performance for some typical organic chemicals such as aliphatic hydrocarbons， aromatic hydrocarbons， ketones， acetates， ethers， halogenated hydrocarbons and fuel oils were investigated through adsorption experiments. The results indicated that the molecular weight and polarity of organic chemicals were important factors for the absorbency performance of this resin. The oil absorption resin presented favorable absorbency to most of the organic chemicals with an absorption rat of 10~30 g/g， and it possessed an amazing absorption rate of 50.48 g/g to chloroform.
CHEN Yirong, LAI Jindi, MO Yihua, DENG Jingyi, XU Ziwei, ZHANG Jingjing
Abstract (
882 )
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501
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7 )
In this work， the morphology， and electrical and thermal conductivities of polypropylene （PP）/polyamide 6 （PA6）/styrene?ethylene?butylene?styrene copolymer （SEBS）/graphene nanoplatelets （GNPs） nanocomposites were investigated in terms of different blending sequences. The selective distribution and migration of GNPs in the matrix and their effects on the properties of nanocomposites were analyzed. The results indicated that in PP/PA6/SEBS/GNPs blending system， GNPs were more easily distributed in the PA6 phrase during the melt mixing process regulated by thermodynamic factors. When GNPs were added into PP at first and then blended with PA6， GNPs migrated from the PP phrase to the interface of co?continuous PP/PA6 blending domain. This facilitated the construction of thermal conductive paths at the blend interface， resulting in an enhancement in thermal conductivity of the nanocomposites. As a result， the nanocomposites achieved a thermal conductivity of 0.83 W/（m·K） with the addition of 7 wt % GNPs. Moreover， the addition of SEBS improved the interfacial compatibility between the PP and PA6 phrases and therefore eliminated the surface gaps between the two phrases.
ZHANG Liang, CHAI Weisheng, WANG Shanshan, LI Wenzhu, WU Qiang, ZHANG Wenbiao, DAI Chunping
Abstract (
1056 )
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845
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8 )
The poly（vinyl chloride） （PVC） /bamboo charcoal （BC） composites with different veneers were prepared by melt mixing， hot pressing and surface veneering， and their combustion behavior and smoke generation characteristics were characterized by cone calorimetry， thermogravimetry and thermogravimetry infrared analysis. Their combustion safety was also evaluated comprehensively. The results indicated that the PVC veneer could improve the thermal stability of the composites. The yield of carbon residue was 67.99 wt % at 600 °C with lower amounts of HCl and aromatics formed in the early stage of combustion， which was disadvantageous to the control of total heat release. After the wood veneer was added， the initial thermal degradation started in advance， and the thermal degradation rate increased， resulting in a maximum peak heat release rate of 423.91 kW/m2， a maximum total heat release of 76.63 MJ/m2 and a maximum total smoke release of 2 121.51 m2/m2. In this case， the yield of carbon residue was only 41.78 % at 600 °C with more harmful gas released. In addition， the veneer was easy to make smoke release during a longer period， which was advantageous for smoke suppression in the early stage of combustion. This provides more opportunities for safe evacuation in the early stage of a conflagration. Therefore， the composites developed by this work exhibit some application prospects for home decoration.
KANG Wei, LIU Xijun, CAO Weiyan, WANG Yuwei, YAN Jie
Abstract (
837 )
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606
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In this work， the surface of reduced graphene oxide （RGO） was modified with diethylaminoethyl methacrylate （DEAM） and then dispersed in an MMA monomer. The PMMA/DEAM-RGO nanocomposites were prepared by emulsion polymerization， and their structure and properties were investigated using Fourier-transform infrared spectrometer， Raman spectrometer， scanning electron microscope， transmission electron microscope， X-ray diffractometer， differential scanning calorimeter and thermogravimetric analyzer. The results indicated that RGO was completely covered by PMMA with the aid of DEAM and thus achieved a uniform dispersion in the PMMA matrix. The experiments also confirmed that there was a strong interaction between the DEAM amine groups and surface the functional groups on the RGO surface. The modified RGO could act as a physical cross-linking point in the PMMA matrix. This led to an increase in the toughness and strength of PMMA/RGO nanocomposites with an increase in the amount of modified RGO. Moreover， the thermal stability and antistatic properties of the nanocomposites were also improved.
ZHOU Hongtao, QIAN Kun, DONG Shuo
Abstract (
811 )
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607
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11 )
This paper reported an investigation on the tearing performance of triaxial woven fabric and its reinforced rubber composites. The study was aimed at two cases， including the pre-incision along the yarn direction and the pre-incision along any two groups of yarn angle bisectors. A comparative investigation was also carried out with the plain weave fabric reinforced rubber composites. The variation laws in the tearing load and tearing damage characteristics of the specimens were analyzed. The results indicated that the tearing process of the triaxial woven fabric and its reinforced rubber composites could be divided into three stages： the initial stage， the pre?notch opening stage and rip expansion stage， which were related to low modulus area， high modulus area and shock area， respectively. When the pre-cut was parallel to the yarn， the triaxial woven fabric and its reinforced rubber composite exhibited a higher tear load and tear initiation position. Compared to plain weave fabrics， the triaxial woven fabric and its reinforced rubber composites showed a much smaller difference in the tear load along the two pre?cuts.
Processing and Application
WANG Yanqing, KUANG Tangqing, LAI Jiamei, FENG Qiang, LIU Wenwen
Abstract (
532 )
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716
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An experimental study was carried out to investigate the effect of the projectile on the wall thickness of pipe fitting in the water-projectile-assisted injection molding（W-PAIM）. Through constructing an experimental platform， the effect of the four factors including the projectile material， head shape， straight length and cross-sectional size on the residual wall thickness of the W-PAIM polypropylene （PP） pipe fittings were studied. A comparative experiment showed that the residual wall thickness of the pipe fitting formed by the PA6 projectile was more uniform than those of the PA6， ABS and PTFE projectiles， indicating the optimum quality. Among the heads with the hemispherical， parabolic， arc and conical shapes， the parabolic head achieved the optimum quality fittings. For the projectile with a length of 7 mm in straight section and a section size of 13 mm， the obtained residual wall thickness was the most uniform and the quality of the molded pipe fitting was the best.
XU Bin, DENG Lingping, YANG Hongtao, LUO Taojia, FENG Xueliang, HU Li
Abstract (
655 )
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634
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4 )
The right-angle corners and spherical corners were arranged in the grading part of the flow channel to improve the filling imbalance of microinjection-molded parts. An eight?cavity injection mold with micro-cylinder holes at diameters of 200 and 300 μm was designed. The injection-molding experiment was carried out with high?density polyethylene （PE-HD） as a raw material. The results indicated that as the injection rate and mold temperature increased gradually， the spherical corners became better than the right?angle ones for improving filling imbalance. With an increase in the feature size of the micro?cylindrical hole， the improvement of the filling imbalance could be further enhanced by the right?angle corners and the spherical corners.
NI Jia, DUAN Kaige, ZHU Hui, HU Mingyuan, CHENG Zhi, YU Dongming
Abstract (
908 )
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970
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10 )
In this work， we adopted a manometric method to test the oxygen gas transmission of plastics pipe. The test principle was introduced， and the oxygen permeability of the representative plastic tube， oxygen barrier tube， and new alloy oxygen barrier tube developed by our laboratory were measured. The influence of pipe structure on the test results was discussed. The obtained data were found to have a good regularity， high repeatability， and a short test period as short as only 2 days. This result is helpful to quickly and qualitatively judge the quality of the oxygen resistance of plastic pipes.
QIU Weilun, ZHOU Yanwu, SHI Mengliang
Abstract (
694 )
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438
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4 )
The method based on micro-laser Raman spectroscopy and multivariate modeling was proposed to realize the fast， non-destructive and accurate classification of vehicle bumpers in the forensic science. The automatic baseline correction， peak area normalization， and Savitzky-Golay smoothing （3rd degree polynomial， 7-point smoothing） were selected for pre-processing. A classification model was constructed through principal component analysis and linear discriminant analysis. The results indicated that the overall classification accuracy rate was 95.24 % as an ideal result. For the unknown sample in the actual case， this method was used to determine the brand as Buick， which was consistent with the real result. A micro-laser Raman spectroscopic analysis technology and multivariate modeling methods can realize the classification of different brands of vehicle bumpers exactly. This can provide a certain reference for the relevant research in the trace evidence identification.
Additive
TAN Yulin, WANG Cuicui, LI Mingpeng, WANG Ge, CHENG Haitao
Abstract (
1037 )
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1143
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9 )
To understand the effect of antioxidant 1010 （KY1010） on the properties of poly（lactic acid）（PLA） wire materials for 3D printing， a modified wire material for 3D printing was prepared by melt blending extrusion， and then a composite material was prepared by FDM process using this modified wire material. The effect of antioxidant addition on the oxidation induction period， tensile properties， dynamic thermal mechanical properties and mechanical properties of PLA wire material was investigated. The results indicated that KY1010 effectively improved the oxidation resistance of PLA. The tensile strength and storage modulus of PLA increased at first and then tended to decrease with an increase in the concentration of KY1010. However， its elongation at break decreased gradually， and the oxidation induction time and oxidation induction temperature increased gradually with an increase in the concentration of KY1010. On the other hand， the tensile strength and elastic modulus of the composites increased at first and then decreased with the concentration of KY1010， but the impact strength and notch impact strength increased gradually. The PLA wire material achieved the optimum comprehensive performance with the addition of 0.5 wt % KY1010. In this case， the oxidation induction time and oxidation induction temperature of the PLA wire material increased by 1 655.19 % and 16.91 %， respectively. Its tensile strength increased by 15.35 %， but its elongation at break decreased by 29.43 %. Moreover， its storage modulus reached a maximum value. The composite material achieved an increase in tensile strength by 26.04 % and in elastic modulus by 33.23 %. A comparative experiment indicated that TGA was more suitable to measure the oxidation induction period of PLA than DSC.
Standard and Test
FU Junze, ZHANG Jianan, JIANG Hong
Abstract (
667 )
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735
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5 )
Plastic beverage bottles are a type of common material evidence at the scene of the crime. Fourier-transform infrared spectroscopy （FTIR） was used to detect 41 different brands of plastic beverage bottles. After pretreatment， the samples were divided into polyethylene terephthalate and polyethylene. The infrared characteristic peaks of each sample in each category were different. For the largest number of samples， the spectral data dimension was reduced， and the principal components were extracted by the principal component analysis. The samples were further grouped by a K-means clustering method. Finally， the clustering results were used as dependent variables to construct a neural network algorithm to train the data to predict the classification of samples. With the help of random number generator， 86.5 % of the samples were selected as the training set and 13.5 % of the samples were selected as the test set. The results indicated that the accuracy of the training set and test set reached 100 %. Meanwhile， the accuracy of the K-means clustering results was verified， and a fast classification model for plastic beverage bottles was established. This classification model has good operability with accurate and reliable results. This work provides a reference for the police grassroots to handle cases.
Machinery and Mould
ZHANG Weihe, FENG Jing, YAN Lijing, LIU Fangfang, DENG Chenglin
Abstract (
807 )
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978
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12 )
In this work， we designed a large?scale injection mold with hot runners for the car bremsleuchte cover according to its structural characteristics and technical requirements. The problem in the large angle inclined roof lateral core?pulling process was successfully solved by using a new type of diagonal push rod with a cross assist bar. The accuracy and appearance of plastic parts were improved by using a hot runner and an arc latent gate. The safety and reliability of ejection balance of plastic parts and mold reset were ensured by taking the way of cylinder ejection and reset. The molding cycle was shortened to 35 s， and the production efficiency of the mold was increased by about 8% after adopting a mesh pattern 3D cooling system.
LIU Hongyan
Abstract (
822 )
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598
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11 )
In order to address a difficulty in the mold design of cylindrical plastic parts， a simplified injection mold with one mold， one cavity and two plates mold was designed to realize its automatic injection molding. In this mold， the horizontal layout was used to simplify the mold cavity parting， thus simplifying the overall structure of the mold. A hot runner pouring system was used to ensure the molding quality of the cavity. Three types of four mechanisms were used to demould the inner and outer walls of the plastic part. In these mechanisms， one was the single core-pulling mechanism of oil cylinder slider， one was the three core-pulling mechanisms of oil cylinder plus inclined guide pillar， and the other was the two-sided core pulling mechanism of a Half slider. A simple oil cylinder slider mechanism and a compound inner wall three times core?pulling mechanism were used to demould the inner wall of the plastic part. In the compound mechanism， the slider to pull the core of the inner wall was driven by the inclined guide column at first， and then the inner wall core drove three retracted inclined top core-pulling mechanisms to pull the core and demould the inner wall turndown table. Finally， the oil cylinder drove the slider and the molding part to pull the core completely from the plastic part. The wall tube was moved out to realize the complete demoulding of the plastic part. For the demoulding of the outer wall of the plastic part， a group of second core-pulling Haff slider mechanisms were used to demould the core. Through the optimizing the selection of the layout together with the innovative design of the mechanism， the overall structure of the mold is simplified， and its manufacturing cost is reduced.
Review
XU Weikun, WANG Huili, DONG Yizheng, YUAN Huiqiang, FAN Ping
Abstract (
1181 )
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832
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18 )
This paper reviewed the research progress in the modification of epoxy resin with hyperbranched polyesters （HBPEs）. The synthetic methods of hydroxyl-terminated/carboxyl-terminated/epoxy-terminated/amino-terminated HBPEs were summarized at first. The research progress in the impact modification of epoxy resins by the HBPEs with different end groups and their toughening mechanism was introduced. The influence of the HBPEs with different end groups on the curing properties of epoxy resin was also discussed. In addition， the problems in the modification of epoxy resins with HBPEs were analyzed. The research directions in future will focus on the green synthetic methods of HBPEs with a low cost as well as the multifunctionalization of HBPEs.
PENG Hui, ZHAO Wei, CHANG Weiwei, WANG Yiliang
Abstract (
1974 )
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1573
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57 )
In this paper， the recent research process in the laser?induced graphene （LIG） was reviewed and its applications were introduced. The influences of material type， atmosphere control， laser power， scanning speed， scanning times， and other parameters on the preparation of LIG were summarized. The applications of LIG in micro-supercapacitors， flexible sensors， catalyst， and environmental treatment were reviewed. In addition， the research directions in future were briefly discussed.
TANG Wei, QIAN Lijun, QIU Yong, CHEN Yajun, XU Bo, ZHAO Zhen
Abstract (
1222 )
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4753
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47 )
This paper reviewed the recent research progress in the halogen-free flame-retardant technology for polypropylene （PP） and also analyzed the flame-retardant mechanism. The halogen-free flame retardants used for PP mainly included magnesium-aluminum flame retardants， phosphorus flame retardants， and intumescent flame retardants. In the research of halogen-free flame-retardant technology for PP， the development of charring agent and the research of compounding scheme were most popular. In this case， the charring agent for PP was introduced in detail.
