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2015, Volume 29 Issue 03 Publication date: 26 March 2015 Previous Issue Next Issue

Research Progress in Flame Retardant of Poly (lactic acid)

2015, 29 (03): 1-8 ; DOI: 10.19491/j.issn.1001-9278.2015.03.001

Abstract ( 701 )

Research progress in fire retardant poly (lactic acid) (PLA) in recent years was briefly summarized. The application of different kinds of environmentally friendly flame retardant systems such as phosphorus, phosphorusnitrogen, silicon, intumescent systems, and inorganic powers in PLA was investigated. Meanwhile, various flame retardant mechanisms were also explored, and the development trend of the flame retardant PLA in future was prospected.

Engineering Application Research of Glass Fiber Reinforced Composite Materials

2015, 29 (03): 9-15 ; DOI: 10.19491/j.issn.1001-9278.2015.03.002

Abstract ( 721 )

The characteristics and forming process of glass fiber reinforced composites (GFRP) were introduced.The engineering application of GFRP as wind turbine blades，wind turbine couplings，leaf springs，polyurethane sleepers，and multifunction track boards were introduced．In the end，the development trend of GFRP composites and prospect of new engineering applications in the rail transit and automobile industry was discussed.

Research Progress in Failure Mode Analysis of Polyethylene Gas Pipelines

2015, 29 (03): 16-20 ; DOI: 10.19491/j.issn.1001-9278.2015.03.003

Abstract ( 520 )

Assessment methods of failure of polyethylene (PE) gas pipelines have been introduced, and the failure analysis and mechanism study on PE gas pipelines were discussed. It was observed that the failure of polyethylene gas pipeline was usually assessed by mechanical testing, nondestructive testing was seldom employed. Future research direction and contents in nondestructive testing for PE gas pipelines were also anticipated.

Study on Thermal Conductivity of Thermal Insulative Composites of PA6 Filled with BN Particles

2015, 29 (03): 21-25 ; DOI: 10.19491/j.issn.1001-9278.2015.03.004

Abstract ( 477 )

Thermal insulative composites were prepared with PA6 as a matrix and BN as thermal conductive filler through a twinscrew extruder. The effect of BN content and particle size on the insulation property was studied. For various particle size, the thermal conductivity of the composites increased with increasing content of the filler. When the particle size of BN was 5 μm, filling content was 25 vol %, the thermal conductivity reached 1.2187 W/(m·K). For improving the thermal conductivity, flaky BN filler was more effective than spherical filler, and bimodal particles were more effective than monomodal ones. Using a binary filler mixture at a content of 20 vol % in which the size of the two fillers were 5 and 150 μm, and the volume ratio was 1:3, the thermal conductivity reached 1.3573 W/(m·K).

Blending Modification of Isotactic Polypropylene and Liquid Crystal Nucleating Agents

2015, 29 (03): 26-32 ; DOI: 10.19491/j.issn.1001-9278.2015.03.005

Abstract ( 906 )

β-form containing polypropylene was prepared using a liquid crystal monoacrylate monomer (RLC) as a nucleating agent. Polarized light microscope was adopted to study the nucleation process, crystallization behavior, and spherulites morphology of the polypropylene. The crystal structure was also investigated by X-ray diffraction and differential scanning calorimeter (DSC). When the mass fraction of RLC was 0.5 wt % and the crystallization temperature was 110 ℃. Compared with α-form, β-form was thermodynamically metastable and could be affected by the temperature fluctuation. The metalstable β-form could transform into αcrystal form, while a higher heating rate would inhibit this transformation.

Preparation and Characteristics of PE-HD/Heat-treated Straw Composites

2015, 29 (03): 33-37 ; DOI: 10.19491/j.issn.1001-9278.2015.03.006

Abstract ( 506 )

PE-HD composites were prepared with heat-treated straws. The influence of heat-treating temperature and time on the water absorption and mechanical properties of the composites was studied. It was found that the heat-treatment reduced the water absorption, increased the tensile and flexural strengths, however, a little decreased the impact strength. SEM revealed that the straw was uniformly mixed with PE-HD.

Influence of Nano-CaCO₃ on Nonisothermal Crystallization Kinetics of FEP

2015, 29 (03): 38-44 ; DOI: 10.19491/j.issn.1001-9278.2015.03.007

Abstract ( 555 )

Poly(tetrafluoroethylene-co-hexafluoropropylene)/nano calcium carbonate (FEP/nano-CaCO3) composites were prepared by melt blending method. The nonisothermal crystallization behavior of the FEP and FEP/nano-CaCO3 composites were investigated by differential scanning calorimetry (DSC). Moreover, the nonisothermal crystallization kinetics was carried out and analyzed by Jeziorny, Ozawa, and Mo methods. It was confirmed that the nonisothermal crystallization of FEP and FEP/nano-CaCO3 could be described by the above kinetic equation except Ozawa method. The analysis showed that the initial and maximum crystallization temperatures of FEP/nano-CaCO3 composites were higher than those of neat FEP at the same cooling rate, and the addition of nano-CaCO3 extended the crystallization half time. The nano-CaCO3 promoted the nucleation of FEP, however, decreased the overall crystallization rate of the FEP.

Preparation and Properties of PBAT/PLA Film

2015, 29 (03): 45-50 ; DOI: 10.19491/j.issn.1001-9278.2015.03.008

Abstract ( 1517 )

In this study, blends from poly(lactic acid) (PLA)and polybutyleneadipate-co-terephthalate (PBAT) was fabricated and the mechanical and bio-degradation properties were studied. It showed that with increasing PLA content, the tensile strength of PBAT/PLA blends increased firstly and then decreased, the elongation at break decreased continuously, and the blends underwent a ductilebrittle transition. When PLA content reached 30 wt %, a mechanical property change point occurred. When PLA content reached 50 %, phase separation took place. The addition of PLA could accelerate the crystallization rate of PBAT, which increased the crystallization temperature from 38 ℃ to 82 ℃. PBAT/PLA film could be fabricated with good mechanical property only if PLA content was below 70 %.

Study on Mechanical Properties of Poly(methyl-vinyl siloxane)-toughened Poly (phenylene sulfide)

2015, 29 (03): 51-56 ; DOI: 10.19491/j.issn.1001-9278.2015.03.009

Abstract ( 583 )

A series of blends based on poly (phenylene sulfide) (PPS) and poly (methylvinyl siloxane) (PMVS) were prepared by melt mixing process. The mechanical properties and the fracture morphology of the blends were investigated. It showed that the elastomers were well dispersed in PPS matrix. The toughening effect of the elastomers was obvious. When the mass fraction of the elastomers was 3 %, the elongation at break of PPS/NPMVS and PPS/SPMVS blends were 3.9 and 2.4 times higher than that of neat PPS, respectively. The impact strength of PPS/NPMVS (NPMVS 3 mass %) and PPS/SPMVS (SPMVS 10 mass %) blends were 1.8 and 1.4 times higher than those of neat PPS, respectively.

Preparation and Properties of Polyethylene/Nano Graphite Platelet Conductive Composites

2015, 29 (03): 57-62 ; DOI: 10.19491/j.issn.1001-9278.2015.03.010

Abstract ( 460 )

Conductive PELLD plastics was prepared by blending with graphite nano-platelet(GNP). The effect of GNP, surfactant sodium dodecyl benzene sulfonate (SDBS), and dispersant polyethylene glycol (PEG) on the mechanical and conductive properties was investigated. It was found that when the loading of GNP was 40 %, a conductive network was formed, the electrical resistivity reached 8.95×10^8 Ω·cm. The optimal recipe was found as PE-LLD 100 phr, GNP 40 phr, SDBS and PEG 4 parts.

UV-protective Properties of Transparent Polystyrene/TiO₂ Nanocomposite Films with High Particle Loadings

2015, 29 (03): 63-69 ; DOI: 10.19491/j.issn.1001-9278.2015.03.011

Abstract ( 480 )

The anatase TiO2 nanoparticles with diameter of smaller than 20 nm were prepared in a nonaqueous sol-gel approach, which was modified with 3-(trimethoxysilyl)propyl methacrylate and dispersed in a PS solution in para-xylene. TiO2 containing solution was spin-coated to a film, in which the TiO2 contents was up to 95 wt %. UV-protective properties were examined by a UV-Vis spectrometer. The experiments indicated that the UV-protective property was enhanced with increasing TiO2 content. The transmittance of visible light became saturated, rather than linearly decreased. When the particle content was 95 wt %, the transmissivity was still higher than 82 %.

Effect of Compounds on the Flame Retardancy and Thermal Degradation of Ethylene-propylene Elastomer/IFR System

2015, 29 (03): 70-74 ; DOI: 10.19491/j.issn.1001-9278.2015.03.012

Abstract ( 459 )

The effect of lanthanum oxide(La2O3)and 4A zeotile (4A) on the flame retardancy and thermal degradation of ethylene-propylene elastomer(MEP)/IFR system was investigated by means of limited oxygen index, scanning electrical microscopy (SEM), thermogravinity analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). It was found that the limited oxygen index values of the composites increased when 1 % compounds were incorporated into it, and 4A had the better synergistic effect with its limited oxygen index reaching to 28.6 %. SEM observed that much more compact char layers were formed when the compounds was added into MEP/IFR system. TGA and FTIR results revealed that the IFR remained more char residue when La2O3 and 4A zeotile were introduced into MEP/IFR, and more polyaromatic spacies, and more P—O—C and P—O—P connected structures were formed.

Effect of Nucleating Agents on Polypropylene Batch Foaming Process

2015, 29 (03): 75-78 ; DOI: 10.19491/j.issn.1001-9278.2015.03.013

Abstract ( 755 )

Influence of types, particle sizes, and dosages of nucleating agent on the cell structure of the batch foaming of polypropylene with supercritical carbon dioxide was investigated. When calcium carbonate was used, better cell integrity and more uniform cell size distribution, and higher expansion ratio were obtained compared with the foam using talc and montmorillonite. The smaller the particle size, the more the nucleation sites, and the larger the cell density. A loading of 3 phr calcium carbonate was optimal to achieve high expansion ratio and cell density.

Numerical Study on the Influence of the Flow Rate of Unit Volume of Melt During Gas-assisted Coated Co-extrusion of L-shaped Plastic Profiles

2015, 29 (03): 79-85 ; DOI: 10.19491/j.issn.1001-9278.2015.03.014

Abstract ( 482 )

A threedimensional isothermal viscoelastic numerical model for PE-LD and PE-HD was established with PTT constitutive equation and finite element method. Using the model, conventional and gasassisted coating coextrusions and the extrusion swell of gasassisted coating coextrusion were simulated. It showed that in the gasassisted coating coextrusion the whole die swell, core and shell die swell kept at zero with the relaxation time when the unit volume flow rate of the core and shell melt were equal. However, when the core and shell melt unit volume flow rate were different，the melt with large unit volume flow rate swelled, and that with small one shrank.

Preparation of PDMS/PVDF/PTFE Ternary Blend Microporous Membranes for Membrane Distillation

2015, 29 (03): 86-90 ; DOI: 10.19491/j.issn.1001-9278.2015.03.015

Abstract ( 501 )

The flat-sheet ternary blend microporous membranes from poly(vinylidene fluoride-co-tetrafluoroethylene/dimethylsiloxane) were prepared by the phase inversion process. The membrane distillation process of 20g/L aqueous NaC1 solution was applied as a final test of membrane performance. The influence of PTFE content on the membrane structure and performance were studied by scanning electron microscope (SEM), contact Angle, membrane porosity and average pore size of membrane. The results showed the finger-like hole at cross-section of the blend microporous membrane was gradually replaced by a sponge-like structure with the increased of PTFE content. The mean pore radius from 0.234μm to 0.354μm and the porosity of prepared membranes varied from 53.4% to 81.3%; A contact angle of water droplet on the membrane bottom surface was increased from 118.52o to 131.11o; When the PTFE content was 40wt.%, the permeate flux and rejection were 16.60 kg/(m2h) and 99.99%, respectively. That was the rejection reached the maximum. Keywords: poly(dimethylsiloxane); poly(tetrafluoroethylene); poly(vinylidene fluoride); Hydrophobic microporous membrane; vacuum membrane distillation

Effects of 3D Printing Conditions on Mechanical Properties of Biodegradable Poly(lactic acid)

2015, 29 (03): 91-94 ; DOI: 10.19491/j.issn.1001-9278.2015.03.016

Abstract ( 540 )

Biodegradable poly(lactic acid) samples were prepared by 3D printing. The effect of printing conditions on the impact strength, tensile strength and modulus, and elongation at break of the samples was studied. It was found that with increasing filling density, the impact strength, tensile strength and modulus increased but the elongation at break decreased after an initial increase. With increasing print speed, tensile properties increased, the impact strength and elongation at break decreased. With increasing print temperature, impact strength and tensile properties increased, the elongation at break decreased. The sample provided the best comprehensive performance when the filling density was 70 %, the print speed was 100 mm/s, the print temperature was 210 ℃.

Preparation and Characterization of Poly(vinyl alcohol)/Starch Nanocrystals Composite Films

2015, 29 (03): 95-99 ; DOI: 10.19491/j.issn.1001-9278.2015.03.017

Abstract ( 500 )

Starch nanocrystals (SN) was prepared by sulfuric acid hydrolysis with waxy maize starch as the starting material and polyvinyl alcohol (PVA)/SN nanocomposite films were prepared by solution casting method. The effect of SN on the structure and properties of the PVA/SN composite films was studied. The characterization results showed that SN was composed of nano particles as disk shape with an average diameter around 30~60 nm. With the increase of SN in the composite films, both mechanical properties and barrier performance firstly increased and then decreased. When the content of SN increased to 10 %, the tensile strength of the composite film reached 54 MPa from 47 MPa of neat PVA film. In addition, the gas permeability of the composite films also decreased 70 % compared with the neat film.

Application of Curcumin as Thermal Stabilizer for PVC

2015, 29 (03): 100-104 ; DOI: 10.19491/j.issn.1001-9278.2015.03.018

Abstract ( 672 )

The thermal stabilizing effect of curcumin on PVC was studied by Congo red testing and FTIR and compared with commercial lead salt and Ca/Zn compound stabilizers. Rheological performance and mechanical property of PVC constaining these stabilizers were studied. It was found that the static thermal stability was 14 min when 3 part curcumin was used. FTIR indicated that curcumin could reduce the oxidatized degradation of PVC. Curcumin had obvious synergistic effect with lanthanum lauric and calcium stearate. Static and dynamic thermal stable time could reach 50 min and 47 min with ratios of curcumin: lanthanum lauric:calcium stearate eqoal 1:0.8:0.5. Rheological and mechanical properties were similar to those of lead salt, better than those of Ca/Zn compound stabilizer. Dynamic thermal stability time was significantly longer than that of the lead and Ca/Zn containing systems.

Synthesis of Novel Carboxylates of Long-chain Plant-oil and Its Application in PVC

2015, 29 (03): 105-111 ; DOI: 10.19491/j.issn.1001-9278.2015.03.019

Abstract ( 557 )

Erucic acid, hydrogen peroxide，and formic acid were used to synthesize epoxidized erucic acid, from which epoxidized calcium and zinc erucates were synthesized by double decomposition reaction. The two erucates were used as thermal stabilizers for PVC. Through the method of Congo red test, conductivity test, and thermogravimetry the stabiling effect was measured. It was found that the epoxy calcium/zinc erucates (mass ratio of 3∶1) provided a thermal stable time (T2) of 118 min and depressed zinc burn. When 1,3-dimethyl-6-amino uracil(DMAU), β-diketone, and pentaerythritol were compounded separately, initialstage whiteness was highly improved. The statically thermally stable time was increased by 31.1 min based on neat PVC, the order in synergistic effect of compounding was DMAU>β-diketone> pentaerythritol.

Design of Centralized Temperature Control System Based on Profibus-DP/Modbus Gateway and Its Application in Tandem Extrusion Systems

2015, 29 (03): 112-117 ; DOI: 10.19491/j.issn.1001-9278.2015.03.020

Abstract ( 529 )

The design of centralized temperature control systems for tandem extrusion systems was discussed, and a method to realize the communication between Siemens S7-300 and temperature control instruments was presented. By this way, the temperature of tandem extrusion systems can be controlled in integrity so that the production process can be managed smoothly and the technical data can be recorded and archived. This communication mode has the merits of fast response, simple software design and low cost.

Research Fuzzy Coordinating Control of Drive Systems on Plastic Injection Molding Machines

2015, 29 (03): 118-123 ; DOI: 10.19491/j.issn.1001-9278.2015.03.021

Abstract ( 603 )

A fuzzy coordination control method was proposed based on pump selfpriming ability decline inflection point. Pump switch was designed on the base of the minimum speed of the variable hydraulic pump. According to the actual characteristics of the system, Stype function was got by the choice of the transformation of normal function. To determine the role of the different error domain controller strength, error universe point discrete way was used to deal with the choice of the membership function. Due to the uncertainty of the system parameters and load parameters, fuzzy control method was used to overcome the difficulty in establishment of the model, better dynamic characteristics was obtained. Simulation and experiments show that this method can solve the problems of lowspeed characteristics.