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2017, Volume 31 Issue 01 Publication date: 26 January 2017 Previous Issue Next Issue

An Observation at K 2016 for Development Trends of Injectionmolding Technology

2017, 31 (01): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2017.01.001

Abstract ( 589 )

This article described an observation at German K 2016—International Trade Fair for Plastics and Rubber for the worldwide development trends of some representative injectionmolding technologies, including intelligent manufacturing, lightweight and green manufacturing, high efficiency and precision, additive manufacturing, etc. The opportunities for the development of Chinese injectionmolding industry on the background of “Industry 4.0” and “Made in China 2025” were also proposed.

Progress in Toughening Modification of Poly(lactic acid)

2017, 31 (01): 7-12 ; DOI: 10.19491/j.issn.1001-9278.2017.01.002

Abstract ( 567 )

This paper summarized the most recent development of toughening modification for poly(lactic acid) (PLA) in terms of copolymerization and blending technologies. The mechanisms and progresses in toughening techniques for PLA resin with plant fibers were focused, and the development prospects of modified PLA products were predicted.

Effects of Organosilicon on Microstructure and Properties of Waterborne Damping Materials for Vehicles

2017, 31 (01): 13-19 ; DOI: 10.19491/j.issn.1001-9278.2017.01.003

Abstract ( 412 )

The acrylate copolymer latexes containing different contents of organosilicon were synthesized by emulsion polymerization and then characterized by Fouriertransform infrared spectroscopy. Their morphologies and dynamic mechanical properties were investigated by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA), respectively. A series of waterborne damping materials for vehicles were prepared by compounding the resulting copolymer latexes with inorganic fillers. SEM observation demonstrated that the incorporation of organosilicon could improve the compatibility between the copolymer latexes and inorganic fillers and thus resulted in a better interfacial combination between them. DMA investigation showed that the damping properties of the damping materials were enhanced significantly. Moreover, the mechanical properties of the damping materials also presented a remarkable improvement due to the addition of organosilicon.

Study on Applications of HumiditySensitive Carbon Nanotubes for Antistatic Poly(vinyl chloride) Composites

2017, 31 (01): 20-24 ; DOI: 10.19491/j.issn.1001-9278.2017.01.004

Abstract ( 438 )

In the study, humiditysensitive carbon nanotubes (CNTs) were prepared through adsorption between CNTs and cetyltrimethyl ammonium bromide (CTAB), and their chemical compositions were characterized by Fouriertransform infrared spectroscopy and thermogravimetric analysis. Such humiditysensitive CNTs were introduced into poly(vinyl chloride) (PVC) as a conductive additive. The effect of humiditysensitive CNTs on the volume conductivity of the composites was investigated under a simulated moisture environment. The results indicated that the PVC/CNTs composites achieved a percolation threshold at a low CNTs loading of 4 wt.% due to the surfacemodification of CNTs, and the electronic conductivity of the composites increased by four orders of magnitude after the absorbing moisture.

Study on Antistatic Properties of StarchBased Antistatic Agent for Polypropylene

2017, 31 (01): 25-28 ; DOI: 10.19491/j.issn.1001-9278.2017.01.005

Abstract ( 424 )

A starchbased antistatic agent was first prepared, and then the antistatic polypropylene (PP) compounds were prepared by meltblending of PP with the antistatic agent. The effects of the antistatic agent on the surface resistivity of PVC compounds were investigated when being used individually or combined with nonionic antistatic agent, ionic antistatic agent and inorganic salt. The results indicated that the combination of the starchbased antistatic agent with the ionic antistatic agent could lead to a synergistic effect on PP and thus resulted in excellent antistatic performance and durability.

Study on Blending Modification of PLA/PHBV

2017, 31 (01): 29-35 ; DOI: 10.19491/j.issn.1001-9278.2017.01.006

Abstract ( 416 )

Poly(L-lacticacid) (PLA)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) blends were prepared by a meltblending method. The effects of PLA/PHBV weight ratio and talc content on the properties of PLA/PHBV blends were investigated. With a continuous increase of PHBV content, the crystallinity degree of the blends showed a decrease at first and then began to increase. The blends achieved an increase by 35.9 % in impact strength and by 21.81 % in elongation at break, whereas the tensile strength was reduced. On the other hand, the crystallinity degree of the blends also increased with increasing talc content and their impact strength increased by 12.4 %, followed by a decrease in tensile strength and elongation at break. The mechanical properties of the blends achieved optimum values with addition of 20 wt % PHBV and 1.5 wt %talc.

Effect of Temperature Cycle on Quasistatic Mechanical Behavior of Representative Foam Plastics

2017, 31 (01): 36-42 ; DOI: 10.19491/j.issn.1001-9278.2017.01.007

Abstract ( 296 )

The quasistatic tensile and compression tests of temperaturecycling treated silicone rubber foam（SRF） and rigid polyurethane foam (RPUF) were conducted to investigate the effect of temperature cycle on their mechanical properties by threedimensional digital speckle dynamic deformation techniques. The results indicated the tensile strength of SRF and highdensity RPUF were influenced by temperature cycle more significantly compared with lowdensity RPUF in the quasistatic tensile process, which led to a remarkable improvement in tensile strength. In the case of SRF, the compressive strength and Young’s modulus were improved remarkably, and the elastic deformation was also increased to some extent. However, its yield phenomenon was not so evident. In the case of lowdensity RPUF, the temperaturecycling treatment led to an improvement in yield stress but resulted in shortening of yield stage and a decrease in plastic deformation. As for the high density RPUF, not only the elastic deformation was improved, but the yield stage was also extended due to the temperaturecycling treatment. However, its loading capability to pressure was reduced in the quasistatic compression process.

Effects of Melting Temperature on Isothermal Crystallization Behavior of Poly(vinylidene fluoride)

2017, 31 (01): 43-48 ; DOI: 10.19491/j.issn.1001-9278.2017.01.008

Abstract ( 439 )

A poly(vinylidene fluoride) (PVDF) film was prepared by a solventcasting method, and its crystalline structures after a isothermally crystallizing treatment was characterized by Fouriertransform infrared spectroscopy and Xray powder diffraction. The effect of melting temperature on the isothermal crystallization behavior of this film was investigated by a cycling meltcrystallization technique. The results indicated that, after the isothermally crystallizing treatment, only αphase crystals were formed in the film, and its equilibrium melting point of PVDF is around 197 ℃. The effect of melting temperature on the isothermal crystallization behavior of the film was not significant above the equilibrium melting point. However, when the melting temperature was lower than the equilibrium melting point, the number of spherulites increased with an increase of melting temperature, but its size decreased.

Synthesis and Application of Tricalcium Silicatemethyl Caged Phosphorothioate

2017, 31 (01): 49-54 ; DOI: 10.19491/j.issn.1001-9278.2017.01.009

Abstract ( 426 )

A caged phosphorothioate flame retardant, tricalcium silicatemethyl-1-thiophospha-2,6,7-trioxabicyclo ［2.2.2］ octyl-4-methyl ester (MSTSPE), was synthesized by a reaction between methyl trimethoxysilane (MTMS) and 1-thiophospha-4-hydroxymethyl-2,6,7-trioxabicyclo ［2.2.2］ octane (SPEPA), and its structure and properties were characterized by means of Fouriertransform infrared spectroscopy, 1HNMR and thermogravimetric analysis. The effects of solvent, reaction temperature, reaction time and mass ratio of raw materials on product yield were investigated. The results indicated that the optimum synthetic method for MSTSPE was a solventfree synthesis, the molar ratio of MTMS and SPEPA was determined as 1∶3.1, and the synthetic temperature was set to 100 ℃ for 2 h and then 140 ℃ for 5 h. In such a synthetic condition, the production yield reached 92.4 %. The melting point of the resultant MSTSPE was (191±2) ℃, and its decomposition temperature was (340±5) ℃. The MSTSPE product synthesized in this work exhibited a high flameretardant effect and charring efficiency on poly(butylece terephthalate) (PBT). In addition, a combination of MSTSPE with melamine pyrophosphate could generate a synergistic flameretardant effect on PBT.

Study on Encapsulation of Melamine Pyrophosphate with Epoxy Resin as Flame Retardant for EVA

2017, 31 (01): 55-59 ; DOI: 10.19491/j.issn.1001-9278.2017.01.010

Abstract ( 415 )

A flameretardant (EPMPP) based on a melamine pyrophosphate (MPP) core and epoxy shell were prepared through an insitu polymerization reaction at a reaction temperature of 75 ℃ with curing time of 4 h, and its morphology and microstructure were characterized by scanning electron microscopy, Fouriertransform infrared spectroscopy and water contact angle. The results confirmed that MPP particles were successfully encapsulated by epoxy resin. The flameretarded poly (ethylene-co-vinyl acetate) (EVA) composites were fabricated by a combination of EPMPP with aluminium diethylphosphinate (ADP) as an intumescent flameretardant system, and their flameretardant properties were investigated by limiting oxygen index, vertical burning experiment and thermogravimetric analysis. The results indicated that the composites achieved a UL 94 V-0 classification and an oxygen index value of 31 % when the intumescent flame retardant system was incorporated into EVA at a weight fraction of 40 % with an ADP/EPMPP mass ratio of 2/1. In addition, the composites exhibited an initial decomposition temperature of 303 ℃ and a char yield of 18 %.

Study on Computer Simulation for Relationship Between Chemical Structure and Thermal Stability of Poly(vinyl chloride)

2017, 31 (01): 60-65 ; DOI: 10.19491/j.issn.1001-9278.2017.01.011

Abstract ( 444 )

The orders of C—Cl bond in three different types of poly(vinyl chloride) (PVC) were simulated by a B3LYP/631 method using a GAUSSIAN 09 software according to the Wiberg Bond Index theory. The results indicated that the isotactic isomers in PVC macromolecule were more stable than syndiotactic ones on the basis of the molecular orbital theory. Chemical structures of PVC samples were characterized by 13CNMR, suggesting that the PVC macromolecules containing more isotactic isomers were more stable. The thermal degradation behaviors were also investigated by thermogravimetricinfrared combination analysis, which indicated that the first degradation of PVC was mainly derived from the dehydrochlorination. Dynamic thermal stabilities of PVC samples were investigated with a torque reheometer. The results indicated that the PVC macromolecules with a fewer isotactic isomers were more thermally unstable. These results were in good agreement with the structural characterizations.

Influence of Flash Well on Warp in Gas-assisted Injection Molding Process

2017, 31 (01): 66-69 ; DOI: 10.19491/j.issn.1001-9278.2017.01.012

Abstract ( 703 )

The warp defects of a gasassisted injectionmolded polypropylene (PP) part were analyzed by numerical simulation and orthogonal experimental method. The effects of gasdelay time, gas pressure and the structure of flash well on the warp defects were investigated. The results indicated that the relationship between the gas-injection pressure and the structure of flash well played a key role in determining the degree of warps for the PP part. A rational structure of flash well along with a certain gasinjection pressure could reduce the degree of warps significantly.

Study on Applications of Different Inorganic Fillers in Polyethylene Wood-plastic Composites

2017, 31 (01): 70-74 ; DOI: 10.19491/j.issn.1001-9278.2017.01.013

Abstract ( 376 )

In this study, polyethylene (PE) woodplastic composites were prepared with addition of calcium carbonate, talc powder and wollastonite as inorganic fillers. Particle size, morphologies and specific surface areas of these inorganic fillers were examined, and the effects of these fillers on various properties of the composites were investigated. The mechanical results indicated that bending strength of the composites with wollastonite achieved an optimum value while the composites containing talc powder obtained better impact toughness. Most of all, the mechanical properties, specific gravity, water absorption and hardness of the composites were improved gradually with addition of inorganic fillers up to 15 phr. However, when the inorganic fillers were excessive over 20 phr, the density and hardness of the composites still kept an increase, but their water absorption and linear thermal expansion coefficients tended to decrease.

Optimization of GasAssisted Injectionmolding Process for Vertical Beam Base Parts Based on Moldflow

2017, 31 (01): 75-79 ; DOI: 10.19491/j.issn.1001-9278.2017.01.014

Abstract ( 489 )

In this study, polyethylene (PE) woodplastic composites were prepared with addition of calcium carbonate, talc powder and wollastonite as inorganic fillers. Particle size, morphologies and specific surface areas of these inorganic fillers were examined, and the effects of these fillers on various properties of the composites were investigated. The mechanical results indicated that bending strength of the composites with wollastonite achieved an optimum value while the composites containing talc powder obtained better impact toughness. Most of all, the mechanical properties, specific gravity, water absorption and hardness of the composites were improved gradually with addition of inorganic fillers up to 15 phr. However, when the inorganic fillers were excessive over 20 phr, the density and hardness of the composites still kept an increase, but their water absorption and linear thermal expansion coefficients tended to decrease.

A Method for Interference Checking of Injection Mold Cooling System Based on Geometry Features

2017, 31 (01): 80-86 ; DOI: 10.19491/j.issn.1001-9278.2017.01.015

Abstract ( 344 )

A new geometry-based automatic interference checking method of injection mold cooling system is proposed. The centerlines of cooling circuit are extracted correctly by the core or cavity cooling system feature recognition. The central line of the cooling system loop is traversed to determine the spatial geometric position of any two section of the water center line in the loop of the cooling system. For these geometry relationships, different methods for calculating the minimum distance are summarized. According to the established allowable safe distance criterion of the cooling circuit, the interference detection of cooling circuit is implemented using the calculated minimum distance. The case study shows that this method is available to check interference of cooling system of injection mold efficiently, improve user productivity, reduce the error rate and realize the automation of interference checking of cooling system.

Synthesis and Performance of Phenyl-2-naphthylamine Antioxidant

2017, 31 (01): 87-92 ; DOI: 10.19491/j.issn.1001-9278.2017.01.016

Abstract ( 382 )

A phenyl 2-naphthylamine antioxidant was synthesized via Michael addition and amidation reactions with parabromoaniline, lauryl amine and 2-naphthylamine as raw materials, and its chemical structure was confirmed by 1H- and 13C-NMR spectroscopy and liquid chromatographymass spectrometry. Thermal analysis results indicated that this phenyl 2-naphthylamine antioxidant had a high thermal stability. The oxidation induction time for a polyethylene compound containing the phenyl 2-naphthylamine antioxidant was 157.53 min and the carbonyl index was 0.25, suggesting that the phenyl 2-naphthylamine antioxidant had an excellent stabilizing efficiency.

Study on Thermal Decomposition Behavior of BBP and DBS Plasticizers at Different Temperature

2017, 31 (01): 93-97 ; DOI: 10.19491/j.issn.1001-9278.2017.01.017

Abstract ( 804 )

The thermal decomposition behaviors of benzyl butyl phthalate (BBP) and dibutyl sebacate (DBS) were investigated by pyrolysisgas chromatographymass spectrometry (Py/GCMS) in the temperature range of 500~700 ℃ under a helium atmosphere. The results indicated that the major pyrolysates of BBP were 2butylene, benzyl alcohol, ophthalic anhydride and benzyl benzoate, whereas the major ones for DBS were 2butylene, cyclononanone and sebacic acid. The pyrolysis mechanisms of BBP and DBS were presented on the basis of these pyrolysates as well as the relevant variation of their concentrations. This study provides an important means for optimization of the thermal degradation condition of waste plastics containing different plasticizers.

Design of Injection Molds for Toilet Seats Based on Moldflow and UG Software

2017, 31 (01): 98-104 ; DOI: 10.19491/j.issn.1001-9278.2017.01.018

Abstract ( 669 )

The structural characteristics of thermoplastic parts was analyzed in the cases of a toilet seat and cover. The structure of the injection mold was optimized by a Moldflow software, and then the mold was designed by UG software. The structural characteristics and conducting process of the mold were introduced. The toilet seat and cover were injectionmolded by the mold. The mold joint was designed only in the periphery of the plastic parts. Molding of the side holes for the toilet seat and cover was achieved by using lifter and angle pin respectively. The guide unit is consisted of guide pillars, fourcorners side positioning and chain. The injection mold of the toilet seat and cover had a rational structure and high reliability.

Design of Heating System of Outside Mold Decoration of Automobile Dashboards

2017, 31 (01): 105-109 ; DOI: 10.19491/j.issn.1001-9278.2017.01.019

Abstract ( 515 )

A heating system of automobile dashboards was designed on the basis of the technological procedure of outside mold decoration, which was mainly composed of heating plates, guide rails and ball screws. The model of heating system was determined by calculating the work load of guide rails and ball screws. A temperature control system was also designed, and the transfer function of overall characteristics of the heating system was obtained by calculating thyristor regulation characteristics, quartz heater amplification coefficient and quartz lamp time constant. The transfer function was also simulated by a Matlab software, and the analysis results indicated that the heating system had a high stability. The heating process for thin films was also simulated by an Abaqus software. The analysis results indicated that the temperature of the heating tile on film was in the range of 393.4~398.5 K, the heating temperature was uniformly only with about 10.6 % of heat loss.