Materials and Properties
ZHENG Pengcheng, LI Ruilong, CHEN Couxi, ZHANG Shouyu, JIANG Ruyuan, CHEN Tonghai, SONG Chengpeng, JIAO Qi
Abstract (
787 )
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A series of novel ternary composite antioxidant systems with different types and mass ratios were designed.
These antioxidant systems were based on the BASF antioxidant Irganox®1010 as a main antioxidant and Irgafos®168 as an
auxiliary antioxidant at a basis mass ratio of 1∶1 together with Revonox®420 as a carbon radical capture agent. Such antioxi⁃
dant systems were applied for the modification of coal⁃based homopolypropylene（homo⁃PP）to enhance its thermo⁃oxida⁃
tive aging performance. The resultant modified homo⁃PP was evaluated with oxidation induction time（OIT），yellow index，melting flow rate and mechanical performance. The results indicated that the modified homo ⁃PP achieved optimum anti⁃oxidative performance by means of an antioxidant composite system based on Irganox®1010，Irgafos®168，and Revonox®420. This composite antioxidant system resulted in the longest oxidation induction time of 9. 8 min，a yellow index of 1. 3，and a melting flow rate of 10. 7 g/10 min for the modified homo⁃PP. Moreover，the modified homo⁃PP gained an optimum anti⁃yellowing effect at a mass ratio of Irganox®1010 and Irgafos®168 of 1∶2. These results provide a good reference for the design and development of high⁃efficient and long⁃term antioxidant system for the coal⁃based homo⁃PP.
CHEN Yuhong, ZHAN Maosheng
Abstract (
915 )
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Transparencies were injection-compression-molded under different compression conditions using polycarbonate （PC） as a raw material. Through combining the mold cavity pressure test during the molding process， the effect of the core compression process parameters on the residual stress of the PC transparencies such as compression start position， compression distance， melt temperature and mold temperature were investigated using two methods， qualitative （stress polarization method） and quantitative （hole drilling strain gage method）. The results indicated that the cavity pressure increased as the compression start position was delayed or the compression distance increased. This resulted in a decrease in both flow residual stress and thermal residual stress and a decrease in the residual stress of the product. When the compression start position was delayed from 10 % to 70 %， or the compression distance increased from 0.5 mm to 2.0 mm， the Von Mises equivalent residual stress at the test point of the transparent parts obtained an average decrease by 82.0 % and 64.7 %， respectively. With an increase in melt temperature or mold temperature， there is no significant change in cavity pressure. However， a decrease in thermal residual stress resulted in a decrease in the residual stress of the PC transparencies. When the melt temperature rose from 290 ℃ to 320 ℃， or the mold temperature rose from 80 ℃to 120 ℃， the Von Mises equivalent residual stress at the test point of the transparencies decreased by an average of 56.2 % and 77.0 %， respectively.
YIN Peng, MA Hongpeng, GUO Bin, LI Panxin
Abstract (
778 )
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To improve the mechanical and water resistance of thermoplastic starch （TPS） plastics， TPS based compo?sites reinforced with poly（lactic acid） fiber （PLAF） and poly（vinyl alcohol） fiber （PVAF） were prepared through extrusion molding. The effects of PVAF content on the mechanical properties， cross-section morphology， water resistance， and torque rheological properties of TPS/PVAF/PLAF composites were investigated. The results indicated that the mechanical properties and surface water resistance of the composites were improved effectively with the synchronous addition PLAF and PVAF. When the contents of PLAF and PVAF were 1 wt%， the tensile strength of the composites increased from 1.98 MPa to 10.53 MPa， the impact strength increased from 33.4 kJ/m2 to 62.23 kJ/m2， and the balance torque of TPS/PVAF/PLAF compsite reached a maximum of 15.75 N·m.
LIN Haichuan, ZHANG Qi, LU Jing, MA Qing, YUAN Wei, LUO Faliang
Abstract (
817 )
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In this paper， low-density polyethylene （PE-LD） and NX8000K nucleating agent were blended with polypropylene （PP） to enhance the toughness and transparency of PP. Differential scanning calorimetry， X-ray diffraction analysis， polarized light microscope analysis， haze test analysis and impact test analysis were used to characterize the crystallization behavior， crystal morphology， transparency and mechanical properties of the resultant PP compounds. PE-LD could prevent PP from crystallization PP and reduce its crystallinity， thus reducing the fog of the compounds. A combination of PE-LD and PP could improve the toughness of the compounds significantly. When 50 wt% PE-LD and 0.6 wt% NX8000K nucleating agent were incorporated， the PP/PE-LD/NX8000K composite exhibited a haze value of 16.43 %. The compounds presented impact strength of 77.94 kJ/m2， which was lower than that of pure PP by 45.18 %. However， their impact strength increased by 1 465 %.
BAO Lulu, LIU Yi, HAN Liwang, YANG Tingjie, MENG Xin, GUO Xiaodong, WANG Yong, GOU Rongheng, LI Guofeng, ZHANG Minghui
Abstract (
842 )
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935
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The melt crystallization properties， optical properties， molecular weight distribution， mechanical properties， capillary rheological properties， and thermal shrinkage properties of three types of thin-walled injection-molded polypropylenes were investigated. The results indicated that K1860 has the same properties with the commercial PP products， PP1 and PP2， and its molecular weight distribution was narrower than PP1 and PP2. The bending and tensile properties of the K1860 were better than those of PP1 and PP2. The K1860 can completely meet the requirements for the production of large thin?walled injection-molded products.
YIN Nianwei, CHEN Feng, FU Xuejun, CAO Shaoqiang
Abstract (
1217 )
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In this paper， the effect of mas ratio of PET to PBT on the surface of flame?retardant reinforced PET/PBT Alloy was investigated. The surface fiber?floating phenomenon was characterized semi?quantitatively using a two?dimensional image tester and visual inspection. The results indicated that the surface fiber?floating phenomenon became less serious with an increase in the PBT content. When the ratio of PET to PBT was close to 1：1， the fiber floating became weakest. When the PBT content further increased， the fiber floating became worse. The flame retardant reinforced PBT exhibited weaker fiber floating than the flame retardant reinforced PET.
HAN Xianxin, LIU Xijun, WANG Yuwei
Abstract (
883 )
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435
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PP/EPR/modified cellulose （M?C） composites were prepared through melt blending using binary ethylene propylene rubber （EPR） as a toughening material， cellulose as a reinforcing material， and vinyl?alcohol?grafted EPR （EPR?g?VA） as a compatibilizer. Their structure was verified by infrared spectroscopy and X?ray diffraction analysis， and their micromorphology， spherulite size， thermal stability， and mechanical properties were analyzed using scanning electron microscope， polarizing microscope， thermogravimetric analyzer， plastic dynamic property testing machine， and electronic universal testing machine. The results indicated that a skin?core?like structure was formed in the alkali?pretreated cellulose coated with EPR and EPR?g?VA. Compared to the PP/EPR blends， the PP/EPR/M?C composites exhibited a significant improvement in thermal and mechanical properties. When the content of PP/EPR/M?C was 6 wt%， the composites exhibited a Vicat softening temperature of 146.5 ℃ and impact strength of 12.59 kJ/m2. Meanwhile， the spherulite size of PP phase in the composites became smaller and its crystal interface became blurry.
ZHANG Ze, JIA Yao, CUI Yongyan
Abstract (
766 )
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438
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Acrylonitrile?butadiene?styrene copolymer （ABS） was melt blended with aluminum diethylphosphinate （ADP） as a main flame retardant， ammonium polyphosphate aluminum diethylphosphinat （APP） as an auxiliary flame retardant. The resultant compounds achieved good flame?retardant performance and smoke suppression. Based on the analysis results obtained from the ultimate oxygen index， smoke density， cone calorimetry， scanning electron microscopy， and differential scanning calorimetry， the compounds gained an increase in limited oxygen index by 29 vol% at a ABS/ADP/APP mass ratio of 100∶16∶4. Their smoke density decreased down to 68.5， but their fire potential index increased to 0.215 s / （kW·m-2）. During the combustion process， the compounds decomposed to produce phosphorus oxygen free radicals， inhibiting the chain reaction of the matrix combustion. This resulted in the formation of a huge number of small cavities as well as the expanded and loose carbon layers on the surface of the compounds， generating a good synergetic effect between the gas?phase and condensed?phase flame retardants.
ZHENG Debao, ZHAI Qianchao, LIU Guangyuan, WANG Fengwu, WANG Yihui, ZHANG Zhongjie, CHEN Xiangying
Abstract (
1201 )
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In this work， POE?g?MAH as a compatibilizer of adhesive resin was prepared through extrusion with a twin?screw extruder using maleic anhydride （MAH） as a graft monomer， polyolefin elastomer （POE） as a matrix resin， and diisopropyl peroxide （BIBP） as an initiator. The effects of reaction temperature， screw speed and MAH amount on the melt flow rate and graft rate of this compatibilizer were investigated and its applications for adhesive resins were explored. The compatibilizer was characterized and analyzed using melt flow rate meter， Fourier transform infrared spectroscopy， and universal testing machine. An adhesive resin was further prepared through melt extrusion with the compatibilizer， matrix resin and related additives， and its mechanical properties were measured using universal testing machine. The results indicated that MAH was successfully grafted onto POE with the aid of odorless diisopropyl peroxide （BIBP） as an initiator. When 1 wt% MAH and 0.1 wt% BIBP were added， the graft rate of compatilizer reached 0.7 wt%， its melt flow rate reached 0.691 g/10 min.The adhesive resin exhibited tensile strength， elongation at break and peel strength of 14.8 MPa， 1031.1%， and 178 N/25mm， respectively， when 20 wt% compatibilizer was added into the adhesive resin.
Processing and Application
LIU Xiaorui, ZHAO Feng, WANG Xiumei, GUO Wei, MAO Huajie, YAN Hongxu, DENG Jingwen
Abstract (
559 )
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A self?designed mold was used to conduct hemispherical non?isothermal deep drawing tests for the double?layer glass?fiber?reinforced polypropylene composite unidirectional laminates. The effects of preheating temperature and drawing speed of composite unidirectional laminates on the thickness distribution and forming quality of the part were investigated through microscopic observation and other methods. The results indicated that an increase in preheating temperature resulted in the formation of the thinner laminates. The surface quality of the laminates was improved with an increase in drawing speed. The laminates presented cracks and delamination defects with a drawing speed of over 150 mm/min.
YU Shengrui, ZOU Jiayong, LUO Jie, ZENG Yihe, LIU Guang, LING Yan, WANG Yunming, HAN Wen, ZHOU Huamin
Abstract (
661 )
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636
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Taking the tensile test sample as an example， we investigated the effects of main process parameters on the warpage under molding condition of asymmetric temperature field in the process of microcellular foaming and in?mold decoration combined injection molding （MIM/IMD） using an orthogonal experimental design and flow simulation to obtain an optimal combination of process parameters with minimum warpage. The simulation results of four injection molding processes （MIM/IMD， IMD， MIM， CIM） were then compared in the directions of X， Y and Z axis， including the warpage variation in different directions of samples， cell size and density to explore the influence of the microporous structure and distribution on the warpage. The results indicated that the warpage reached the minimum and the warpage decreased by a maximum of 3.414 mm when the melt temperature， injection rate， filling/holding pressure （V/P） switch， supercritical N2 concentration， and cooling time we set as 210 °C， 55 cm3/s， 98 %， 0.2 wt%， 40 s， respectively. The application of microcellular foaming technology in the injection molding process can facilitate to reduce the warpage of the molded products. The asymmetric temperature field made the cell size and density greater those that in the non?film side. Moreover， the temperature in the film side was also higher than that in the non?film side. This made the shrink of sample in the film side slower than that in the non?film side. As a result， the unbalanced warpage in both sides of the sample tended to concave and curl towards the non?film side.
SUN Linjie, ZHANG Jingwei, CHEN Shushan, LAI Huansheng, WEI Zuoyou
Abstract (
646 )
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517
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To investigate the chlorine oxidation resistance of high density polyethylene （PE?HD） pipes， a closed cycle test system was designed on the basis of the ASTM F2263 standard. The test system accelerated the oxidation failure of samples through changing the temperature， pressure， and available chlorine content under the flowing condition. The results indicated that the system could measure the 24 DN 20 PE?HD tubular samples independently， and the programmable logic controller could be used as a control host to control the pressure， temperature， and flow of the pipelines. Furthermore， the visual human?computer interface could be realized through coupling with various sensors， and the built?in alarm system could ensure the safety and reliability of the test. Therefore， the test system can be used to evaluate the chlorine oxidation resistance of the PE?HD pipes.
NIU Xu, LIU Yue, ZHANG Yajing
Abstract (
609 )
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219
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The granulation template is one of the main parts of the granulation system. The internal graining template includes the heating channel and the material channel， and the internal flow media in the channel are thermal oil and polyethylene respectively. In this paper， we explored the uniformity of material extrusion velocity and particle size zone temperature distribution in the case of 0.01 m/s， 0.05 m/s， and 0.1 m/s when other conditions are consistent. The effect of the flow heat transmission process of thermal oil on the temperature and flow fields of the granulation template were investigated. The SolidWorks software was used to model the granulation template in a 3D form， and the ANSYS software was used to numerically simulate the flow and heat transmission of polymer and thermal oil. The temperature and fluid flow field distributions of the granulation template were obtained. The results indicated that the import speed of thermal oil generated a significant effect on the temperature field of the granulation template. The import speeds of thermal oil were 0.01 m/s， 0.05 m/s and 0.1m/s under the three conditions， and the extrusion speed of the material did not show a significant change. Moreover， the temperature differences of the granulation belt were 14.08 ℃， 7.14 ℃， and 5.39 ℃. The granulation belt exhibited the most uniform temperature distribution at 0.1 m/s for the thermal oil entrance.
PENG Xinlong, ZENG Yuqing, LIANG Zhuoen, XIE Yi
Abstract (
926 )
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The curing reaction process of epoxy/glass fiber prepregs for compression molding was studied using a dynamic DSC method. The curing kinetic parameters of the prepregs were obtained using the Kissinger′s and Crane′s methods， and the phenomenological curing kinetic model was established. The gelation time of the prepregs were obtained using a free rotor vulcanizer at different temperatures. The functional relationship between the curing temperature and gelation time was calculated through a linear fitting method， and the curing process of the prepregs was optimized. The results indicated that the apparent activation energy， pre?exponential factor， and the reaction order of the prepregs were calculated to be 89.9 kJ/mol， 1.17×1011 and 0.93， respectively， through the Kissinger and Crane methods. The epoxy resin exhibited a certain mobility when the molding temperature and preheating time were set as 150 ℃ and 40 s， respective. The composites presented optimal comprehensive properties after holding 300 s at a molding pressure of 2 MPa.
Additive
GAO Xinxin, JIANG Pingping, SHI Yimin, LENG Yan, ZHANG Pingbo
Abstract (
616 )
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Diethylene glycol ether maleate （MD） was prepared using maleic anhydride and diethylene glycol ether as raw materials without a catalyst， and its molecular structure was determined to be ester groups， ether bonds， and carbon?carbon double bonds. This intermediate product was respectively reacted with calcium acetate and zinc acetate to prepare diethylene glycol ether maleate calcium/zinc salt （MD?Ca/Zn）. The structure of the resultant product was further analyzed with FTIR spectroscopy， indicating that its molecule contains ether bond， ester group， carbon?carbon double bond， and carboxylate structure. This indicated that it could be used as a heat stabilizer for PVC. The thermal stabilizing effect of the MD?Ca/Zn was verified through the Congo red， thermal aging， thermogravimetry， electrical conductance measurements as well as the comparation the commercially available calcium/zinc stearate. Its thermal stabilization mechanism was analyzed and explored. Furthermore， the synergistic effect of the MD?Ca/Zn with an auxiliary heat stabilizer， β?diketone （stearoyl benzoyl methane）， was investigated. The results indicated that the PVC compound exhibited an optimal thermal stability at an MD?Ca/Zn mass ratio of 2∶1， and its initial whiteness and static stabilization time reached 40 min and 35 min， respectively. The thermal stability could be further improved by combination with 10 % β?diketone in the total amount of heat stabilizers.
HUANG Xubo, LIU Zhaogang, ZHAO Jingang, YANG Yuxuan, CHEN Mingguang, WU Jinxiu, HU Yanhong, FENG Fushan
Abstract (
555 )
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A new type of rare?earth heat stabilizer， lanthanum 2?benzoylbenzoate （LBA）， was synthesized and characte?rized with FTIR， thermal analysis， and elemental analysis. The results indicated that the molecular formula of lanthanum 2?benzoylbenzoate was determined to be La（C14H9O3）3·2H2O. The PVC compounds exhibited a heat?stabilization time of 16 min when using this complex heat stabilizer alone， indicating a general initial anti tarnishing effect. However， the PVC compounds presented excellent mechanical properties. When the mass ratio of the complex heat stabilizer to zinc stearate and pentaerythritol was set as 1∶1∶3， the thermal stability time rose to 58 min， and the PVC compounds exhibited optimal anti?tarnishing effect and mechanical properties. Lanthanum 2?benzoylbenzoate can absorb HCl gas from the thermal decomposition of PVC to form LaCl3， reducing the thermal degradation of PVC.
WANG Wenchao, WANG Yanzhi, ZHANG Zhenli, ZHANG Juliang, LIU Shaolei, WEI Bing
Abstract (
632 )
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444
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To solve the cracking problem of the PP filter plate and frame commonly used in China， the mechanical properties， thermal deformation temperature， crystallization behavior， and crystal morphology of the PP modified with a β?nucleating agent were investigated using differential scanning calorimetry and polarizing microscope. The results indicated that the tensile strength and modulus of PP decreased at first and then tended to increase with an increase in the β?nucleating agent content. Its elongation at break and impact strength also showed an increase at first and then a decrease. When 0.05 wt% β?nucleating agent was added， the β crystal in PP was nearly perfect， and the relative content of β crystal increased to 85.25 %. Meanwhile， the modified PP exhibited an increase in impact strength by 4 times compared to pure PP， and the losses in tensile strength and modulus were small. When the content of β?nucleating agent was 0.5 wt%， the modified PP showed a thermal deformation temperature by approximately 40 ℃ higher than pure PP.
Plastic and Environment
WANG Zhiqin, LI Hui, ZHU Bingyu, CHEN Chang
Abstract (
1110 )
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The waste plastic films used in agricultural production was recycled mechanically or manually. These recycled films were further made into particles through cleaning， modification， and other technological processes. According to the proportion of 10 wt%~50 wt%， the recycled material were used in the manufacturing of pipes and woven bags （cloth）， boards with straw， the production of manhole covers or the refining of gasoline and diesel.
Standard and Test
CHANG Hao, YANG Zhenghao, WEI Yougong, CHAI Guang, LI Yanzhou
Abstract (
570 )
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Aiming at the problem that the film ruptures due to too high or too low temperature in the incubator during film processing without real time detection due to the high temperature and structural obscuration of the incubator， an image detection technology was proposed by a combination with the current machine vision method. This rupture image detection technology can effectively monitor the rupture of the film and reduce the production loss. In the study of the image processing methods for the rupture area of ??the transversely stretched film， the common image enhancement， denoising， and edge segmentation techniques were analyzed comparatively. The preprocessing and segmentation methods suitable for the ruptured image of the transversely stretched film were determined. Through the analysis and comparison of the film rupture images， the rupture modes were divided into the small?scale rupture and longitudinal rupture according to the rupture form， and the visual recognition characteristic parameters for distinguishing the two rupture modes by area and circumference were discovered. These parameters played a positive role in the adjustment of the processing temperature. The experimental results indicated that the proposed detection technology could accurately determine the form of film rupture with an accuracy rate of 92.7 %， which can meet the requirement of industrial production.
Machinery and Mould
WU Junchao
Abstract (
901 )
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1133
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Taking a large plastic car dashboard as an example， the CAE analysis software Moldflow was used to analyze the optimal gate position of multiple gates. The orthogonal experiment scheme was established with the warpage deformation as a main analysis index， and the optimal process combination was obtained through analysis and comparison. Based on the simulation analysis of the analysis model， the excessive warpage deformation and welding marks on the surface were found to become the main defects. The uneven shrinkage， orientation effect， and uneven cooling were considered as the main reasons for the excessive warpage deformation. Through using a sequential valve gate technology， the gating system， cooling system， and related process parameters were optimized， the obvious weld marks on the appearance surface were basically eliminated， and the amount of warping deformation could meet the production requirements of enterprose. Finally， the optimized process parameters and mold structure were obtained. The research results indicated that the use of Moldflow for the CAE analysis of large plastic parts could effectively shorten the design cycle， improve the molding quality of large plastic parts， and reduce production costs.
SUN Lingzhen, YE Shuo
Abstract (
789 )
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Aiming at the problem that the split air conditioning chassis is easy to fracture and deform during injection production， an injection mold with a simple structure and a reliable operation was developed. According to the structure of the air conditioning chassis， the combined slider structure was adopted to solve the demolding problem of the air outlet and the upper stud of the air outlet. The demolding structure of sliding block plus horizontal inclined top was adopted to solve the problem that the central axis of the air guide plate hole in the middle could not stay on the same line with that of the air guide plate hole at both ends. The demolding structure of inclined core pulling plus slider and cylinder was adopted to solve the problem that the drainage hole of chassis was easy to produce the edge. A damping spring was installed on the inclined guide pillar slider. This can effectively overcome the impact of the slider on other mold parts when opening and closing the mold. The inclined top seat of the fixed mold inclined top was installed on the hot runner electrical parts plate. This makes the two plate molds have the characteristics of the three plate molds， and the demolding problem of the fixed mold inclined top is solved. A reinforcing rod was installed on the inclined top of the fixed mold to effectively avoid the deformation of the inclined top of the fixed mold.
Review
LIU Shaoshuai, RAN Qidi, HUANG Jianwen, LI Jinlong, ZHANG Shiqi, ZHU Kai, GONG Xinchao, CAO Kun
Abstract (
972 )
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2149
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The modification methods and foaming process of polyethylene terephthalate （PET） were reviewed. The modification methods include solid state polycondensation， in?situ copolymerization， and chain extension modification， and the foaming processes mostly involves autoclave foaming， molded?press foaming， extrusion foaming， etc. Moreover， the applications of PET foaming materials were briefly introduced.
YANG Xiaolong, LI Yongqing, YAN Xiaokun, CHEN Wenjing, MA Xiuqing
Abstract (
681 )
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912
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The permeation theory of small gas molecules and gas barrier model were introduced. The preparation methods of gas barrier graphene/polymer composites and the characterization methods of gas barrier properties were reviewed. The main factors affecting the gas barrier properties of the graphene/polymer composites and the corresponding improvement measures were analyzed and summarized. The future research directions were also prospected.
FANG Yunfeng, MA Biao, WANG Xiaoqing, KANG Xingxiang, TANG Yuting
Abstract (
1575 )
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1890
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31 )
Based on the above advantages， single?component epoxy materials have become the current research hotspot in the field of epoxy resins. In view of this situation， this article summarized the curing agents for one?component epoxy resins at home and abroad and introduced the curing agents for the latent one?component epoxy resins， including the heating?type， wet?type， light?type， and microcapsule?type epoxy resins. A detailed overview of its preparation and synthesis methods and curing mechanism was performed， and the problems of the curing agent for one?component epoxy resin were pointed out. These can further clarify the research ideas at the next stage.
WANG Suwei, ZHANG Wenxin, XUE Ping, ZHANG Guangpu, HU Yubing, JIANG Wei
Abstract (
616 )
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697
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To solve the problem of significant difference between the actual strength and theoretical strength of polymer， the solid?state molding technology was investigated， and the self?reinforcing process characteristics of solid?state extrusion， solid?state drawing and other technologies were described in detail， which could effectively improve the mechanical strength of polymer?based composites without any reinforcement elements. Moreover， the self?reinforcing mechanism of materials was further studied through analyzing the morphology and molecular configuration of samples during the solid?state deformation. Finally， the factors affecting the reinforcement of process were summarized to explore the upper performance limit of composites and broaden the high?performance applications of self?reinforced materials in different fields.
