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2018, Volume 32 Issue 04 Publication date: 26 April 2018 Previous Issue Next Issue

China Plastics Industry(2017)

2018, 32 (04): 1-5; DOI: 10.19491/j.issn.1001-9278.2018.04.001

Abstract ( 463 )

General situation of China plastics industry in 2017 was reviewed, including the output, import and export of plastics products, as well as major economic data, such as the total industrial values, sales and profits of plastics products, etc. Analysis of the market of plastics products in 2017 was made, and the developing trend of China plastics industry in 2018 was proposed.

Research Progress in Production Technologies and Measurement Methods of Highly Glossy Impact Polystyrene

2018, 32 (04): 6-11; DOI: 10.19491/j.issn.1001-9278.2018.04.002

Abstract ( 499 )

This paper overviewed the production and demand development of polystyrene (PS) in the global market and especially analyzed its yield, main manufacturers and marketing situation in China. The current research status and applications of highly glossy impact PS were also described. According to the analysis results of production technologies, the impactmodifying rubber used for the highly glossy impact PS has a bimodal distribution in its particle size, and the rubber particles exhibited large and small sizes in two different distribution ranges. The bimodal distribution in the particle size of rubber could be realized by using two types of rubbers with different particle sizes and then incorporating them in different synthetic stages of PS. Finally, the principle of glossiness measurement was introduced and the major effect on the glossiness of highly glossy impact PS was discussed.

A Survey of Defects and Process Optimization of Water-assisted Injection Molded Parts

2018, 32 (04): 12-17; DOI: 10.19491/j.issn.1001-9278.2018.04.003

Abstract ( 495 )

Aimed to the quality of waterassisted injection molded parts, this paper presented a survey for their defects and relevant process optimization from the macroscopic phenomena such as the first penetration process of highpressure water instability, the phenomenon of melt accumulation at the mold cavity variable cross section, the formation of water fingerings during the process and the microscopic phenomena like fiber orientation and distribution along the thickness of the parts, and crystal types and structures in different regions.

Research Progress in WearResistant Modification of PEEK and Its Application Prospect

2018, 32 (04): 18-23; DOI: 10.19491/j.issn.1001-9278.2018.04.004

Abstract ( 736 )

This paper reviewed the current research progress in the wearresistant and reinforcing modifications of PEEK. The friction and wear types of PEEK composites were summarized and the research progress in tribological mechanism of PEEK composites under certain conditions was introduced. Finally, the application prospect of PEEK composites was also described.

Effect of Epoxidized EPDM on Structure and Properties of PBT

2018, 32 (04): 24-31; DOI: 10.19491/j.issn.1001-9278.2018.04.005

Abstract ( 487 )

An epoxidized ethylenepropylenediene rubber (eEPDM) was prepared by epoxidation of EPDM and then melt blended with poly(butylene terephthalate) (PBT) for the impact enhancement of PBT. The structure of eEPDM, morphology and properties of PBT/eEPDM were characterized by Fouriertransform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, torque rheometry, dynamic mechanical analysis and mechanical measurements. The results indicated that eEPDM achieved a good dispersion in the PBT matrix in comparison with pristine EPDM at the content lower than 15 wt %. However, the dispersion of eEPDM became worse when the content of eEPDM was higher than 15 wt %. PBT was partially miscible with eEPDM. The addition of eEPDM increased the torque of PBT blends. The incorporation of only 5 wt % eEPDM could generate a significant toughening effect on PBT, which led to an increase in notched impact strength by 100 %.

Preparation and Mechanical Properties of PPS/GF Commingled Yarn Composites

2018, 32 (04): 32-39; DOI: 10.19491/j.issn.1001-9278.2018.04.006

Abstract ( 584 )

PPS/GF fabrics with a commingled yarn structure were prepared by a mixing method, and then their composite laminates were prepared by compression molding. The effects of mold temperature and holding time on the mechanical properties of the laminates based on 20 wt % PPS and 80 wt % GF was investigated. Furthermore, the influences of processing parameter like pressure and holding time on the microstructure of the laminates were evaluated by scanning electron microscopy, and the influence of process conditions on the void formation was analyzed. The results indicated that the composite laminates gained the optimum mechanical properties when the molding temperature was set to 320 ℃, the forming pressure was set to 2.0 MPa, and the molding time was set to 10 min. In this case, the laminates achieved the tensile strength of (502.9±2.9) MPa and the flexural strength of (530.1±5.6) MPa.

Analysis of Influence Factors of Creep Variables of PE-based Wood-plastic Composites

2018, 32 (04): 40-44; DOI: 10.19491/j.issn.1001-9278.2018.04.007

Abstract ( 502 )

The effects of raw material ratio and process parameters and material preparation process parameters on the 24 h creep properties of PEbased woodplastic composites at different loads and constant room temperature. The results indicated that the wood/plastic ratio was the first significant factor, although there are different superior factors on the creep variable of the composites during the 24 h creep tests. Furthermore, the wood plastic ratio and the rotation speed of the screw are significant factors at the load of 30 % bending strength, and the wood/plastic ratio was the significant factor at the load of 50 % bending strength. However, only the wood/plastic ratio became the most significant factor at the load of 70 % bending strength.

Effect of Particle Size of Graphite on Tribological Performance of Polyimide

2018, 32 (04): 45-50; DOI: 10.19491/j.issn.1001-9278.2018.04.008

Abstract ( 569 )

Five types of natural flake graphite (NG) with particle sizes of 10, 20, 30, 40 and 50 μm were used to prepare polyimide (PI)/NG composites via a hotpressing technology, and the dynamic thermomechanical properties, tribological performance and morphologies of fracture and worn surfaces were investigated. The results indicated that the storage modulus and loss modulus of PI were enhanced with the addition of NG, and however, they were seldom affected by the particle size of NG. Moreover, the coefficient of friction and wear rate of PI/NG composites continuously decreased with a decrease in particle size. The PI/NG composites achieved a coefficient of friction of 0.0882 and a wear rate of 6.19×10-7mm3/N·m when NG with a particle size of 10 μm was added. In addition, the PI/NG composites exhibited a smoother worn surface than pure PI, in which a more continuous and compact transfer film was obtained.

Experimental Study on Cool Storage Performance of PEG/EG Composite Phase Change Materials

2018, 32 (04): 51-57; DOI: 10.19491/j.issn.1001-9278.2018.04.009

Abstract ( 548 )

Composite phase change materials (PCMs) were prepared by melt mixing poly(ethylene glycol) (PEG, molecular weight<1 000) with expanded graphite (EG) as a thermally conductive enhancer, and various effects on the cool storage performance of the PEG/EG composite PCMs were analyzed. The influences of EG content and pressing level on the thermal conductivity of PCMs were investigated by a flash thermal analysis method, their microstructures were determined by scanning electron microscopy, and their cool storage performance was characterized by an engineering survey method to obtain phase transition curves. The results indicated that the effects of EG content and pressing level on the thermal conductivity of PCMs were caused by changing the internal structure of thermally conductive network in the PEG matrix. The cool storage performance was improved with the increase of EG content, and EG also could weaken the influences of coolant content and coolant temperature on the cool storage process.

Effect of SIPM on Physical and Emulsifying Properties of High Refractive Polyester

2018, 32 (04): 58-64; DOI: 10.19491/j.issn.1001-9278.2018.04.010

Abstract ( 418 )

A series of polyester resins were prepared by a melt polycondensation method using dimethyl5sodium sulfoisophthalate (SIPM), selfmade polyether polyol, dimethyl 2,6naphthalene dicarboxylate (NDC) and ethylene glycol as raw materials. The effect of SIPM content on the properties of resultant polyester resins was investigated, and the structure and physical and emulsifying properties of polyester resins were characterized by nuclear magnetic resonance, Fouriertransform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, Abbe refractometer and particle size analyzer. The results indicated that the glass transition temperature of the polyester resins increases with the increase of SIPM content. The polyester resins exhibited a high thermal stability, but their refractive index was reduced slightly from 1.606 3 to 1.600 4. The polyester resins could be easily emulsified by Tween80, and the lower the concentration of the emulsifier, the better the transmittance of the emulsions. The polyester aqueous emulsions showed excellent dispersion and stability after being stored for 100 days.

Preparation of Microencapsulated Liquid Paraffin with Polysulfone

2018, 32 (04): 65-68; DOI: 10.19491/j.issn.1001-9278.2018.04.011

Abstract ( 468 )

The microcapsules composed of a liquid paraffin core and polysulfone (PSF) shell were prepared by a solvent evaporation method. The morphology, chemical structure, thermal properties and shell hardness of the microcapsules were investigated by scanning electron microscopy, Fouriertransform infrared spectrometry, thermogravimetric analysis and nanoindentation. The results indicated that the microcapsules exhibited a smooth surface with a mean particle size of about 15 μm when being synthesized at 35 ℃ by using poly(vinyl alcohol) and sodium dodecyl sulfate as emulsifiers. The microcapsules also achieved a high thermal stability and good mechanical properties.

Environmental Stress Cracking Resistance of ABS and PS-HI in Rust Preventive Oil

2018, 32 (04): 69-73; DOI: 10.19491/j.issn.1001-9278.2018.04.012

Abstract ( 672 )

The environmental stress cracking tests of ABS and HIPS were performed by a flexural loading method using rust preventive oil as a solvent, and the effects of stress, solvent and their combination on the tensile and flexural properties of ABS and HIPS were investigated. The results indicated that the tensile and flexural strength of HIPS decreased remarkably due to the combination of stress and solvent, whereas there was almost no influence on the tensile and flexural strength of ABS. In addition, the elongation at break of ABS and HIPS was reduced significantly as a result of the environmental stress, leading to a transition in fracture behavior from ductile fracture into the brittle one.

Research of 3D Printing Molding Process of PCL and Its Mechanical Analysis

2018, 32 (04): 74-78; DOI: 10.19491/j.issn.1001-9278.2018.04.013

Abstract ( 982 )

The effects of molding temperature and print height on the warpage deformation of the 3D printed part were investigated by using polycaprolactone (PCL) as a raw material. The mechanical properties of 3D printing molded parts were evaluated and compared with those of the injectionmolded part. The results indicated that the warping deformation of the 3D printed part increased at first and then decreased with the improvement of molding temperature and print height. Moreover, the 3D printing molded part achieved much higher tensile strength, flexural strength and elongation at break than the conventional injectionmolded one.

Design Simulation and Performance Investigation of ScrewPlasticizing 3D Printing Devices

2018, 32 (04): 79-85; DOI: 10.19491/j.issn.1001-9278.2018.04.014

Abstract ( 414 )

A screwplasticizing 3D printing system was fabricated by designing the structures of a screw, barrel and spiral blade in this work. The pressure, velocity and shear rate were simulated by Polyflow software, and the extrusion performance of this device was investigated. The results indicated that the forced feeding could be realized by an axial force through spiral blade, and the pressure of the melt was improved with increasing rotation speed of the screw along the extrusion direction. The designed laddershaped threads favored the flow of the melt. The materials were molten by a synergic effect of shear and heat transfer within the heating appliance. The diameter of the extrudate increased slightly when the rotation speed increased from 0.1 r/s to 1 r/s.

Investigation on Tensile Fatigue Damage of GFRP Bars Based on Dynamic Residual Stiffness

2018, 32 (04): 86-91; DOI: 10.19491/j.issn.1001-9278.2018.04.015

Abstract ( 439 )

A cycle tensile test was carried out on the GFRP bars with diameters of 16 and 20 mm at the stress levels of 0.3, 0.5 and 0.6 and the stress ratios of 0.3 and 0.5. The residual stiffness evolution curves under different working conditions were obtained by characterizing the damage of GFRP bars with dynamic residual stiffness, and the validation and fitting results from experimental data were obtained according to the EEB and YLS models. The results indicated that, at the stress levels of 0.3 and 0.5, the YLS model could well characterize the fatigue damage characteristics of GFRP bars in most stages, whereas the EBB model was not in good agreement with the experimental results. According to the fitting curves obtained from experimental results, the curve fitting with piecewise exponential functions was found to better characterize the fatigue damage during the cycle tensile test.

Optimization Design and Failure Analysis of Plastic Structure Part Based on CAE Simulation

2018, 32 (04): 92-96; DOI: 10.19491/j.issn.1001-9278.2018.04.016

Abstract ( 818 )

The failure mode of a sagged plastic structure part was analyzed by a combination of the CAE simulation and laboratory experiments, and then an improving design was performed for this plastic structure part on the basis of the principle of failure analysis. Finally, the optimized design proposal was validated by a combination of the CAE simulation and experiments. The results indicated that the static stiffness, creep resistance and fatigue durability of this plastic structure part were improved by this optimized design, and its service life was also extended.

Structure and Properties of Halogen-free Flame Retardant Ethylene-vinyl Acetate Copolymer with Aluminum Hydroxide

2018, 32 (04): 97-102; DOI: 10.19491/j.issn.1001-9278.2018.04.017

Abstract ( 569 )

The halogenfree flame retardant ethylenevinyl acetate (EVA) composites were prepared by using surfacemodified aluminum hydroxide (ATH) as a flame retardant and linear lowdensity polyethylene grafting copolymer as a compatibilizer, and their structure, flameretardant performance and mechanical properties were characterized by scanning electron microcopy, dynamic mechanical analysis, limiting oxygen index and vertical burning experiment. Furthermore, the effects of the surface treatment and compatibilizer on the dispersion of ATH in the EVA matrix and the interfacial compatibility between ATH and EVA were investigated. The results indicated that a combination of the surface treatment and compatibilizer effectively improved the interface adhesion between the matrix and ATH. Moreover, the smaller the ATH size, the better the flameretardant performance of the composites.

A Comparative Investigation on Aging Performance of Polypropylene Modified with HWPAN-g-TiO₂ and Other Light Stabilizers

2018, 32 (04): 103-109; DOI: 10.19491/j.issn.1001-9278.2018.04.018

Abstract ( 573 )

A type of macromolecular light stabilizers with UVabsorbing and shielding performance was prepared by using waste acrylic fabrics as a raw material, and then the weatherable for polypropylene (PP)based composites were prepared by mixing this light stabilizer with PP and conventional hindered phenolic light stabilizers. The effect of this macromolecular light stabilizer on the aging performance of PP was investigated. Compared with the conventional hindered phenolic light stabilizers, the macromolecular light stabilizer exhibited much better UVabsorbing and shielding effects on PP. The carbonyl index of PP reached 150.3 after artificially accelerated aging for 500 h under the UV light, and however, the PP/HWPAN-g-TiO2 composites only achieved a carbonyl index of 53. Moreover, PP/macromolecular light stabilizer composites exhibited a decrease in tensile strength by 72.4 %. On the other hand, PP/HWPAN-g-TiO2 composites only showed a decrease in tensile strength by 13.8 %.

Research and Analysis of Standard System Construction and Safety Supervision System of Plastic Products

2018, 32 (04): 110-117; DOI: 10.19491/j.issn.1001-9278.2018.04.019

Abstract ( 539 )

The current paper states the contrast on standard system structure of plastic products between China, international standardization organization (ISO) and US, and also compares the plastic products safety supervision system of China and that of the other countries. It is found that in the field of daily plastic products, there are lots of product standards in China, but lack of systematicness. For the plastic products which have the potential to contact food or skin, there is lack of framework standards or relevant regulations to prevent risk of products safety. In the field of plastic pipes, fittings and valves, the standard system in China is largely consistent with that in ISO, however, it is suggested to accelerate the establishment of national standards on plastic pipes for trenchless renovation, due to the rapid development of this industry in China.

Detection of Erucamide in Low-density Polyethylene Films and Its Migration to Simulant Foods

2018, 32 (04): 118-124; DOI: 10.19491/j.issn.1001-9278.2018.04.020

Abstract ( 997 )

Using gas chromatography-mass spectrometry (GC-MS) method to detect erucamide in three kinds of low density polyethylene films and study the migration of erucamide to food simulants. Using the threshold of toxicological concern (TTC) The contents of erucamide in three types of lowdensity polyethylene (PE-LD) films were detected by gas chromatographymass spectrometry (GCMS), and the migration of erucamide from PELD films to a simulant food was investigated. The threshold of toxicological concern (TTC) was also used to assess the safety of erucamide in foods. The results indicated that the erucamide standard curve presented a good linear relationship (R=0.999 3) in the range of 100~5 000 μg/L. The limit of detection of erucamide was 30 μg/L, the recovery were in the range of 78.3 %~115.6 % with a RSD of 2.9 %~11.6 %. The migration of erucamide increased with the increase of time, temperature and erucamide concentration in the certain range. The partition coefficient of erucamide between PE-LD and simulant foods increased slightly with the increase of erucamide concentration in PE-LD.

Optimization Design of Injection Molds of Automobile Built in Storage Boxes Based on MPI

2018, 32 (04): 125-131; DOI: 10.19491/j.issn.1001-9278.2018.04.021

Abstract ( 500 )

In this paper, a mold flow analysis was performed for an automobile builtin storage box by Moldflow software according to the rheological principle of polymers. Aimed to the defects of the storage box occurring during the injection molding process, which included the surface sink marks, long time to reach the ejectiopm temperature and the large warpage deformation, the gating and cooling systems of the mold were redesigned. These defects were found to be eliminated or reduced through an evaluation for the quality of the injectionmolded product. The shrinkage index was reduced from 0.638 2~4.009 to 0, the time to reach the ejection temperature was reduced from 37.92~92.68 s to 19.87~21.40 s, and the total warpage deformation decreased from 1.166~1.782 mm to 0.024 0~0.416 5 mm. These results indicated a significant effect. Based on the above results, the injection mold of the automobile builtin storage box was designed and the qualified parts were produced by using this mold.

Optimal Design of Injection Molding Process for Lightweight Stabilizer Bar Links

2018, 32 (04): 132-137; DOI: 10.19491/j.issn.1001-9278.2018.04.022

Abstract ( 538 )

The injection molding process of lightweight stabilizer bar links was designed and optimized on the basis of the feature of glassfiberreinforced polyamide as a raw material as well as the loadbearing characteristics required for the molding process. Furthermore, the gate location and number of injection molds were designed and the injection molding parameters were optimized. Combined with the results of finite element analysis, the molding qualities including fiber orientation, weld line and warpage obtained from the 3gate proposal were compared, and then a proper design proposal for the gate was determined to meet the requirements of injection molding process. Taking the warpage deformation as an optimization target, this design proposal of the gate was further optimized by an orthogonal method to obtain a set of optimized parameters for the injection molding process. A warpage value of 1.514 mm was achieved when the injection molding was performed under these optimized parameters. Finally, the molding process and the design of the mould should be adjusted to ensure good loadbearing performance for the stabilizer bar link.

Design of Injection Molds of Deep Cavity Drawers with Oblique Clasp Hands

2018, 32 (04): 138-142; DOI: 10.19491/j.issn.1001-9278.2018.04.023

Abstract ( 400 )

The technological characteristics of a deep cavity drawer with an oblique clasp hand were analyzed, and then the structural design and operating process of the injection mould for this part were described. The position of the gate was determined by the results of mold flow analysis. The clasp hand was formed and demoulded by using an inclined ejecting mechanism and a hydraulic core pulling mechanism. The multiple channels of cooling water were designed to achieve a uniform cooling effect on the plastic part. It was practically confirmed that the designed structure of this mold was reasonable and stable.