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2016, Volume 30 Issue 10 Publication date: 26 October 2016 Previous Issue Next Issue

Recent Progress in Liquid Crystalline Elastomers with Shape Memory Properties

2016, 30 (10): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2016.10.001

Abstract ( 651 )

This article reviewed the research and development progresses of shape memory polymers, and also introduced the main types of liquid-crystal elastomers with a shape memory property in detail. These liquid-crystal elastomers included thermal-induced elastomers, photochromic-deformation elastomers, electrical and chemical stimulated-deformation elastomers. In addition, the article also provided a view of prospective development in future for liquid-crystal elastomers.

Research Status of Transparent Polypropylene

2016, 30 (10): 7-13 ; DOI: 10.19491/j.issn.1001-9278.2016.10.002

Abstract ( 378 )

This article reviewed the oversea and domestic research status of transparent polypropylene (PP), and briefly summarized the preparation methods, transparent mechanisms, and the main factors that affect the transparency of PP, including the amount of nucleating and toughening agents added, the structure of PP, and extrusion technology, etc. Finally, some suggestions were proposed for the research and development of transparentPP.

RheologicalProperties and Foaming Performance of PPC/Nano-SiO₂ Systems

2016, 30 (10): 14-19 ; DOI: 10.19491/j.issn.1001-9278.2016.10.003

Abstract ( 395 )

The compounding systems based on propylene carbonate(PPC) and silica nanoparticles (nano-SiO2) were fabricated by usinga co-rotating twin-screw extruder, and their rheological properties werecharacterized by dynamic rheometer. The batch foaming process was conducted toinvestigate the effect of nano-SiO2 content on the rheological andfoaming properties of PPC/nano-SiO2 systems. The results indicatedthat a percolated network was formed at a nano-SiO2 content of 5phr, which led to the finest cell diameter of 9.65μm, the highestcell density of 2.37×10^9cells/cm3, the narrowest distribution of cell diameter, and the mostuniform cell structure.

Structure and Properties of Spontaneously Polymerized Poly (methyl methacrylate)

2016, 30 (10): 20-24 ; DOI: 10.19491/j.issn.1001-9278.2016.10.004

Abstract ( 900 )

In this paper, the chain structure, thermal properties, molecular weight and its distribution of spontaneously polymerized poly(methyl methacrylate) (PMMA) were characterized by nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). Meanwhile, the mechanisms of spontenous polymerization for methyl methylcacrlate (MMA) was disscussed. GPC results indicated that spontenously polymerized PMMA had a higher molecular weight and a wider distribution in comparison of the PMMA polymerized by using initiators. NMR and DSC measurements indicated that the spontenously polymerized PMMA contained peroxy bonds within its chain. These peroxy bonds are thermally instable, and their presence makes the thermal stability of PMMA poor without any effects on its heat resistance. It was also confirmed that the spontenous polymerization of MMA was initiated by the peroxides resulting from the reaction between MMA and oxygen.

Effect of Surface Modification of Coupling Agents on Properties of Intumescent Flameretardant Polypropylene

2016, 30 (10): 25-31 ; DOI: 10.19491/j.issn.1001-9278.2016.10.005

Abstract ( 400 )

A halogenfree intumescent flame-retardant (IFR) was surfacemodified with the silane, titanate, and Al-Ti and Al-Si complex coupling agents. A comparative study of the effects of surface modification on the bulk density and the angle of repose of IFR was performed. The effects of surface modification on limited oxygen index, dispersion property, mechanical properties and flame retardancy of polypropylene (PP)/IFR composites were investigated. The combustion behaviors of the composites were evaluated by cone calorimeter before and after the surface modification of IFR. The results indicated that the Al-Si complex coupling agent had a high efficiency in surface modification. With the surface modification by use of the Al-Si complex coupling agent, the dispersion of IFR in PP matrix was enhanced greatly, and the flame retardancy and impact toughness of the composites were improved. Furthermore, the heat release rate, total heat release, smoke production rate, and total smoke production of the composites were reduced by 30 %.

Effects of UF/MPOP and PEA/MPOP Flame-retardant System on Wood Combustion Performance

2016, 30 (10): 32-35 ; DOI: 10.19491/j.issn.1001-9278.2016.10.006

Abstract ( 408 )

A flame-retardant coating was prepared by using of urea-formaldehyde resin (UF) or pure acrylic emulsion resin (PEA), melamine polyphosphate (MPOP), melamine (MEL), and pentaerythritol (PER). The thermal stability and flame-retardant mechanism of the flame retardant coating were investigated by thermogravimetric analysis. The flame-retardant properties of the wood coated with this flame retardant coating were evaluated by cone calorimetry and limited oxygen index. Compared with UF/MPOP system, PEA/MPOP exhibited better flame-retardant properties, higher thermal stabilities, and stronger smoke suppression, and its limited oxygen index value was increased by 9.4 %. Moreover, its heat release rate, total heat release rate and rate of flue gas were reduced due to the integrated carbon layer formed on the surface of the wood.

Investigation on Compatibility of TPU and SEBS with Using Infrared Spectroscopy

2016, 30 (10): 36-41 ; DOI: 10.19491/j.issn.1001-9278.2016.10.007

Abstract ( 1353 )

This work investigated the effects of three types of compatibilizers, i.e. polypropylene grafted with maleic anhydride (PP-g-MAH), styrene-b-(ethylene-co-1-butylene)-b-styrene triblock copolymer (SEBS), and a selfmade compatibilizer, on the red shift of amino characteristic peaks in the infrared spectra of TPU/SEBS blends by using of Fouriertransform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM) and thermogravimetric analysis (TGA). The results indicated that the self-made compatibilizer exhibited the best compatibilizing effect among the three compatibilizers. The blend containing 6 wt% of the self-made compatibilizer was found to present the greatest red shift for the amino characteristic peak in its infrared spectrum. SEM observation indicated that SEBS domain achieved a uniform dispersion in the matrix due to the corporation of the self-made compatibilizer, which also led to a minimum size in the dispersed phase. This is due to the remarkable improvement in interfacial adhesion between TPU and SEBS. TGA results suggested the decomposition temperatures of the blends were increased with addition of these compatiblizers, and the selfmade compatibilizer had the best effect on the improvement of thermal stability for the blends among the three compatibilizers.

Study on Modification of Poly(hydroxybutyrate-co-hydroxyvalerate) with Epoxy-terminated Hyperbranched Polyester

2016, 30 (10): 42-49 ; DOI: 10.19491/j.issn.1001-9278.2016.10.008

Abstract ( 460 )

Hyperbranched polyester (HBPE) was synthesized through a “one-step” process by using 2,2dimethylol propionic acid and trimethylolpropane as raw materials and ptoluene sulfonic acid as a catalysts. The epoxyterminated HBPE with three generations (EHBP-G3) was prepared through the modification of HBPE with epichlorohydrin. The poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/EHBP blends were prepared through a melt processing method and then characterized by differential scanning calorimetry (DSC), polarizing microscopy, and mechanical and rheological evaluations. The results indicated that the degree of crystallinity of PHBV decreased by 16.1 % with addition of 1.5 wt% of EHBP-G3, and meanwhile, its impact strength increased by 34.28 %. The reduction in crystallinity may lead to an improvement in impact toughness for PHBV/EHBP blends.

Structure and Properties of Polyamide 6/Rare Earth Composites

2016, 30 (10): 50-54 ; DOI: 10.19491/j.issn.1001-9278.2016.10.009

Abstract ( 424 )

Polyamide 6 (PA6)/rare earth composites were prepared by a melt-blending method, and their structure and properties were investigated by Fourier-transform infrared spectroscopy, differential scanning calorimetry, powder X-ray diffraction, etc. The results indicated that there was no chemical interaction between PA6 and rare earth, and rare earth only acted as heterogeneous nucleating agents to promote the formation of γ-form crystals but to hinder the growth of α-form crystals. Both the crystallinity and crystallization temperature of PA6 domain in the composites were higher than those of pure PA6. The tensile strength of PA6/rare earth composites decreased slightly with increasing content of rare earth, while the elongation at break increased first and then decreased. When 6 wt% of rare earth was added into PA6, the elongation at break reached 328.25 %. The initial light intensity of the composites increased with increasing content of rare earth, and their light intensity presented a typical exponential attenuation.

Study on Rapidly Thermal Cycle Injection Molding Using Carbide-bonded Graphene Coating

2016, 30 (10): 55-59 ; DOI: 10.19491/j.issn.1001-9278.2016.10.010

Abstract ( 391 )

A novel dynamic mold temperature control strategy was proposed for injection molding using carbidebonded graphene coating in this paper. A chemical vapor deposition process was employed to prepare the continuous, dense and chemically bonded graphene coating on the mold cavity surface. The cavity surface temperature increased rapidly above the glass transition temperature of a polymer by using a low voltage power suppler and could be realtime controlled. The cavity surface also achieved a uniform temperature distribution and a high cooling rate to meet the requirements for rapid thermal cycle injection molding. The experimental results indicated that the melt flow behavior was improved significantly by rapid thermal cycle injection molding with the carbidebonded graphene coating, and the weld line defects were also eliminated.

Mixing Performance of Eccentric PolygonElements in Intermeshing

2016, 30 (10): 60-67 ; DOI: 10.19491/j.issn.1001-9278.2016.10.011

Abstract ( 455 )

Based on the self-designed eccentric polygon element, three-dimensional non-Newtonianisothermal flow field simulation was performed by means of POLYFLOW software tocharacterize the mixing performance of polygon and eccentric polygon elements.It was found that the dispersive and distributive mixing capabilities ofeccentric polygon elements are better than those of polygon elements.Furthermore, the extension flow was also introduced into the flow field ofeccentric polygon elements. A compounding experiment for the reinforcedpolycarbonate with 10 wt% of glass fiber was conducted to evaluate andcharacterize the mixing performance of polygon and eccentric polygon elements.The results indicated that the composite prepared by the eccentric polygonelements exhibited a better mechanical property and a higher heat deformationtemperature than that prepared by polygon elements.

Structural Optimization of PC/ABS Alloy Airbag Cover Plates

2016, 30 (10): 68-72 ; DOI: 10.19491/j.issn.1001-9278.2016.10.012

Abstract ( 374 )

This article reported a case study for the soft plastic cover plate made of polycarbonate (PC)/acrylonitrile-butadiene-styrene copolymer (ABS) alloys in terms of the structure analysis by ANSYS finite element method and experimental verification. The results indicated that the H-type and the double-Y-type air bag soft plastic cover plates could be opened precisely during the blast, but there were some debris generated. For this defect, two structural optimization schemes were proposed by reducing the residual thickness and adding supporting blocks and antislip strips on the surface of the cover plate. These optimization schemes were verified, and the results indicated that these two optimization schemes were helpful to reduce the generation of debris in the air bag flexible plastic cover plate made of PC/ABS alloys.

Service Life Prediction of Cable Ties Used for High-speed Trains Based on Arrhenius Equation

2016, 30 (10): 73-76 ; DOI: 10.19491/j.issn.1001-9278.2016.10.013

Abstract ( 565 )

This paper reported the study on the service life prediction of cable ties used for high-speed trains through hot-air accelerated aging according to Arrhenius equation. The relationship between aging time and stretching strength was investigated, and a predicting model was established. The service life of the cable ties was analyzed and predicted by an MATLAB software, and the obtained data were proved by the least square method. The results indicated that the service life of the cable ties was predicted as 28.44 years at a room temperature of 25 ℃.

Analysis and Optimization of Warpage Defect in Injection-molded Parts with Complicated Shapes Based on CAE Technology

2016, 30 (10): 77-80 ; DOI: 10.19491/j.issn.1001-9278.2016.10.014

Abstract ( 454 )

To reduce the warpage defects of thermoplastic parts with complicated shapes during the injection molding, a case study was conducted for an actually molded part with outoftolerance warpage defects, and a computer numerical simulation was also performed by use of a CAE analysis platform. Based on the simulation results, the optimized mold scheme was proposed through the reasonable technical analysis. The results indicated that the maximum warpage degrees of the part in X and the Z directions were reduced from 0.1726 and 0.1622 mm to 0.0488 and 0.1156 mm, respectively. These data met the requirement for the quality specifications of this part, and the qualified parts were achieved eventually. This further confirms the reliability and practicability of CAE technology when used for mold design and technological optimization.

Poly(silicic acid)/Polyacrylamide Composite Flocculant for Oil-containing Waste Water Treatment

2016, 30 (10): 81-85 ; DOI: 10.19491/j.issn.1001-9278.2016.10.015

Abstract ( 553 )

Silica sol was prepared by using sodium silicate as a precursor, and then the poly(silicic acid)/polyacrylamide composite flocculant was synthesized through in-situ polymerization. The chemical structure of the composite flocculant was characterized by Fourier-transform infrared spectroscopy (FTIR). The effects of pH value, reaction time and temperature on flocculation effectiveness were investigated by light transmittance and removal ratio for the oil-containing waste water. It was found that the composite flocculant exhibited the best flocculation performance when the synthetic conditions were set to the sodium silicate concentration of 0.5 mol/L, the acrylamide amount of 5.0 g, the initiator amount of 0.3 g, the poly(silicic acid) acidity of pH=5, the reaction time of 90 min, the aging time of 24 h, and the temperature of 70 ℃.

Design of Hydraulic System and Pneumatic System for Out-side Decoration Equipment of Mold

2016, 30 (10): 86-90 ; DOI: 10.19491/j.issn.1001-9278.2016.10.016

Abstract ( 473 )

A hydraulic systems for upper cavity lifting and down cavity lifting was designed for the out-side decoration equipment of mold on the basis of the process principle. The hydraulic system includes a variable capacity pump-hydraulic cylinder volumetric speed control loop, and a dual master cylinder directional control valve in a series of interlocking circuits. Meanwhile, a pre-directional control valve was adopted to make the master cylinder reverse smoothly after the cavity pressure was released. A pneumatic system for upper blank holder lifting and heating mechanism moving was designed by use of electromagnetism directional valves to control the out-side decoration system of molds. An AMESim software was employed to simulate this hydraulic system, and the result confirmed a high accuracy for the hydraulic system designed in this work.

Design of a Large-sized and Precision Injection Mould for Automobile Headlight Lenses

张维合 allenzhang

2016, 30 (10): 91-96 ; DOI: 10.19491/j.issn.1001-9278.2016.10.017

Abstract ( 819 )

A large-sized and precision injection mold was designed on the basis of the structural feature and aspect of automobile headlight lenses. The design ideas and experiences were summerized in terms of the inclined side core-pulling mechanism, the fixed distance parting mechanism, the “vertical water pipe+gradient water pipe+buffle-type water way” cooling mode, and the “elector pad+ejector pin” stripping system.

Design of Injection Moulds for Blender’s Shells

2016, 30 (10): 97-101 ; DOI: 10.19491/j.issn.1001-9278.2016.10.018

Abstract ( 320 )

The forming process of a blender’s shell was analyzed, and the structure of their injection molds and working principle were described. The injection mold for this blender’s shell was designed, and it includes inner slides on front cavity, angledlift splits, tunnel slides on the stationary mold fixed half, slides on the movable mold fixed half, and angles from pin, etc. The injection molding was also carried out successfully for the blender’s shells.