Materials and Properties
Tianhao GUO, Yiquan LU, Tao LIU, Ling ZHAO
Abstract (
872 )
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A series of long?chain branched PP compounds were prepared by double?monomer reactive extrusion of conventional isotactic polypropylene with pentaerythriol triacrylate (PETA) and Styrene (St), their faomability was characterized with FTIR, DSC and rheology tests, and their foam structure was observed with SEM. The results indicated that for the modified PP samples without crosslinking structure, the PP compound with 2 wt% of PETA and 3 wt% of St exhibited the optimum comprehensive performance. Meanwhile, the PP compounds showed a different strain hardening behaviors because of the different branching structure. The batch melt foaming experiment was conducted to evaluate the melt foamability of PP compounds with CO2 as the foaming agent. It was found that the PP compounds with a long branching structure had a better melt foamability, and the the PP samples showed a foaming window temperature of 25 ℃ after grafted with PETA/St double monomers. The resulting PP foams achieved a maximum expansion ratio of 33, an average diameter of 36 μm, and a cell density of 3.17×108 cells/cm3.
Wenqian KANG, Zongli MA, Yulin GAO, Xiong WANG, Bao YANG, Gongchen YAN
Abstract (
744 )
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The structure of heat?resistant polypropylene special material (H8020) was characterized by gel permeation chromatography, temperature rising elution fractionation, differential scanning calorimetry and X?ray diffractometer, and its mechanical and heat?resistant properties were investigated by melting flow rate instrument, universal material testing machine, pendulum machine and thermal deformation & Vicat softening temperature tester. The results indicated that the heat?resistant polypropylene exhibited the flexural strength of 39.4 MPa, the flexural modulus of 1 820 MPa, the tensile strength of 37.5 MPa and the izod impact strength of 3.2 kJ/m2, presenting a good balance between rigidity and toughness. Moreover, this special material also showed a thermal deformation temperature of 115 °C and a Vicat softening temperature of 158 °C. It is concluded that the comprehensive performance of the domestic product H8020 is superior to that of foreign products.
Baolei CHEN, Tifeng JIA, Zhongshang ZHOU, Tiekun GUO
Abstract (
656 )
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Monomer?casting polyamide 6 (MCPA), the glass fiber?reinforced MCPA (GMCPA) at a fiber content of 30 wt% and the carbon fiber?reinforced MCPA (CFMCPA) at a fiber content of 35 vol% were prepared, and their friction and wear properties were investigated under the four wearing conditions of dry friction, clean water, dry sand and water sand. The results indicated that the friction coefficient of samples presented a decrease trend by the order of CFMCPA < GFMCPA < MCPA under the conditions of dry friction and clean water and by the order of MCPA < CFMCPA < GFMCPA under the conditions of dry sand and water sand. For the same sample under different conditions, its friction coefficient exhibits a drop by the order of clean water < water sand < dry friction < dry sand, and its shows an increase trend by the order of dry friction < clean water < water sand < dry sand. However, for the different samples under the same condition, their volumetric wear rates decrease by the order of GFMCPA < CFMCPA < MCPA. The experimental results demonstrated that the friction and wear properties of these three samples had their own characteristics under the four wearing conditions, and they could be used according to the specific requirement for their performance.
Xinyu SONG, Yunxuan WENG, Caili ZHANG, Zhigang HUANG
Abstract (
890 )
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455
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In this work, polylactic acid (PLA)/bamboo flour (BF) composites were prepared by a XSS?300 torque rheometer using ethylene octene copolymer grafted with glycidyl methacrylate (POE?g?GMA) as a compatibilizer and TPW604 as a lubricant. The effects of addition amounts of BF, POE?GMA and TPW604 on the tensile and impact properties, thermal stability, morphology and rheological properties of PLA/BF composites were investigated in details. The results indicated that the composites exhibited the optimum mechanical properties at the BF content of 35 phr, the POE?g?GMA content of 10 phr, and the TPW604 content of 1 phr, and meanwhile their compatibility and fluidity of were also improved significantly.
Jie YING, Qihao QIU, Haojie ZHANG, Hainan GU, Hao ZHOU
Abstract (
673 )
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This paper reported an investigation on the effects of five types of toughening agents on the mechanical properties, heat deformation temperature and melting flow rate of polycarbonate (PC). Moreover, the influences of these toughening agents on the thermal oxidative aging properties, water?boiling performance at 70 °C, and hygrothermal aging performance of modified PC were studied. The results indicated that the addition of toughening agent coudl improve the impact toughness of PC. The S2001 and MR?502 exhibited a better enhancement effect in thermal oxygen aging performance than M?577, M?732 and M?722. However, M?732, M?577 and MR502 have a better enhancement effect in water?boiling and hygrothermal aging performance than S2001 and M?722.
Yu ZU, Yanan REN, Jing HU
Abstract (
708 )
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461
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A series of polylactic acid (PLA)/poly(3?hydroxybutyric acid?co?3?hydroxyvalate) (PHBV), PLA/PHBV/styrene?methacrylate glycidyl copolymer (ADR) and PLA/PHBV/tributyl citrate (TBC) blends were prepared by a melt blending method, and the standard test bars were prepared by injection molding and fused deposition molding (FDM) techniques. The effects of ADR and TBC as modifiers on the thermal and mechanical properties of PLA/PHBV blends and 3D?printed specimens were investigated. The results indicated that the crystallinity of PHBV was decreased, and the injection?molded sample with ADR exhibited the maximum elongation at break with an increment rate of 32 %. Moreover, the incorporation of TBC also improved the tensile strength and impact strength of the injection?molded sample, and its elongation at break increased by 2.8 %. The 3D?printed specimens presented a decrease in tensile strength but an increase in elongation at break due to the introduction of ADR. Meanwhile, the compatibility of 3D?printed specimens was improved significantly in the presence of TBC. There was no obvious particle phase observed from SEM, and the tensile strength of blends did not change significantly after the modification.
Can JIANG, Peng CHEN, Shuo HAN, Shihong CHEN, Zhiyin YE, Xiangdong WANG
Abstract (
707 )
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Polyethylene terephthalate (PET)/polyamide 6 (PA6)/Surlyn composites and PET/ pyromellitic dianhydride (PMDA)/Surlyn composites were prepared by a melt blending method. The effects of Surlyn on morphology of composites, crystallization and rheological behavior of PET were investigated. The morphology of PET/PA6/Surlyn composites were observed by scanning electron microscope (SEM), and the result showed that Surlyn could decrease the diameter of PA6 dispersion phase particles and improve the compatibility of PET and PA6 phase. A rotational rheometer and a differential scanning calorimeter (DSC) was used to study the rheological and crystallization behavior of PET. And the result indicated that Surlyn could enhance the melt strength of PET/PA6/Surlyn composites significantly. Moreover, Surlyn could act as nucleating agent in PET/PA6/Surlyn composites to promote the crystallization temperature and accelerate the crystallization rate of PET considerably. And the rheological and crystallization properties of PET were improved. While Surlyn has no significant effects on the crystallization behavior of the PET that chain extended by PMDA.
Processing and Application
Yanghui WANG, Yulu MA, Linsheng XIE, Guo SONG, Huihao ZHU
Abstract (
779 )
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369
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On the basis of the research of the thermal conduction process of high?filled modified composites, the thermally conductive prediction model for high?filled modified composites which considering the effect of the interfacial thermal resistance at the same time was established based on the series?parallel/parallel?series model. Polypropylene/alumina （PP/Al2O3） composites with two types of alumina particle sizes under different loadings were prepared by a two?rotor continuous mixer. The thermal conductivity of the composites was characterized by a laser thermal conductivity instrument and then was compared with the model prediction results. The results show that: The established model has higher accuracy in predicting the thermal conductivity of the highly filled composites. The interfacial thermal resistance factor in the model is highest when the alumina loading is low; the factor significantly reduce as the alumina loading reaches to a certain level; finally, the factor remains stable when the alumina loading continues to increase. The interfacial thermal resistance of the same filled and modified composite prepared by the same preparation process under high filling capacity is approximately the same.
Dawei WANG, Longhui LI, Ji FU, Zhihao LIU, Jiaxu QIN, Tianchun ZOU
Abstract (
683 )
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383
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A series of specimens were fabricated by using a single lap adhesive connection of aramid fiber composite material with titanium alloy, and the ultimate load, stress field strain distribution and failure mode of the bonded joints were characterized with a universal testing machine, DIC and strain acquisition system. The strain distribution of bonded joints under tensile load and the stiffness reduction law of composite laminates were analyzed. Moreover, the failure process of single lap adhesive joints of dissimilar materials was also studied. The results indicated that the failure modes of bonded joints were ascribed to the adhesive interfacial failure at the two ends of overlap region and the composite delamination failure in the middle part. When the joint was under the load, the composite end was subject to the large shear strain, which led to the cracks occurring at the composite end and then continuously expanding to the metal end. The entire failure process of the joint belongs to a progressive failure. The stiffness of composite was continuously reduced with the propagation of cracks until the adhesive failure suddenly took place due to the small area.
Zhinan DONG, Fengxiang XU, Wei GUO, Lin HUA, Jianjun SU
Abstract (
753 )
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550
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This paper reported an investigation on the mechanical properties of opening plate injection?molded by short?fiber?reinforced thermoplastic composites by means of the Mori?Tanaka homogenization method. The Mori?Tanaka method was adopted to predict the stress?strain curves of the composites in both unidirectional and two?dimensional distributions, and then the effect of fiber orientation on the mechanical properties of the opening plate were analyzed by experimental methods. Finally, a multi?scale method was used to study the effects of different injection positions and different opening methods on the mechanical properties of the opening plate. This study was coupled with the fiber direction distribution of the injection molding simulation and the material parameters obtained by the Mori?Tanaka homogenization method in the macroscopic finite element analysis. The results indicated that the opening plate molded by short?side injection exhibited better comprehensive mechanical properties, and the fiber distribution around the hole was the main factor affecting the stress concentration. The overall fiber orientation distribution influenced the stiffness of the opening plate, and however there is a complicated influence from the angle of unidirectional fiber?reinforced composites on the material properties.
Sha LI, Jiayu ZHAN, Yanjun LI, Zhenxin LIU, Feihua YANG
Abstract (
556 )
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384
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This paper reported a study on the total lead leaching and relevant mechanisms of three PVC?U drainpipes products with a lead stabilizer at different time, temperature and pH value. The results indicated that the leaching law was consistent for these three types of products, which presented an increase trend in the leaching amount of lead at first and then a decrease trend with the time. The leaching amount of lead reached a maximum value at the time of 4 h. The temperature also influenced the leaching amount of lead significantly. Moreover, the leaching amount of lead in the strong acid environment is greater than that in the strong alkaline environment, the products showed a minimum leaching amount in the partial alkaline environment.
Additive
Jing YU, Minxian LI
Abstract (
688 )
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412
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A piperazinyl monobutyric amic acid calcium/Zinc (PSACa/Zn) thermal stabilizer was synthesized by a two?step reaction using succinic anhydride, piperazine, calcium chloride and zinc chloride as raw materials, and its chemical structure of the synthesized product was characterized by elemental analysis, inductively coupled plasma atomic emission spectrometry and Fourier?transform infrared spectroscopy. The thermal stabilization effect of PSACa/Zn on PVC was investigated by a Congo red paper method, torque rheometer and thermogravimetric analysis (TGA), and an optimum mass ratio of PSACa/PSAZn was achieved. The results indicated that the static thermal stability time of PVC modified with PSACa and PSAZn reached 74.5 and 41.5 min, respectively, which was better than the stabilization effect of calcium stearate and zinc stearate. With the combination of PSACa and PSAZn (mPSACa∶mPSAZn = 1∶1), the modified PVC exhibit a static thermal stabilization time of 92 min, and a dynamic thermal stabilization time of 905 s. PSACa/Zn has a long?term thermal stabilization effect on PVC according to the thermal analysis result.
Standard and Test
Jin ZHANG, Hong JIANG, Jingshun ZHANG, Feng LIU, Bin DUAN
Abstract (
609 )
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In order to establish a fast, accurate and non?destructive method for distinguishing the sneaker soles, a differential Raman spectrometer combined with cluster analysis was used to examine the sole samples obtained from 40 different brands and different series of white sports shoes. The experimental results indicated that these samples could be divided into five categories according to the different main components of the sole samples. The same types of samples could be grouped according to the different main filler components added in the sole materials, and the same group of samples could be distinguished based on different relative peak height ratios of characteristic peaks. The data from these samples was processed by a cluster analysis method. When the parallel distance was 2, the samples were divided into five categories with an ideal classification result. This method was found to be simple and quick for operation, the obtained results were accurate and reliable, and there was no destruction in the inspected materials. The method developed by this work can provide help for police offices to handle the criminal cases.
Jianqiao SUN, Xiaoping LIU, Zhenhua LIU, Fengjin LI
Abstract (
666 )
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522
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This paper reported the analysis and research of the important performance indexes of MIL?PRF?81705E Barrier Materials, which included flexible, electrostatic discharge protective and heat?sealable properties. the paper also analyzes and compares the US military standard with the corresponding Chinese national standards, and proposed the recommendation for the application of this standard.
Machinery and Mould
Yinglong FU, Mingchao SHAO
Abstract (
796 )
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397
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According to the characteristics of plastic parts, a single?parting surface and hot?runner mold with one module and one cavity was designed by using the UG software. For the lateral demolding products easy to generate some problems like deformation and the limitation in mold space distance, we designed an ejector in the small slider and a hydraulic core?pulling mechanism with small sliders on the top of big sliders, and emphatically analyzed the key points for the design of each system in the mold. The practice production proved that the structural design of the mold were reasonable and advanced to realize the automatic production of products, and all of performance index could meet the requirements for the plastic parts.
Qiuhe YANG, An YANG
Abstract (
1064 )
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570
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In view of the difficulties in the design of the forming mold for the vane plastic part of the micro centrifugal pump, an improved three?plate point?gate mold was designed for the forming of the vane plastic part of the pump. In order to control the deformation of the plastic part, a three?point gate was adopted to balance the injection molding. The mold cavity was arranged in one mold and one cavity. In view of the difficulty of demolding in the groove area of plastic parts, a three?layer and three?time composite core pulling demolding system was designed to demold the characteristic module of the groove part. In this mechanism, after the forming block with the characteristic module of the groove part was divided into two layers of forming parts, the first core pulling action of the mechanism was driven by the spring and the upper slider to implement the core pulling of the upper forming block, and then the second core pulling action of the mechanism was driven by the inclined guide pillar. Finally, the two side core pulling sliders were driven by the base slide block driven by the bending pin to pull out the core so as to make the moving space of the plastic part completely ejected from the demolding. The driving forces of the second core pulling and the third core pulling were driven by the third and fourth mold opening of the mold base template, respectively. The final demolding of the plastic part was realized by the cylinder driving the ejector pin plate and the ejector rod. Based on the action needs of the plastic part, runner demolding and core pulling mechanism, the typical three?plate point?gate mold base was modified to a four?plate four?time opening point gate. In this case, the core pulling demolding could be carried out by the plastic part, runner waste and driving slider mechanism in sequence. The action setting of mold demolding mechanism is found to be reasonable, the design of mechanism structure is ingenious, and the overall work of mold is reliable, which can become a good reference for mold design.
Review
Dagang ZHUO, Shengli XIE
Abstract (
1073 )
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The current situation of agricultural film industry in China was analyzed in terms of from the market perspective, and its development strategy was proposed. In 2020，the total usage of agricultural films including greenhouse films and much films in China was about 2 200 kt. In view of the problems existing in the industry, some solutions were put forward to promote the healthy development of agricultural film industry.
Jinyu LI, Yajie DAI, Yu CHEN, Tongbing SUN
Abstract (
954 )
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This paper reviewed the latest research progress in synthesis and applications of polyester plasticizers at home and abroad, which mainly focused on the synthesis and preparation methods of hyperbranched, bio?based, and petroleum?based polyester plasticizers. The paper also introduced the latest research progress in the applications of the different types of polyester plasticizers for poly(vinyl chloride), starch, polylactic acid, polyurethane elastomers and rubber products. Finally, the development direction of polyester plasticizers in future was prospected.
