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2016, Volume 30 Issue 07 Publication date: 26 July 2016 Previous Issue Next Issue

Comparison of Three Kinds of the Determination Methods of ¹⁴C Content in Bio-based Plastics

2016, 30 (07): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2016.07.001

Abstract ( 724 )

The definition of bio-based plastics was introduced. Three determination methods of 14C content were summarized, including accelerator mass spectrometry (AMS), liquid scintillation-counter method (LSC), and Beta-ionization (BI). The advantages and disadvantages of the three kinds of method were compared. It was found that LSC was easier and more effective.

Preparation and Property of PVA / Chlorogenic Acid Blends

2016, 30 (07): 7-11 ; DOI: 10.19491/j.issn.1001-9278.2016.07.002

Abstract ( 456 )

In this paper, chlorogenic acid (CA) was used as a free radical scavenger in poly(vinyl alcohol)(PVA), and the effect of chlorogenic acid on the thermal stability of PVA was studied. Blends of PVA/chlorogenic acid were investigated by FTIR, DSC, TGA, universal testing machine，and ultraviolet visible spectrophotometer，etc. It showed that chlorogenic acid significantly improved the thermal stability, flexibility, and elongation at break of PVA, but reduced the melting point. When the content of chlorogenic acid was 5.0 wt%, improved thermal stability, mechanical properties, and light transmittance were observed.

Flame Retardant and Smoke Suppression of Compound Composites for Soft Poly(vinyl chloride)

2016, 30 (07): 12-17 ; DOI: 10.19491/j.issn.1001-9278.2016.07.003

Abstract ( 417 )

Microcapsule red phosphorus (MRP), zinc borate (ZnBO3), Al(OH)3(ATH) and Mg(OH)2(MH)were applied to soft poly(vinyl chloride)(PVC) to impart flame retardance, and limiting oxygen index,cone calorimeter test and thermal analysis were used to study the flame retardance and smoke suppression. It was shown that PVC/MRP/ZnBO3/ATH/MH composite with a mass ratio of 100/3/1/20/20 have the largest limiting oxygen index value of 33.9 %;PVC/MRP/ZnBO3/ATH/MH exhibits better flame retardancy and smoke suppression than PVC/ATH/MH and pure PVC. Moreover, data from CONE and TG show that in contrast with PVC/ATH/MH, the release of heat, smoke gas of PVC/MRP/ZnBO3/ATH/MH was much decreased, the charring ability was enhanced appreciably, and CO and CO2 gas release was lower;it was more difficult to ignite, and the fire performance index (FPI) was improved, FGI fire spread index was decreased to reduce fire risk. In the summery,MRP/ZnBO3/PVC composite exhibits optimal comprehensive fire retardancy.

Enzymatic Degradation of Poly(butylene succinate)

2016, 30 (07): 18-22 ; DOI: 10.19491/j.issn.1001-9278.2016.07.004

Abstract ( 442 )

The degradation of polybutylene succinate (PBS) membrane accelerated by cutinase was studied. PBS membranes before and after degradation were analyzed by SEM, DSC, and TG and the degradation products was analyzed by MS. It showed that, when enzyme concentration was 2.5 U/g, temperature was 37 ℃, pH was 7.4, and reaction time was 16 h, the degradation rate reached 93.88 %, the maximum degradation rate was 32.97 μg/cm2·h. SEM showed that under the reaction of cutinase, the PBS membrane was degraded into slices. DSC showed that with increasing degradation time, the crystallinity degree of PBS decreased. The result of TG also showed with increasing degradation time, the thermal stability of PBS membrane became worse. The results of MS showed that PBS film was degraded into monomers or oligomers.

Morphology and Properties of Silica Nanosphere/Rigid Polyurethane Composite Foams

2016, 30 (07): 23-29 ; DOI: 10.19491/j.issn.1001-9278.2016.07.005

Abstract ( 478 )

Two kinds of silica (SiO2) nanospheres were introduced into rigid polyurethane (PU-R) forming PU-R/SiO2 composite foams. Morphology of the composite foams was characterized by SEM. Mechanical properties, dimensional stabilities, and thermal conductivities of the composite foams were investigated by compressive test, dimensional stability test, and thermal conductivity measurements, respectively. It showed that, the cellular size of the composite foams was lowered obviously (from 303 μm of neat PU-R foam to 170 μm of the composite foam), the compressive properties were improved effectively (the specific compressive strength and specific compressive modulus increased by 8.3 % and 12.5 %, respectively, compared with those of neat PU-R foam), the coefficient of linear thermal expansion was decreased, the thermal conductivity was reduced slightly, and the dimensional stabilities almost keep invariable, after the introduction of SiO2 nanospheres. In addition, compared with 400 nm sized ones, 700 nm sized SiO2 nanospheres could be dispersed more homogeneously, and lead to better mechanical properties.

Effect of Ammonium Polyphosphate on Flame Retardancy and Mechanical Property of Polylactic Acid/Wheat Straw Composites

2016, 30 (07): 30-33 ; DOI: 10.19491/j.issn.1001-9278.2016.07.006

Abstract ( 406 )

Influence of ammonium polyphosphate (APP) on flame retardancy, mechanical properties, and thermal degradation of polylactic acid (PLA)/wheat straw composites was investigated. It showed that limited oxygen index of the composites improved by 33 %, and UL 94 flammability rating was V-0, and char yield was increased by 330 % when APP’s loading reached 20 %. Unnotched Izod impact strength was reduced and the stiffness was improved with the addition of APP, while flexural strength and density were not affected. TGA test indicated that the thermal degradation behavior was changed when adding APP, which made the decomposition temperature lower and PLA matrix stable. Expansion layer after burning served an important role in against heat and oxygen.

Modification Research on Electron Beam Irradiation Resistance of PP

2016, 30 (07): 34-37 ; DOI: 10.19491/j.issn.1001-9278.2016.07.007

Abstract ( 1019 )

In order to improve the stability of polypropylene (PP) in electron beam, irganox 1010, irganox 1076, tinuvin 770, and chimassorb 944 were introduced as stabilizers. DSC, TG, SEM analysis, mechanical property and color test were carried out. It showed that the tinuvin 770 at 0.5 phr provided the lowest yellow index; the join of antioxidant and light stabilizer after irradiation could improve the crystallinity, reduce thermal gravimetric epitaxial starting temperature, decrease the tensile strength and elongation rate, increase the impact strength, and sections of the composite show ductile failure.

Preparation and Optical Properties of EVA Film Doped with Europium Complex

2016, 30 (07): 38-43 ; DOI: 10.19491/j.issn.1001-9278.2016.07.008

Abstract ( 651 )

In this study, europium quaternary complex was doped into ethylene vinyl acetate (EVA) by casting method, and then an EVA composite film was produced through curing. The curing temperature, time and loading of initiator in EVA film were optimized. SEM showed that the complex was uniformly dispersed in EVA. UV and fluorescence spectra were used to characterize EVA composite film. It showed that when the doping amount of europium complexes was 1 %, EVA film could emit strong red fluorescence through high absorption of 200~400 nm UV light and the visible light transmittance of EVA film was still good.

Cold Crystallization of Polylactide at the Presence of Carbon Dioxide

2016, 30 (07): 44-49 ; DOI: 10.19491/j.issn.1001-9278.2016.07.009

Abstract ( 510 )

Isothermal cold crystallization behavior of polylactide (PLA) at atmosphere was studied by using a differential scanning calorimeter (DSC), and the crystalline morphology of PLA samples obtained at different temperature for 100 min was characterized by using a polarized optical microscopy (POM). Using CO2 as a media, PLA samples isothermally crystallized at 5 MPa at different temperature for 100 min were prepared in a high-pressure vessel. The crystal morphology and crystalline structure of PLA samples prepared at atmosphere and under CO2 were compared by a POM and a wide-angle X-ray diffractometer (WAXD), respectively. The results showed that CO2 had a significant plasticizing effect on PLA and enhanced the mobility of PLA macromolecular chains, resulting in cold crystallization at a lower temperature. Compared with PLA samples crystallized at atmosphere, the size of spherulites decreased, the quantity of spherulites increased and the degree of perfection increased for PLA samples treated under CO2 while the final crystallinity decreased.

Effects of Silane Coupling Agent on Mechanical Properties of PE-HD/Rice Husk Powder Composites

2016, 30 (07): 50-56 ; DOI: 10.19491/j.issn.1001-9278.2016.07.010

Abstract ( 382 )

Rice husk powder was treated with a coupling agent and blended with high density polyethylene forming composites. The composites were subjected to infrared and SEM analysis, their mechanical and rheological properties were tested. It showed that the addition of coupling agent reduced the melt flow rate and improved the dispersion and compatibility of PE-HD/rice husk powder. Optimal mechanical properties of the composites were obtained while the mass ratio of coupling agent, PE-HD, and rice husk powder was 1∶100∶50. The introduction of coupling agent increased the bending strength and impact strength of the composite by 32.2 and 140 %, respectively. When the rice husk powder content increased, the melt flow rate of the composite decreased, the bending strength increased, and the tensile strength, impact strength and elongation at break were reduced. The infrared analysis of silane grafted PE-HD showed that the grafting reaction between coupling agent and PE-HD was occurred.

On-line Test Technique for PVT Property of Polymer Materials and Its Application in Mold Design

2016, 30 (07): 57-61 ; DOI: 10.19491/j.issn.1001-9278.2016.07.011

Abstract ( 535 )

PVT property under real molding conditions was obtained through a on-line tester of polymer materials, so injection material shrinkage could be achieved and was used for mold design. In addition, the mold size was also calculated，which was based on off-line PVT property parameters. The numerical simulation method was used for simulating the above-mentioned two kinds of mold size so that mold precision could be analyzed comparatively. It showed that the product dimension precision based on on-line PVT test results were closer to the actual ones.

Numerical Simulation on Thermalfluidstructure Coupling Deformation of Chip Plastic Encapsulation Process

2016, 30 (07): 62-68 ; DOI: 10.19491/j.issn.1001-9278.2016.07.012

Abstract ( 708 )

In order to predict accurately chip thermal-fluid-structure coupling warpage deformation, based on the Castro-Macosko cure kinetic model, theoretical model describing plastic encapsulation filling process and thermal-fluid-structure coupling warpage deformation formatting process was established, and the formation mechanism of thermal-fluid-structure coupling warpage deformation was revealed. Research results showed that the thermal-fluid-structure coupling warpage of chip increased rapidly at first with increasing melt filling time, after reaching the maximum value decreased gradually and leveled off. The comprehensive thermal-fluid-structure coupling warpage of chips was mainly composed of the thermal-fluid-structure coupling pressure field induced warpage deformation and nonuniform temperature field induced thermal deformation, the thermal-fluid-structure coupling pressure field induced deformation was warping outward, which was proportional to the melt filling unbalance flow length difference and velocity difference of chip up and down surface, explicit first increased and then decreased symmetric parabolic distribution along the axial direction, and was far greater than the nonuniform temperature field induced thermal deformation. The comprehensive thermal-fluid-structure coupling warpage of the chips was mainly controlled by the thermal-fluid-structure coupling pressure field induced deformation.

Optimization of Processing Parameters of Water-assisted Co-injection Molding Pipes Using Response Surface Methodology

2016, 30 (07): 69-76 ; DOI: 10.19491/j.issn.1001-9278.2016.07.014

Abstract ( 463 )

In order to obtain the minimum values of the total residual wall thicknesses (RWT) and the inner melt RWT, response surface methodology (RSM) was used to optimize the processing parameters. A pipe with a 20 mm diameter and a 200 mm length was chosen as a test case. High density polyethylene (PE-HD) and polypropylene (PP) were used as the skin layer and the inner layer plastics in the experiments, respectively. Based on single factor experiment main influence factors of the total RWT and the inner melt RWT of O-WACIM were obtained. The result of a Plackett-Burman experiment exhibited the key influence factors of the total RWT and inner melt RWT of O-WACIM. Based on a Box-Behnken experiment and a RSM analysis and optimization, the optimized processing parameters to get the minimum values of the total RWT and the inner melt RWT were obtained: the water pressure 7.5 MPa, the water injection delay time 2 s, the inner melt temperature 215 ℃. Under the optimized conditions, the predicted total RWT of Design-expert was in good agreement with the experiment results. The research indicated that RSM could be used to optimize the processing parameters to obtain the minimal total RWT and inner melt RWT of O-WACIM pipes.

Study on the Synthesis, Synergism and Thermal Stability of Lanthanum Tyrosine for PVC

2016, 30 (07): 77-81 ; DOI: 10.19491/j.issn.1001-9278.2016.07.015

Abstract ( 705 )

Lanthanum tyrosine was synthesized with tyrosine, lanthanum nitrate and sodium hydroxide as the raw materials. Thermal stability of lanthanum tyrosine and its compound with calcium stearate and zinc stearate was studied by means of Congo red testing method, thermal aging oven method, conductivity method, and torque rheometer. Stabilization mechanism of lanthanum tyrosine was also studied by infrared spectrum. The results indicated that lanthanum tyrosine alone had good thermal stability for PVC. Thermal degradation of PVC was slowed down by coordination of lanthanum and chlorine, and the reaction of amidogen and HCl. The composite of lanthanum tyrosine, calcium stearate, and zinc stearate could extend greatly thermal stability time and delay color change of PVC.

Properties of Flame-retarded POM Based on Caged-phosphate and Microcapsulated Red Phosphorus

2016, 30 (07): 82-87 ; DOI: 10.19491/j.issn.1001-9278.2016.07.016

Abstract ( 461 )

A novel char agent and flame retardant, caged-phosphate (trimer) was compounded with microcapsulated red phosphorus (MRP) and melamine (ME) as intumescent flame-retardant (IFR), which was used to prepare flame-retarded polyoxymethylene (POM). The flame retardancy was studied through vertical burning experiment, limit oxygen index, and thermal gravimetric analysis (TGA). Char residue collected after vertical burning was characterized by Fourier transform infrared spectroscopy (FTIR). And the mechanical properties of FR-POM were also studied. The results showed that there was a good synergistic effect between trimer and MRP. The trimer/MRP/ME flame-retarded POM achieves UL 94 V-0 rating, and limit oxygen index was up to 29.4 % with the loading of 23 %.

Enzymatic Degradation of PBSA and PBSH by Lipase N435 and Its Molecular Simulation

2016, 30 (07): 88-95 ; DOI: 10.19491/j.issn.1001-9278.2016.07.017

Abstract ( 483 )

PBS was modified by diol and diacid separately forming two copolyesters, PBSH and PBSA, which were introduced into phosphate buffer as substrates with lipase N435 for investigating the degradation behavior. Gel permeation chromatography, thermogravimetric analysis, and wide-angle X-ray diffraction were employed to investigate the change in the molecular mass, thermal properties, and crystallinity of the copolymer before and after enzymatic degradation. Polarized optical microscopy was employed to investigate the surface morphology of the copolymers. It indicated that the sensitivity of PBSA and PBSH to lipase was significantly improved with degradation rates after 24 h greater than 90 % and 60 %, respectively. The degradation rate of PBSA was significantly higher than that of PBSH. The number-average molecular weight of the two copolymers changed marginally, but the molecular weight distribution became wider, and crystallinity increased. The thermal stability of PBSA decreased, while the thermal stability of PBSH improved after 3 days. The results obtained from the molecular enzymesubstrate binding model were in agreement with experimental results.

Residence Time of Single Screw Extruders with Grooved Barrels

2016, 30 (07): 96-101 ; DOI: 10.19491/j.issn.1001-9278.2016.07.018

Abstract ( 736 )

Residence time of plastics in single screw extruders is an important parameter of polymer processing. The residence time in single screw extruders with groove barrels is different from that of traditional single screw extruders. We provide a new method to analyze the residence time in an extruder. Experiments showed that under the same screw speed, the residence time in single screw extruders with groove barrels was lower than that of traditional single screw extruders and IKV single screw extruders. Single screw extruders with groove barrels can effectively improve extrusion melting efficiency and solve the contradiction between high solid conveying efficiency and low melting efficiency.

Numerical Simulation of Mixing Process in Rotary Disc Mixers

2016, 30 (07): 102-106 ; DOI: 10.19491/j.issn.1001-9278.2016.07.019

Abstract ( 628 )

In this paper, based on the development of rotary disc mixers，the dynamic mixing of particles was studied by analyzing the distribution of velocity and the shear rate with the software of Polyflow. Moreover, the distribution and dispersion in a rotary disc mixer were analyzed based on the distribution of residence time and maximum shear stress. The results show that the rotary disc mixer can exert strong shearing and compression as well as displacement actions. Meanwhile, dispersion mixing performance is promoted and axial distribution mixing is decreased with the increasing rotating speed of the rotary disc.

Design of Large Injection Moulds for Printer Base Boards

2016, 30 (07): 107-111 ; DOI: 10.19491/j.issn.1001-9278.2016.07.020

Abstract ( 799 )

According to the structural characteristics of printer base boards, a large injection mold was designed by using hot runner, side core pulling, fixeddistance parting, and reset mechanism. The analysis of the mold was focused on the forming parts, gating system, side core pulling mechanism, temperature control system, oriented positioning system, and stripping system. The practice had proved that the mold structure was reasonable, and the quality of molding parts reached the design requirements.