Abstract (
414 )
PDF (2104 KB)(
167
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A grafting process for the polypropylene grafted with fluorinated acrylate was carried out in a co-rotating twin screw extruder by using linear isotactic polypropylene (iPP) as a matrix and trifluoroethyl methacrylate (FA-3F), dodecafluoroheptate methacrylate (FA-12F) and heptafluorodecyl methacrylate (FA-17F) as functional co-monomers. The results indicated that the long-chain fluorine-containing co-monomers had more advantages than the short-chain ones in the grafting process due to their higher boiling point. The grafting degree of fluorine-containing co-monomers increased rapidly with increasing the contents of co-monomer and initiator, and then such an increasing trend was depressed. The grafting efficiency also increased at first and then tended to decrease with the increase of co-monomer and initiator contents. The molecular weight of grafted polypropylene was influenced by process conditions and formulation. The higher degree of monomer grafting can result in a higher molecular weight.
LIANG Shuai, MAN Zibo, ZHANG Zhibin, YANG Fengmin, CAO Chunlei
Abstract (
534 )
PDF (1848 KB)(
206
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ACS resin is a type of grafting copolymer, in which styrene (St) and acrylonitrile (AN) as co-monomers were grafted onto the molecular chain of chlorinated polyethylene (CPE). The effect of swelling conditions of CPE rubber on the grafting rate, Izod impact strength and phase morphology of the ACS resin synthesized in this work through bulk polymerization were synthesized by bulk polymerization, and the molecular weight and molecular weight distribution of free SAN in the ACS resin were also investigated. The results indicated that the swelling temperature and time of CPE rubber significantly influenced the grafting rate, Izod impact strength and phase morphology of ACS resin and the molecular weight of free SAN in the ACS resin. However, there was no effect on the molecular weight distribution of free SAN. The optimum grafting rate, phase morphology, Izod impact strength of ACS resin and the optimum molecular weight of free SAN could be achieved for the synthesized resin only when CPE rubber swelled fully. The CPE rubber could swell quickly and fully at 100 ℃ within 3 h. The resin could gain an optimum grafting rate of 23.1 %, Izod impact strength and phase morphology under the above condition.
ZHAO Qing, HE Shaojian, LIN Jun, LIN Qianguo
Abstract (
647 )
PDF (2040 KB)(
272
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Polymer blending can produce the blend membranes with different properties from different polymers. In order to improve the comprehensive performance of gas separation membranes, two different types of poly(ether-co-amide), Pebax 1657 with high selectivity and Pebax 2533 with high permeability, were used as membrane materials to prepare gas-separation membranes by a blending method, and the structure, separation performance and mechanical properties of the resulting separation membranes were investigated. The results indicated that the chain spacing of polyamide segments, free volume fraction and elongation at break increased with an increase of the content of Pebax 2533, and however the glass transition temperature decreased. Compared to pristine Pebax 1657 membrane, the blend membranes exhibited an increase in permeability coefficients of CO2 and N2 and a gradual decrease in selectivity. The permeability coefficient of N2 was found to increase faster than that of CO2. Compared to pure Pebax-type membranes, the blended membranes presented an improvement in comprehensive properties.
LI Wei, XIA Xinshu, LIN Hongyu, YANG Yujin, CHEN Qinghua, XIAO Liren
Abstract (
548 )
PDF (2794 KB)(
218
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The 3D printed wire with a diameter of （1.75±0.05） mm was prepared by melt blending through twin-screw extrusion using poly(lactic acid) (PLA) as a matrix and thermoplastic polyurethane elastomer (TPU) as a modifier. Furthermore, fused deposition molding (FDM) was performed to prepare the 3D-printed items by use of this PLA/TPU blending wire. The effects of TPU content and deposition style on the impact properties of PLA/TPU blends were investigated by using pendulum impact tester and scanning electron microscope. The results indicated that the addition of TPU greatly improved the impact toughness of PLA by 631.0 %. The fused deposition style also exhibited a significant effect on the notched impact strength of PLA/TPU blends. The blends achieved optimum impact toughness at 45 °/45 ° to present an increase by 101.9 %. This work provided a scientific evidence for the design of 3D printing process parameters in an FDM mode.
WANG Xiangyu, ZHANG Yuxia
Abstract (
468 )
PDF (2294 KB)(
187
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The PLA/OMMT composites were prepared by a torque rheometer and then blended with PBAT to obtain the PLA/OMMT/PBAT ternary composites in the two-step process. Meanwhile, the ternary composites were also prepared by melt blending in the one-step process for comparative investigation. The interfacial tension of two types of composites was evaluated, their microstructures were observed by TEM and SEM, and their melting and crystallization behaviors were analyzed by DSC. The results indicated that the addition of OMMT reduced the size of PBAT domain and improved the compatibility between PLA and PBAT. OMMT could generate a better compatibilizing effect on the PLA/PBAT blends when the composites were prepared in the two-step process. OMMT tended to be distributed in the PLA phase and on the interface between PLA and PBAT due to a good affinity. There is a synergistic toughening effect of OMMT and PBAT on PLA.
Abstract (
471 )
PDF (2488 KB)(
144
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Poly(styrene-random-acrylic-random-methyl methacrylate)［P(St-r-AA-r-MMA)］was prepared by free-radical polymerization and then used to modify the surface of high-density polyethylene (PE-HD)/wheat-straw fiber (WF) composites through a solution method. As a result, a superhydrophobic surface with a water contact angle (WCA) > 150 ° was obtained. The preparation parameters of superhydrophobic surface, mechanical properties and water absorption of these wood-plastic composites were investigated. The optimum preparation parameters were determined as follows: the ratio of polymer monomer was nSt∶nMMA∶nAA=2∶1∶1, the WF content was 40 wt%, the polymer concentration was 3 %, the drying time was 15 h, and the drying temperature was 70 ℃. The results indicated that the surface of the composites prepared under the optimal modification conditions achieved a WCA of （156±2.9） ° , which increased by 84 ° compared to that of unmodified composites. Moreover, their tensile and flexural strength increased by 6.1 % and 6.9 %, respectively, and however their water absorption decreased by 1.70 %. After placed for 5 months, a WCA of （142±5.7） ° was gained for the modified PE-HD/WF composites but only a WCA of （54 ± 6.2） ° was obtained for the unmodified ones.
WANG Limei, TU Buxin, YU Yifan, LU Yueyuan, CHUN Yan, DONG Tungalag
Abstract (
782 )
PDF (479 KB)(
215
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The PBAT/PLLA blend films were prepared by melt extrusion, and the effect of PLLA content on the mechanical, thermal and gas barrier properties of blend films were investigated. The results indicated that the PBAT/PLLA blend system was thermodynamically incompatible. The blend films exhibited a decrease in permeation coefficients of O2 and CO2 with an increase of PLLA content. When 30 wt% of PLLA was incorporated, the blend films achieved the permeation coefficients of 34.2 % and 70.8 %, for O2 and CO2, respectively. The two values were lower than those of pure PBAT films. The permeation coefficient radio of O2/CO2 was found to decrease from 10.20 to 4.52, indicating that the barrier properties of blend films were significantly improved. The addition of PLLA could effectively prevent the deformation and warpage of blends films.
ZHOU Jianshi, LIN Chong
Abstract (
496 )
PDF (1032 KB)(
242
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Poly(ethylene terephthalate-co-1,4-cylclohexylenedimethylene terephthalate) (PETG) pre-coating films were prepared by using hexamethylene diisocyanate (HDI), polycarbonate diol (PCDL), polytetrahydrofuran diol (PTMG), methacrylic acid-β-hydroxyethyl (HEMA), and dimethylol propionic acid as raw materials. The chemical structure of pre-coating films were characterized by infrared spectroscopy and scanning electron microscopy, and the effect of raw materials on the thermal cladding properties of pre-coated films were investigated. The results indicated that the activation temperature of pre-coated films became lower when the amounts of polyether diol and acrylate increased and hydrazine hydrate was used, resulting in optimum peeling strength.
LI Yang, YIN Dexian, ZHU Min, ZHOU Hongfu, WANG Xiangdong, YE Zhiyin
Abstract (
431 )
PDF (2945 KB)(
154
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The poly(lactic acid) (PLA)/high-density polyethylene (PE-HD) blends was prepared by a melt-mixing method with ethylene-glycidyl methacrylate copolymer (GEMA) as a compatibilizer, and then the blending foams were prepared in a stainless-steel autoclave with CO2 as a foaming agent. With the addition of GEMA, the crystallinity of PLA/PE-HD blends decreased but their rheological properties increased slightly. On the other hand, the size of PE-HD dispersed phase decreased and its number increased due to an increase in the content of GEMA. There was a transition from a complex cellular structure to the mono-porous cell one observed in the blending foams.
DOU Xiyu, XU Yuxuan, LIU Gang, DANG Kaifang, XIE Pengcheng
Abstract (
365 )
PDF (1260 KB)(
195
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The cavity pressure curve could be calculated quantitively by its integral value. The linear relationship between the integral value of cavity pressure curve and the various process parameters could be explored by adjusting the injection speed, the position of rotary pressure point, and the holding pressure and time. According to this linear relationship, the optimal process parameters were obtained, and the traditional empirical parameters were transformed into precise numerical parameters.
LIU Zhikang, FAN Yuanxun, LU Pengcheng, ZHANG Jiacheng
Abstract (
581 )
PDF (1570 KB)(
148
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Aiming at the difficulty of fiber feeding in the production of glass-fiber-reinforced thermoplastics, this work proposed a simple vibrating feeding method and verified its feasibility in practical applications. The motion characteristics of vibrating feeder were analyzed, and the form of motion required for the transportation of glass fiber was determined as the throwing motion and forward slip. The associated conditional formula was derived and used to determine four sets of vibration parameters. A simulation model was established by a discrete unit method with the EDEM simulation software, and the corresponding parameters were set to simulate the fiber vibration feeding condition with four parameters. The simulation results verified the validity of the motion condition formula. Meanwhile, the simulation data for the vibrating feeder in the end region were analyzed. It was found that the vibration feeding method could realize uniform feeding of glass fiber at a constant speed with a suitable mechanical index, and the amplitude showed a significant influence on the velocity of vibration feeding. In this case, the feed rate can be quantitatively adjusted by changing the amplitude.
LIU Yueyun
Abstract (
500 )
PDF (1112 KB)(
156
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Taking the central distance of cooling water channel, the distance from the water channel center to the die wall, and the cooling channel diameter of the plastic chain plate injection mold as the experimental factors, a second-order response surface model between the three experimental factors, the temperature difference of the model wall and the cooling time was constructed by a response surface method. The Pareto genetic algorithm was used to iteratively optimize the two response surface models, and a set of optimum solutions for design parameters of cooling water channel was obtained when the temperature differences of the die wall and cooling time were both small. The results indicated that the optimum design parameters of the cooling water channel were follows as: the central distance of cooling water channel was 30 mm, the distance from the center of the channel to the die wall was 15 mm, and the diameter of the channel was 10 mm. The corresponding temperature difference of die wall was determined as 7.61 ℃, and the cooling time was determined as 62.74 s. Such data was smaller than the experimental results of any groups of response surface. This analysis method was proved to be feasible.
LI Ya
Abstract (
525 )
PDF (1415 KB)(
222
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To solve the problems of imbalance melt flow in the injection mold combination cavity of the soap box, the Moldflow software was used to perform the numerical simulation for the injection molding process. The initial plan was analyzed from three aspects including filling time, the pressure of velocity/pressure conversion points and the pressure at the injection position to determine the optimization index of the gating system. The size of the runner was optimized by the automatic optimization scheme of flow balance analysis. The results indicated that the unbalance rate of filling time between cavities and pressure unbalance value were less than 5 % and 5 MPa, respectively, after the gating system was optimized. Moreover, the pressure curve at the injection position rose steadily, and the melt flow imbalance were also improved effectively.
ZHANG Xin
Abstract (
900 )
PDF (1894 KB)(
296
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The flat sheet ultrafiltration membranes were prepared through phase inversion with polyether sulfone (PES) as a membrane material, N-methyl-2-pyrrolidone as a solvent and polyvinyl pyrrolidone (PVP) with different molecular weights (PVP K10, PVP K30, PVP K50, PVP K70) as additives, and the effects of preparation conditions on the structure and performances of the resultant membranes were investigated. The results indicated that the average water flux and average rejection ratio of the membrane reached 90.7 L/（m2·h） and 95.1 %, respectively, when 18 wt% of PES and 6 wt% of PVP K30 was added. The rejection ratios of these five types of membranes for the boving serum albumin solution (1 g/L) were measured, and their silting density index (SDI) values of the water samples obtained from a drinking tap water and a swimming pool were also measured. It was found that the SDI5 min value from the drinking tap water after five minutes filtering decreased with an increase of rejection ratio, but the SDI5 min of filtered water in swimming pool kept a stable value with the rejection ratio.
ZHAO Han, WEI Simiao, MA Wen, YANG Musen, BAI Yichen, XU Bo
Abstract (
447 )
PDF (1688 KB)(
215
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A type of high-phosphorous-containing flame retardant (PCDB) was synthesized, and its chemical structure was characterized with FTIR and 1H-NMR spectroscopy. The flame-retardant performance of the polyurethane foam flame-retarded with PCDB was evaluated by limiting oxygen index and cone calorimetry, and its thermal behavior was investigated by thermogravimetric analysis. Moreover, the morphology of the residual char obtained from flame retardant test was observed by SEM. The results indicated that PCDB could effectively reduce the limited oxygen index, peak heat release rate and average effective combustion heat of the flame-retardant polyurethane foam. PCDB was found to improve the carbonization ability of polyurethane foam and impart the carbon residue with a more compact microstructure.
HAN Yangyang, ZHU Guangming, Ren Tianning
Abstract (
447 )
PDF (3698 KB)(
199
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With a rapid development of aerospace technology in recent years, there is a continuous increase in the amount of space debris in the near orbit of the earth. It is a time to consider the incorporation of some microcapsules into the spacecraft material so as to control the degradable time of the spacecraft materials by controlling the photodegradable rate of wall materials of microcapsules. In this work, we investigated the photodegradable performance of starch-based materials prepared with starch as a matrix and iron stearate (FeSt3) and cerium stearate (CeSt4) as photosensitizers. The results indicated that starch had certain photodegradability, and the addition of photosensitizers could effectively promote the photodegradation of starch. The photodegradable performance was optimum at the photosensitizer content of 0.3 wt% after 72 h irradiation. The starch-based material containing 0.3 wt% of FeSt3 showed a decrease in intrinsic viscosity by 67.64 % and in impact strength by 59.59 %. The carbonyl index was found to rise up to 17.68, indicating a most significant influence by photodegradation. These results confirmed that the starch-based materials achieved the optimum photocatalytic degradation with the addition of 0.3 wt% FeSt3. However, there was a drawback found in the early stage of irradiation, in which the starch-based material containing 0.3 wt% of FeSt3 exhibited a lower photoinitiation rate than that with 0.3 wt% of CeSt4.
XIA Tian, ZHU Gang
Abstract (
420 )
PDF (1781 KB)(
155
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The problems in the flange end arc core pulling, flange and flange hole linear core pulling and groove demolding of complex plastic pipe were solved by use of a hydraulic cylinder and pull rod mechanism as a driving force. The arc stripping of the large diameter end of the complex plastic pipe on the inclined plane were realized with the straight cylinder as a driving force as well as the gear and rack drive. This work provides a good reference for the development and application of injection mould with the similar structure in the parts and components.
LIU Qingdong
Abstract (
349 )
PDF (2095 KB)(
198
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The car storage box has a complex structure, and there is no defect allowed on its appearance surface. For this reason, a flip injection mould was designed with a gate on the back of appearance surface. A hot runner system, a hydraulic cylinder ejecting mechanism, a four-sided hydraulic cylinder slide-pulling mechanism, and a two-step slide-pulling mechanism of lifter in large slide and little slide in larger slide on the fixed mould were designed. The results indicated that the structure of mould was reasonable and reliable and could meet the requirement for production.
WEN Rui, LU Yinghua
Abstract (
381 )
PDF (3481 KB)(
228
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This paper reported a structure design of injection mold with one mold, one cavity and three plates for the plastic part of purifier framework. In this mold, the mold cavity was designed with a 5-point gate, and the cooling system was designed with cooling water wells and pipes. The full ejection of plastic parts was arranged by an improved cylinder head type ejector pin. Aiming at the difficulty in demolding of plastic parts, two types of core-pulling mechanisms were set for demolding with a characteristic side edge, in which one was a compound secondary core-pulling mechanism of slider ejector and another was a bending pin slider core-pulling mechanism. A delay ejector on the side slider was set in the compound secondary core-pulling mechanism of slider ejector needle, and a push rod block on the fixed mold was designed in the ejector rod. The delayed ejection ensured the core-pulling of the side forming block at first and then the core-pulling of the side ejector pin on the slider. Such a design avoids the deformation of plastic parts when the side core-pulling is one-off. The structure design of this mechanism is exquisite and the structure of the mold is reasonable. This may provide a useful reference for the design of mold for the plastic parts with the same structures.
WU Yanzhi, HOU Heping, XU Zhuofei, LIU Shanhui
Abstract (
384 )
PDF (807 KB)(
233
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The nozzle blocking by melt and the low forming accuracy of products are two potential troubles for the fused deposition molding (FDM) technology. The optimization of a FDM nozzle system is beneficial to the reduction of the incidence of equipment failures and the improvement of the quality and printing efficiency of molding products. During the printing process, the working state of nozzle system is complex and variable. This paper reviews the research progress and development trends of the nozzle system both at home and abroad in recent years, which mainly included the flow channel structure of the nozzle system, cooling device and nozzle. Based on research and analysis, the nozzle system was found to become the core part of FDM equipment, and there were a number of great challenges in the current nozzle systems. However, with the continuous development of advanced technologies, the future nozzle systems can well face these challenges. The development of innovative technologies in nozzle systems may bring about a breakage in the limitations of FDM equipments, leading to the successful production of new products for the demands in industrial and civil applications.
冯伟丽, 康兴隆, 鲁哲宏, 刘保英, 房晓敏, 丁涛
Abstract (
367 )
PDF (295 KB)(
248
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Natural fibers and their reinforced composite have been widely used in civil and automotive industries due to their excellent mechanical properties, low cost and eco-friendly characteristics. However, flammability is always an inevitable problem in the applications of natural fibers and their reinforced polymer-matrix composites. Therefore, the research on the flame retardant modification for corresponding products has attracted more and more attention. This paper reviewed the latest research progress in the flame retardant modification of natural fibers and their polymer-matrix composites, and their development and applications were prospected.
LI Minxian, YU Jing, LI Shutong, SHU Shili, LI Deling, SHEN Yulong
Abstract (
508 )
PDF (666 KB)(
261
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The paper summarized the thermal degradation mechanisms of poly（vinyl chloride） (PVC) and its thermal stabilization mechanisms with rare-earth thermal stabilizers. The main properties of rare-earth thermal stabilizers were introduced, and their development status was discussed. Their future research direction and development trend were pointed out.
