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2018, Volume 32 Issue 02 Publication date: 26 February 2018 Previous Issue Next Issue

Research Progress in Rheological Behaviors of Highly Filled Polymers Based Nanocomposites

2018, 32 (02): 1-9; DOI: 10.19491/j.issn.1001-9278.2018.02.001

Abstract ( 1010 )

This paper overviewed recent research progress in rheological behaviors of highly filled polymer-matrix nanocomposites and introduced effects of the content, size, shape, surface treatment and dispersibility of nano-fillers and polymer melts on the rheological behaviors of polymeric nanocomposites. Viscoelastic mechanisms of highly filled polymer-matrix nanocomposites were also summarized.

Research Progress of Triazine- based Charring Agents

2018, 32 (02): 10-18; DOI: 10.19491/j.issn.1001-9278.2018.02.002

Abstract ( 967 )

This paper overviewed the raw materials, synthetic technology and flame retardant effect of triazinebased charring agents in terms of their molecular structures including small molecules, linear macromolecules and hyperbranched macromolecules. Charring agents prepared by using cyanuric chloride, melamine, cyanuric acid and its derivatives as raw materials were emphatically introduced. Moreover, advantages and disadvantages of different types of triazinebased charring agents were analyzed, and their development prospect was discussed.

Development of Polypropylene Resins for Automobiles and Their Application Situation in China

2018, 32 (02): 19-26; DOI: 10.19491/j.issn.1001-9278.2018.02.003

Abstract ( 605 )

This article introduced the current development situation of polypropylene (PP) resins for automobiles and also overviewed the application status of PP-based modified materials in vehicles. Moreover, the trend in development of PP-based automotive plastics was predicted. PP resins with a high modulus, high impact-resistance and high fluidity become major automotive plastics. The modified PP-based automotive plastics included inorganic-filler-reinforced and elastomer-toughened PP, glass-fiber-reinforced PP, modified PP with total low volatile organic compounds, scratch-resistant PP, etc. The recycling and reuse of PPbased automotive plastics has also become more and more important.

Optimization of Extrusion Process Parameters of Polypropylene with Butane Gas

2018, 32 (02): 27-32; DOI: 10.19491/j.issn.1001-9278.2018.02.004

Abstract ( 1196 )

Extrusion foaming parameters (i.e. nucleating agent, gas injection and die pressure) of PP with butane gas were investigated by an orthogonal experimental method. Cell structures obtained under different process conditions were determined by scanning electron microscopy. The effects of process parameters on the expansion ratio, average cell diameter and cell density of PP foams were analyzed, and the relevant mechanisms were discussed. The foaming process was further optimized with the Design Expert software, and the resulting process parameters were confirmed by the relevant experiments. The results indicated that the PP foams achieved a high expansion ratio, a high cell density and a large average cell diameter when the content of nucleating agent, die pressure and gas injection amount were set to 1.4 wt %, 4.66 MPa and 7 %, respectively. The experimental results also verified the theoretical predication with a deviation lower than 5 %.

Effect of Annealing on Properties of Polypropylene Nucleated with Sodium Phosphate

2018, 32 (02): 33-36; DOI: 10.19491/j.issn.1001-9278.2018.02.005

Abstract ( 1096 )

An annealing treatment was performed for polypropylene (PP) by using sodium phosphate as a nucleating agent, and the effects of annealing temperature and annealing time on mechanical performance, heat resistance, and crystalline properties of PP were investigated. The results indicated that the annealing treatment effectively improved the mechanical properties, heat resistance and crystallinity of PP. After being annealed at the temperature of 120 ℃ for 0.5 h, PP achieved an increase in tensile strength from 38.0 to 39.4 MPa, in flexural modulus from 1227 to 1882 MPa and in heat deflection temperature from 112.2 to 122.7 ℃. Moreover, the degree of crystallinity was improved from 36 % to 44 %.

Study on In-situ Modification of Polyoxymethylene with Silica Nanoparticles with Different Surface Structures

2018, 32 (02): 37-43; DOI: 10.19491/j.issn.1001-9278.2018.02.006

Abstract ( 561 )

Polyoxymethylene (POM)/silica nanoparticle composites were fabricated by in-situ polymerization using silica nanoparticles surface-modified with epoxy (RNSE) and methyl groups (DNS) as fillers, and their structure, thermal stability and crystallization behaviors were investigated by scanning electron microscopy, thermogravimetric analysis (TGA), differential scanning calorimetry and polarized light microscopy. The results indicated that RNSE was well dispersed in the POM matrix at the content lower than 1 phr. RNSE exhibited a better dispersibility in the matrix than DNS. The silica nanoparticles could promote the crystallization of POM, thus resulting in the decrease of spherulite size and the improvement of crystalline degree. Compared with DNS, RNSE presented a more effective enhancement on the crystallinity of POM. However, the thermal stability of the composites was reduced by the silica nanoparticles.

Effect of Molecular Weight Distribution on Isothermal Crystallization Kinetics of Bimodal Polyethylene Resin for Films

2018, 32 (02): 44-48; DOI: 10.19491/j.issn.1001-9278.2018.02.007

Abstract ( 581 )

Isothermal crystallization kinetics of two types of bimodal polyethylene resins (9455F1-W and 9455F1-100) for films was studied in this work, and the effect of bimodal molecular weight distribution on their crystallization behavior was discussed. The results from gel permeation chromatography measurements indicated that these two types of resins exhibited a bimodal distribution feature. They had a similar molecular weight but different fractions in high- and low-molecular-weight macromolecules. 9455F1-W sample had a higher fraction in-molecular-weight macromolecules than 9455F1-100 sample. Isothermal crystallization investigation indicated that the crystallization rate constant increased with an increase in the fraction of low-molecular-weight macromolecules, and however the half crystallization time decreased, suggesting an increase in crystallization rate.

Phase Morphology and Properties of Ternary PLA/PPC/OMMT Nanocomposties

2018, 32 (02): 49-56; DOI: 10.19491/j.issn.1001-9278.2018.02.008

Abstract ( 628 )

PLA/PPC blends and PLA/PPC/OMMT(organically modified layered silicate) nanocomposites were prepared by melt mixing in a co-rotating twin-screw extruder. Phase morphology, thermal behavior, and mechanical properties of the resultant PLA/PPC blends and PLA/PPC/OMMT nanocomposites were analyzed by polarizing optical microscope, differential scanning calorimetry and universal testing machine equipments, respectively. The results showed that there were two Tg occurred between PLA and PPC, when the loadings of PPC are equal to and more than 30 wt %, which suggests that the compatibility of PLA and PPC becomes worse, and phase separation occurred obviously at the loading of 50 wt % PPC. With the increasing loadings of PPC, the elongation at break of PLA/PPC blends went up. When the mass fractions of OMMT were less than 1.5 wt %,the crystallinity, tensile strength, elongation at break and impact strength of the nanocomposites all increased.

Preparation of Zinc Ferrite Nanorods and Their Application in Flame-retardant Epoxy Resin

2018, 32 (02): 57-62; DOI: 10.19491/j.issn.1001-9278.2018.02.009

Abstract ( 533 )

In this paper, zinc ferrite nanorods (R-ZFO) were prepared by a microemulsion method, and their microstructure were characterized by X-ray powder diffraction, transmission electron microscopy and scanning electron microscopy. The results indicated that the synthesized R-ZFO had a particle size of approximately 200 nm and a length of 1~10 μm. Afterward, epoxy resin/R-ZFO composites were prepared and their flame-retardant properties and thermal stability were investigated by limiting oxygen index (LOI), cone calorimeter and thermogravimetric analysis. The results demonstrated that LOI of epoxy resin was improved to 28.3 % by incorporating 3 wt % R-ZFO, its initial decomposition temperature increased up to 48.8 ℃, and the peak heat release rate decreased by 34.16 %. These results suggested an enhanced thermal stability and good flame-retardant performance of epoxy resin/R-ZFO nanocomposites.

Study on Modification of Poly(vinyl chloride) with Ethylene-vinyl Acetate Copolymer

2018, 32 (02): 63-66; DOI: 10.19491/j.issn.1001-9278.2018.02.010

Abstract ( 674 )

This article reported a study on the modification of poly(vinyl chloride) with an ethylene-vinyl acetate copolymer (EVA, 25 wt % vinyl acetate). The effect of EVA content on structure and properties of PVC compounds was investigated extensively. The results indicated that EVA not only effectively toughened PVC but also avoided the deterioration in low-temperature elastic modulus and color change in high temperature in comparison with butyronitrile rubber as a traditional impact modifier. EVA also exhibited a much better dispersibility in PVC matrix.

Toughening Modification of Poly(hydroxybutyrate-co-hydroxyvalerate) by an Amino-terminated Hyperbranched Polymer

2018, 32 (02): 67-73; DOI: 10.19491/j.issn.1001-9278.2018.02.011

Abstract ( 565 )

Blends of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with an amino-terminated hyperbranched polymer (HBP) were prepared by a melt-blending method and then characterized by differential scanning calorimetry, rotational rheometer, polarized light microscopy, scanning electron microscope, and tensile and impact tests. The results indicated that the blend containing 1.0 wt % HBP achieved an increase in impact strength by 31.3 % and in elongation at break by 45.5 %. Compared with pure PHBV, the crystallinity of the blend was also reduced from 71.7 % to 59.1 %, whereas the tensile strength almost did not change.

Surface Decoration of Polyetheretherketone with RGD Peptide and Its Compatibility with Osteoblast

2018, 32 (02): 74-80; DOI: 10.19491/j.issn.1001-9278.2018.02.012

Abstract ( 696 )

Surfaces of polyetheretherketone (PEEK) were incorporated with carboxyl groups through the plasma treatment with acrylic acid, and then bioactive arginine-glycine-aspartic acid (RGD) peptide was covalently immobilized onto the PEEK surface through a reaction with carboxyl groups. The resulting surface-decorated PEEK was characterized by X-ray photoelectron spectroscopy, water contact angle, surface profiler and mechanical measurements. MC3T3-E1 osteoblast was used as a model cell to evaluate its biocompatibility with the carboxyl group-modified PEEK and RGD peptide-decorated PEEK. The results indicated that carboxyl groups and RGD peptide were successfully grafted onto the surface of PEEK, which led to an improvement in hydrophilicity and surface roughness. Both the plasma treatment and the decoration with RGD peptide seem not to influence the tensile and flexural strength of PEEK, and however they enhanced the interfacial adhesion, spreading and proliferation on osteoblast. PEEK surface decorated with RGD peptide was found to exhibit much better adhesion, spreading and proliferation.

Effect of Extrusion Processing Methods on Microfibrillar Micromorphology of PP/PET Blends

2018, 32 (02): 81-85; DOI: 10.19491/j.issn.1001-9278.2018.02.013

Abstract ( 566 )

Polypropylene (PP)/poly(ethylene terephthalate) (PET) blends were prepared by a twin-screw extruder, and a singlescrew extruder with different screw construction and high-shearing extrusion die respectively, and effect of extrusion processing methods on their microfibrillar micromorphology was investigated by scanning electron microscopy. The results indicated that only PET particles as a dispersion phase were formed in the PP matrix when processed by the twin-screw or singlescrew extruder with threezone screws. When using the single-screw extruder equipped with a Maddock mixing section screw, some short and thick PET microfibrils were observed. Nevertheless, the microfibrils with a mean diameter of 5 μm and a length (L)/diameter (D) ratio over 20 could be achieved in the PP/PET blends when being melt-extruded with the single-screw extruder, followed by hot stretching and quenching. However, the equipment for this process is too complicated to realize the industrialization. Moreover, using a single-screw extruder equipped with a customdesigned high-shearing extrusion die, the microfibrils with a diameter of 5~7 μm and a L/D ratio over 20 could also be generated in the matrix. This method is facile to be industrialized.

Effects of Process Parameters of Slitsurface Melt Differential Electrospinning on Interjet Distance

2018, 32 (02): 86-90; DOI: 10.19491/j.issn.1001-9278.2018.02.014

Abstract ( 436 )

Polypropylene (PP) fibers were electrospun by a self-made slit-surface melt differential electrospinning device, and effects of process parameters such as spinning voltage, spinning distance and spinning temperature on the interjet distance were investigated. The results indicated that the interjet distance decreased with an increase in spinning voltage but increased with a decrease in spinning distance. After the spinning distance was lower than 8 cm, the interjet distance was kept stable with a variation of spinning distance. The interjet distance also decreased with an increase in spinning temperature. However, the interjet distance was kept stable after the spinning temperature was higher than 230 ℃. The interjet distance achieved the minimum value of 3.3 mm at a spinning voltage of 60 kV, a spinning distance of 100 mm and a spinning temperature of 245 ℃.

Study on Numerical Simulation of Thermal Viscoelastic Plastic Deformation Filling Mechanism in Micro-hot Embossing Process of Polymers

2018, 32 (02): 91-97; DOI: 10.19491/j.issn.1001-9278.2018.02.015

Abstract ( 539 )

This paper reported a study on the patterning superhydrophobic surface with a PMMA-pillared array based on the micro-hot embossing technology. The effect of process parameters on the micro hot embossing process was investigated by means of numerical simulation, and the thermal viscoelastic plastic deformation filling mechanism was described. Moreover, the key control parameters were clarified. The results indicated that the elastic modulus of the base materials, hot embossing temperature and pressure are the key control parameters for the micro-hot formation. The hot embossing pressure and deformation stress were reciprocally correlated with the hot embossing temperature, whereas the filling height of polymers was proportionally correlated with the hot embossing temperature. With increasing hot embossing temperature over the glass transition temperature of a polymeric base material, the base material could be kept in a high elastic state. In this case, the base material is easy to perform a significant thermal viscoelastic plastic deformation in a rapid way, which can minimize the hot embossing pressure and deformation stress. This is beneficial for polymeric base materials to avoid fracture damages and promote filling flow.

Temperature Analysis and Optimization Design of Nozzles of Powder Feeding 3D Printers

2018, 32 (02): 98-102; DOI: 10.19491/j.issn.1001-9278.2018.02.016

Abstract ( 629 )

To improve the forming accuracy of 3D printers, a model of nozzle devices was drawn by the 3D printing innovation center of Qingdao University of Science & Technology using the 3D SolidWorks software. The resulting model was imported into the thermodynamic analysis module of the Ansys software for finite element analysis. As a result, the thermal boundary of the nozzle device was set, and its temperature distribution was obtained. In order to reduce the temperature difference between the nozzle and melt temperature, an annular heating resistor was installed in the nozzle, and the nozzle structure was optimized. Moreover, an experimental verification was also carried out. The experimental results confirmed that the analysis by the Ansys software was reliable, and the nozzle device had better practicability after optimization.

Synthesis and Technological Optimization of Dibutylfuran-2,5-dicarboxylate as a Bio-based Plasticizer

2018, 32 (02): 103-109; DOI: 10.19491/j.issn.1001-9278.2018.02.017

Abstract ( 571 )

In this work, dibutylfuran-2,5-dicarboxylate (DBF) was synthesized by a transesterification method using dimethyl furan-2,5-dicarboxylate (DMF) and n-butyl alcohol as raw materials and potassium carbonate as a catalyst. The effects of synthetic conditions including reaction time, catalyst dosage and reaction temperature on the yield of DBF were investigated by a response surface methodology on the basis of singlefactor experiments. The results indicated that the optimum conditions for the synthesis of DBF were obtained at a reaction temperature of 90 ℃, a catalyst content of 4 wt % in DMF and reaction time of 76.05 min, and an average yield of 96.47 wt % was achieved for DBF when being synthesized at such conditions.

Preparation and Properties of Polypropylene-matrix Lubrication System with Low VOC

2018, 32 (02): 110-115; DOI: 10.19491/j.issn.1001-9278.2018.02.018

Abstract ( 584 )

Two polypropylene (PP)matrix lubrication systems were prepared by a melt-blending method using ethylene bis bisstearamide (EBS) and bishydroxyethyl ethylene bisstearamide (HBS) as lubricants, and their melt flow rate, complex viscosity, tensile strength and the release of volatile organic compounds (VOC) were investigated. The results indicated that both EBS and HBS generated good lubrication for PP, and HBS exhibited a much better lubrication effect on PP than EBS, and the lubrication system containing 1 wt % HBS achieved an increase in melt flow rate by 404.8 %. Both HBS and EBS could inhibit the release of VOC in PP effectively, but the inhibitory effect of HBS was stronger than that of EBS.

Study on Biodegradation of PBS Film by Pseudozyma Antarctica Lipase

2018, 32 (02): 116-121; DOI: 10.19491/j.issn.1001-9278.2018.02.019

Abstract ( 391 )

This paper reported a study on the biodegradation of poly (butylene succinate) (PBS) film as degraded substrate, the degradation behavior of PBS film by a Pseudozyma Antarctica Lipase, Lipozyme CALB. The effects of acidity, temperature, enzymatic concentration and degradation time on the degradation of PBS film were investigated, and then the post-degraded films were characterized by scanning electron microscopy, thermogravimetric analysis and differential scanning calorimetry. The degradation products were also analyzed by mass spectrometry. The results indicated that the optimum conditions for the degradation of PBS film by Lipozyme CALB were obtained at an acidity of pH 7, a temperature of 50 ℃ and an enzymatic concentration of 20 U/mL, and a weight loss of 90 wt % was achieved for the PBS film degraded for 24 h at these conditions. The morphologic observation indicated that the surface of PBS film became more and more rough, and some holes appeared with increasing degradation time. The thermal analysis results demonstrated that the crystallinity of the degraded film was found to increase with the increase of degradation time, but their thermal stability trended to increase gradually. The mass spectrometric analysis indicated that the PBS film was degraded into 1,4-succinate and succinate-butanediol, but no 1,4-butanediol was found.

Application of Cross-fractionation Technology in Study of Branch Structure of High-density Polyethylene

2018, 32 (02): 122-127; DOI: 10.19491/j.issn.1001-9278.2018.02.020

Abstract ( 607 )

The high-density polyethylene (PEHD) resin was fractionated by different methods, and its branch structure and distribution were investigated. A three-dimensional relationship graph for the short-chain branching content, elution temperature and molecular weight was established by a combination of temperature rising elution fractionation and other cross-fractionation methods, which well reflected the branch-structural distribution characteristics of PE-HD. The results indicated that the PE-HD resin was composed of four parts including a low molecular wax containing a certain amount of branch structure, a part of linear low-density polyethylene with larger short-chain branching numbers, a part of high-density polyethylene with small short-chain branching numbers, and the linear polyethylene almost without any branching chains. It was also found that the fraction of the linear low-density polyethylene increased with an increase of relative molecular weight, whereas the part of the high-density one kept a uniform molecular weight distribution.

Structural Analysis of Injection Moulds Based on Moldflow and Abaqus Softwares

2018, 32 (02): 128-133; DOI: 10.19491/j.issn.1001-9278.2018.02.021

Abstract ( 1672 )

In this work, an optimal simulation analysis for the injection-molding process was conducted for the ‘fixed sleeve’ injection mould using the Moldflow software and then the maximum cavity pressure parameters were obtained as an output. Based on the process parameters obtained from the Moldflow analysis and using the ABAQUS software, a deformation simulation was performed for the template related to the ‘fixed sleeve’ injection mould to verify the reliability of mould structure. The results indicated that a combination of the simulations based on MoldFlow and ABAQUS softwares could effectively evaluate the structural performance of the mold in case of meeting the molding requirement, which provided a reliable guarantee for the success of injection-molding tests.

Design of Large Injection Molds with Hot Runners for Automobile Side Aprons

2018, 32 (02): 134140-134140; DOI: 10.19491/j.issn.1001-9278.2018.02.022

Abstract ( 569 )

According to the structural characteristics, material characteristics and plastic appearance quality of an automobile side apron as well as the requirements for batch production, a large complex injection mould with a hot-runner-plus-common-runner structure was designed. An optimal design proposal for gating system was determined as a 5-point hot runner feed system through a careful mold flow analysis, and the feed sequence was adjusted by the sequence valve according to the quality of molded parts. It was confirmed that the side core pulling mechanism of the die was complicated, the temperature control system was balanced and efficient, and the guide positioning system was accurate and reliable. The results indicated that the molding cycle could be controlled within 75 s and the dimensional accuracy of plastic parts achieved MT4 thanks to the advanced design and reasonable structure for the mould developed by this work. The mould was kept a stable operation since the formal production.