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2016, Volume 30 Issue 03 Publication date: 26 March 2016 Previous Issue Next Issue

Research Progress of Black Polyimide Films

2016, 30 (03): 1-9 ; DOI: 10.19491/j.issn.1001-9278.2016.03.001

Abstract ( 1171 )

Recent research and industrial production of black polyimide film were reviewed, including four classes, insulation, antistatic, electrically conductive, and thermal conductive ones. The frequently used additives, conductive and nonconductive carbon black pigments, inorganic or organic matting agents, and frequently used methods, such as ceramic packing, adopt pretreatment, mixing, and in situ polymerization were discussed. In the end, development trend of the black polyimide films was predicted.

Research Progress of Melamine Based Flame Retardants in Epoxy Resin

2016, 30 (03): 10-16 ; DOI: 10.19491/j.issn.1001-9278.2016.03.002

Abstract ( 652 )

Flame retarding mechanism and application of melamine based flame retardants inepoxy resinwere summarized. The development trend of the melamine based flame retardant was forecast.

Diffusion Effect of Melting at High Temperature on PP/EPR/PE-UHMW and Its Influence on Rheological and Crystallization Behavior

2016, 30 (03): 16-21 ; DOI: 10.19491/j.issn.1001-9278.2016.03.003

Abstract ( 508 )

A simple method was used to promote the diffusion of highlyentangled molecular chains of ultra high molecular weight polyethylene (PE-UHMW) and ethylene propylene rubber(EPR) leading to blends of EPR/PE-UHMW, which was further mixed with polypropylene (PP) forming PP/EPR/PE-UHMW ternary blends. The blends were characterized by rheological measurement and differential scanning calorimeter (DSC). The rheological tests displayed a long relaxation mechanism occurring in the lowfrequencies region. The interentanglement structure restricted the diffusion of EPR into PP matrix. DSC showed that the plasticization of PE-UHMW resulted in decreasing in crystallization temperature and increasing indegree of crystallinity. The addition of EPR/PE-UHMW blend to PP matrix caused a multiple melting behavior of PP.

Thermal Conductivity and Fire Resistance of PE-LD/EVA Blends Filled with Inorganic Fillers

2016, 30 (03): 22-27 ; DOI: 10.19491/j.issn.1001-9278.2016.03.004

Abstract ( 652 )

Aluminum oxide (Al2O3) and magnesium hydroxide ［Mg(OH)2］ were introduced into low density polyethylene/ethylenevinyl acetate copolymer (PE-LD/EVA) to improve the thermal conductivity and flame retardancy. Thermal conductivity test, limiting oxygen index, UL94 test and thermal gravimetric analysis were used to characterize the thermal conductivity, flammability, and thermal behavior of PE-LD/EVA/Al2O3/Mg(OH)2 composites. The results showed that the thermal conductivity reached 1.21 W/m·K at the presence of 50 phr Al2O3 and 50 phr Mg(OH)2 and the PE-LD/EVA mass ratio of 1/1; the introduction of EVA into composites apparently increased the limited oxygen index from 27.0 % to 31.5 % , and the UL 94 level was improved from no rating to V-0, the residual char increased from 46.5 % to 57.7 % in TG at 800 ℃.

Preparation and Conductivity Characterization of PPy/Ni/NanoG Composites

2016, 30 (03): 28-32 ; DOI: 10.19491/j.issn.1001-9278.2016.03.005

Abstract ( 474 )

Polypyrrole/Ni/graphite nanosheet (PPy/Ni/NanoG)was prepared via insitu polymerization,using polypyrrole (PPy) as a matrix, FeCl3 as an oxidant, sodium dodecyl benzene sulfonate (DBSNa) as a doping agent, nickle coated graphite nanosheets (Ni/NanoG) as a twodimensional nanofiller.Microstructure and electrical performance of the composites were characterized. It was found that the surfaces and edges of Ni/NanoG sheet were coated by PPy particles, the curling and cross linking of PPy molecular chain could be effectively suppressed by the barrier effect of Ni/NanoG, and the conductivity of the composites was improved by the enhanced conjugation of PPy molecules and increased π electron delocalization. Comparison of cyclic voltammetry between PPy and PPy/Ni/NanoG composites indicated that the conducting property of the composites was higher than that of polymers. The conductivity increased from 8.2 to 103.6 S/cm as Ni/NanoG content reaching 2 wt%.

Preparation and Crystallization Behavior of PBT/nano-ZnO Composites Through In Situ Polymerzation

2016, 30 (03): 33-37 ; DOI: 10.19491/j.issn.1001-9278.2016.03.006

Abstract ( 581 )

Terephthalic(PTA) and butanediol (BDO) were condensed in a 5 L reactor and nanoZnO was introduced into the system leading to poly(butylene terephthalate)/ZnO nanocomposites. The non-isothermal crystallization behavior of the nanocomposites was investigated using differential scanning calorimetry (DSC). It showed that the nanoZnO could act as a nucleation agent for PBT. The Jeziorny method could be applied to analyze the nonisothermal crystallization process.

Preparation and Barrier Behavior of Multi-layer Biodegradable PBAT/PPC Films

2016, 30 (03): 38-42 ; DOI: 10.19491/j.issn.1001-9278.2016.03.007

Abstract ( 731 )

A three layer films composed of poly(propylene carbonate)(PPC) and poly(butylene adipatecobutylene terephthalate)(PBAT) having excelled barrier and mechanical properties were prepared bycoextrusion multilayer. The effect ofthe thickness of PPC layer, PBAT layer, anddifferent traction speed at a constant extrusion output on properties of PBAT/PPC/PBAT films was investigated. The results showed that the tensile strength and the processibility of PBAT/PPC/PBAT films were improved in comparison with PPC films. The maximum of the tensile strength was increased by about 200 %. Thickness of the films and molecular chain orientation degree has great effect on barrier behavior of the composite films. At a maximal PPC layer thickness of about 12 μm, oxygen permeation is the lowest, 9.5×10^-15 cm3·cm/(cm2·s·Pa). At the highest traction speed, that is,the molecule chain orientation degree is the maximum, oxygen permeation is the lowest, 9.52×10^-15 cm3·cm/(cm2·s·Pa).

Preparation of Higher Grafting Ratio PP-g-MAH and Its Application in PP/GF

2016, 30 (03): 43-48 ; DOI: 10.19491/j.issn.1001-9278.2016.03.008

Abstract ( 593 )

The effects of comonomer and initiators with different halftime on the melt grafting process of polypropylene with malic anhydride were investigated in a twin screw reactive extruder. It showed that the preaddition of comonomer could effectively reduce the crack of macromolecular radicals during the melt grafting process. The addition of peroxide with different half time through different feed throats showed an excellent synergistic effect, which could greatly improve the grafting efficiency of MAH and reduce its residue. In a glass fiber reinforced PP system, a loading of 1.6 % of our PP-g-MAH may achieve the same performance using 3 % of traditional PP-g-MAH. Thus the heat resistance was enhanced.

Preparation and Properties of Allochromatic Film for End-tidal Carbon Dioxide

2016, 30 (03): 49-53 ; DOI: 10.19491/j.issn.1001-9278.2016.03.009

Abstract ( 556 )

In this study, blends from ethyl cellulose, MCP, TBP,TBAH, and TiO2 was fabricated and the influence of molecular weight of ethyl cellulose, concentration of ethyl cellulose, volume of TBP, drying temperature, and thickness of the film on sensitivity and speed of color change was studied. It showed that the film can change color reversibly in the CO2 concentration range of 0~5 %. The molecular weight of ethyl cellulose should be 80000. The sensitivity increased with decreasing concentration of ethyl cellulose, volume of TBP, thickness of the film, and increasing dying temperature. The speed of changing color became faster with decreasing volume of TBP and increasing thickness of the film. Particularly, recovery time of 300 μm film was increased by three times.

UV Accelerated Aging Properties of PVC/Modified Sisal Fiber Composites Materials

2016, 30 (03): 54-59 ; DOI: 10.19491/j.issn.1001-9278.2016.03.010

Abstract ( 565 )

A composite board was prepared with KH-550 modified sisal fiber as a reinforcer and polyvinyl chloride (PVC) as the matrix. Five light stabilizers were introduced into the composite separately, two commodity ones, UV-0 and UV-531, and three homemade benzophenone polymer light stabilizers, designated as P(HABP-co-MTMP-co-OA), P(HABP-co-MTMP-co-mPEGA), P(HABP-co-MTMP-co-OA-co-mPEGA). Accelerated UV aging was carried out on the samples, and tensile strength retention rate, contact angle, and loss rate of heat extraction before and after aging were determined. It was found that the polymer light stabilizers had better UV aging resistance than that of UV-0 and UV-531, with P(HABP-co-MTMP-co-OA-co-mPEGA) being the best. Observed by SEM, after UV aging of 50 days, less surface microcracks were observed in the systems with the polymer light stabilizers than those without.

Peroxide Crosslinked PE-HD/EVA Waterproof Materials

2016, 30 (03): 60-66 ; DOI: 10.19491/j.issn.1001-9278.2016.03.011

Abstract ( 577 )

To improve the stability of waterproof materials, dicumyl peroxide (DCP) was introduced into the high density polyethylene/ethylenevinyl acetate copolymer (PE-HD/EVA) as a crosslinking agent. Effect of DCP on thermal stability and mechanical properties of PE-HD/EVA was studied. The materials were characterized by Fourier transform infrared spectrometer (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and crosslinking degree test methods. It showed that with the increasing crosslinking degree, the softening temperature, grain size, and crystallinity of PE-HD/EVA samples were gradually reduced, however, the tensile strength increased. When the DCP dosage was 1.2 wt%, the tensile strength of the sample reached the maximum value and the elongation at break was reduced by 77 % compared with neat PE-HD/EVA.

Diffusion of O₂/N₂ in PMMA Melts During Packing Stage of Injection Molding

2016, 30 (03): 67-72 ; DOI: 10.19491/j.issn.1001-9278.2016.03.012

Abstract ( 552 )

The diffusion behavior of the mixture of O2/N2 in PMMA melts during the packing stage of injection molding was studied. According to the characteristics of injection molding, the diffusion of the gas in the packing stage was simplified asaquasistatic diffusion. Establishing a kind of a diffusion mappingmodel was formulated made up of O2/N2 gas and ten isotactic PMMA chains whose degree of polymerization was 10.By energy minimization and annealing algorithm, this diffusion model achieved an energy initialization.Based on the COMPASS force field,the diffusion of the mixture gas of O2/N2 in PMMA melts was simulated successfully. The result was that the diffusion coefficients of O2 and N2 increased with increasing temperature, and at the same temperature, the diffusion of O2 was easier than N2. Plotting lg(MSD) against lg(t) for O2 and N2, both the slopes of the curves were close to 1 at different temperatures, which conformed to the diffusion mechanism of Einstein. In addition, the activation energy of diffusion of N2 was higher than that of O2.

Dominant Factor Analysis of Dynamic Elastic Modulus of PE Based WPC

2016, 30 (03): 73-77 ; DOI: 10.19491/j.issn.1001-9278.2016.03.013

Abstract ( 581 )

Using bending and longitudinal vibration methods, the dynamic elastic moduli of PE based woodplastic composite (WPC) were detected. The effect of wood/plastic ratio, the loading of coupling agent and other factors on the dynamic elastic modulus was studied. It was found that the wood/plastic ratio constituted the primary factor. When the wood/plastic ratio was between 55:45 and 70:30, the dynamic elastic modulus was proportional to the composition. The dynamic elastic modulus increased with increasing loading of coupling agent. It was possible to predict the dynamic elastic modulus from molding temperature, loading of coupling agent, and density.

Steady Experimental Design of Injection Compression Molding Process for LED Aspheric Lens

2016, 30 (03): 78-83 ; DOI: 10.19491/j.issn.1001-9278.2016.03.014

Abstract ( 523 )

Using steady experimental design method, refractive index variation of LED aspheric lens as the objective, compression distance, compression speed, compression force, holding pressure, melting temperature, cooling time, and injection rate as the influence factors, an L27(37)orthogonal experimental was carried out. Injection compression molding process for lens was simulated using Moldflow 2015 software, and the optimum process parameter A3B1C2D3E3F2G2 was obtained. It showed that the influence factors on refractive index of lens from high to low were melting temperature, injection rate, compression distance, cooling time,holding pressure, and compression speed,compression force. High melting temperature and injection rate could reduce volume shrinkage and improve interior residual stress, in which refractive index variation reduced 45 % and warpage deformation decreased 4.3 %. Therefore, optical performance and processing quality of LED aspheric lens were improved.

Numerical Simulation of Melt Flow in Pressure Drop Die Under Different Process Parameters

2016, 30 (03): 84-87 ; DOI: 10.19491/j.issn.1001-9278.2016.03.015

Abstract ( 546 )

During the extrusion of microcellular plastics, the melt flow in the pressure drop die was simulated using Ployflow software, and then the distribution of pressure and velocity and extrusion swell in the pressure drop die was studied under different CO2 concentration and melt volume flow. It was found that the melt pressure in the die increased with increasing melt volume flow, and decreased with increasing CO2 concentration. The melt average velocity at the exit was sensitive to the change of melt volume flow, but not to the change of CO2 concentration. The optimal CO2 concentration was found to be 2 wt%. The higher the melt volume flow, the less the extrusion swell.

Effect of Compatibilizer DT on Properties of PLA/PBAT Blends

2016, 30 (03): 88-93 ; DOI: 10.19491/j.issn.1001-9278.2016.03.016

Abstract ( 631 )

An unsaturated ester compound(DT) was added to poly(lactic acid) (PLA)/poly(butylene adipatecoterephthalate) (PBAT) blends as a compatibilizer through a twin screw extruder. The influence of DT on the compatibility, crystallization behavior, thermogravimetric and mechanical properties were investigated by scanning election microscope, rotational rheometer, polarized optical microscope, differential scanning calorimetry, thermal gravimetric, and mechanical property tests. It was found that interface adhesion was increased with moderate DT and contributed to a preferable compatibility between PLA and PBAT. Elongation at break increased by 46.3 % while adding 0.3 wt% DT, and the same amount of DT gave rise to the excess of impact strength measuring range.

Effect of Combining Different Chain Extender Agents on the Chain Extending Reaction and Rheological Behavior of PETG

2016, 30 (03): 94-98 ; DOI: 10.19491/j.issn.1001-9278.2016.03.017

Abstract ( 666 )

In this paper,chain extenders were added to poly(ethylene terephthalateco1,4cylclohexylenedimethylene terephthalate)(PETG) to improve its melt strength and viscosity through reactive processing. Effect of chain extenders on structure and rheological behavior of PETG was studied by fusion index instrument, rotational rheometer,and torque rheomoeter. It was revealed that, the simultaneous addition of pyromellitic dianhydride(PMDA) and triglycidylisocyanurate(TGIC) to PETG led to higher melt strength and viscosity. In this case, the melt flow index of the extended PETG decreased from 12.83 to 7.50 g/10 min. While the zeroshearing viscosity (η0) increased from 2020 to 4760 Pa·s and the characteristic relaxationtime (τ0) increased from 0.78 to 3.58 s. Moreover, the extended PETG remained a linear structure and no gel was formed.

Design and Analysis of Ultrasonic Units of Ultrasonic Micro-injection Molding Machines

2016, 30 (03): 99-104 ; DOI: 10.19491/j.issn.1001-9278.2016.03.018

Abstract ( 511 )

This paper presented an ultrasonic microinjection molding machine with the ultrasonically driven technology for polymer plasticization and injection.Firstly, the structure and working principle of the ultrasonic microinjection molding machine were introduced.Then the structure of the ultrasonic plasticization and injection unit and the ultrasonic vibration module were designed. Finally, modal analysis and static analysis of the ultrasonic vibration module were conducted using ANSYS software, the resonance frequency and the corresponding longitudinal vibration model as well as the stress and strain distribution of ultrasonic vibration module were obtained. The ultrasonic vibration of ultrasonic micro injection modules could provide longitudinal vibration to meet the needs of the material performance requirements.

Extrusion-injection-compression Integrated Equipment for Solid Waste Plastics

2016, 30 (03): 105-108 ; DOI: 10.19491/j.issn.1001-9278.2016.03.019

Abstract ( 535 )

In this paper, an integration technology of extrusioninjectioncompression was proposed, in which a secondary clamping by innovative toggle direct pressure was used, and injection molding problems caused by the large gas content and poor fluidity of the waste melt were solved by injection compression molding process.Meanwhile, solid waste plastics could be converted to products directly by using the intermediate connecting device that could coordinate and automatic linkup the “continuous” and “intermittent” process between extrusion and injection compression molding.In this way, it achieved the purpose of efficient processing and highvalue recycling of solid waste polymer materials by greatly reducing processing cost and improving recycling ratio of solid waste polymer materials.

Injection Mold Design of Motor Canteen Rear Covers with Threads

2016, 30 (03): 109-112 ; DOI: 10.19491/j.issn.1001-9278.2016.03.020

Abstract ( 694 )

An injection mold of motor canteen rear covers with threads was designed using UG NX software. Gating system, cooling system, and demolding mechanism were designed and calculated. With the electric motor, gears rotating transfers the power to mold core, and the plastic parts could be demolded successfully. This mold was suitable for stable, high quality, high efficiency production.