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2017, Volume 31 Issue 07 Publication date: 26 July 2017 Previous Issue Next Issue

Research Progresses in Processing Technology of Optical Grade BOPET Films

2017, 31 (07): 1-8 ; DOI: 10.19491/j.issn.1001-9278.2017.07.001

Abstract ( 435 )

This article reviewed the recent research and manufacturing progresses of optical grade bioriented stretching poly(ethylene terephthalate) (BOPET) film, and intensively introduced two class optical grade BOPET films processed by biaxially oriented and coating technologies. Moreover, the biaxially oriented processing technology in the improvement of stretching temperature, stretching ratio, stretching rate and heat setting temperature as well as the introduction of surface coating technology for the preparation of optical grade BOPET film were also introduced. Finally, the development trend of optical grade BOPET film was prospected.

A Review on Applications of Additives for Poly(lactic acid)/Plant Fiber Composites

2017, 31 (07): 9-15 ; DOI: 10.19491/j.issn.1001-9278.2017.07.002

Abstract ( 386 )

This paper reviewed the research progresses in the preparation of poly（lactic acid）/plant fiber composites at home and abroad and introduced the relevant processing additives including compatibility agents, toughening agents, lubricants, flame retardants and plasticizers in detail. Finally, the development of the additives used for poly(lactic acid)/plant fiber biodegradable composites was prospected.

Research Progresses of Reinforced Thermoplastic Composite Pipes Used for Oil and Gas Industry

2017, 31 (07): 16-22 ; DOI: 10.19491/j.issn.1001-9278.2017.07.003

Abstract ( 486 )

This paper reviewed the commercial products, specifications and manufacturers of reinforced thermoplastic composite pipes (RTP) as well as properties of different types RTP products. The current international and domestic standards for RTP were summarized, their molding processes were introduced, and the best winding angle for the processing of RTP was simulated. Finally, the future development of RTP used for oil and gas industry was prospected.

Kinetic Study of Isothermal Melt and Non-isothermal Cold Crystallization of sPS/PBA-aPS Blends

2017, 31 (07): 23-29 ; DOI: 10.19491/j.issn.1001-9278.2017.07.005

Abstract ( 351 )

This paper reported a kinetic study on crystallization behavior of blends of syndiotactic polystyrene with poly(butyl acrylate)-atactic polystyrene (sPS/PBA-aPS) core-shell latex particles by differential scanning calorimetry (DSC). Isothermal melt and non-isothermal cold crystallization process of sPS/PBA-aPS blends were analyzed by Avrami‘and Mo‘ equations, respectively. The results indicated that the crystallization time of sPS/PBA-aPS blends increased with an increase of isothermal crystallization temperature, but there was a decrease in crystallization rate. As the heating rate increased, there was hysteresis for the crystallization of sPS phase, and the crystallization peak temperature shifted to a high temperature.

Study on High-performance Lightweight Epoxy Nanocomposites

2017, 31 (07): 30-34 ; DOI: 10.19491/j.issn.1001-9278.2017.07.006

Abstract ( 412 )

Versatile high-performance epoxy nanocomposites were successfully prepared by co-incorporating organo-montmorillonite (OMMT) and TiO2 nanoparticles into the epoxy matrix. The X-ray powder diffraction and transmission electron microscopy characterizations indicated that OMMT layers were highly exfoliated into some of nanoscale OMMT mono-platelets by the strong interaction among the OMMT, TiO2 nanoparticles and epoxy matrix, and the 2-dimensional OMMT mono-platelets obtained an interlacing arrangement with the 0-dimensional TiO2 nanoparticles in the matrix. Mechanical tests and thermal analyses showed that the resulting epoxy/OMMT/TiO2 nanocomposites achieved a considerable improvement in various properties over pure epoxy resin.

Effect of Different Blowing Agents on Properties of PE-HD/Wheat Straw Wood-plastic Composites

2017, 31 (07): 35-39 ; DOI: 10.19491/j.issn.1001-9278.2017.07.007

Abstract ( 345 )

This paper reported an investigation on the effect of NaHCO3 and azodicarbonamide (AC) foaming agents on high-density polyethylene (PE-HD)/wheat straw wood-plastic composites. The PE-HD/wheat straw foaming wood-plastic composites were prepared by a hot-pressing method, and their various properties were investigated. The results indicated that the addition of foaming agents into the PE-HD/wheat straw wood-plastic composites could improve the mechanical and water-absorption performance significantly. AC foaming agent exhibited a better modification effect than NaHCO3, and the composites achieved the optimum performance with the Rockwell hardness of 82.9, tensile strength of 13.0 MPa, water absorption of 19.53 % and water contact angle of 83.2 ° at AC content of 1.5 wt %.

Fabrication and Properties of Polypropylene/Multi-wall Carbon Nanotubes Composites

2017, 31 (07): 40-47 ; DOI: 10.19491/j.issn.1001-9278.2017.07.008

Abstract ( 531 )

Polypropylene (PP)-based composites containing multi-wall carbon nanotubes (MWCNTs) with contents of 1.0 wt %~5.0 wt % were prepared by melting extrusion, and their thermal, crystallization, mechanical and electrical properties were investigated. The results indicated that the MWCNTs were dispersed in the matrix in two modes, i.e. existing in grain and distributing along the grain boundaries. These two modes are beneficial to the improvement of mechanical properties, heat distortion temperature and melt flow rate for the composites. As the content of MWCNTs reached 3.0 wt %, the composites exhibited an electrical percolation behavior, with which the composites exhibited excellent conductivity at room temperature. The polarizing microscopy showed that PP grains became smaller due to the addition of MWCNTs, and the grain size tended to decrease with an increase of MWCNTs content. XRD measurement demonstrated that the presence of MWCNTs did not influence the crystal form and crystalline structure of PP. In addition, MWCNTs could act as a nucleating agent to enhance the crystallinity of PP, thus resulting in a shift of α-crystallization peak to a high temperature with an increase of crystallization temperature and improving the thermal stability significantly.

Effect of Alumina on Properties of Heat Resistant Polyethylene Composites

2017, 31 (07): 48-52 ; DOI: 10.19491/j.issn.1001-9278.2017.07.009

Abstract ( 463 )

In the work, a surface modification was performed toward alumina (Al2O3) powders by silane coupling agent, and then the modified Al2O3 powders were incorporated into polyethylene (PE) as a conductive filler to fabricate heat-resistant polyethylene (RTPE) composites through melt blending. The effect of Al2O3 powders on properties of the composites was investigated extensively. The results indicated that thermal conductivity of the composites increased with an increase of Al2O3 content, and it was improved by a factor of 2 compared with pure PE when 50 wt% of Al2O3 powders with a size of 38 μm was loaded. However, its mechanical properties decreased gradually and its melt fluidity also became worse, resulting in a poor processability. This study also indicated that Y Agari model could well simulated the thermal conductivity of the composites as a function of Al2O3 content, and the theoretical value was most close to the actual one when Al2O3 content exceeded 30 wt%.

Study on Flame Retardancy and Mechanical Properties of PS/MH/MRP Composites

2017, 31 (07): 53-57 ; DOI: 10.19491/j.issn.1001-9278.2017.07.004

Abstract ( 529 )

In this paper, polystyrene (PS)-based flame-retardant compounds were prepared by incorporation of magnesium hydroxide (MH) and microencapsulated red phosphorus (MRP) as flame-retardant additives. The effect of the two flame-retardant additives on flame-retardant and mechanical properties of PS was investigated by limiting oxygen index, vertical burning tests, thermal analysis and mechanical measurements. The results indicated that the flame-retardant properties were improved with an increase of the content of flame-retardant additives, but the mechanical properties tended to decline. The limiting oxygen index was improved by 25 % compared with that of pure resin when 60 phr of flame-retardant additives was introduced, and the compound revealed a compact char layer after combustion.

Study on Preparation and Properties of Modified PP/ tetrapod-shaped ZnO whisker composite

2017, 31 (07): 58-62 ; DOI: 10.19491/j.issn.1001-9278.2017.07.010

Abstract ( 473 )

Polypropylene (PP)/ZnO whisker composites were prepared with the help of compatilizer, and the ZnO whisker was surface treated by different coupling agents. The mechanical properties, crystallization behaviors and antibacterial performance were investigated. The results indicated that types of coupling agents did not influence the crystallinity and content of β-form crystal of the composite, and the treatment of coupling agents also did not damage the structure of ZnO whisker. The mechanical properties were improved in the presence of surface-modified ZnO whisker. This may be due to the formation of β crystals induced by ZnO whisker. Moreover, when 4 wt % of surface-modified ZnO whisker was incorporated, the composites exhibit a high sterilization rate up to 50 % against staphylococcus aureus, escherichia coli and bacillus subtilis.

Study of Flame-retardant Polypropylene Based on Phosphorus-nitrogen Intumescent Flame Retardant and Brominated Flame Retardant

2017, 31 (07): 63-69 ; DOI: 10.19491/j.issn.1001-9278.2017.07.011

Abstract ( 474 )

Low-cost and low brominated flame-retardant polypropylene (PP) composites were prepared by a complex of phosphorus-nitrogen intumescent flame retardant (SR201A) and bromine-antimony flame retardant, and the effect of flame-retardant agents on combustion performance and mechanical properties of flame-retardant PP were investigated. The combustion behavior and mechanical properties of PP were evaluated by vertical burning experiments, limiting oxygen index, cone calorimeter measurement, thermogravimetric analysis and mechanical measurements. The results indicated that composite achieved a classification of UL 94 V-2 in the vertical burring test when 20 wt % of complex flame retardants was added, and their limiting oxygen index reached 31.4 %. The cone calorimeter testing results confirmed that there was a synergistic effect derived from the complex flame retardant agent systems, which could effectively promote the formation of residual char during the combustion of PP composites. In addition, the tensile and flexural strength of flame-retardant polypropylene composites was higher than those of pure PP resin.

Systematic Test and Evaluation Methods for Resin Lubrication Performance of PVC Lubricants

2017, 31 (07): 70-74 ; DOI: 10.19491/j.issn.1001-9278.2017.07.012

Abstract ( 444 )

This paper reported an investigation on systematic tests and evaluation methods for resin lubrication performance of poly(vinyl chloride) (PVC) lubricants. It was found that the resin lubrication functions, the internal lubrication, primary external lubrication and secondary external lubrication, and the efficiencies of these functions of PVC lubricants could be identified by determining their effects on the fusion time of PVC when used alone and in combination with a high-performance resin external lubricant at the common use level using a torque rheometer under the common processing condition, and comparing comprehensively the results.

Mixing Characteristics of a Chaos Rotor and Its Application for Preparation of Thermally Conductive ABS/Al₂O₃ Composites

2017, 31 (07): 75-81 ; DOI: 10.19491/j.issn.1001-9278.2017.07.013

Abstract ( 347 )

Models for chaos rotors and standard rotors are established by a Polyflow software. Effects of rotor configuration and rotor speed on dispersive and distributive mixing capabilities were investigated through mixing index, cumulative deagglomerating energy and Lyapunov index of flow fields. ABS/Al2O3 composites were also prepared to study effects of particle size, rotor structure and mixing process on their thermal conduction. The results indicated that a better dispersion could be achieved by using the chaotic rotors and increasing rotating speed. Composites containing 70 wt % of Al2O3 achieved the maximum thermal conductivity and mechanical properties when the chaotic rotor was used at a rotating speed of 500 r/min, and the thermal conductivity reached 1.3 W/(m·K). In addition, the addition of graphite fiber could improve thermal conductivity of the composites, and the thermal conductivity reaches 2.1 W/(m·K) when 65 wt % of Al2O3 and 5 wt % of graphite fiber were incorporated.

Investigation and Quantitative Measurement of Gas Surge in Supercritical Fluid Microcellular Foam Injection Molding

2017, 31 (07): 82-86 ; DOI: 10.19491/j.issn.1001-9278.2017.07.014

Abstract ( 379 )

There are often some uneven mixing cells with uneven sizes in supercritical fluid (SCF) microcellular foam injection molding products. This fault was named as “gas surge” phenomenon, and it influenced the quality of foam products, significantly. In this paper, the procedure of gas injection was deduced through the observation and analysis of the experimental phenomena. It was found that the occurrence of gas surge in SCF micro-foam injection molding was due to the clearance for hardware devices. Influencing factors of gas surge were confirmed by the experiment designed in this work and then studied quantitatively. A measurement method of initial gas surge was also proposed as a reference for precise injection of microcellular foam injection.

Effect of Diluent Mixing Ratio on PVDF Hollow Fiber Membrane Fabricated by Thermally Induced Phase Separation

2017, 31 (07): 87-94 ; DOI: 10.19491/j.issn.1001-9278.2017.07.015

Abstract ( 393 )

This paper reported an investigation on the effect of mixing ratio of γ-butyrolactone and dodecanol on the morphology and properties of poly(vinylidene fluoride) (PVDF) hollow fiber membranes fabricated by a thermally induced phase separation method on the basis of principle of polymer-solvent compatibility. It was found that a solid-liquid phase separation between PVDF and dilutes occurred with a decrease of temperature when the fraction of γ-butyrolactone in the mixing diluents exceeded 30 wt %. A spherical structure was formed in the membrane, thus resulting in poor pore connectivity, low porosity, low pure water permeability and poor chemical resistance. When the fraction of γ-butyrolactone was less than 30 wt %, a liquid-liquid phase separation took place with a decrease of temperature. In this case, a cross-linking bi-continuous structure was formed, which led to high tensile strength and good chemical resistance for the hollow fiber membranes.

Structure Analysis and Performance Test of Auto Water Tank Supports Based on Polypropylene/Glass Fiber Composites

2017, 31 (07): 95-98 ; DOI: 10.19491/j.issn.1001-9278.2017.07.016

Abstract ( 416 )

This paper reported a case study on structure analysis and performance test for a water tank support based on polypropylene/glass fiber composites. A 3D model was first established with Catia software and then a simulation analysis was carried out with Ansys software to obtain the stress cloud. Rigidity and strength obtained from this model were in accordance with the requirements of theoretical analysis. On the other hand, a series of performance measurements were performed, which included impact, rotation torque, weathering, pull-out and aging tests. The results indicated that not only the performance of auto water tank supports met the requirements, but it also achieved a lightweight nature for a cost-effective demand.

Study of Influencing Factors for Structure of Blown Molded Medical Infusion Bottles’ Based on Minimum Mass

2017, 31 (07): 99-106 ; DOI: 10.19491/j.issn.1001-9278.2017.07.017

Abstract ( 410 )

This paper reported a case study on influencing factors for structure by taking a 100 mL blown molded medical plastic infusion bottle as a sample. A finite element model was established for the blow molding process of this bottle and then analyzed with Ansys software. For the uneven wall thickness and other defects appearing in the deformation process of the bottle, a mathematical model for the structure of an infusion bottle embryo was established based on a minimum bottle embryo mass, and then it was analyzed and calculated by nonlinear curve fitting using universal global optimization. The optimum value for wall thickness in various parts of the infusion bottle embryo was achieved, and the evenness of wall thickness and the minimum mass of the bottle obtained from blow molding were calculated. Compared with the unoptimized results, the wall thickness evenness was improved, whereas the minimum mass was reduced. In this case, the production cost was reduced due to a decrease in the consumption of PP raw material after optimization.

Study on Flame Retardancy of Polyester Textiles Flame-retarded by a Compound Containing Phosphaphenanthrene and Triazine-trione Groups

2017, 31 (07): 107-113 ; DOI: 10.19491/j.issn.1001-9278.2017.07.018

Abstract ( 438 )

A self-made flame retardant containing phosphaphenanthrene and triazine-trione groups (TGD) was used to enhance the flame retardancy of polyester textiles by a back coating method, and the flame-retardant properties of resulting textiles was investigated intensively by limited oxygen index, UL 94 vertical burning experiment and cone calorimeter measurement. The results indicated that the incorporation of TGD could improve the flame-retardant properties of the textiles. When 8.1 wt % of TGD was introduced, the textiles achieved a limited oxygen index of 23.9 %, and it also exhibited a shorter burning distance and self-extinguishment in the vertical burning test. Meanwhile, the peak value of heat release rate, average effective heat of combustion, total heat release rate, and average CO2 yields of the textiles all decreased with an increase of TGD content. However, the average CO yields and total smoke release revealed a rise with increasing mass fraction of TGD. The data obtained from cone calorimeter measurement also confirmed an obvious flame-retardant effect in gas phase by using TGD. Morphology of residual char obtained from vertical burning test indicated that TGD also generated a condensed phase flame-retardant effect because of the increased char yields.

Study on Application of a Novel Multifunctional Additive for Polypropylene/Talcum Powder Composites

2017, 31 (07): 114-120 ; DOI: 10.19491/j.issn.1001-9278.2017.07.019

Abstract ( 384 )

This article reported a study on the application of a novel multifunctional additive, DZHA-200, for polypropylene (PP)/talcum powder composites. Effect of this additive on processing and mechanical properties of the composites as well as dispersibility of talcum powder were investigated through characterizations of melt and thermal stability of DZHA-200. The results indicated that DZHA-200 could improve processability of the composites and enhance the dispersibility of talcum powder in the matrix in comparison with commercially available additives. When 1 phr of DZHA-200 was added into the composites, melt flow rate, tensile strength, elongation at break, notched Charpy impact strength and un-notched Charpy impact strength were improved by 53 %, 5 %, 27 %, 6 % and 18 %, respectively. However, there was little influence on flexural properties of the composites.

Research Progresses in Accelerated Evaluation Methods for Slow-crack-growth Resistant Performance of Polyethylene Pipes

2017, 31 (07): 121-125 ; DOI: 10.19491/j.issn.1001-9278.2017.07.020

Abstract ( 411 )

This paper reviewed modes of slow crack growth (SCG) failure for polyethylene pipes and their evaluation methods, and also analyzed advantages and disadvantages of current evaluation methods for the slow crack growth-resistant performance of the pipes. For problems in the evaluation methods such as a long testing period and low efficiency, main accelerated evaluation methods for charactering the slow crack growth-resistant performance of the pipe was introduced in detail, and finally, the future development direction of this field was prospected.

Study on Operating Characteristics of Valve Controlled Melt Differential 3D Printers

2017, 31 (07): 126-131 ; DOI: 10.19491/j.issn.1001-9278.2017.07.021

Abstract ( 473 )

This paper presented a valve-controlled melt differential pellet 3D printer used for direct print with a variety of plastic particles and also simulated the extrusion process of non-Newtonian fluid in the valve cavity by using a multiphase flow and a dynamic grid technique. It was found that there is a positive correlation between extrusion flow rate and downward speed of the valve needle as well as between the ratio of valve needle and valve cavity diameters. The closer the valve needle to the nozzle, the greater the diameter ratio, and the greater the fluctuation of flow rate. The optimal valve needle movement distance could be determined as 0.5~1 mm. Moreover, the extrusion flow rate was improved with an increase of the ratio of the valve and valve cavity diameters. The larger the diameter ratio, the greater the fluctuation of flow rate. The melt exhibited a back flow phenomenon, when the ratio of the valve needle movement speed and back pressure was greater than 0.5. When the process parameters were accurately controlled, the steady extrusion could be realized and the precision of molded parts could be improved.

Application of CAE Technology in Mold Design of Car Engine Hood

2017, 31 (07): 132-136 ; DOI: 10.19491/j.issn.1001-9278.2017.07.022

Abstract ( 390 )

This article reported a case study on the application of CAE technology for mold design of car engine hood. The hot runner system was first designed by combination of CAE technology and rheological theory. The projects derived from the original design and optimized design was analyzed and compared through simulating the whole injection molding process of a car engine hood. The feasibility of the optimized design project was confirmed by the practical production, and the qualified products were also manufactured successfully.