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2017, Volume 31 Issue 02 Publication date: 26 February 2017 Previous Issue Next Issue

Progresses in Toughening Modification of PPbased Wood Plastic Composites

2017, 31 (02): 1-7 ; DOI: 10.19491/j.issn.1001-9278.2017.02.001

Abstract ( 427 )

This paper introduced the formulation, compositions and traditional processing methods of wood plastic composites (WPC) and also analyzed the latest three processing technologies, in which the subcritical fluidassisted reactive extrusion technology was considered as a novel processing method for the preparation of WPC. These technologies provide a new route for the preparation of highperformance WPC.

A Review on Preparation of ASA Resin and Its Alloys with PC

2017, 31 (02): 8-16 ; DOI: 10.19491/j.issn.1001-9278.2017.02.002

Abstract ( 622 )

This article reviewed the technologic progresses in the synthetic methods and modification techniques of acrylonitrilestyreneacrylate ternary copolymer (ASA) and also introduced the current studies on modification of polycarbonate (PC)/ASA alloys including the modifications for its electrical conduction and flame retardancy. The effect of different additives on properties of the alloys was evaluated. Most of all, the applications of ASA resin and its alloy were summarized, and its prospects were looked over.

Study on Intrinsic Viscosity and Crystallization Behavior of Recycled PET Modified by Chain Extenders

2017, 31 (02): 17-26 ; DOI: 10.19491/j.issn.1001-9278.2017.02.003

Abstract ( 526 )

Recycled poly(ethylene terephthalate)（PET）bottle flakes were prepared by melt extrusion, and the chain extension was performed during the extrusion process by addition of methylene diphenyl diisocyanate (MDI), pyromellitic dianhydride (PMDA) and MDI/PMDA mixture as chain extenders. The results indicated that the intrinsic viscosity of recycle PET reached a maximum value of 0.87 dL/g when using PMDA as a chain extender, whereas the ecycle PET only achieved an intrinsic viscosity of 0.68 dL/g by use of MDI chain extender. Furthermore, when using a mixture of MDI and PMDA for the chain extension of recycled PET, the intrinsic viscosity research 0.62~0.68 dL/g. The crystallization temperature of recycled PET decreased due to the addition of PMDA or MDI, whereas its crystalline enthalpy increased. However, the crystallization rates always exhibited little change with the addition of chain extenders.

Effect of Hollow Glass Microspheres on Microstructure and Properties of Waterborne Damping Materials for Vehicle Use

2017, 31 (02): 21-26 ; DOI: 10.19491/j.issn.1001-9278.2017.02.004

Abstract ( 660 )

The composite damping materials based on the siliconecontaining styreneacrylate emulsion and hollow glass microspheres with two different particle sizes were prepared in this work, and their chemical structure and damping properties were studied by Fouriertransform infrared spectroscopy and dynamic mechanical analysis. The morphology of damping materials was investigated by scanning electron microscopy. The results indicated that the hollow glass microspheres with larger size were much easier to be damaged, although they had a better interfacial adhesion with the latex matrix. The combination of these two types of glass microspheres improved the mechanical performance of the damping materials effectively. Most of all, the composite damping materials achieved optimum damping properties when 15 wt % of mixed hollow glass microspheres were incorporated into the composites at a weight ratio of 1：1 for largesized and smallsized glass microspheres.

Study on Technological Optimization for ABS Resin Prepared by Continuous Bulk Polymerization

2017, 31 (02): 27-33 ; DOI: 10.19491/j.issn.1001-9278.2017.02.005

Abstract ( 636 )

ABS resin was synthesized by continuous bulk polymerization in a selfdeveloped plug flow reactor, and effects of process parameters including reaction temperature, concentration of initiator, concentration of chain transfer agent on the grafting ratio, molecular weight and particle size of the resultant ABS resin were investigated. The relationship between impact strength and microstructure was also studied. On the basis of the results, the synthetic technology for ABS was optimized, and the impact strength of ABS products was improved from 160 J/m to 221 J/m.

Mechanical Properties of Polypropylene Modified by Calcium Pimelate

2017, 31 (02): 34-37 ; DOI: 10.19491/j.issn.1001-9278.2017.02.006

Abstract ( 447 )

A series of polypropylene compounds modified by calcium pimelate (CaHA) were prepared by a meltblending method, and their mechanical performance, thermal properties and fracture surface were investigated extensively. The results indicated that CaHA could well act as a βform nucleating agent to promote a crystalline transformation from αform crystals to the β one in PP. The compounds achieved optimum mechanical performance when 1.0 wt % of CaHA was incorporated into PP, and their impact strength，tensile strength and flexural strength reached 32.79 kJ/m2, 38.8 MPa and 31.6 MPa, respectively.

Preparation and Performance of POE/PP Compounding System

2017, 31 (02): 38-42 ; DOI: 10.19491/j.issn.1001-9278.2017.02.007

Abstract ( 679 )

The POE/PP compounding system was fabricated by adding different contents of ultrahigh flowable PP into POE. The processing performance, mechanical properties, electrical insulation properties and compatibility of this compounding system were investigated extensively. The results indicated that the melt flow rate increased along with a decrease in processing torque with increasing content of ultrahigh flowable PP. The elongation at break presented an increase in the beginning and then kept stable at a certain value, whereas the tensile strength showed a trend from rise to decline. On the other hand, the volume resistance of compounding system revealed a drastic increase when the content of ultrahigh flowable PP exceeded 20 wt %. The compounding system achieved a maximum value in dielectric strength at a PP content of 5 %, but the dielectric strength began to decline over this loading of ultrahigh flowable PP. This compounding system presented a microstructural evolution from a “seaisland” form to the network one and then to the ribbon one with an increase of the content of ultrahigh flowable PP.

Effect of Oxidation Treatment of Expandable Graphite on Combustion Behavior of Flame-retardant Polyurethane Coating

2017, 31 (02): 43-50 ; DOI: 10.19491/j.issn.1001-9278.2017.02.008

Abstract ( 500 )

The expandable graphite (EG) and oxidized expandable graphite (OEG) were compounded with ammonium polyphosphate (APP)/magnesium hydroxide ［Mg(OH)2］ and APP/aluminum hydroxide ［Al(OH)3］ to prepare flameretardant polyurethane (PU) coating, respectively. The flameretardant properties of the composite coating were evaluated in terms of limiting oxygen index (LOI) and cone calorimeter tests. The results indicated that the presence of OEG led to a higher LOI compared with EG at the same particle size, whereas the peak heat release rate decreased dramatically. The morphology of residual char was investigated by scanning electron microscope, and the results revealed that the residual char was more integrated and compact for the composite coating containing OEG, and its expansion height was also improved.

Study on BMI-modified Structural Acrylic Adhesive

2017, 31 (02): 51-55 ; DOI: 10.19491/j.issn.1001-9278.2017.02.009

Abstract ( 488 )

A secondgeneration acrylate structural adhesive (SGA) was prepared by mixing component A and B at a mass ratio of 1：1. In this SGA, the component A was a mixture of monofunctional acrylate, trifunctional acrylate, N,N′(4,4′methylenediphenyl) dimaleimide (BMI), ABS toughening agent, amine reductant and inhibitor as well as other auxiliaries, and the component B was a mixture of stabilizers, oxidizing agents and other auxiliaries. The effect of BMI content on the curing performance and heat resistance of the SGA was investigated. The results indicated that the SGA achieved an increase in hightemperature mechanical properties and glass transition temperature (Tg) due to the addition of BMI, and it obtained an optimum heat resistance with addition of 3 wt % BMI. Moreover, Tg also increased from 108.23 to 109.25 ℃, while the shear strength increased by 6 %, 40.8 %, and 103 % at room temperature, 120 ℃ and 200 ℃, respectively.

Study on Crystallization Capability of β-crystal-modified Polypropylene Random Copolymer Reinforced with Isotactic Polypropylene

2017, 31 (02): 56-64 ; DOI: 10.19491/j.issn.1001-9278.2017.02.010

Abstract ( 452 )

This study reported an enhancement of crystallization capability for the βcrystalmodified polypropylene random copolymer (PPR) by incorporation of small amount of isotactic polypropylene (iPP). The investigations indicated that the relative content of βform crystals was increased to 92.4 % through an optimization of experimental conditions, and the βform crystallization capability also increased by 61.5 %. The investigation on crystal growth process indicated that iPP formed βcrystal nucleus at first and then induced the βform crystallization for PPR. The high content of βform crystals resulted in a significant great improvement in impact toughness. The impact strength obtained an increase from 22.8 to 45.9 kJ/m2 while the elongation at break increased to 574.4 %, which was almost by a factor of three compared with pure PPR. There is a synergistic effect between the rigidity of iPP and the high content of βform crystals, leading to little change in tensile strength of PPR/iPP compounds.

Structure and Properties of Polypropylene/Nano-SiO2 Composites

2017, 31 (02): 65-71 ; DOI: 10.19491/j.issn.1001-9278.2017.02.011

Abstract ( 539 )

Polypropylene (PP)/nano-SiO2 composites were prepared by melting blending, and their condensed structure was investigated by means of polarized light microscope and differential scanning calorimetry. The results indicated that incorporation of nano-SiO2 particles not only enhanced the crystallinity of PP but also decrease the size of spherulites along with a fuzzy boundary. As a result, the crystallization temperature and melt temperature increased by 6.5 % and 2.6 %, respectively. Moreover, the presence of KH-560 silane coupling agent and maleic anhydridegrafted PP enhanced the compatibility between nano-SiO2 particles and PP matrix. This leads to an improvement in interfacial adhesion and a better dispersion of nano-SiO2 particles in the matrix, thus resulting in an increase in impact toughness by 40 %.

Thermal Fluid Structure Coupling Deformation Characteristics of Polymer Micro Component

2017, 31 (02): 72-76 ; DOI: 10.19491/j.issn.1001-9278.2017.02.012

Abstract ( 332 )

Taking the inmold micro assembly molding of polymer micro mechanical motion pair as a research object, the effects and mechanisms of secondary molding process parameters and micro axial constraint on the thermalfluidstructure coupling deformation of preformed micro shaft induced by the secondary molding melt filling flow were investigated extensively. The resulted indicated that the thermalfluidstructure coupling deformation of preformed micro shaft induced by the secondary molding melt filling flow exhibited an increase with an improvement in secondary molding melt injection temperature, but a decrease with an increase of the constraining degree of two end for the preformed micro shaft in the secondary molding die. The reduction of secondary molding melt injection temperature or the increase of the constraining degree of the preformed micro shaft in the secondary molding die is favorable to the decrease of thermalfluidstructure coupling deformation of preformed micro shaft induced by the secondary molding melt filling flow. This can improve the inmold micro assembly forming precision of polymer micro mechanical motion pair.

Study on Weakening of Hard Plastic Airbag Cover Plates by Ansys Software

2017, 31 (02): 77-81 ; DOI: 10.19491/j.issn.1001-9278.2017.02.013

Abstract ( 562 )

This article reported the stress analysis of weakened structure and structural optimization for hard plastic airbag cover plates in an implicit airbag by an ANSYS software. Through simulating the degree of blowingup for the hard plastic airbag cover plate at six different residual thicknesses of 0.1, 0.3, 0.5, 0.7, 1.0 and 1.5 mm, an optimal residual thickness could be determined as around 0.5 mm. This result was also verified by a balloon blasting experiment.

Surface-molding Accuracy of FDM Thin Plastic Parts Molded by 3D Printing

2017, 31 (02): 82-87 ; DOI: 10.19491/j.issn.1001-9278.2017.02.014

Abstract ( 322 )

This article analyzed the main factors which influenced the surface error of thin parts molded by 3D printing on the basis of the fused deposition modeling (FDM) method, and then the relevant experiments were designed. The effects of layer thickness and extrusion speed on the surface precision of the thin part were investigated, and the influence of printing speed on the surface roughness was evaluated. The results indicated that the parameters for the minimum errors in precision of parts could be determined as a layer thickness of 0.2 mm, an extrusion speed of 30 mm/s and a printing speed of 40 mm/s. As a result, the general principles were achieved for the optimization of processing parameters.

Comparative Investigation on Orthogonal Design and Response Surface Method for Injection Molding Process Optimization of Air Filter Covers

2017, 31 (02): 88-93 ; DOI: 10.19491/j.issn.1001-9278.2017.02.015

Abstract ( 389 )

Taking the volume shrinkage as an evaluation index for an air filter cover, a series of injection molding process parameters including melt temperature, mold temperature, flow rate, packing time and packing pressure on assembly dimension were optimized by means of orthogonal experiment and response surface method (RSM). The results indicated that, on the basis of orthogonal experiment, the injection molding conditions were optimized for a melt temperature of 210 ℃, a mold temperature of 50 ℃, a flow rate of 80 cm3/s, packing time of 12 s and packing pressure of 100 MPa, which resulted in a volume shrinkage of 5.988 %. On the other hand, the process conditions optimized by RSM were determined as a melt temperature of 214.91 ℃, a mold temperature of 59.46 ℃, a flow rate of 80 cm3/s, packing time of 12 s and packing pressure of 109.94 MPa, which resulted in a volume shrinkage of 5.520 %. The results also demonstrated that the volume shrinkage rate derived from RSM was lower than that from orthogonal design, indicating that the processing conditions optimized by RSM is more suitable for the injectionmolded parts with much higher precision.

Chain Extension and Modification of Polypropylene Carbonate Using Diphenylmethane Diisocyanate

2017, 31 (02): 94-98 ; DOI: 10.19491/j.issn.1001-9278.2017.02.016

Abstract ( 366 )

Polypropylene carbonate (PPC) was chemically modified by use of diphenylmethane diisocyanate (MDI) as a chain extender in an internal mixer, and then the thermal performance, mechanical behavior and barrier behavior of the modified PPC were investigated by means of elemental analysis, differential scanning calorimetry, universal material testing machine, gas permeability tester, water vapor permeability tester and other instruments. The results indicated that the glass transition temperature (Tg), mechanical properties, and O2, CO2 and H2O barrier properties of PPC were enhanced due to the chemical modification. Tg of PPC was increased from 30.37 ℃ to 33.48 ℃ in the presence of 5 % MDI, and meanwhile, the tensile strength was improved from 20.9 MPa to 49.0 MPa. Moreover O2 permeability of PPC decreased from 15.8×10^-5 cm3/m2d·Pa to 5.8×10^-5 cm3/m2d·Pa, CO2 permeability decreased from 38.6×10^-5 cm3/m2d·Pa to 15.0×10^-5 cm3/m2d·Pa, and water vapor transmission rate decreased from 23.7 g/m2·d to 10.3 g/m2·d.

Studies on Simulation of Plasticization Properties for Grooved Barrel Single Screw Extruders

2017, 31 (02): 99-107 ; DOI: 10.19491/j.issn.1001-9278.2017.02.017

Abstract ( 448 )

This article performed a comparative investigation on the design feature, transport mechanism, melting heat source and melting model of traditional singlescrew extruders and groovedbarrel singlescrew extruders. Melting rate, melting lengths and original melting cite of the three types of singlescrew extruders with different structures were simulated and effect of the barrel structure on melting performance of singlescrew extruders was investigated. The results indicated that singlescrew extruders with a groovedbarrel is superior to traditional ones in structure, mechanism and performance. The melting performance can be improved significantly for singlescrew extruders by extending the barrel groove from the solid conveying section to the melting one.

Design of Injection Molds for a Sequentially Injection-molded Auto Front Bumper

2017, 31 (02): 108-111 ; DOI: 10.19491/j.issn.1001-9278.2017.02.018

Abstract ( 450 )

A Moldflow software was used to analyze the injection molding conditions for auto front bumper production and also to simulate the injection gate distribution for the injection mold. The balance injection molding process was realized by use of the needle valve hot runner sequential injectionmolding technology. A threestep ejection for inner lateral structure was adopted to achieve automatic ejection with the high production efficiency and quality for the auto front bumper.