Materials and Properties
LI Niexin, LI Minggang, TANG Tao, WANG Yi, XING Haiping
Abstract (
1008 )
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In this paper, the propylene?based elastomer/ethylene?vinyl acetate copolymer (PBE/EVA) blends with different phase structures are prepared by melt blending and then foamed under CO2 batch foaming. The effect of PBE/EVA phase structure on the foam cell structure was investigated by differential scanning calorimetry, dynamic mechanical analysis and scanning electron microscopy. When the phase structure of blends presented the “see?island” phase, a conventional honeycomb?foamed structure was obtained. An open?cell network structures was achieved when the blends possessed a bicontinuous phase structure. The formation of such a special cell structure is ascribed to the difference in viscosity between the two components in the bicontinuous phase structure. This study helps to strengthen the understanding of the relationship between polymer phase structure and foaming behavior and therefore provides an important reference for preparation of polymer foams with specific open cells.
YANG Lu, CHEN Hanting
Abstract (
691 )
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It is very difficult to obtain a driving force
from purely hydrophilic random copolymers self-assembly
in water, and therefore the research
on self-assembly is more complex
due to random segment distribution and purely hydrophilicity. The molecular
structure of poly(NVF-co-AA)
was specially designed, and the controllable self-assembly
could be obtained via a variation of pH responsiveness. The results indicated
that the spherical self-assembly
aggregates could be formed at pH 9.0~7.4. When pH value decreased to 5.0,
these spherical self-assembly aggregates
disintegrated into some small aggregates. The morphology of self-assembly
aggregates was still stable with the temperature rising up to 38 ℃. The
embedding and controlled release of alpha-arbutin
were realized by using this controllable self-assembly
structure. The results indicated that more than 90 % of alpha-arbutin
could be entrapped stably at pH 9.0~7.4 and 20~38 ℃,
and the cumulative release rate of alpha-arbutin
was over 95 % within 100 min under a skin environment of pH 5.0 and 38 ℃.
YANG Kang, ZENG Huayu, ZHONG Anlan, YUAN Huilin, ZENG Shu, MA Yulong
Abstract (
1163 )
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A vinly chloride-butyl acrylate-methly methacrylate copolymer elastomer (VCE) was used to modify PVC resin for improvement of impact resistance, and a comparative investigation was also carried out for the modification effect on PVC with MBS, ACR and CPE. The rheological, mechanical and thermal deformation properties of the modified PVC resins were investigated, and their cross-sectional morphologies were observed. In the view of the comparative results, the modified PVC resins presented a decrease in tensile strength and bending strength but an increase in impact strength and elongation at break increased. Moreover, their thermal deformation temperature decreased with an increase of VCE content. VCE was found to have better modification effect than ACR and CPE but a similar effect with MBS. VCE shows a significant toughening effect on PVC, and therefore it can be taken as a promising impact modifier for PVC.
DING Yongyue, WU Zhifeng, WANG Zhiwei
Abstract (
887 )
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671
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In this paper, we simulated the influence of different cooling methods on the performance of injection-molded fittings based on high-density polyethylene. We found that in the actual production process, water-dipping cooling resulted in a too fast cooling rate for the fittings and thus greatly shortened the period of the fittings staying at a maximum growth rate. This led to the formation of more microcrystals inside the fittings, which depressed the growth of larger crystals. As a result, an obviously loosen structure was generated inside the fittings with non-uniform crystals and large internal stress, thus resulting in poor performance. However, the natural cooling could avoid these defects and therefore led to better properties including oxidation induction time, density value, crystallinity, and tensile yield stress for the fittings in comparison with water cooling.
LI Chengcheng, XU Jie, ZHAO Wenjian, HUANG Cong, ZHONG Jinfu
Abstract (
840 )
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661
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A series of heat conductive and insulating foams were prepared by melt blending using low?density polyethylene (PE-LD), maleic anhydride-grafted polyethylene (PE-g-MAH) and boron nitride (h-BN) as raw materials. The effects of PE-g-MAH and h-BN on the thermal conductivity, insulation, mechanical properties and thermal stability of PE-LD/PE-g-MAH/h-BN foams were investigated. The result indicated that the foams achieved an improvement in elongation at break and tensile strength, and their thermal conductivity was also enhanced significantly due to the strong interaction between PE-LD and h-BN bridged by PE-g-MAH. The foams gained a thermal conductivity of 0.256 W/（m·K） at the h-BN content of 30 wt%, and their thermal conductivity increased by 118 % and 657 % compared to PE-LD/h-BN foam and pure PE-LD foam, respectively. Moreover, the PE-LD/PE-g-MAH /h-BN foams obtained good insulation and thermal stability.
TIAN Yincai, DONG Anwang
Abstract (
1782 )
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As a biodegradable thermoplastic, PBAT has some application limitations due to its high price. In this study, the low?cost corn starch was used as a filler to modify PBAT. The corn starch was first plasticized with glycerol and then extruded with a twin-screw extruder to obtain the thermoplastic corn (TPS) granules. PBAT/TPS composites were prepared at different ratios by melt blending, and the effect of TPS content on their structure and mechanical property was investigated. The results indicated that there were a large number of hydroxyl groups formed in the starch after plasticized with glycerol. PBAT exhibited the same crystalline structure with PBT. In the PBAT/TPS composites, the PBAT domain showed a gradual decrease in the level of crystallization perfection with an increase of TPS content, and meanwhile its crystallization temperature shifted to a high temperature. As the TPS content increased, the tensile strength and elongation at break of the composites decreased gradually but their elastic modulus tended to increase
E?mail：slbj.yzsh@sinopec.com http://xdsl.cbpt.cnki.net
LI Meilan, HE Zichun, MU Kaifei, GONG Wei, LAI Qian, YANG Meng, LIU Bailing
Abstract (
1010 )
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646
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A carboxyl-terminated hyperbranched green scale inhibitor based on the xylitol core was successfully prepared by melt polymerization, and its chemical structure was characterized by FTIR and 1H-NMR. The effects of scale inhibitor dosage, pH of water environment and water temperature on calcium carbonate and calcium sulfate inhibition were investigated by means of a static scale inhibition method. The results indicated that the green scale inhibitor exhibited excellent inhibition efficiency on calcium scale (CaCO3 and CaSO4) under a wide range of temperature and a water environment of pH 6~9. The scale inhibition efficiency of calcium carbonate reached 91.6 % at the scale inhibitor dosage of 24 mg/L, while the scale inhibition efficiency of calcium sulfate reached 94.7 % at the dosage of 15 mg/L. Moreover, the SEM observation showed that this green scale inhibitor could greatly reduce the regularity of calcium scale crystal. As for calcium carbonate scale, the green scale inhibitor could promote its lattice distortion of calcium carbonate scale to achieve the purpose of dispersion scale inhibitor.
Materials and Properties
HONG Xiansheng, QIU Hongfeng, HUANG Mian, ZHENG Yuying
Abstract (
775 )
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643
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The organic modified rectorite (OREC) was prepared with dodecyl trimethyl ammonium bromide, and then the EVA/OREC composite foaming materials were prepared by a melting intercalation technology. The morphology and mechanical properties of the composites were investigated by FTIR spectroscopy, X-Ray diffraction, scanning electron microscopy and universal testing machine. The effects of interlayer spacing and content of rectorite on the mechanical properties of the composite were investigated. The results indicated that the interlayer spacing of rectorite increased by 10.9 % after organic modification, and the tensile strength, elongation at break, tear strength of the composite foaming materials were enhanced significantly. The composite foaming materials achieved the optimum mechanical properties at the OREC content of 1.8 %.
Processing and Application
WANG Zhigang, YANG Bo, WANG Jingran, XU Qingyong, SHEN Yang
Abstract (
823 )
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553
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The strain-hardening test was adopted to evaluate the slow crack growth (SCG) resistance of polyethylene (PE) pipe butt-fusion welded joint under different welding processes. The variation rule for the SCG resistance of PE pipe butt?fusion welded joint was analyzed under different welding process parameters by establishing a welding temperature gradient between 190 and 250 °C, a welding stress gradient between 0.6 and 1.4 MPa, and an endothermic time gradient between 40 and 140 s. The effects of cold-welding and over-welding defects on the SCG resistance of PE pipe joint were investigated. The results indicated that the welding temperature, welding pressure and the endothermic time were all the important process parameters that influenced the SCG resistance of the PE pipe butt-fusion welded joints, and the optimum welding parameters could be determined as 220 °C, 1 MPa and 100 s for the PE 100 pipe (dn110, SDR11). The selection of lower or higher welding parameters could result in the formation of cold-welding or over-welding defects in the pipe joint, thus reducing the SCG resistance.
YE Zhiyin
Abstract (
1284 )
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1421
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In this paper, a self-designed one?mold four-cavity injection standard mold was employed to fabricate the high-density polyethylene (PE-HD) samples through injection molding with different sprue sizes. By changing the injection molding process parameters such as melt temperature, mold temperature, and injection pressure, the mechanical properties of injection-molded samples including tensile, impact, and bending behaviors were investigated. These samples exhibited a significant improvement in mechanical properties when using the sprue with modified cross?sectional dimensions, and their tensile strength, impact strength, bending strength and bending modulus increased by about 3.40 %, 79.86 %, 18.11 % and 113.36 % in maximum, respectively. The relationship between the injection process parameters and properties was also established. After modification for sprue, the injection-molded sample could be fully filled, and there was no defect like collapse observed. The mold designed by this work has a reasonable overall structural layout after the modification of sprue. This design can provide a useful reference for mold design of test samples with a similar standard.
YIN Hongmei, LIU Yongli, WANG Jianan, MEI Ye
Abstract (
935 )
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A PC/ABS alloy?based air bag cover plate with a weakening groove of ‘H’ type was selected as a research object, and its finite element model was constructed. The reliability of finite element model was verified by comparing the results of finite element mechanical simulation analysis with theoretical calculation. Through the integration of CATIA and ANSYS in ISIGHT software, four parameters including the lateral width and depth, and longitudinal width and depth of the weakening groove of the air bag cover were selected as the design variables, and the lateral maximum stress and longitudinal maximum stress of the weakening groove were selected as the response variables. The contribution distribution of design variables to the response variables was analyzed, and the multi?objective optimization of the response variables was carried out by the NSGA genetic algorithm. The results indicated that the lateral depth and longitudinal width had a negative contribution to the lateral maximum stress, but the lateral width and longitudinal depth had a positive contribution. On the other hand, the lateral width and longitudinal depth had a negative contribution to the longitudinal maximum stress, but the lateral depth and longitudinal width had a positive contribution. The multi?objective optimization of four parameter values were realized within the reasonable range, which could reduce the lateral maximum stress but increase the longitudinal maximum stress. This effectively reduces the amount of debris produced when the airbag cover plate explodes, thus improving the safety performance.
Additive
Fang GUO, Zhun XU, Jingyu WANG, Han ZHAO, Bo XU
Abstract (
801 )
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478
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A linear phosphorus?rich flame retardant (LPRFR) was synthesized by interfacial polymerization, and its chemical structure was characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy. Flame retardant polyurethane foams (RPUF) were prepared by compounding with LPRFR and expandable graphite (EG). The RPUF achieved a limiting oxygen index of 26.1 vol% when 10 wt% of LPRFR and 8 wt% of EG were added. The cone calorimeter test results indicated that the addition of LPRFR and EG could significantly reduce the heat release of RPUF and improve the carbonization ability of the matrix. In addition, the microstructure and chemical structure of carbon residue were analyzed by scanning electron microscopy and infrared spectroscopy. The results demonstrated that LPRFR involved in the carbonation reaction during the combustion process, leading to the formation of a high?quality carbon layer with P—O—C and P=O structures, which effectively isolated oxygen and heat. Therefore, LPRFR can be taken as a new flame retardant of polyurethane foams with excellent flame retardant properties.
Standard and Test
WU Jingwen
Abstract (
628 )
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1114
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12 )
To gain a rapid, accuracy and economic test result, an inductively coupled plasma atomic emission spectrometry (ICP-OES) method was adopted to detect the contents of metal elements and metal ions in plastic infusion containers. The test samples were treated according to the method of National standards for package of medicine (2015). The solution containing the test sample was directly analyzed by the ICP-OES, and the methodological investigation was carried out. The optimum detection scheme was selected by comparing with the standard atomic absorption method. Based on the analysis of test results, the spectral lines of lead, cadmium, copper, aluminum, barium, tin and chromium were determined as 220.353, 214.438, 324.754, 167.079, 445.403,189.989 and 283.563 nm, respectively. The detection limits were 2.09, 0.05, 0.67, 0.60, 0.32, 0.88 and 0.90 ng/mL, respectively. The precisions at 20 ng/mL were determined as 2.53 %, 0.12 %, 0.96 %, 0.42 %, 0.33 %, 1.22 % and 1.55 %, respectively. The recovery rates of metal elements and ions were determined as 80.71%~113.95 % and 72.30 %~129.36 %, respectively. The ICP?OES method can be used to determine the contents of metal elements and ions in plastic infusion containers quickly and accurately.
ZHANG Jingshun, JIANG Hong, MAN Ji
Abstract (
513 )
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423
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Sole materials can provide trace evidence in forensic science. In this paper, we examined 30 sole samples by using a hand?held X-ray fluorescence spectrometer (XRF) to obtain information about the content of elements in the inorganic fillers of soles. The samples were classified into five categories by the Biplot, which showed the differences in the inorganic filler content of each sample. The feature information of each sample in the variable was explored. The hierarchical cluster was used to verify the classification results. The results indicated that this method had an ideal effectiveness for the classification of XRF data. XRF and Biplot can be used to examine and classify sole materials from the perspective of inorganic fillers. The Biplot method has a great potential application for analysis of XRF experimental data.
Machinery and Mould
XU Xinhua
Abstract (
933 )
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743
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A type of rotary bi-color hot runner mould was designed for production of the bi-color plastic parts of knob cover. In this mould, a four-plate with 3-time opening bi-color moldbase was adopted. The bi-color mould was composed of two sub-moulds, in which the first one was the injection sub-mould for the plastic lining matrix, the second one was the injection sub-mould for the plastic over layer, and the cavity layout of the two sub-molds was based on the one mold with two cavities. In the two sub-moulds, the combination of hot runner and cold runner was used for gating. In the first sub-mould, the three inner wall hidden gates were used for gating in the single cavity, and the three inner wall hidden gates were adopted for gating as well in the second sub-mould. The difficulty in filling the cylindrical wall mold cavity was overcome through this design scheme, and the automatic removal of runner waste was guaranteed. In this mould, 36 locking-block T-groove driving slider mechanisms with a similar structure and a small design space were designed to implement side core pulling demolding, which could reduce the overall size of the mould. These 36 mechanisms were driven by 3 times opening of the plates, and a type of inserting bar mechanism was designed to control the sequential opening and closing of the plates. This mechanism is reliable for operation.
LIU Shaohua, XIONG Jianwu, XU Wenqing, HU Zhiqing, CHEN Liming, WANG Zheneng
Abstract (
825 )
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859
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Aiming at three defects in the current mold, we designed a hot runner two?plate injection mold with two cavities for a bottom cover plastic part. In view of the difficulty in demolding plastic parts, we first designed an inclined roof mechanism consisting of an inclined head and a round rod lifter to reduce the machining and assembly difficulties of the lifter mechanism. Afterward, we designed a lifter mechanism with a flat lifter guided by a round rod to overcome the short lifetime of the flat lifter and improve the overall service life of the mold. Thirdly, we designed a hot side gate removing mechanism in the mold, which could effectively improve the production efficiency of plastic parts and reduce the cost of manual gate removing. The reliability of the mold was guaranteed by setting the equal distance type exhaust slot, one side positioning and pressing installation of the forming part, closing the balance block of the mold, and slotting and ventilation of the guide sleeve. The cold side-gate hot removing mechanism in the mold was composed of a gate remo-ving mechanism and a driving mechanism. The mechanism has a simple structure and exhibits a potential for future practical application.
Review
WANG Hexiang, PENG Jiong, GE Zhen, ZHANG Yongtao, GUO Bingyi, LI Zhongshan
Abstract (
1163 )
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1319
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29 )
In the study on twin-screw extrusion process of polymers, the numerical simulation method can overcome the limitations of traditional experimental methods and provide important guidance for design and processing of twin-screw extruder. This paper reviewed the research progress in the numerical simulation of twin-screw extrusion process at home and abroad in recent years, and also introduced the advantages and disadvantages of mathematical description of the extrusion process by the one?dimensional mathematical model and three?dimensional mathematical model. The relevant research progress was summarized in the aspects of flow field characteristics, transient mixing performance, residence time distribution and reactive extrusion in the twin-screw extruder. Moreover, the future development direction of the numerical simulation of twin-screw extrusion process was prospected.
Jingyun LUO, Shijian BAI, Yuxia ZHANG, Hongfu ZHOU
Abstract (
1024 )
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1108
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This paper reviewed the research progress in the effect of nanoparticle type on the rheological behavior of poly(lactic acid) (PLA)?based composites under a shear force. These nanoparticles include biological fillers, carbon?based fillers and nano clay. The paper also introduced the effects of filler content, surface treatment and particle?matrix interaction on the rheological behavior of the composites. Moreover, the relevant mechanisms were further discussed.
