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2018, Volume 32 Issue 03 Publication date: 26 March 2018 Previous Issue Next Issue

Research Progress in Unsaturated Polyester Resin Modified by Inorganic Nanoparticles

2018, 32 (03): 1-5; DOI: 10.19491/j.issn.1001-9278.2018.03.001

Abstract ( 480 )

This paper introduced recent research progress in the modification of unsaturated polyester resin (UPR) with various inorganic nanoparticles, and effects of nanoparticles on mechanical properties, thermal properties, corrosion resistance and flame retardant performance of UPR-based nanocomposites were introduced in detail. The modification mechanisms for UPR were also described. Moreover, the future trend for the study on this subject was discussed.

Research Progresses in Thermally Conductive Polymeric Composites with Metal Particles

2018, 32 (03): 6-11; DOI: 10.19491/j.issn.1001-9278.2018.03.002

Abstract ( 601 )

This paper overviewed latest research progresses in thermally conductive composites based on polymer matrix and metal particles. Effects of metal filler type, shape, particles size, content, processing method and microstructure on thermal conductivity of composites were introduced and the thermally conductive mechanisms were described. A number of studies indicated that the high thermal conductivity as well as other good properties could be achieved for polymeric composites by fabrication of a continuous network of metal fillers for phonon transfer. The composites based on elastomer matrix and liquid alloys could also obtain high thermal conductivity and large strain. Such composites are suitable for wearable and flexible electronic components and become a direction for future development in high thermally conductive materials.

Patent Analysis of Polyimide from DuPont Company

2018, 32 (03): 12-21; DOI: 10.19491/j.issn.1001-9278.2018.03.003

Abstract ( 721 )

This article statistically analyzed the patent situation of DuPont Company in the field of polyimide on the basis of research hotspots, distributions of patent applications, and patent protection strategies. The development process and trends of patent applications by DuPont Company were introduced, and their product features, R&D teams and patent protection strategy for polyimide were also discussed according to the obtained patent data.

Preparation and Properties of Polylactic Acid/Cellulose Nanocrystal Composites

2018, 32 (03): 22-26; DOI: 10.19491/j.issn.1001-9278.2018.03.004

Abstract ( 469 )

Dispersibility of cellulose nanocrystal (CNC) in water before and after adding a dodecyl trimethyl ammonium chloride (DTAC) surfactant was investigated, and then polylactic acid (PLA)/CNC composites were prepared by a solution casting method. The results indicated that the aggregation of CNC was effectively reduced with the aid of DTAC, and the compatibility between PLA and surface-treated CNC was improved due to the formation of hydrogen bonding. Moreover, the heterogeneous nucleation of PLA could be promoted in the presence of surface-treated CNC, leading to an increase in crystallinity of PLA matrix. The tensile strength of composites was improved by 70.7 % with the addition of 2 wt % surface-treated CNC, but their elongation at break decreased.

Effect of Hybrid Modes on Properties of PP Composites

2018, 32 (03): 27-32; DOI: 10.19491/j.issn.1001-9278.2018.03.005

Abstract ( 494 )

A mixing needled felt was first prepared by knitting a reinforcing fiber with the fiber made from the matrix resin according to the hybrid principle, and then the composites based on this needled felt and the matrix were prepared by a laminating method. Mechanical properties of the composites were evaluated, and the effects of hybrid modes and lamination technology on the mechanical performance were discussed. The results indicated that there was a significant influence on mechanical performance derived from the new hybrid mode adopted in this work. The content of hybrid fibers was found to have a great effect on the mechanical properties of the composites. Moreover, the effects of lamination temperature and pressure on mechanical performance were more significant than those from the traditional composite technology.

Study on Polypropylene/Talc Composites Toughened by POE

2018, 32 (03): 33-36; DOI: 10.19491/j.issn.1001-9278.2018.03.006

Abstract ( 549 )

The co-polypropylene (PP) based composites with talcum powders and polyolefin (POE) were prepared by melt extrusion using a twin-screw extruder. The effects of POE content and storage time on mechanical properties of the composites were investigated, and the fractography of the composites was observed by scanning electron microscopy. The results indicated that a brittle-ductile transition occurred at POE content of 7 wt %. The impact strength of the composites increased gradually with the addition of POE over 11 wt %. There was little change in impact strength after the composites were stored for 24 h. The increase of POE content resulted in a decrease in the size of POE dispersed phase.

Flame-retardant Behaviors of Polyurethane Foams Containing Expandable Graphite and Phosphates as Typical Add-type Flame Retardants

2018, 32 (03): 37-43; DOI: 10.19491/j.issn.1001-9278.2018.03.007

Abstract ( 432 )

Three types of phosphates, dimethyl phosphate (DP), (5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl) methyl dimethyl phosphonate P-oxide (EMD) and dimethyl methylphosphonate (DMMP) were used as typical add-type flame retardants for the flame retardancy of rigid polyurethane foam (RPUF), and expandable graphite (EG) was also added as a flame-retardant additive. The flame-retardant behaviors and mechanisms of the resulting composite foams were investigated. The results indicated that the composite foams containing DMMP and DP exhibited greater limiting oxygen indices than that containing EMD at the same content of phosphate flame retardant. The composite foam containing DMMP also presented the lowest heat release and total heat release rates. Owing to the oxidation reaction of DP during combustion, the heat release rate increased, resulting in a reduction in flameretardant effect. Although EMD could be decomposed into DMMP molecules during combustion, its flame retardant efficiency was lower than that of DMMP due to a low content of phosphorus. DMMP exhibited the best flame-retardant effect due to its high phosphorus content and high flame retardant efficiency in both gas and condensed phases.

Study on Properties of Poly(lactic acid)/Polyethylene Glycol or Polypropylene Glycol Blends

2018, 32 (03): 44-50; DOI: 10.19491/j.issn.1001-9278.2018.03.008

Abstract ( 822 )

Blends of poly(lactic acid) (PLA) with poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) were prepared by melt blending, and effects of PEG molecular weight on thermal and mechanical properties of the blends were investigated. Furthermore, a comparative investigation on the effects of PEG and PPG on the properties of the blends was performed at the same molecular weight but different molecular structures. The results indicated that an optimum modification effect was achieved at the PEG molecular weight of 2 000. PEG exhibited a better modifying effect on PLA than PPG at the same molecule weight.

Effects of Size and Shape of Graphene Nanoplatelet (GNP) on Electrical and Thermal Conductivity of PP/GNP Nanocomposites

2018, 32 (03): 51-58; DOI: 10.19491/j.issn.1001-9278.2018.03.009

Abstract ( 528 )

PP/graphene nanoplatelet (GNP) nanocomposites were prepared by using five different type of GNP fillers through a melt blending methods, and effects of size and content of GNP on electrical and thermal conductivity of nanocomposites were investigated. The results indicated that, at the same thickness of GNP, GNP with larger diameters could provide a greater contact area between the layers, thus improving the electrical and thermal conductivity of the nanocomposites. Moreover, at the same diameter of GNP, the thinner thickness resulted in a better dispersion of GNP in the matrix, and the nanocomposites achieved an improvement in electrical and thermal conductivity accordingly. It was also found that the effects of GNP content on the electrical and thermal conductivity were different for the samples of PG-100, PG-030 and PG-G5. PG-030 could easily form a conductive network at the lowest percolation threshold, and however, PG-G5 exhibited the highest electrical conductivity and thermal conductivity at a high content of GNP.

Preparation and Characterization of Polyamide 6 Powders by Precipitation Method in Ethanol/Water Mixed Solvent

2018, 32 (03): 59-64; DOI: 10.19491/j.issn.1001-9278.2018.03.010

Abstract ( 493 )

Polyamide 6 powders were prepared by a precipitation method in different ethanol/water mixed solvents. Morphology, thermal properties, particle size and distribution, stacking angle and density of the resulting powders were investigated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and laser particle size analyzer. The results indicated that the interaction between the solvent and polyamide 6 increased gradually with an increase of the volume fraction of ethanol in the mixed solvents, and there was a change in morphology of polyamide 6 powders from an irregular loose structure to the regular sphere-like one. The particle size decreased to 78.81 μm and the particle distribution became narrower. There is no change in the crystal form of polyamide 6 powders. However, the thickness of crystals increased and the melting point decreased. The stacking angle of polyamide 6 powders decreased gradually, whereas its density increased gradually. The solubility parameter of the solvents exhibited an important effect on the properties of the powders.

Preparation and Properties of Neroli Oil Microcapsules Modified by PVA Filled with Doped Inorganic TiO2 Nanoparticles

2018, 32 (03): 65-71; DOI: 10.19491/j.issn.1001-9278.2018.03.011

Abstract ( 475 )

To improve mechanical properties of microcapsules and reduce the release rate of core materials, neroli oil microcapsules were prepared by fabricating a melamine formaldehyde resin shell modified by poly(vinyl alcohol) (PVA) filled with Fe3+-, Zr4+- and Ce4+-doped TiO2 nanoparticles through in-situ polymerization. The effect of doped TiO2 nanoparticles on morphology and mechanical and thermal properties of the resulting microcapsules were investigated by Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The results indicated that the release rate of the core material was reduced with the addition of doped TiO2 nanoparticles into the wall material. When 0.5 wt % of Fe3+-doped TiO2 nanoparticles was incorporated into the wall, the microcapsules achieved a cracking rate of 18.1 % and a release rate of 4.5 %.

Poly(lactic acid) Flame Retarded by Phosphazene-triazine Bi-groups Compound

2018, 32 (03): 72-78; DOI: 10.19491/j.issn.1001-9278.2018.03.012

Abstract ( 472 )

A novel flame retardant based on phosphazene and triazine groups (HTTCP) was used to modify poly(lactic acid) (PLA) by a combination of hexaphenoxycyclotriphosphazene (HPCTP) and pentaerythritol octahydrogen tetraphosphate (PEPA) via a melt blending method. Thermogravimetric analysis, limiting oxygen index (LOI), vertical burning experiment and cone calorimetry were conducted to investigate the effect of different flame retardants and their weight ratios on thermal stability and flame retardant properties of PLA matrix composites. Moreover, the morphology of residual char was analyzed by scanning electron microscopy, and the flameretardant mechanisms were investigated. The results indicated that PEPA/HTTCP system exhibited a better flameretardant effect on HPCTP/HTTCP one due to its excellent protective and barrier effect. The composites gained a maximum LOI of 27.2 vol % with the addition of 20 wt % flame retardants at PEPA and HTTCP mass ratio of 3∶1. Furthermore, their heat release rate, average heat release rate and total heat release also reached the minimum values, and meanwhile, the composite achieved a UL94 V-0 classification in the vertical combustion experiment.

Effect of Blending Condition on Performance of ABS Resin Through Twin-rotor Continuous Extruder

2018, 32 (03): 79-84; DOI: 10.19491/j.issn.1001-9278.2018.03.013

Abstract ( 490 )

An acrylonitrile-butadiene-styrene (ABS) resin was prepared through a self-developed twin-rotor continuous extruder. The effect of blending condition on mechanical properties of ABS resin was investigated, and the mixing ability of extruders was evaluated by POLYFLOW software. The rheological behavior and microstructure of ABS resin were characterized to investigate the effect of blending condition on the micro-morphology of rubber particles. The results indicated that the dispersive and distributive mixing abilities of the extruder were improved with an increase of rotor speed. As a result, the aggregation of rubber particles was reduced and their dispersibility was enhanced. When the rotor speed was set to 400 r/min, the tensile strength, flexural strength, flexural modulus and impact strength of ABS resin were improved by 16.8 %, 15.4 %, 30.7 % and 7.7 %, respectively. However, at the rotor speed of 500 r/min, the tensile strength, flexural strength, flexural modulus and impact strength decreased by 7.6 %, 7.5 %, 21.8 % and 32.6 %, respectively, compared with the sample obtained at the rotor speed of 400 r/min. This may be due to the internal grafting of rubber particles caused by an intensive shear effect.

Study on Preparation and Fused Deposition Modeling Technology of PBS/PLA/Talc Filament for 3D Printing

2018, 32 (03): 85-91; DOI: 10.19491/j.issn.1001-9278.2018.03.014

Abstract ( 590 )

Poly(lactic acid) (PLA) and talc powder were used to modify poly(butylene succinate) (PBS), and then a PBS/PLA/talc composite filament was prepared for fused deposition modeling (FDM). The effect of PLA content on 3D printing processability was investigated by crystallinity analysis, rheological behavior, mechanical performance, scanning electron microscopy and 3D printing effect. The experimental results indicated that the crystallization temperature of PBS decreased by 5 ℃ with an increase of PLA content, but the complex viscosity and storage and loss moduli increased gradually in the presence of PLA. Moreover, with increasing PLA content, the tensile strength and notched impact strength of the composite decreased by 1.71 MPa and 2.63 kJ/m2, respectively. The fracture surface of tensile specimens also became rougher. 3D printing process parameters for PBS/PLA/talc composite filament was investigated by a FDM method. The results indicated that the printing effect was improved with the addition of PLA. The warpage was improved significantly when the plate temperature exceeded 110 ℃, and meanwhile, the tensile strength increased with an increase of printing temperature.

Revelation of the American Plastic Pipe Failure Data to China Plastic Pipe Safety Management

2018, 32 (03): 92-98; DOI: 10.19491/j.issn.1001-9278.2018.03.015

Abstract ( 642 )

This paper reported a systematic analysis for plastic pipe failure data collected from American Plastic Pipe Data Association. By combining the relevant failure data obtained from European gas pipeline failures, failure reasons of plastic pressure pipelines were systematically analyzed from the aspects of third-party damage, defects, biological damage and aging, and then some suggestions were proposed for the safety management of plastic pipe in China.

Elastic Hysteric Effect and Constitutive Model of PTFE, PA66 and Polyester-type TPU Under Rolling Contact

2018, 32 (03): 99-103; DOI: 10.19491/j.issn.1001-9278.2018.03.016

Abstract ( 575 )

The rolling friction coefficient was theoretically deduced from the elastic hysteric effect according to the standard linear solid model. The static creep and relaxation characteristics of PTFE, PA66 and polyester-type TPU(PEUR) was evaluated by a CETR UMT-2 type equipment and an LKDM-2000 tester, and their rolling friction behavior under different loads and velocities was investigated by a rolling friction testing equipment. The coupling relationship between the viscoelasticity and rolling friction coefficient was discussed through a comparison between experimentals data and theoretical results. The results indicated that the rolling friction coefficient of the three polymers increased with an increase of the rolling velocities. The ratio of rolling friction coefficient for PEUR, PA66 and PTFE was 1.12∶1.02∶1 under the same experimental condition. The theoretical data of the rolling friction coefficient were consistent with the experimental results, indicating that the friction resistance force was mainly originated from the elastic hysteresis effect.

Influence of Halogen-free Flame Retardants on Thermal-oxidative Aging Performance of Flame Retardant Polyolefin Composites

Hanjing -YOU

2018, 32 (03): 104-109; DOI: 10.19491/j.issn.1001-9278.2018.03.017

Abstract ( 524 )

The polyolefin compounds with halogen-free flame retardants were prepared by a melt blending method, and the thermal-oxidative aging and thermal cracking properties, oxidation induction time of the resulting flame-retardant compounds were characterized by means of oven heating, universal testing machine and differential scanning calorimetry. The results indicated that, when different halogen-free flame retardants were incorporated, the flame-retardant polyolefin compounds presented the improved thermal oxidative aging performance by an order of zinc borate>Mg(OH)2>Sb2O3>melamine cyanurate>Al(OH)3>phosphate>CaCO3. The smaller the particle size of halogen-free flame retardants, the poorer the thermal oxidative aging performance. In addition, the surface treatment of halogen-free flame retardants improved the thermal oxidative aging performance of flame-retardant polyolefin compounds.

Synergistic Effect of Zinc Hydroxystannate/Reduced Graphene Oxide Hybrid and Magnesium Hydroxide on Flame-retardant PVC

2018, 32 (03): 110-115; DOI: 10.19491/j.issn.1001-9278.2018.03.018

Abstract ( 501 )

A self-made zinc hydroxystannate (ZHS)/reduced graphene oxide (RGO) hybrid (ZHS-RGO) was synergized with magnesium hydroxide (MH) to prepare flame-retardant soft PVC, and synergistic effects of ZHS/MH and ZHS-RGO/MH on flame retardant performance and smoke suppression of the resulting soft PVC were investigated by limiting oxide index, micro-scale combustion calorimetry (MCC) and cone calorimetry (CCT). The results indicated that there was a synergistic effect between MH and ZHS or ZHS-RGO on the flame retardant performance and smoke suppression of the soft PVC. PVC/10ZHS-RGO/5MH samples presented a peak heat release rate of 436 kW/m2 in MCC test and total smoke release of 23.62 m2 in CCT test, which was lower than those of PVC/10ZHS/5MH sample by 38.8 % and 12.0 %, respectively. RGO in the hybrid exhibited a good physical barrier effect.

Analysis of Water Vapor Permeability of Barrier Plastic Films by Electrolytic and Infrared Detection Sensor Methods

2018, 32 (03): 116-121; DOI: 10.19491/j.issn.1001-9278.2018.03.019

Abstract ( 407 )

Water vapor transmission rates of barrier plastic films were investigated at different temperatures and relative humidity by electrolytic and infrared detection sensor methods. Effects of temperature and film type on the water vapor permeability were analyzed, and the experimental results obtained from the electrolytic and infrared detection sensor methods were compared. The results indicated that PET film with a thickness of 12 μm presented greater water vapor permeability than that with a thickness of 25 μm. PET/Al film with a thickness of 12 μm and PVDC film with a thickness of 25 μm exhibited smaller water vapor permeability than that of the two PET films. The water vapor transmission rates increased with an increase in temperature for these four barrier plastic films. However, the temperature had less effect on the water vapor transmission rates of PET/Al film with a thickness of 12 μm and PVDC film with a thickness of 25 μm, and there was a linear relationship between the logarithm of water vapor transmission rate and the reciprocal of thermodynamic temperature. Test results obtained from the infrared detection sensor method were greater that those from the electrolytic detection sensor one. The difference between these two test results for PET/Al film with a thickness 12 μm and the PVDC with a thickness 25 μm was larger than those for PET films with thicknesses of 12 and 25 μm.

Feature Array Replication Fidelity Analysis of Microlens On of Injection Molded Thin-wall Light Guide Plates

2018, 32 (03): 122-126; DOI: 10.19491/j.issn.1001-9278.2018.03.020

Abstract ( 500 )

For replication fidelity and anisotropic formation of microlens feature array during injection molding processes, a thin-walled light guide panel with a microlens feature array was taken as an example to perform a warpage analysis by using numerical simulation and orthogonal experiment methods. The results indicated that the deformation trend of microlens features in the middle region exhibit a homogeneous decrease along the contour curve, whereas the deformation tendency of the side microlens features presented a deviation toward the center. According to the different replication characteristics, the melt temperature, flow rate and mold temperature were found to have a great effect on the reproduction fidelity of microlens feature array.

Optimal Design of Core Component Structure of Axial Flow Fans

2018, 32 (03): 127-132; DOI: 10.19491/j.issn.1001-9278.2018.03.021

Abstract ( 408 )

The traditional combination process of riveting and pressing was modified by using a shaft rotor as an insert to be injection-molded with wind blades together as an integral. This design led to a reduction in cost and an improvement in productivity. To eliminate the influence of rotor quality, a static balance guiding track framework was adopted to conduct a static balance test on the pure fan, which effectively avoided misjudgments toward the balance correction caused by rotor factors from mold repairing. Owing to the simple structure of static balance frame, the experimental results were accurate and reliable for the correction of equilibrium amount using a deweighting method.

Design of Large Precision Injection Molds with Complex Side Core Pulling Mechanisms for Feeding Frames of Printers

张维合 allenzhang

2018, 32 (03): 133-137; DOI: 10.19491/j.issn.1001-9278.2018.03.022

Abstract ( 500 )

Based on the structural feature of feeding frames of printers and rheological characteristics of thermoplastic resins used, a three-plate mould with single cavity and three core pulling mechanisms were designed. The design skills were carefully analyzed, which include mould forming parts, gating system, fixed distance parting mechanism, side-core pulling mechanism, temperature control system, demoulding system and guiding positioning system. The deformation problem of side-core pulling plastic parts under a large tight force was solved by using a horizontal push rod. The precision of the injection-molded product reached MT3, the molding cycle was shortened by 8 % to 35 s compared with other same type of plastic parts.