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2017, Volume 31 Issue 08 Publication date: 26 August 2017 Previous Issue Next Issue

Research Progresses in Branched Polyamide 6

2017, 31 (08): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2017.08.001

Abstract ( 422 )

This paper reviewed the research progresses in branched polyamide 6 including starbranched, random branched and hyperbranched structures,and mainly introduced the preparation, properties and application of three kinds of branched polyamide 6, and also compared various technologies for characterization of long chain branching. The development trend of branched polyamide 6 was prospected.

Patent Situation Analysis in Polyimide Industry

2017, 31 (08): 7-17 ; DOI: 10.19491/j.issn.1001-9278.2017.08.002

Abstract ( 285 )

This article statistically analyzed the current patent situation in the field of polyimide industry on the basis of the trends and regional distributions of patent application, technical topics, and the status of principal applicants. Moreover, the product features and applications as well as the relevant patent information obtained from the major global polyimide manufacturers were presented.

Research Progresses in Conductive Carbon-based Polymeric Composites with Dual-percolation Threshold

2017, 31 (08): 18-23 ; DOI: 10.19491/j.issn.1001-9278.2017.08.003

Abstract ( 401 )

This paper introduced the mechanisms of percolation and dualpercolation thresholds for conductive carbon-based polymeric composites and reviewed the research progresses in the conductive polymeric composites with a dual-percolation threshold, in which carbon materials mainly including carbon black and carbon nanotubes were used as conductive fillers. The development trend of conductive polymeric composites with dual-percolation threshold was prospected.

Study on Chain Extension and Flame Retardancy of Poly(lactic acid) with Modified Silica Molecular Sieves

2017, 31 (08): 24-29 ; DOI: 10.19491/j.issn.1001-9278.2017.08.004

Abstract ( 462 )

In this paper, mesoporous silica molecular sieve, SBA-15, was surface modified by reacting with a silicon coupling agent, and then its structure was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction and scanning electron microscopy. The results indicated that the framework structure of molecular sieve was well maintained and the amino groups were grafted on the molecular sieve through covalent bonding. When 0.5 wt % of modified silica molecular sieve was added into poly(lactic acid) (PLA), the complex viscosity and storage modulus of PLA increased significantly. This suggests that the molecular sieve performed an effective chain extension for PLA. Moreover, the chain-extended PLA exhibits a decrease in cold crystallization temperature, indicating a better crystallization capability. Furthermore, its release rates of carbon oxygen and heat were also reduced as a result of the enhancement of flame retardancy.

Study on Properties of Irradiation-crosslinked Flame-retardant Polyolefin Containing Modified Pentaerythritol

2017, 31 (08): 30-34 ; DOI: 10.19491/j.issn.1001-9278.2017.08.005

Abstract ( 424 )

Irradiation-crosslinked polyolefin composites were prepared by ethylene-vinyl acetate copolymer with intumescent flame retardant （IFR）of modified pentaerythritol as charforming agent through melt blending, and their flame retardant performance, electrical properties and thermal stability were investigated by limiting oxygen index, high resistance meter, breakdown tester and thermogravimetic analysis. The results indicated that, when 40 wt % of the complex flame retardants was introduced and the irradiation dose was less than 90 kGy, the resulting EVA/IFR-MPER systems achieved an improvement in flame retardancy by 1.5 %. Furthermore, their breakdown field strength, volume resistivity, maximum decomposition temperature and carbon yield at 600 ℃ increased by 2.2 MV/m, 0.6×1013 Ω·m, 4.43 ℃ and 8.52 %, respectively.

Preparation of FGO-WPUPA Barrier Coating and Its Effect on Oxygen Barrier Performance of PLA Film

2017, 31 (08): 35-40 ; DOI: 10.19491/j.issn.1001-9278.2017.08.006

Abstract ( 483 )

Graphene oxide/waterborne polyurethane acrylic (GO-WPUPA) and silane coupling treated graphene oxide/waterborne polyurethane acrylic (FGO-WPUPA) barrier coatings were prepared and then coated on the surface of poly(lactic acid) (PLA) films. An investigation on the oxygen barrier performance was conducted toward these coated PLA films. The results indicated that FGO-WPUPA coating was more effective for the improvement of oxygen barrier performance than GO-WPUPA. The addition of a small amount of FGO into WPUPA can significantly reduce the oxygen transmission rate of PLA film. When 0.5 wt % of FGO was added, the oxygen transmission rate was reduced to 234 cm3/（m2·24 h） for the film coated by 0.5 % of FGO-WPUPA coating. This resulted in a decrease by 42 % in comparation with pristine PLA film. An optimal content of FGO in the coating was determined as 1.0 wt %, and meanwhile, the optimal thickness of FGO-WPUPA barrier coating could be determined as 45 μm. With such optimal conditions, the oxygen transmission rate of the films was reduced by 51.6 % compared with pristine PLA film.

Preparation and Performance of Poly(vinyl alcohol)/Graphite Nanoplatelet Composite Films

2017, 31 (08): 41-46 ; DOI: 10.19491/j.issn.1001-9278.2017.08.007

Abstract ( 300 )

In this work, graphite nanoplatelets (GNP) were prepared by the ultrasonic exfoliation of expanded graphite in distilled water, and then poly(vinyl alcohol) (PVA)/GNP composite films were prepared by a solution casting method using the mixture of PVA and GNP. The effects of GNP content and its dispersion in PVA matrix on the structure and properties of the composite films were investigated by means of scanning electron microscopy, resistivity tester and universal material tester. The results indicated that the graphite had been well exfoliated into GNP with a high diameter-to-thickness ratio and also well dispersed in the matrix. The volume resistivity and water resistance of the composite films decreased continuously with an increase of GNP content, whereas their mechanical properties exhibited an increase at first and then tended to decrease. Most of all, the composite films containing 2 wt % GNP achieved the optimum performance. Its volume resistivity was reduced to 108 Ω·cm as an electrical percolation threshold and its tensile strength was improved to 7.34 MPa. Meanwhile, its water contact angle increased from 56.3 ° to 97.9 °, indicating better water resistance and hydrophilic properties in comparison with pure PVA.

Preparation and Properties of Poly(methyl methacrylate)/ZnO Nanocomposites

2017, 31 (08): 47-51 ; DOI: 10.19491/j.issn.1001-9278.2017.08.008

Abstract ( 371 )

In this work, ZnO nanoparticles were synthesized by liquid phase precipitation and then modified with a titanate coupling agent. Poly(methyl methacrylate) (PMMA)/ZnO nanocomposites were prepared by solvent mixing of surfacemodified ZnO nanoparticles with PMMA. The resulting nanocomposites were analyzed by Fourier-transform infrared spectroscopy and scanning electron microscopy. The effect of ZnO content on the surface hardness, optical performance, thermal properties and solvent resistance was investigated. The results indicated that the surface-modified ZnO nanoparticles were well dispersed in PMMA, and the surface hardness of the nanocomposites increased with increasing ZnO content at first and then tended to decrease. The addition of ZnO nanoparticles enhanced the heat resistance and thermal stability of the nanocomposites. The ultraviolet shielding performance and solvent resistance of the nanocomposites were improved remarkably with an increase of ZnO content, and however, their visible light transmittance did not seem to decrease significantly.

Study on Termite-resistant Polyethylene Gas Pipes

2017, 31 (08): 52-55 ; DOI: 10.19491/j.issn.1001-9278.2017.08.009

Abstract ( 423 )

In this work, termite-resistant gas pipes were manufactured by using four types of polyethylene (PE) and two types of polypropylene (PP) and their resistance to termite damage was investigated intensively. Effects of coextrusion technology and adhesion modifiers on peel strength of PP protection layer were also evaluated. The results indicated that damage level of the pipes by termites reached 3 when being prepared by using PE, but it could reach 1 by using PP protection layer with a shore hardness of 73.5. The step-by-step coextrusion technology was considered as an optimum choice for the preparation of termite-resistant gas pipes. The peel strength of the protection layer increased with an increase of the content of the adhesion modifier, and it reached an optimum value when more than 3 phr of adhesion modifier was added into the protection layer.

Study on Compatibilization of PHBH/PLA Blends

2017, 31 (08): 56-61 ; DOI: 10.19491/j.issn.1001-9278.2017.08.010

Abstract ( 282 )

Poly(3-hydroxybutyrate-3-hydroxyhexanoate)/poly(lactic acid) (PHBH/PLA=80/20) blends were prepared via a melt blending method by using poly(ethylene oxide) (PEO), styrene-glycidyl methacrylate copolymer (REC), ethylene-co-glycidyl methacrylate (E-GMA), ethylenemethyl acrylateglycidyl methacrylate terpolymer (E-MA-GMA) and maleic-anhydride-grafted poly(lactic acid) (PLA-g-MAH) as compatiblizers. Mechanical properties, morphology and thermal properties of the blends were characterized by differential scanning calorimetry, dynamic thermomechanical analyzer, scanning electron microscopy and universal testing machine. The compatibility of PHBH/PLA was evaluated, and the effect of the compatibilizers on their compatibility was investigated. The results indicated that the effect of the compatibility was better with addition of REC or PLA-g-MAH, and the presence of REC or PLA-g-MAH reduced the difference between the glasstransition temperatures of PHBH and PLA and also reduced the particle size of dispersed phase with a more uniform distribution in the blends. Moreover, at a content of 4 wt % of REC or PLA-g-MAH,the impact strength increased by 43.8 % and 53.6 %,and the elongation at break increased by 100 % and 120 %, respectively.

Two-dimensional Fractal Characteristic of Fractography of Polypropylene/Diatomite Composites

2017, 31 (08): 62-67 ; DOI: 10.19491/j.issn.1001-9278.2017.08.011

Abstract ( 365 )

Two types of polypropylene (PP)/diatomate composites, PP/281 and PP/700, were prepared via melt blending, their impact strength (σⅣ) was evaluated by impact tests, and their fractography obtained from impact testing was observed by scanning electron microscopy. The profile curve of the fractography was extracted by an Image Pro-Plus image processing software, and their fractal dimension (DL) was calculated by a structure function method. The relationship between DL and σⅣ was investigated intensively. The results indicated that the fracture of PP and its composites with diatomate exhibit an evident fractal feature, and DL was in the range of 1.6474～1.7361, which could be used to characterize the fractography of PP/Diatomate composites quantitatively. PP/281 composites had a maximum DL of 1.7361 at a filling fraction (φf) of 10 vol %, whereas PP/700 composites showed a maximum DL of 1.7143 at the φf of 5 vol %. The relationship between DL and σⅣ had a positive correlation and was exponential.

Study on Prevention of Fiber-floating Phenomenon on Injection-molded PP Parts with Graphite-assisted Rapid Heat Cycle Molding Technology

2017, 31 (08): 68-72 ; DOI: 10.19491/j.issn.1001-9278.2017.08.012

Abstract ( 590 )

A temperature control for mold cavities was realized during injection-molding process by a graphene-assisted rapid heat cycle molding technology, and an intensive investigation indicated that the improvement of the surface temperature of mold cavities could reduce the temperature difference between mold surface and melt, and also resulted in a decrease in heat exchange. This made the melt have a low viscosity and prevented glass fiber depositing on mold surface when cooled. In this case, the glass fiber-floating phenomenon on the surface of injection-mold parts could be well prevented. Fiber-floating defects could be completely eliminated when temperature of the mold cavities was set to 120 ℃.

Production and Application of Facilely Processible Type PE-mLLD—EZP2010HA

2017, 31 (08): 73-78 ; DOI: 10.19491/j.issn.1001-9278.2017.08.013

Abstract ( 717 )

This paper introduced the production status of a facilely processible type of metallocene polyethylene resin (PE-mLLD, EZP2010HA) developed by the 600,000-ton grade production facility of high-density polyethylene. A comparative investigation on physical and thermal properties as well as microstructures was conducted on EZP2010HA, Ziegler-Natta-catalyzed PE and imported metallocene PE. A processing experiment was carried out for EZP2010HA in terms of different formulations. The results indicated that EZP2010HA had a wider molecular weight distribution and better mechanical properties than imported metallocene PE. By use of EZP2010HA, the resulting film can achieve the enhanced mechanical and optical performance, and its properties meet the requirement of Chinese standard GB 4455—2006.

Simulation Analysis of Heat Balance of Rollers During Continuous Injection Direct Rolling Process

2017, 31 (08): 79-83 ; DOI: 10.19491/j.issn.1001-9278.2017.08.014

Abstract ( 289 )

A theoretical model for heat balance of rollers during the continuous injection direct rolling process was established according to basic heat transfer theory, and then a simulation analysis was performed for heat balance of the roller. The results indicated that the heat transfer oil could reach the branch pipe in contact with the inner surface of the roller sleeve at a certain inlet flow rate, and no dead point was found. The flow rates kept uniformity from the inlet to the far ends of various tributaries. The temperature of roller surface was homogeneous with a deviation of 3 ℃ after the heat transfer oil was passed through. The design of oil channels is reasonable, and it can effectively adjust the temperature of the rollers.

Study on Mechanical Behaviors of Thermoplastic Materials Used for Automobile Rear Door Panels

2017, 31 (08): 84-87 ; DOI: 10.19491/j.issn.1001-9278.2017.08.015

Abstract ( 336 )

In order to develop a type of thermoplastic materials used for automobile rear door panels, a polypropylene (PP)-based composite was prepared via melt blending by using POE as an impact modifier and talcum powders as an inorganic filler. Effects of stain speed and test temperature on tensile strength and effect of talcum content on mechanical properties and linear expansion coefficient were investigated extensively. The results indicated that tensile strength of the composites increased with an increase of strain rate, but the elongation at break showed an increase at first and then tended to decrease. On the other hand, the tensile strength decreased with increasing test temperature. With increasing content of talcum powders the flexural modulus increased, the impact strength decreased, and linear expansion coefficients also decreased. The optimum content of talcum powders in this material was determined as 20 wt % when being used for automobile rear door panels.

Simulation Study on Interfacial Friction Heat Generation of Ultrasonically Plasticized Amorphous Polymer Particles

2017, 31 (08): 88-93 ; DOI: 10.19491/j.issn.1001-9278.2017.08.016

Abstract ( 246 )

In order to analyze the interfacial friction heat generation process of ultrasonically plasticized polymer particles and effect of ultrasonic plasticization parameters on interfacial friction heat generation rate, both LS-DYNA and Ansys software were used to simulate the interfacial friction heat generation process. The results indicated that the increase of ultrasonic frequency, ultrasonic amplitude and plasticized pressure can significantly improve the interfacial friction heat generation rate of polymer particles, but the effect of ultrasonic amplitude on the interfacial friction heat generation rate was more significant. When the processing conditions were set to an ultrasonic amplitude of 20 μm, an ultrasonic frequency of 30 kHz and a plasticized pressure of 0.8 kN, the local temperature of the polymer was improved to 224.5 ℃ at 0.05278 seconds and the heat generation rate reached 3874.5 ℃/s. In this case, the friction heat generation was considered as a transient process.

Synthesis and Application of Caged-shaped Trimethyl Silicate Thio PEPA Ester Flame Retardant

2017, 31 (08): 94-99 ; DOI: 10.19491/j.issn.1001-9278.2017.08.017

Abstract ( 346 )

A new flame retardant, trimethyl silicate-1-thiophospha-2,6,7-trioxabicyclo［2.2.2］ octyl-4-methyl ester (TMSSPE), was synthesized by the reaction of trimethyl chlorosilane(TMCS) with 1-thiophospha-4-hydroxymethyl-2,6,7-trioxabicyclo［2.2.2］ octane (SPEPA). The effects of solvent, reaction temperature, reaction time and molar ratio on the yield were investigated extensively. The structure and flame retardant properties of the obtained product were characterized by means of Fourier-transform infrared spectroscopy, 1H-nuclear magnetic resonance spectroscopy, thermogravimetric analysis and limiting oxygen index. The results indicated that the yield reached 93.2 % when the optimal synthetic conditions were set to a n（SPEPA：TMCS）=1.2, a reaction temperature of 45 ℃ and a reaction period of 9 h as well as using dioxane as a solvent. The reactant flame retardant achieved a good thermal stability and the char yield was 25 % at 700 ℃, the limiting oxygen index of PP was 27 % at a content of 20 wt % when being applied for polypropylene (PP). In addition, when this flame retardant was complexed with melamine pyrophosphate or melamine cyanurate, it can generate a high synergistic flame-retardant efficiency for PP.

Study on Preparation of Branched Poly(butylene adipate) and Its Effect on Plasticization of PVC

2017, 31 (08): 100-104 ; DOI: 10.19491/j.issn.1001-9278.2017.08.018

Abstract ( 356 )

A series of branched poly(butylene adipate) (BPBA) were synthesized by using adipic acid and 1,4-butanediol as raw materials and glycerol as a branching agent. BPBA was used as a plasticizer for poly(vinyl chloride) (PVC), and a comparative investigation on the plasticizing effect was performed between BPBA and other four classical plasticizers, including dioctyl phthalate (DOP), linear poly(butylene adipate) (LPBA), epoxy soybean oil (ESBO) and acetyl acetyl citrate (ATBC). The results indicated that the resultant BPBA achieved a minimum viscosity of 0.105 dL/g at the branching agent content of 0.5 % and the reaction time of 5 h. BPBA exhibited a better plasticizing effect for PVC than LPBA and ESBO, and the PVC plasticized with 0.5 wt % BPBA gained an improvement by 22.4 % and 14.6 % in elongation at break compared with LPBA and ESBO, respectively. Moreover, the low temperature toughness also increased by 15.7 % and 34.8 %. In addition, BPBA exhibited a better thermal stability and resistance to migration in comparison with DOP and ATBC.

Research Progresses in Physical Recovery Technology of Automotive Waste Plastics

2017, 31 (08): 105-111 ; DOI: 10.19491/j.issn.1001-9278.2017.08.019

Abstract ( 391 )

This paper reviewed the recent research progresses in recycling and reusing technologies of commonly used automotive plastics, which included polypropylene, polyethylene, ABS, poly(vinyl chloride) and polyamide. Applications of these technologies in physical recovery of automotive waste plastics were introduced in detail, and some new ideas for the development of recycling and reusing technologies in automotive waste plastics were proposed.

Study on Modification of Waste Polypropylene with Mica Powders and PE-HD

2017, 31 (08): 112-116 ; DOI: 10.19491/j.issn.1001-9278.2017.08.020

Abstract ( 437 )

For the recycling and reutilization of waste polypropylene (PP), the waste PP was compounded with mica powders and high-density polyethylene (PE-HD) through a melt blending method. Effects of mica powders and PE-HD on various properties of the resulting composites were investigated extensively. The results indicated that mechanical properties of the waste PP exhibited an increase at first and then tended to decrease with increasing content mica powders, but the melt flow rate decreased continuously. There were lots of fiber bundles observed on the fracture surface of the composites. However, both mechanical properties and melt flow rate presented an increasing trend with increasing content of PE-HD. Morphology of the fracture surface also reveals more fiber bundles, indicating a typical ductile fracture.

Design of Control Systems of Outside Manufacturing Mechanisms for Plastic Parts

2017, 31 (08): 117-121 ; DOI: 10.19491/j.issn.1001-9278.2017.08.021

Abstract ( 255 )

Control systems of outside processing mechanism for plastic parts was designed by use of Mitsubishi FX3U type PLC on the basis of process principle of outside processing for plastic parts. This control system included an automatic mode and a manual mode. The connection with the PLC control system was established. The variables were defined, and the animation was connected through the supervisory control and data acquisition. Moreover, the automatic control of plastic outside molding and processing was achieved, and the motor speed and flow rate of electrohydraulic proportional valve were also accurately controlled.

Design of Bicolor Injection Moulds for an Interior Trim Part in Bentley Automobiles

Qing-Dong LIU

2017, 31 (08): 122-126 ; DOI: 10.19491/j.issn.1001-9278.2017.08.022

Abstract ( 359 )

Taking an interior trim part in Bentley automobile as an example, the injection molding principle for bicolor plastic parts was analyzed. Because the powder of opening mould cannot be used for core-pulling, a slide driven by an ejector plate was designed. A cooling water channel between slides was designed to make it apart from the interior. Moreover, the multiple pin-point gates were designed to overcome the difficulty of ejection. The results indicated that the structure of designed mould in this work was reasonable and reliable, and it could meet the requirements of production of bicolor injection-molding parts.