Current Issue

2015, Volume 29 Issue 09 Publication date: 26 September 2015 Previous Issue Next Issue

Reclamation of Waste Crosslinked Polyethylene

2015, 29 (09): 1-5 ; DOI: 10.19491/j.issn.1001-9278.2015.09.001

Abstract ( 535 )

The current study on the recycling of waste crosslinked polyethylene(XLPE) was reviewed. The recycling methods for XLPE included pulverization, heat assistant shearing, supercritical fluid process, ultrasonically aided singlescrew extrusion, and solid state mechanochemical milling. The mechanisms, advantages and disadvantages of the recycling methods were outlined, which provided experimental and theoretical foundation for recycling XLPElike waste thermosetting plastics with low cost.

Research Progress in Reinforced Modification of Polyoxymethylene

2015, 29 (09): 6-11 ; DOI: 10.19491/j.issn.1001-9278.2015.09.002

Abstract ( 393 )

This paper reviewed the polyoxymethylene composites reinforced with granular, fibrous, and platelike fillers. Future developments of polyoxymethylene composites was prospected briefly.

Evaluation of Mixing Uniformity of Ultrafine Powder Filler Based on Shannon Entropy Theory

2015, 29 (09): 12-16 ; DOI: 10.19491/j.issn.1001-9278.2015.09.003

Abstract ( 510 )

A quantitative characterization method for the dispersion uniformity of ultrafine powder was proposed based on Shannon entropy theory. In a system of HDPE/CaCO3 composite, the dimension information of the aluminum particles was first obtained with the software Photoshop and Image-pro, and then the relative Shannon entropy S’ and agglomeration factor Kc were calculated, which characterize the distributive mixing and dispersive mixing, respectively. Subsequently the general mixing condition was evaluated by a new parametermixing factor γ. The results demonstrated that the system had a higher value of γ of CaCO3, which rendered a better performance of tensile and bending strengths.

Preparation and Properties of Wheat Straw Fiber-reinforced Polyethylene Composites

2015, 29 (09): 17-21 ; DOI: 10.19491/j.issn.1001-9278.2015.09.004

Abstract ( 475 )

wheat straw Fiber-Reinforced polyethylene Composites was fabricated Wheat straw fiber-reinforced polyethylene composites were fabricated by molding process. The effect of modifier (NaOH), mass fraction of wheat straw fiber, molding temperature on the composites’ mechanical properties was investigated. It showed that a 5 % NaOH solution could dissolve the hemicellulose and pectin in wheat straw, thus refined the fiber and increased its specific surface area. The wheat straw fibers could be uniformly mixed with polyethylene when its mass fraction was 30 %, and the impact and tensile properties were improved. The optimal molding temperature was 170 ℃, at which a uniformly dispersion of wheat straw fibers in polyethylene was obtained. The impact and tensile properties of composites reached the maximum values of 46.1 MPa and 13.8 MJ/m2, respectively.

Effects of Powder Particle Size of Strontium Aluminate Phosphor on Properties of Rare Earth Fluorescent Bamboo Plastic Composites

2015, 29 (09): 22-26 ; DOI: 10.19491/j.issn.1001-9278.2015.09.005

Abstract ( 463 )

The fluorescent capacity, mechanical property, and thermal stability of strontium aluminate phosphor containing bamboo plastic composites were studied using fluorescence spectrophotometer, electronic universal testing machine, pendulum impact tester, and thermogravimetric analyzer. The tensile fractured surface of the composites was observed by field emission scanning electron microscopy. It showed that with decreasing particle size of strontium aluminate phosphor, the bending strength, bending modulus, tensile strength, and impact strength of the composites first increased, and then decreased, and the luminous intensity was increased. The particle size about 18 μm may result in optimal mechanical properties.

Preparation of Dicyclopentadiene Microcapsules Coated with Polysulfone

2015, 29 (09): 27-31 ; DOI: 10.19491/j.issn.1001-9278.2015.09.006

Abstract ( 430 )

Polysulfone coated dicyclopentadiene microcapsules were prepared by means of solvent evaporation method. The reaction temperature, dispersant, mass ratio of core to wall, and stirring speed on the performance of the microcapsules were discussed The microcapsule surface structure, morphology, and thermal properties were studied by scanning electron microscopy, optical microscopy, and thermogravimetric analyzer. It showed that, using gelatin solution as the dispersing agent and the reaction temperature being 30 ℃, the particle size and wall thickness of spherical microcapsules were controllable. The wall thickness reduced with increasing core/wall mass ratio, and the particle size reduced with increasing stirring speed.

Effect of the Ratio of Si—H/C=C of Organosilicone Resin Materials for Large-power LED Packaging on Curing Behavior

2015, 29 (09): 32-37 ; DOI: 10.19491/j.issn.1001-9278.2015.09.007

Abstract ( 591 )

A organosilicone resin for largepower LED packaging was prepared through Si—H addition reaction of hydrogensilicone with vinylsilicone catalyzed by Pt coordination compound in this paper, and the effect of the ratio of Si—H/C=C on curing behavior of the organosilicones was investigated by nonisothermal DSC method. It was found that when the ratio of Si—H/C=C was 1.6, the curing temperature was the lowest. After the process for vacuum deaeration the curing temperature program was 80 ℃ for 1h and then 95 ℃ for 2 h.

Effect of Ester-terminated Poly(amidoamine) Dendrimer on Crystallization Properties of Poly(hydroxybutyrate-co-hydroxyvalerate)

2015, 29 (09): 38-44 ; DOI: 10.19491/j.issn.1001-9278.2015.09.008

Abstract ( 380 )

Ester-terminated poly(amidoamine) (PAMAM) dendrimer of generation 3.5(G3.5) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) were blended in chloroform and casted into film. Properties of the film were characterized using differential scanning calorimetry, polarizing microscope, tensile tester, and right angle tearing tester. The results indicated that with the addition of PAMAM dendrimer, the glass transition temperature of the film became more distinct, indicating a greater toughness. The crystallinity of the PHBV/PAMAM film was much lower than that of neat PHBV (0~24.02 % vs 61.70 %). Moreover, the addition of PAMAM dendrimer considerably increased the tangential breaking strength of PHBV from 8.90 kN/m to 22.10 kN/m. The optimal toughening effect was observed with a PAMAM dendrimer content of 2.0 phr.

Mechanical Properties and Barrier Behavior of EHA/PE Composite Films

2015, 29 (09): 45-48 ; DOI: 10.19491/j.issn.1001-9278.2015.09.009

Abstract ( 456 )

EVOH, PA6, EVOH/PA6, and EHA/PE films were compared in testing of oxygen transmission rate, water vapor permeability, and texture using UV visible spectrophotometer and differential scanning calorimeter. It was found that EVOH and PA6 had good compatibility, EHA/PE composite film had a good barrier to oxygen and water vapor and a good visible light transmittance, and thus more suitable for food packaging.

Mechanical Properties of Kosteletzkya Virginica Bast Fiber Reinforced Polypropylene

2015, 29 (09): 49-53 ; DOI: 10.19491/j.issn.1001-9278.2015.09.010

Abstract ( 304 )

This paper studied the mechanical properties of the Kosteletzkya virginica bast fiber reinforced polypropylene composites. The influence of fiber content on the tensile and flexural properties was studied and compared with those reinforced with ramie fiber composites. It showed that with increasing Kosteletzkya virginica bast fiber content, the tensile strength and modulus increased, and the bending strength and modulus was first increased and then decreased with the maximum at 40 % fiber content. When the fiber content was 30 %, the mechanical properties of Kosteletzkya virginica bast fiber reinforced composites were inferior to those reinforced with ramie fiber, except for the tensile modulus.

Optimization Design of Injection Molding Based on EBF Neural Network and Particle Swarm Algorithm

2015, 29 (09): 54-59 ; DOI: 10.19491/j.issn.1001-9278.2015.09.011

Abstract ( 484 )

The EBF neural network model was established to describe the relationship between the process parameters and warpage based on the Latin hypercube method. Compared with Kriging model, the EBF neural network model could more accurately describe the relationship between the process parameters and warpage. The process parameters were optimized with the EBF model combined with multiobjective particle swarm algorithm, and the result was compared with Neighborhood Cultivation Genetic Algorithm. It was indicated that the injection parameter optimization method based on the EBF neural network and multiobjective particle swarm algorithm approach was feasible, and the warpage was decreased by 11.64 %，production time was shortened because the packing time and cooling time were decreased by 2.53 s.

Numerical Simulation on Thermal-fluid-structure Coupling Deformation of Polymer Micromechanical Motion Pair In-mold Micro Assembly Molding Process

2015, 29 (09): 60-66 ; DOI: 10.19491/j.issn.1001-9278.2015.09.012

Abstract ( 376 )

A mechanical system for inmold micro assembly molding was proposed. A theoretical model was formulated to describe the mechanism of thermalfluidstructure coupling deformation in polymer inmold micro assembly molding. Through finite element numerical simulation, the influence of the die wall temperature on the inmold micro assembly was studied. It was found that the micro assembly was controlled by its thermalfluidstructure coupling pressure field and inhomogeneous temperature field, and its microassembly thermalfluidstructure coupled deformation increased with increasing die wall temperature. Reducing of die wall temperature would help improve its micro assembly molding precision.

Comparative Analysis of Injection Molding and Injection Compression Molding of Aspherical Plastic Lens

2015, 29 (09): 67-72 ; DOI: 10.19491/j.issn.1001-9278.2015.09.013

Abstract ( 344 )

The injectioncompressing and injection moldings of aspherical plastic lens were analyzed and compared. The injectioncompression molding required smaller injection pressure and clamping force. The stress in the melt was uniform and smaller cavitation and weld line, better appearance, and smaller birefringence were obtained on the products. For the injection molding, the hysteresis and phase shift in Z direction were larger, which caused polarization in the products, resulting in worse quality of optical elements.

Influence of Polystyrene on Crystallization Behavior, Tensile Properties and Cavitation Behavior of β-nucleated Isotactic Polypropylene

2015, 29 (09): 73-77 ; DOI: 10.19491/j.issn.1001-9278.2015.09.014

Abstract ( 430 )

In this study, the influence of polystyrene (PS) on the crystallization behavior, morphology, tensile properties, and cavitation behavior of βnucleated isotactic polypropylene (β-PP) was investigated by means of differential scanning calorimetric (DSC), 2D-wide angle X-ray diffraction (2D-WAXD), universe mechanical testing machine, and scanning electronic microscope (SEM). It was found that as the amount of PS increased from 0 to 10 %, the content of β-phase increased gradually from 85.9 to 93.4 %. PS exhibited a good dispersion effect with β-PP, which dispersed uniformly within the β-PP matrix in micrometer sized small sphere. High temperature tensile test revealed that with the addition of PS, the neck width and hardening modulus decreased, indicating that the tensile stress could be better dispersed in the sample. Moreover, the microporous membrane was prepared by twodirection stretching, and the result of SEM observation showed that with the addition of PS, the pore size decreased and the pore size distribution became narrower.

Study on a Mixed Environmentally Friendly Plasticizer for PVC from Rubber Seed Oil

2015, 29 (09): 78-84 ; DOI: 10.19491/j.issn.1001-9278.2015.09.015

Abstract ( 403 )

A self-made rubber seed oil based epoxy fatty acid methyl ester plasticizer (EFAME) and dioctyl terephthalate (DOTP) were used in PVC as a mixed plasticizer. One purpose of the study was to see how many DOTP could be replaced by EFAME. The mechanical and thermal properties, processability, heat resistance, and durability of the plasticized systems were measured by tensile testing, DSC, TGA, dynamic mechanical analyzer, and thermal aging oven. It showed that the mixed plasticizer could significantly improve the flexibility, chemical resistance, thermal properties, and processability of PVC products. When the loading of EFAME was 20 parts, the glass transition temperature decreased from 0.32 to -4.63 ℃, and the T10 and T50 were increased. Furthermore, the discoloration time was increased nearly 4 times.

Mixing Properties of Different Single Screws with Maddock Barrier Mixers

2015, 29 (09): 85-91 ; DOI: 10.19491/j.issn.1001-9278.2015.09.016

Abstract ( 543 )

In this paper, the threedimension nonisothermal flow of modified Maddock mixers was numerically simulated by Polyflow. The profiles of pressure, velocity, temperature, and shear rate were obtained. Statistical analysis was performed on the mixing process of polymer melts in different structures and screw rotating speeds through particle tracking analysis(PTA), using “average deagglomerating energy” as a key parameter. The result of simulation was compared with experiments. It showed that the isosceles inverse modified Maddock mixer could provide sufficient shear force for excellent dispersion of polymer melt. Increasing in screw rotating speed could effectively enhance the dispersive mixing capacity.

Design of Injection Molds with Core-pulling Mechanism and Hot Runner Systems for Screwed-bowl-covers

2015, 29 (09): 92-95 ; DOI: 10.19491/j.issn.1001-9278.2015.09.017

Abstract ( 440 )

An injection mold for a teacup with a screwedcover was designed using a sidecorepulling mechanism and a hot runner system. The hot runner system, outside corepulling mechanism, ejection system, and cooling system were designed based on sophistical calculation. The mold displayed a high efficiency in production.

Design of Injection Molds with Automatic Thread Demoulding Systems for Connecting Pipes

2015, 29 (09): 96-99 ; DOI: 10.19491/j.issn.1001-9278.2015.09.018

Abstract ( 447 )

An injection mold for connecting pipes was designed using a side core pulling mechanism of “oblique guide pillar+slider+positioning ball” and an automatic thread demolding mechanism of “motor+chain+sprocket”. The two mechanisms as well as gating and cooling systems were analyzed. The designed mold worked well in the production.

esign of the Slide on Stationary Mould Fixed Half

2015, 29 (09): 100-103 ; DOI: 10.19491/j.issn.1001-9278.2015.09.019

Abstract ( 382 )

In this article, the structure and working principle of an injection mold of blender’s body were analyzed. The mold’s structure was very complex. It has a slide on the stationary mold, a slide on the movable mould, and lifter etc. The main points of design were summarized.