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2016, Volume 30 Issue 09 Publication date: 26 September 2016 Previous Issue Next Issue

Nano-Barium Sulfate and Its Modification on Polymeric Materials

2016, 30 (09): 1-8 ; DOI: 10.19491/j.issn.1001-9278.2016.09.001

Abstract ( 655 )

In this paper, the current progress on synthesis methods for nanobarium sulfate (Nano-BaSO4), such as complexedprecipitation, microemulsion, microreactor, and so on, was introduced and the corresponding advantages and disadvantages were commented. Besides, the modified effectiveness of NanoBaSO4 on polymeric materials including optical performance, mechanical properties, crystallization behavior, rheological behavior, and thermostability were reviewed and the corresponding modified mechanism was also discussed.

Effect of Steam Foaming and Traditional Foaming Method on Foaming Result of TPU

2016, 30 (09): 9-13 ; DOI: 10.19491/j.issn.1001-9278.2016.09.002

Abstract ( 635 )

Ultra light-weight TPU particles were prepared by using supercritical fluid intermittent micro cellular foaming technology. The effect of four different kinds of foaming agents, water vapor, hot air, water, and glycerol, on the foaming behavior was studied by using scanning electron microscope and gravity meter. It showed that the optimal foaming time of high temperature vapor, hot air, glycerol, and water was 50, 180, 30, and 15 s, and the optimal foaming temperature of high temperature vapor, hot air, glycerol, and water was 120, 115, 75, 80 ℃. High temperature vapor foam particles was better than others for the appearance, particle uniformity, or the uniformity of bubble structure.

Effect of Self-nucleation Process on Crystallization Behavior of Polyxymethylene

2016, 30 (09): 14-20 ; DOI: 10.19491/j.issn.1001-9278.2016.09.003

Abstract ( 701 )

The effect of self-seeding nucleation during the crystallization of polyxymethylene(POM) was studied. It showed that the suitable temperature scope for self-seeding nucleation of POM was 165.5 to 167 ℃.The crystallization temperature of POM increased obviously(about 5 ℃) after the self-seeding nucleation. Additionally, the parameters for Avrami and Lauritzen-Hoffman equations were calculated. The test of polarized light microscopy (PLM) showed that the spherulite size decreased markedly. All of the results prove that self-seeding nucleation technique could improve the nucleation efficiency of POM，reduced its crystal particle size, and improved its crystallization temperature and rate.

Rheological Behavior of Polypropylene Modified by γ Radiation

2016, 30 (09): 21-25 ; DOI: 10.19491/j.issn.1001-9278.2016.09.004

Abstract ( 543 )

1,4-butanediol diacrylate was introduced into polypropylene (PP) using a Hakke internal mixer. Then, the PP samples were irradiated by a gamma ray for different time and subsequently tested with a rheometer and a melt strength tester. It was found that the storage value (G′) and the radius of ColeCole semicircle of the irradiatedPP decreased with increasing irradiation dose. Because the decomposition of PP chain increased with increasing irradiation time. However, melt strength of the irradiatedPP samples was higher than that of plain PP, increasing from 0.17 to 0.30 N.

Effect of α-Nucleating Agent on Brittle-ductile Transition of PP/SEPS Blends

2016, 30 (09): 26-30 ; DOI: 10.19491/j.issn.1001-9278.2016.09.005

Abstract ( 399 )

PP/SEPS blends containing αnucleating agent(α-NA) were prepared by melt mixing process. And the particle size and distribution of dispersed phase were measured by scanning electron microscopy. The interparticle distance in the blends with different content of α-NA was calculated according to a percolation model, and the effect of content of α-NA on the critical interparticle distance was described quantitatively. It was found that the higher the content of α-NA, the greater the inter-particle distance, and the easier the brittle-ductile transition.

Study on Properties of PPES/PPS Blends

2016, 30 (09): 31-34 ; DOI: 10.19491/j.issn.1001-9278.2016.09.006

Abstract ( 538 )

Blends of poly (phthalazinone ether sulfone) (PPES)and poly(phenylene sulfide) (PPS) were prepared by injection molding. The processability, miscibility, and mechanical properties of the blends were investigated. It was found that the melt index of the blends increased with increasing PPS content. DSC and SEM showed that the blends were thermodynamic incompatible systems. With the increasing PPS content, the mechanical properties of the blends first decreased and then increased, the mechanical properties of the blends showed the minimum when the PPS content was about 30%.

Modification of Epoxy Resin with Liquid Hydroxyl Terminated Butadiene-styrene Copolymer

2016, 30 (09): 35-40 ; DOI: 10.19491/j.issn.1001-9278.2016.09.007

Abstract ( 700 )

Liquid hydroxyl-terminated polybutadiene (HTBS) was employed to modify epoxy (EP) at presence of benzyldimethylamine to improve the brittleness and resistivity of epoxy. This paper investigated the thermal stability, morphology, mechanical, and electrical properties of HTBS modified EP. The formation of chemical bond between terminal hydroxyl group of HTBS and epoxy group of EP, enhanced the compatibility between the two materials. The use of HTBS decreased the thermal stability of EP. At low HTBS concentration the bending, tensile, and impact strengths of EP are enhanced obviously. SEM micrographs verified the phase separation, accountable for improved toughness of modified epoxy. Additionally, the HTBS/EP exhibited clear improvements in electrical insulations and dielectric properties, i.e., low dielectric permittivity and dissipation factor as compared with the unmodified one.

Synergistic Effect of Aluminum Phosphate and Graphene on Flame Retardant PBT

2016, 30 (09): 41-47 ; DOI: 10.19491/j.issn.1001-9278.2016.09.008

Abstract ( 413 )

Aluminum phosphate (AHP) and graphene (RGO) were used as flame retardants for poly (1,4-butylene terephthalate)（PBT）. The limit oxygen index and vertical burning tests showed that the addition of suitable amount of RGO could obviously improve the anti-dripping performance of PBT. The Micro calorimeter test showed that the sample of PBT/AHP-0.5 %RGO had the lowest peak heat release rate, which decreased from 518.7 to 433.0 W/g. A proper proportion of RGO could promote the formation of large quantity pores on the surface, which may prevent the escape of the flammable small molecules, thus to improve the flame retardant properties of materials.

Numerical Simulation and Analysis of Corrugation in Foam Sheet Extrusion

2016, 30 (09): 48-53 ; DOI: 10.19491/j.issn.1001-9278.2016.09.009

Abstract ( 603 )

In this paper, the formation of corrugation during the processing of foam sheet was analyzed by combining bubble nucleation with growth theory. The accuracy of simulation was also experimentally verified in foam extrusion. It was found that the number of corrugation first increased and then decreased with decreasing die gap. A conclusion was drawn that increasing zero shear viscosity and relaxation time of polymer melt could decrease the amount of corrugations.

Analysis of Relation Between Fiber Orientation and Gate Locations of Electric Box Covers

Wei HUANG

2016, 30 (09): 54-57 ; DOI: 10.19491/j.issn.1001-9278.2016.09.010

Abstract ( 501 )

The injection molding of glass fiber reinforced PP for anelectric box covers was simulated and analyzed by Moldflow software. The first step was to find the best gate location according to the conventional method, to determine the contrast parameters, and the average fiber orientation value of 0.9956 was detected. The second step was to get fiberglass WIP in the best orientation of value by setting different gate location, and the average fiber orientation value of the best gate location was 0.9992.According to the tensile modulus and poisson cloud graph, this gate location was verified to be the best gate location.

Impact Factor Optimizing Differential Evolution Algorithm and Its Application in the Optimization of Clamping Mechanism

2016, 30 (09): 58-64 ; DOI: 10.19491/j.issn.1001-9278.2016.09.011

Abstract ( 566 )

Based on differential evolution algorithm, an impact factor optimizing differential evolution algorithm was proposed.Feasibility and effectiveness of the algorithm were verified through the simulation experiment of three groups of test function with different Pareto frontier, which provides a novel optimization method for multiobjective optimization problem. Applying this method in the engineering practice, particularly in the clamping mechanism in an injection molding machine, a mathematical model of multiobjective optimization with two objective functions of stroke ratio and force magnification was established, which realized the optimization of clamping mechanism and the comparison with ideal point method.It showed that the stroke ratio and force magnification after the optimization using our algorithm were increased by 10.73 % and 21.42 %, respectively, in comparison with that of 9.93 % and 20.91 % by ideal point method. It may be concluded that the impact factor optimizing differential evolution algorithm was superior to the ideal point method.

Molecular Dynamics Simulation of Bubble Nucleation in Hexadecane/Super Critical Carbon Dioxide

2016, 30 (09): 65-69 ; DOI: 10.19491/j.issn.1001-9278.2016.09.012

Abstract ( 634 )

The nucleation process in hexadecane/super critical carbon dioxide solution was investigated. The full-atom molecular dynamics model was employed and run in isothermal-isobaric ensemble where the number of particles, pressure, and temperature of the system were in equilibrium. An exp-6 field was employed to describe the force field and a distance-based method was proposed to identify nuclei. A series of snapshots were presented to trace the process of bubble nucleation. It showed that low-density nuclei were formed when the pressure of the hexadecane and carbon dioxide saturated system was reduced. Then, carbon dioxide molecules would continue to enter into the gas phase until a bubble with a large number of gas molecules was formed.

Research on Process Optimization of Gas-Assisted Molding Parameters for Hollow Plastics

2016, 30 (09): 70-74 ; DOI: 10.19491/j.issn.1001-9278.2016.09.013

Abstract ( 550 )

In this article, the influence of processing parameters in gas-assisted injection molding on hollow degree, hollow uniform degree, and material saving of hollow products was studied using CAE software as the primary tool. Through orthogonal experimental, the effect on hollow volume ratio and gas core length ratio was also investigated.The ranks of the processing parameters in terms of importance were delay time, the pre-injection volume ratio, the overflow volume ratio and the gas pressure, the best combination of parameters. Through optimization, the actual saving rate of reached product material 47 %, the wall thickness of the product was uniform overall.

Preparation of Hydrocalumites Based on CO₃²- and Its Application Research in PVC

2016, 30 (09): 75-81 ; DOI: 10.19491/j.issn.1001-9278.2016.09.014

Abstract ( 465 )

In this paper, hydrocalumites based on CO32- were prepared from calcium hydroxide, aluminum hydroxide, and anhydrous sodium carbonate, deionized water was used as a solvent. The product was analyzed by FI-TR, XRD and SEM and used as a thermal stabilizer in PVC. Through the methods of thermal aging test, Congo red test, conductivity test, and TGA, the thermal stability was measured. It showed that the Ca4Al2(OH)12CO3·5H2O constituted a long-term thermal stabilizer for PVC. When 3 phr in PVC, the thermal stable time could continue to 70 min and its static thermal stabilization time could be 52 min. When the amount of complex systems of Ca4Al2(OH)12CO3?5H2O/ZnSt2/DMAU was 3 phr and the mass radio of the system was between 3：0.5：1.5 to 3：0：2, the early whiteness of complex system could be up to 60 min. Even to about 110 min, it would not appear "zinc burn."

Influence of PP-g-MAH Content on the Properties of Recycled Polyolefin/Wood Flour Composites

2016, 30 (09): 82-87 ; DOI: 10.19491/j.issn.1001-9278.2016.09.015

Abstract ( 456 )

Waste polyolefin / wood flour composites were prepared, and the influence of PP-g-MAH and other additives on the mechanical properties and microstructure of the composites was studied. The processing property of the composites containing both PP-g-MAH and EVA was significantly better than that containing EVA alone. When the EVA content was 2% and the PP-g-MAH content was higher than 9%, the composite material had a lower shear torque. When the PP-g-MAH was 9~12%, the recycled polyolefin formed a continuous phase structure, the processing and mechanical properties of the composites were excellent.

Design and Analysis of Clamping-Locking-Ejecting Unit belong to Ultrasonic Micro-injection Molding Machine

2016, 30 (09): 88-92 ; DOI: 10.19491/j.issn.1001-9278.2016.09.016

Abstract ( 614 )

In order to overcome the defects of conventional micro-injection molding machine, such as large volume, low machining accuracy, and low availability of material, a new ultrasonic micro-injection molding machine with a linear ultrasonic motor was proposed. The structure and working principle of the machine was analyzed and designed. Topology optimization was carried out to reduce the weight of the moving platen in the clamping system using ANSYS Workbench software, and then a static analysis of the moving platen was carried out. After topology optimization, the total mass of the clamping unit met the requirements and the strength of it met the material performance requirements.

Design of Automatic Film Changing Mechanism Based on Out-side Mold Decoration

2016, 30 (09): 93-96 ; DOI: 10.19491/j.issn.1001-9278.2016.09.017

Abstract ( 493 )

A film changing mechanism was designed based on the principle of outside mold decoration, which was included a smoothing part, a clamping part, a fixing part, a frame part, and a cutting knife. The smoothing and clamping parts were composed of a smoothing wheel, a clamping wheel, a bearing, a bearing sleeve, and a handle. The fixing part was composed of an electric motor, a press block, a press bar, a bearing cap, and a handle. The frame part was composed of a rolling guide rail pair, a bottom plate, a ball screw, a step motor, and a roller bracket. The cutting knife part was composed of a side plate, a guide bar, a slider, and a drive motor.

Influence of Core Size on Core Deformation with Different Mold Structure

2016, 30 (09): 97-100 ; DOI: 10.19491/j.issn.1001-9278.2016.09.018

Abstract ( 646 )

Taking a square plastic part as an example, the core deformation of different mold structure was analyzed with considering the temperature and pressure fields by finite element method. It showed that the core deformation of a three-plate mold was smaller than that of a two-plate mold. The influence of mold width on the core deformation of two kinds of molds was large. The height of lower mold core had a great influence on the deformation of lower mold core, but the height of upper mold core had a small influence on the deformation of upper mold core. The structure and size of the mold core for this plastic part were optimized by consider the stiffness and cost.