Materials and Properties
PAN Bochao, LIN Chenxi, TANG Donglin
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381 )
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A series of bio⁃based poly（urea⁃amide）s （PUAs） with high strength and high toughness were synthesized through a one⁃pot method using urea， 1，10⁃decanediamine， and diacids as raw materials without any catalyst or any solvent. Di（aminodecyl）urea was first synthesized via urea ammonolysis with 1，10⁃decanediamine and then polymerized with different diacids such as 1，10⁃decanedioic acid （DA10）， 1，12⁃dodecanedioic acid， and dimer acid （DmA）. The chemical structures of the as⁃synthesized PUAs were confirmed by 1H⁃NMR and FTIR spectroscopy， and their Mn's are about 12~13 kg/mol. The PUAs are processible with tensile strength of 25~45 MPa and elongation at break of 400 %~700 %. The strain at break value of PUA⁃DA10 is approximately twice as much as PA1010， whereas these two materials exhibit similar tensile strength. The strain at break of PUA⁃DmA is higher than that of PA⁃DmA， but they show similar tensile strength. The introduction of urea groups into the backbones of polyamides can improve their performance. This simple synthetic method is quite suitable for enhancing the performance of bio⁃based polyamide as well as for their diverse design and applications.
XU Yaohui, TANG Yiwen, GUO Peng, LYU Mingfu
Abstract (
241 )
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PP4 was obtained through treating polypropylene with a wide molecular weight distribution （BMWDPP） PP1 using an ion modifier. The molecular structures and rheological properties of PP1 and PP4 were investigated by gel permeability chromatography （GPC）， plate rotational rheology， stretch rheology， and melt strength tests. The PP degradation induced by free radicals reduced the molecular weight and polydispersity of BMWDPP. There was no real long branch chain structure generated due to the “long⁃like branched chain” effect of the ionic interaction between the metal salts on the PP chain segment. PP4 exhibits a stretch hardening phenomenon. The large molecular weight components could weaken the molecular entanglement， whereas the small molecular weight components could enhance the plasticizing effect due to the degradation of PP4. This makes its viscoelasticity lower than that of PP1.The influence of stretch strain hardening on the enhancement of melt strength is stronger than the effect of molecular weight reduction on the weakening of melt strength. Therefore， the melt strength of PP4 is higher than that of PP1 at different temperatures. This indicated that the PP was featured with linear large molecular chains at low temperature and long branched chains at high temperature.
CHEN Cheng, ZHANG Hao, YANG Mengyao, CHEN Haiying, SUN Hao, WEI Lingjun
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287 )
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Poly（vinyl acetate） （PVAc） as a non⁃covalent compatibilizer was incorporated into a polyhydroxybutyrate （PHB）/polycaprolactone （PCL） binary blending system at a mass ratio of 25/75， and its film was prepared through solution casting. The effect of addition amounts of PVAc on the mechanical properties and physicochemical properties of the blend system was investigated. Tensile experimental results indicated that the elongation at break and tensile strength of the PHB/PCL film containing 1 wt% PVAc were 2.50 and 1.19 times higher than those of the counterpart film without PVAc， respectively. FTIR spectra showed that there was an intermolecular hydrogen bonding interaction between the carbonyl and methyl groups of PHB and PCL due to a bridging action of PVAc. This results in a shift of carbonyl absorption band along with a decrease in the peak intensity. SEM showed that the addition of PVAc reduced the size of dispersed phase in the blend system， promoting a more uniform distribution. As a result， and the compatibility of the blend system was improved.
LI Ningli, WANG Rui, CHANG Zipan, LI Peilong
Abstract (
283 )
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Waterborne polyurethane （WPU） was prepared by using isophorone diisocyanate （IPDI）， polypropylene glycol （PPG） as raw materials， and it was further modified by using an acrylic monomer and a crosslinking agent to prepare the waterborne poly（urethane acrylic acid） （WPUA） lotion. The functional groups of the as⁃prepared WPUA were analyzed by Fourier⁃transform infrared spectroscopy. The hardness and adhesion of the WPUA film was measured by using pencil hardness and hundred grid marking methods， respectively， and its hydrophobicity of WPUA film was tested by a water contact angle meter. The optimum formulation of the WPUA heat⁃reflective coating was determined through orthogonal experimental design by taking cooling value， viscosity value， and gloss as evaluation indexes. The cooling effect of the WPUA heat⁃reflective coating was investigated by using indoor solar radiation simulation devices and outdoor solar irradiation experiments. The results indicated that the WPUA film not only exhibited good hydrophobicity but also obtained an improvement in adhesion and hardness. The optimal preparation formulation of the WPUA heat reflective coating was determined to a WPUA lotion with 30 wt% solid content， 16 wt% rutile titanium dioxide， 2 wt% quartz sand， and 4 % hollow glass beads. The WPUA heat⁃reflective coating presents a significant cooling effect both indoors and outdoors.
LI Jie, LU Yiyi, SHI Wentian, GUO Yunjie, WANG Yuke
Abstract (
524 )
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The PDMS/PVDF membranes with a special wetting surface were prepared for oil⁃water separation by using an electrospinning technology. The effect of mass ratio of PVDF to PDMS on the membrane⁃forming performance was investigated. The results indicated that an appropriate amount of PVDF could generate a spinning and plasticizing effect on PDMS， and the presence of microspheres resulted in better hydrophobicity for the membranes compared to those without microspheres. Furthermore， the membranes exhibited a high adhesion to water due to a capillary force and electrostatic interactions. When the mass ratio of PVDF to PDMS was 2∶1， the membranes showed the optimal hydrophobicity with a water contact angle up to 150 ° and an oil contact angle closed to 0 °. The separation rate of the membranes for water⁃in⁃oil emulsions was more than 98 %. This makes the membranes developed in this work a good candidate as an oil⁃water separation material.
YU Bo, ZHAO Bingqian, NI Yezhou, QIAN Kun, YU kejing, CHEN Kunlin
Abstract (
250 )
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In this study， STF microcapsules （STF MCs） were prepared by using a monocoalescence method with chitosan material as a wall material and STF as a core material. The process parameters for the preparation of microcapsules were determined by a single⁃factor experimental study. Span 80 and Tween 80 were used as dispersants at a mass ratio of 3∶1， the addition amount of emulsifier was determined to be 11 wt%， the mass ratio of core to shell was determined to be 2∶1， the stirring speed was 600 r/min， the reaction temperature was 60 ℃， and the oil⁃to⁃water mass ratio of the system was 1∶2. The STF MCs produced under these conditions show a relatively regular spherical morphology with a relatively uniform distribution centered as a particle size of 3 μm. Rheological results indicated that the introduction of carbon nanotubes （CNTs） effectively improved the rheological properties of STFs. The CNTs⁃doped STF system exhibited a smaller critical shear rate， a faster viscosity transition， and an almost doubled peak viscosity. Infrared spectroscopic results indicated that the infrared spectrum of the microcapsule emulsion was almost consistent with that of the core. This indicated that chitosan was successfully adsorbed on the surface of the core droplets to realize the encapsulation of STFs. Thermogravimetric analysis results indicated the wall material could provide protection for the STF core， thus enhancing its thermal stability.
ZENG Yuan, LI Liang, LIU Wei, MA Jingjing, LIU Rangtong
Abstract (
536 )
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A double network hydrogel was constructed by using natural polysaccharide sodium alginate and acrylamide as monomers， and chitosan was introduced to enhance the mechanical toughness of the hydrogel. The morphology， network crosslinking structure， and thermal properties of the as⁃prepared hydrogel were characterized by using scanning electron microscopy， infrared spectroscopy， X⁃ray diffraction， and synchronous thermal analysis， and its crosslinking mechanism was analyzed. The results indicated that the toughness of the hydrogel was improved with an increase in the chitosan content. The increase of toughness at a low chitosan content was caused by the increase of elongation ability， whereas its increase at a high chitosan content it was caused by the simultaneous increase of strength and elongation. The toughness value of the hydrogel with 10 wt% chitosan reached 2.50×105 kJ/m3， which was significantly higher than the hydrogel containing 5 and 7.5 wt% chitosan. The elastic recovery rate of the hydrogel decreased with an increase in the set elongation rate during the constant elongation cycle stretching， and it was higher than 98 % at set elongation of 25 %， but only higher than 90 % at set elongation of 200 %. The hydrogel with 10 % chitosan exhibited the best elasticity with a strong fracture stress of 0.249 MPa and fracture elongation of 1 635.65 %， and it presented an excellent recovery ability at a constant elongation cycle of 200 % or less. This study can provide a solution for the toughening of hydrogels.
Processing and Application
JIAO Xiaolong, DANG Kaifang, ZHOU Yang, MA Yitao, WANG Jinling, XIE Pengcheng
Abstract (
341 )
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The International Plastics and Rubber Fair 2022 （K⁃Show 2022） in Düsseldorf， Germany， came to a successful conclusion， showcasing new ideas， technologies and products brought by exhibitors from all over the world. With the theme of climate protection， circular economy and digitalization， this section of K⁃show focused on the innovative concepts of materials and industries in material recycling， digitalization， intelligence， and low⁃carbon energy saving， and it demonstrated the innovative solutions of the global injection molding industry in relation to the circular economy， intelligent digitalization， and cost reduction， efficiency enhancement， etc. This paper also briefly introduced the innovative highlights that this section of K2022 brought to the exhibition and further explored the trend in future injection molding industrial development.
RONG Di, JIA Zhixin, LIU Lijun, LI Jiqiang, ZHAO Chuantao, GAO Lizhen, WANG Shaofeng
Abstract (
289 )
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The influence of molding temperature， molding pressure， holding time， and closing speed on the impact performance of epoxy resin/carbon⁃fiber⁃laminate⁃molded products was investigated through an orthogonal experiment. The of products exhibited significant anisotropy in their impact strength. A range analysis method was used to demonstrate the influence of each factor on the impact performance by an increasing order as follows： holding time>closing speed>molding temperature>molding pressure. The optimal combination of process parameters was determined to be a molding temperature of 130 ℃， a molding pressure of 500 kN， a holding time of 540 s， and a closing speed of 1 mm/s. Compared to the maximum value obtained in the orthogonal experiment， the validation experiment based on this parameter combination for the new products showed an increase in the impact strength by 9.75 %. The microstructure of typical impact fracture samples was analyzed to explore the microscopic mechanism of the influencing factors on the impact performance of the products.
BAI Xiao, QIAO Liang, FAN Junming, WEN Jiongming, ZHANG Yi
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513 )
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The failure modes such as buckling collapse and yield blistering of the liner can greatly reduces the service life of a cylinder. This paper analyzed the influence of different factors on the hydrogen permeation of plastic liners from both internal and external aspects and summarized their hydrogen permeation mechanism. In addition， the corresponding research progress at home and abroad was introduced and the shortcomings were pointed out. Finally， the future research direction was prospected.
LIU Xuejun
Abstract (
225 )
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On basis of the static bed model， a heat transfer model was established for the rotational molding process heated electrically by a control mode of PID to make the liner of a hydrogen cylinder. The temperatures at the mold surface and inside mold， heating time， and electrical energy were simulated by means of the FLUENT software. These simulated results were in good agreement with the experimental results， indicated that the heat transfer model established in this study was validated. The heat transfer model was then applied to calculate the temperature inside the mold when the heating was stopped， heating time， and electrical energy in 16 cases. A grey relational analysis was conducted to investigate the trigger temperature of the PID mode and the percentage of initial heating power affecting heating time and electrical energy. The results indicated that temperature inside mold after stopping the heating varied with the percentage of initial heating power slightly， and however， it decreased with an increase in the trigger temperature. Both heating time and electrical energy decreased as the trigger temperature increased. The optimal process parameters were determined to be a trigger temperature of 250 ℃ and an initial heating power percentage of 90 %. In addition， the affecting extent of trigger temperature on heating time and electrical energy was larger than that of the percentage of initial heating power.
Additive
ZHAO Xiaobo, WANG Guotai, LIANG Shujun
Abstract (
269 )
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The microencapsulation modification of ammonium polyphosphate （APP） was performed to prepare the modified APP/DMDES， APP/MTES， and APP/PTMS for enhancing their flame retardancy， thermal stability and hydrophobicity through a sol⁃gel process using tetraethylorthosilicate （TEOS） as a main precursor and dimethylldiethoxysilane （DMDES）， methyltriethoxysilane （MTES）， and phenyltrimethoxysilane （PTMS） as co⁃precursors. The structures and performance of the resulting APP coated with polysiloxane was investigated by using Fourier⁃transformation infrared spectroscopy， water contact angle， scanning electron microscope， energy dispersive spectrometer， and thermogravimetric analysis. The effects of modified APP on the flame retardancy， mechanical and thermal properties of low⁃density polyethylene （PE⁃LD） were also studied. The results showed that polysiloxane⁃coated modified APP could be prepared under suitable processing conditions， and its hydrophobicity and thermal stability of the modified ammonium polyphosphate were significantly improved compared to pristine APP. As a PE⁃LD/APP/PTMS/pentaeritritol/melamin mass ratio of 65/18.7/11.7/4.6， the PE⁃LD composite exhibited the best overall performance with a limiting oxygen index of 26.6 vol%， which is 23.3 % higher than that of pristine APP. The composite also reached a UL 94 V⁃0 level in the vertical burning test and obtain the highest tensile strength of 12.84 MPa.
Plastic and Environment
CHEN Zeyu, FU Ye, ZHANG Xi, WENG Yunxuan
Abstract (
596 )
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This paper reviewed the research progress of poly（lactic⁃co⁃glycolic acid） （PLGA） from the aspects of synthesis method， aggregate structure， and degradation performance and summarized the influence of synthesis method and aggregate structure on the degradation of PLGA. Meanwhile， the application of PLGA for controlled drug release， medical surgical suture， and bone tissue engineering scaffold was briefly introduced.
Machinery and Mould
MAO Haijun, MA Yitao, DANG Kaifang, WANG Xinming, XIE Pengcheng
Abstract (
404 )
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This paper reviewed the current research progress in the field of mould temperature control technologies at home and abroad and introduced the mold cooling system， heating system， and control method. Additionally， the paper provided some new insights for the future development trend of mold temperature control.
JIA Mingyin, XU Wenyi, REN Haoyu, XUE Ping
Abstract (
267 )
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This article summarized the similarity amplification criteria proposed for screw extruders both domestically and internationally in recent years， and the commonly used amplification coefficients and applicable ranges were compared and analyzed. Meanwhile， the practical applications of similarity amplification theory in optimizing the structural parameters and processed conditions of screw extruders were introduced. Finally， the further exploration and optimization of similarity amplification theory for screw extruders were pointed out. This paper provided an effective theoretical support for the sustainable development of screw extruder industry.
FEI Qiang, ZHANG Weihe
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231 )
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According to the structural characteristics and technical requirements of the left/right cover car air tank， a large injection mold with a complex core⁃pulling mechanism was designed. The labor productivity increased by 10 %， and the dimensional accuracy reached MT3（GB/T 14486—2008） through using a hot runner⁃gating system and a fast and balanced cooling system. The problem in the ejection system with a complex structure and multiple back buckles was solved by using composite core pulling and delayed core pulling. The accuracy and lifespan of the mold were greatly improved by using a guidance and positioning system with a standard ball⁃guide sleeve.
Review
GUO Xinyi, ZHU Guangming, ZHANG Xuebei, LI Ruichao
Abstract (
307 )
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In this paper， the structures and properties of stable structure carbene precursors such as trifluoromethyl carbene compound， diazo ester carbene compound， and N⁃hybrid carbene compound were analyzed and reviewed， and their applications in the polymer field were summarized and prospected.
HAN Zhiyong, MA Sijing, LU Pengcheng
Abstract (
407 )
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The extensive application of aluminum alloys and composite materials in aviation structures demonstrates their advantages of lightweight and high⁃strength properties in aircraft. At present， the connection technology of aluminum alloys and composite materials is complex and faces various challenges. The surface treatment technology of the connecting parts is an important means to solve such issues. This article introduced the surface treatment technologies for bonding aluminum alloys and composite materials and analyzed the purpose， mechanism， classification， and process parameters that affect the treatment quality obtained from different surface treatment methods. In addition， the principles and advantages of aluminum alloy hybrid processing technology and promising composite material energy treatment technology were analyzed. This paper provides more effective new ideas for material surface treatment.
