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2016, Volume 30 Issue 06 Publication date: 26 June 2016 Previous Issue Next Issue

Progress and Trend of Lignin and Thermoplastic Plastic Blends

2016, 30 (06): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2016.06.001

Abstract ( 677 )

This paper begins with an overview of the structure and properties of lignin, and the compatibility between lignin and thermoplastic resins and the properties of lignin-containing biodegradable composites were reviewed. The trend of these composites was also elaborated.

Study on Heterogeneous Foaming Behavior of Polybutylene

2016, 30 (06): 7-12 ; DOI: 10.19491/j.issn.1001-9278.2016.06.003

Abstract ( 621 )

The polybutylene (PB) foam was prepared by compression molding， and the effect of the content and particle size of nucleating agents on the mechanical properties and cellular structure of foam was studied. When talc and calcium carbonate were used as nucleating agent, the average cell diameter was reduced to 135 μm, and the cell density was increased to 7×105 cells/cm3. The smaller particle size the nucleating agent, the greater the cell density, and the smaller the average cell diameter. When calcium carbonate was used as a nucleating agent with loading of 6 %, a foam with particle size of 10 μm, cell density up to 106 cells/cm3, and average cell diameter size of 85 μm was obtained.

Influence of Maleic Anhydride Content and Processing Conditions on Morphology and Mechanical Properties of Polyamide 6/POE/POE-g-MAH/Nano-CaCO₃ Composites

2016, 30 (06): 13-17 ; DOI: 10.19491/j.issn.1001-9278.2016.06.004

Abstract ( 359 )

In this paper, the influence of MAH content on the morphology and mechanical properties of PA6/POE/POE-g-MAH/nano-CaCO3 composites was studied by changing the ratio of POE and POE-g-MAH. SEM images showed better compatibility between the PA6 matrix and POE elastomer when the MAH content was higher, resulting in the highest impact strength of the composites. Furthermore, it was found that the morphology and mechanical properties of the composites were greatly affected by the processing method. Nano-particles dispersed well in the matrix when the composites were prepared by a two-step processing method. The size of POE phase was enlarged about 100 nm by the formation of core-shell structure with nano-CaCO3 particles. As a result, the impact strength of the composites made by the two-step method increased 21 % compared with that of the composites by the one-step method.

Bismaleimide Resin Toughened by Reactive PFEK with Pendant Propenyl Groups

2016, 30 (06): 18-22 ; DOI: 10.19491/j.issn.1001-9278.2016.06.005

Abstract ( 401 )

Poly(fluorene ether ketone) (PFEK) with pendant propenyl groups was dissolved in a bismaleimide (BMI) resin composed of 4,4-bismaleimidodiphenyl methane (BMDM) and DABPA without using any solvent. The solution was self-cured at a high temperature forming an interpenetrating network which gave a single endothermic peak on a DSC curve. The glass transition temperature (Tg) of the system did not decrease with the increase of PFEK, which rendered the system a good thermal stability. Compared with neat BMI resin, the impact strength was elevated from 9.0 to 15.2 kJ/m2 by 10 phr PFEK. Scanning electron microscopy (SEM) of fracture surface revealed that the material had a good interfacial adhesion.

Mechanical and Thermal Properties of PE-HD/BF/PE-g-MAH Composites

2016, 30 (06): 23-27 ; DOI: 10.19491/j.issn.1001-9278.2016.06.006

Abstract ( 544 )

Bamboo fibers (BF) were treated with 10 wt% NaOH solution, and PE-HD/BF binary and PE-HD/BF/PE-g-MAH ternary composites were prepared by twin-screw extrusion and injection molding, and the composites were analyzed by SEM, TG, melt flow index, heat deflection temperature, and mechanical testing. The thermal stability of BF was found to be improved by alkali treatment. The stiffness, flexural strength, and heat deflection temperature of PE-HD were increased with the addition of alkali treated BF, however, the tensile strength, impact toughness, and melt flow index decreased. The interfacial adhesion between PE-HD and BF could be enhanced by PE-g-MAH With 5 wt% PE-g-MAH, the impact, tensile, and flexural properties, thermal stability and heat deflection temperature of PE-HD/30 wt% BF composites were well improved. The flowability of PE-HD/BF/PE-g-MAH composites was good enough to meet the requirement of injection molding.

Effects of Different UV on Aging Behavior of PP Modified with Inorganic Nanomaterials

2016, 30 (06): 28-33 ; DOI: 10.19491/j.issn.1001-9278.2016.06.007

Abstract ( 475 )

TEM, GPC, IR, and mechanical property tests were carried out to study the effect of inorganic nanomaterials such as TiO2, SiO2, ZnO on the UV aging resistance of PP. It was found that the best dispersion was achieved when the loading of inorganic particles was 0.3 wt%, at which the mechanical properties of PP was obviously enhanced and the anti-UV aging behavior of PP/nano-TiO2 was the best. Compared with neat PP, the elongation at break of the composite after 144 h of aging under 340 nm and 313 nm of UV light was increased by 31.5 % and 11.8 %, respectively

Effect of Layered Silicate Intercalated by Siloxane on Combustion Behavior of Intumescent Flame Retardant Polylactide

2016, 30 (06): 34-39 ; DOI: 10.19491/j.issn.1001-9278.2016.06.008

Abstract ( 378 )

Layered silicate (Clay) was intercalated by four kinds of organic modifiers and was introduced into polylactide (PLA) forming nanocomposites.Thermal degradation behavior and combustion properties of the composites were evaluated through thermogravimetric analysis, UL 94 experiments, limiting oxygen index, and cone calorimeter tests. Morphology of the char residue was investigated by scanning electronic microscopy. It was found that the addition of 1 % siloxane modified clay resulted in a higher limited oxygen index, higher vertical burning class (UL 94 V-0), and lower peak heat release rate compared with other composites. Scanning electronic microscopy revealed that the residual char of the composites containing siloxane modified clay was compact, which enhanced the flame retardant properties.

Mechanical and Antibacterial Properties of PETG/Nano Zinc Oxide/Copper Chlorophyll Acid Nanocomposites

2016, 30 (06): 40-44 ; DOI: 10.19491/j.issn.1001-9278.2016.06.009

Abstract ( 471 )

Nanocomposite based on poly (ethyleneterephthalateco-1, 4-cylclohexylenedimethylene terephthalate) (PETG), nano-ZnO, and copper chlorophyll acid (CCA) were prepared by melt blending. The effect of mass ratio of nano-ZnO/CCA on the antibacterial and mechanical properties was investigated. It was shown that significant increase of the antibacterial effect against Escherichia coli was observed after adding a small amount of CCA. When the mass ratio of nanoZnO was 1.0 % and the CCA content was 0.5 %, the best antibacterial effect was obtained: the antibacterial rate against Escherichia coli of the nanocomposite was proved to 99.9 %.

Effect of Shear on Morphology and Properties of Polypropylene/Graphene Nanoplatelets Nanocomposites

2016, 30 (06): 45-51 ; DOI: 10.19491/j.issn.1001-9278.2016.06.010

Abstract ( 451 )

An extrusion die with two shunt plates was designed to provide high shear effect. The effect of shear on morphology, thermal conductivity, electrical conductivity, and crystallization behavior of polypropylene/graphene nanoplatelet nanocomposite was investigated. It showed that the shear rate of the extrusion die with two shunt plates was eight times that of the extrusion die without two shunt plates. This improved the exfoliation and orientation of graphene nanoplatelets and crystallinity of the nanocomposites, and reduced the electrical percolation threshold from 10 % to 8 %. When the graphene nanoplatelets content reached 12 %, the thermal conductivity of nanocomposites extruded by the die with and without two shunt plates were 1.20 W/(m·K) and 0.90 W/(m·K), respectively.

Mechanical Properties and Rheological Behavior of PBT/ABS-g-MAH/SCF Composites

2016, 30 (06): 52-56 ; DOI: 10.19491/j.issn.1001-9278.2016.06.011

Abstract ( 448 )

Short carbon fiber (SCF) was introduced into blends of maleic anhydride grafted ABS and poly (butylene terephthalate) forming a composite (PBT/ABS-g-MAH/SCF), which was investigated in its phase morphology, mechanical, rheological and crystallization properties by scanning electron microscope (SEM), universal tester, impact tester, rotational rheometer and differential scanning calorimetry (DSC). SEM showed that the interfacial bonding properties between PBT and SCF was better because of epoxy adhesive. The tensile strength, impact strength, and bending strength of the composites reached their maximum with SCF content of about 5 %~10 %. So the SCF had a function of enforcement and toughness for PBT. The rheological behavior showed that complex viscosity reduced firstly and then increased with increasing SCF. In addition, DSC test indicated that SCF component initiated the heterogeneous nucleation, so the crystallization temperature increased when adding appropriate SCF.

Effect of Contents of Dispersed Phase on Properties of POE／PTT In-situ Fiber Reinforced Composite

2016, 30 (06): 57-62 ; DOI: 10.19491/j.issn.1001-9278.2016.06.012

Abstract ( 350 )

POE/PTT in-situ fiberized reinforcing composites were prepared by a method of micronano laminated co-extrusion. Morphology of the dispersed phase of PTT in micronano laminated extrusion composites was analyzed by using SEM. Effect of adding quantity of PTT in composites on static mechanical performance was discussed. DSC analysis was used to study the effect of PTT in the complex system on crystallization properties of POE. The result indicated that in the in-situ fiber reinforcing composites, with the dispersed phase content increased, the number of PTT microfibers gradually increased, while the crystallization of POE decreased. Compared with neat POE, the tensile strength of in-situ fiber reinforcing composites was improved by 16.9 % while POE/PTT was 85/15.

Gas-assisted Injection Molding with Different Flow Patterns of Injection Gas

2016, 30 (06): 63-69 ; DOI: 10.19491/j.issn.1001-9278.2016.06.013

Abstract ( 384 )

In this paper, temperature distribution of cooling stage of GAIM was studied via numerical simulation. Under some reasonable assumptions during the cooling stage of GAIM, the temperature distribution of PE-HD parts was studied via the numerical simulation using software package MATLAB, which used the average heat instead of crystallization latent heat in crystallization temperature interval and the boundary condition was second category of convective heat transfer boundary condition. The velocity of N2 with different pressure was determined and the simulated temperature field was verified by experiment. The experimental results showed that the simulation value of cooling temperature field was consistent with experiment value.

Properties of PP Fibers Prepared by Melt Differential Electrospinning with Supercritical CO₂

2016, 30 (06): 70-73 ; DOI: 10.19491/j.issn.1001-9278.2016.06.014

Abstract ( 392 )

In this experiment PP and supercritical CO2 (SC-CO2) were first mixed in a sealed pressure vessel to form a homogeneous system, which was spun to fiber through melt differential electrospinning. The effect of supercritical CO2 on the fiber was studied. The average diameters of the fiber made from neat PP, PP and mixture of PP and SC-CO2 were 12.8, 8.02, 5.08 μm, respectively. After being mixed with supercritical CO2 the viscosity of PP melt, and the crystallinity of solid PP were decreased.

Effects of Shear Stress on Crystallization Behavior of Polylactide

2016, 30 (06): 74-78 ; DOI: 10.19491/j.issn.1001-9278.2016.06.015

Abstract ( 566 )

The influences of shearing stress on crystallization behavior of polylactide (PLA) resin and casting sheet were investigated by changing heating and cooling circle times, aging time and temperature. It showed that the entanglement or the extent of relative order of PLA molecules affected the crystallization behavior. Under the influence of shearing stress, the disentanglement of PLA molecules happened or the extent of relative order increased, which made the cold crystallization process occur easier.

Microstructure, Rheological Behavior and Thermal Property of Polystyrene/Grapheme Oxide Nanocomposites Prepared by Water-assisted Mixing Extrusion

2016, 30 (06): 79-85 ; DOI: 10.19491/j.issn.1001-9278.2016.06.016

Abstract ( 387 )

Three polystyrene/graphene oxide (PS/GO) nanocomposites (GO contents 0.1 wt%, 0.3 wt%, and 0.5 wt%) were prepared using home-designed water-assisted-mixing extrusion equipment. Microstructure, rheological behavior, and thermal stability of the nanocomposite samples were investigated. It demonstrated that GO was well exfoliated and dispersed in network structure in PS matrix. This was attributed to the fact that PS chain was easy to intercalate and exfoliate GO layers. PS/GO samples exhibited higher elastic moduli, complex viscosities, and relaxation times at low frequencies as compared with neat PS, which was because of the stronger intermolecular force between well dispersed GO layers in network structure and PS. PS/GO samples exhibited higher thermal stability than neat PS sample, which was due to the GO network in PS matrix and π bond at GO surface.

Analysis of Pump Case Molding Process Based on MFI

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2016, 30 (06): 86-91 ; DOI: 10.19491/j.issn.1001-9278.2016.06.017

Abstract ( 512 )

The structure of the pump case was studied. Two plans for the pump case—two-gate system and three-gate system were designed based on its features including thin wall, deep cavity and easy to lack of the material in the edge as well as easy for deformation and heat accumulation. Through the comparison of the two plans in filling time, plastic flow front temperature and cavitation with Moldflow software, a three-gate plan was selected which utilizes one main runner and three second and third subchannel evenly distributed as the gating system of the pump case. In this plan, while injection, the injection pressure was 63.9532 MPa and the clamping force was 47.5293 t. On this base, a fiveloop cooling system of the injection mold was created, and the pump shell buckling deformation was analysized. Warping deformation caused by mold cooling and material orientation was almost zero.

Influence of Novel Charring Agent on Flame Retardancy of PE-LD

2016, 30 (06): 92-96 ; DOI: 10.19491/j.issn.1001-9278.2016.06.018

Abstract ( 371 )

A novel intumescent flame retardant (IFR) was composed by ammonium polyphosphate (APP) and novel charring agent (CNCH-DA), and the influence of CNCH-DA on the flame retardancy of PE-LD was investigated by limited oxygen index, vertical test, microscale combustion colorimeter, thermogravimetric analysis and scanning electron microscopy. It was found that the limited oxygen index of the PE-LD composites was 27.5 % with UL 94 V-0 rating when the mass ratio of APP to CNCH-DA was 5:1. The heat release rate and total heat release measured by MCC decreased remarkably. The composites decomposed at higher temperature when APP and CNCH-DA were composed together. An intumescent and compact char layer was formed for PE-LD/IFR composite with excellent flame retardant properties, while lots of small balls were formed for PE-LD/CNCH-DA with poor barrier properties.

Study on Thermal-oxidative Aging and Combustion Performance of Waste High-density Polyethylene/OMMT Nanocomposite

2016, 30 (06): 97-101 ; DOI: 10.19491/j.issn.1001-9278.2016.06.020

Abstract ( 375 )

The nanocomposite was synthesized through melt intercalation method, with waste high-density polyethylene (HDPE) and montmorillonite (MMT) as materials. The preparation conditions were all evaluated for the impact of thermal-oxidative aging and combustion performance. The result showed that the thermal-oxidative aging performance decreased significantly and the combustion property enhanced when HDPE composite with MMT/organic montmorillonite (OMMT). The thermal-oxidative aging performance of the HDPE/OMMT nanocomposite had no significant change, the combustion performance of the HDPE/OMMT nanocomposite increased first then tends to gentle with the increase of cetyl trimethyl ammonium bromide (CTAB), OMMT, maleic anhydride (MAH) and dicumyl peroxide (DCP) amount. When the amount of CTAB, OMMT, MAH and DCP is 1%, 3%, 1.5% and 1.5% respectively, the limiting oxygen index of the HDPE/OMMT nanocomposite could reach 19.4%, and the combustion performance is the best.

Optimization Design of Molding Process for Automobile CD Panels

2016, 30 (06): 102-107 ; DOI: 10.19491/j.issn.1001-9278.2016.06.021

Abstract ( 478 )

In this paper, a threedimensional mathematical model was formulated for plastic parts of automobile stereo using UG10.0. The gate location was simulated through Moldflow plastics insight 2014, and the optimal gate location was determined. The flow，cooling, and warpage were simulated，and the processing parameters were optimized. For four process parameters, melt flow rate, mold temperature，holding pressure，and dwell time interval, an threelevel orthogonal experimental was carried out and the optimal combination of the parameters was determined.

Optimization and Analysis of Injection Molding Process for Gear Toys Based on BP Neural Network

2016, 30 (06): 108-115 ; DOI: 10.19491/j.issn.1001-9278.2016.06.022

Abstract ( 620 )

In order to produce insert-gear plastic toys more effectively, an injection mold with 144 cavity was designed using natural balance method. The finite element model was reasonably simplified and the flow and warpage in the molding was analyzed by Moldflow software. Focused on the welding marks and warpage and other defects, a BP artificial neural network model was established, the process parameters were trained, the volume shrinkage and the total amount of warpage were predictively analyzed by the BP neural network algorithm. The optimal combination of process parameters after training was applied to the injection molding, the weld mark and warpage were reduced significantly.

Motion Analysis of Clamping Mechanism of Injection Machines

2016, 30 (06): 116-120 ; DOI: 10.19491/j.issn.1001-9278.2016.06.023

Abstract ( 625 )

A theoretical analysis of negative rear angle locking toggle mechanisms was carried out.Through actual measurement of the displacements of cross heads and movable templates, the displacement, velocity and acceleration of the locking mechanism were realtimely analyzed.It showed that the ratio of mold moving to the cylinder speed was related to the parameters of the clamping mechanism.Actual measurement and theoretical estimation were in good agreement.The opening and closing characteristic was excellent.