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2017, Volume 31 Issue 10 Publication date: 26 October 2017 Previous Issue Next Issue

Research Progress in Phosphorus Flame Retardants for Polyesters

2017, 31 (10): 1-5; DOI: 10.19491/j.issn.1001-9278.2017.10.001

Abstract ( 431 )

This paper overviewed flameretardant modification methods for polyesters, which focused on the copolymerization, blending and postprocessing methods for flameretardant modification, and also introduced some new modification technologies. Furthermore, 2carboxyethyl(phenylphosphinic) acid (CEPPA) as a representative phosphoruscontaining flame retardant used for polyesters was introduced in detail, and future development direction of flameretardant polyesters was proposed. It should be pointed out that low toxicity, low smoke and halogenfree flame retardants for polyesters are the current direction in development, but the development of new types of halogenfree flame retardants will be a future trend.

Research Progress of Bamboo Fiber Reinforced Thermoplastic Composites

2017, 31 (10): 6-11; DOI: 10.19491/j.issn.1001-9278.2017.10.002

Abstract ( 641 )

This paper reviewed the research progresses of matrices, reinforcing agents, processing technologies and interfacial modification techniques of bamboo fiberreinforced thermoplastics composites and analyzed effects of raw materials, formulation and processing technologies on properties of bamboo fiberreinforced thermoplastic composites. Meanwhile, the current research status of bamboo fiberreinforced biodegradable plastic composites was introduced. Moreover, the paper especially introduced the effects of surface pretreatment methods for raw materials, graft copolymerization, and the use of coupling agents on properties of the composites. Finally, the trend in the development of bamboo fiberreinforced thermoplastics composites was expounded, their emphases for future researches are briefly described.

Research Progresses in Halogen-free Flame-retardant Thermoplastic Polyesters

2017, 31 (10): 12-19; DOI: 10.19491/j.issn.1001-9278.2017.10.003

Abstract ( 428 )

This article reviewed the recent research progresses in halogen-free flameretardant thermoplastic polyesters and especially introduced the development and applications of halogenfree flame retardants including for poly(ethylene terephthalate), poly(1,4-butylene terephthalate) and polycarbonate in recent five years phosphoruscontaining, phosphorusnitrogen, silicone and inorganic flame retardants. Their flame retardant mechanisms and effects on the flameretardant performance of thermoplastic polyesters were analyzed, and their merits and demerits were evaluated. Finally, the development trend of halogenfree flameretardant thermoplastic polyesters was prospected.

Preparation and Properties of Polyurethane/Isocyanate Modified Oxidized Graphene Foam

2017, 31 (10): 20-25; DOI: 10.19491/j.issn.1001-9278.2017.10.004

Abstract ( 579 )

In this work, graphene oxide (GO) was first prepared by the Hummers method and then was surfacemodified with isophorone diisocyanate to obtain the isocyanatemodified GO. The polyurethanematrix composite foams were prepared by incorporation of the isocyanatemodified GO. Effect of the isocyanatemodified GO on porous structure, thermal conductivity and mechanical properties of the composite foam were investigated. The composite foams achieved the maximum compressive strength and compressive modulus with the addition of only 0.5 % isocyanatemodified GO. However, there is no distinct influence on thermal conductivity observed. Moreover, the composite foams also gained an improvement in glass transition temperature and energy storage modulus.

Effects of Nucleating Agents on Crystallization Behavior of Polypropylene

2017, 31 (10): 26-32; DOI: 10.19491/j.issn.1001-9278.2017.10.005

Abstract ( 519 )

Effects of phosphate nucleating agents, carboxylate nucleating agents, rosin type nucleating agents and sorbitol type nucleating agents on crystallization behavior of isotactic polypropylene (i-PP) were investigated by Fouriertransform infrared spectroscopy, powder X-ray diffraction, differential scanning calorimetry and polarizing light microscopy. The results indicated that the crystallization kinetics of i-PP was significantly influenced by its crystallization rate, crystallization temperature and crystallinity because of the difference in the structure of nucleating agents. Among these nucleating agents, the phosphate nucleating agents exhibit the shortest half time for the crystallization of i-PP, and its crystallization temperature was up to 129.8 ℃.

Synthesis of Transition Metallic Phytates and Its Applications in PVC as an Efficient Flame Retardant

2017, 31 (10): 33-39; DOI: 10.19491/j.issn.1001-9278.2017.10.006

Abstract ( 566 )

Transition metallic phytates (M-Phyt) containing different rare earth elements were synthesized by a direct precipitation method, and then it was used as a flameretardant and smoke suppressant for flexible PVC. It indicated that the prepared MPhyt particles exhibited an irregular shape. Char yields of M-Phyt in nitrogen were in an order of Mn-Phyt>Co-Phyt>Fe-Phyt>Ni-Phyt. PVC compound containing 15 wt % CoPhyt showed the highest LOI, which was improved from 24.9 % to 28.3 %, and its SDR reached 75.09 %. Fe-Phyt exhibited an optimum smoke suppression effect on PVC by reducing SDR of PVC/Fe-Phyt compound from 94.55 % to 48.96 %, and LOI of PVC/Fe-Phyt compound was 27.7 %. Char yields of the compounds were greatly improved with the addition of MPhyt. Char yield of PVC/Co-Phyt composite was as high as 22.08 wt %, but char yield of PVC/Ni-Phyt composite increased by 9.09 %.

Study on Rheological Behavior of Polyamide 6/Ionic Liquid Composites

2017, 31 (10): 40-43; DOI: 10.19491/j.issn.1001-9278.2017.10.007

Abstract ( 609 )

Polyamide 6(PA6)/ionic liquid composites were prepared by melt blending and extrusion. Effect of the content of the ionic liquid on rheological behaviors of the composites was investigated by melt flow indexer and capillary rheometer. The results indicated that the melt flow index of the composites was improved with increasing content of the ionic liquid. The apparent viscosity decreased with an increase of ionic liquid content and temperature, whereas the nonNewtonian index increased. Moreover, the viscous flow activation energy of the composites decreased with the increase of the ionic liquid contents. The structural viscosity index decreased with an increase of temperature at first and then trended to increase with increasing content of the ionic liquid.

Preparation of Oil Resistance ABS/PET/PBT Blends for Battery Shells

2017, 31 (10): 44-48; DOI: 10.19491/j.issn.1001-9278.2017.10.008

Abstract ( 596 )

In this paper, a special ABS/PET/PBT blend used for battery shells was designed to improve the oil resistance of ABS resin, and meanwhile, the compatibility between PET/PBT blends and ABS resin was enhanced. The results indicated that the impact strength of ABS/PET/PBT compound was improved to 17 kJ/m2. The oil resistance test indicated that the ABS/PET/PBT blend could prevent the corrosion of battery shells by brake oil, when the blend contains 30 wt % of PET/PBT.

Preparation and Properties of Polypropylene/Modified SiO₂ Composites

2017, 31 (10): 49-54; DOI: 10.19491/j.issn.1001-9278.2017.10.009

Abstract ( 572 )

Surfacemodified SiO2 particles with γ-metharyloxyethylpropyl trimethoxy silane, a silane coupling agent (KH570), and oleic acid (OA) were insitu synthesized in a solgel process and then were used to prepare polypropylene (PP) composites to enhance their impact toughness. Effects of types of surface modifiers and contents of KH570modified SiO2 particles on tensile, flexural and impact properties, as well as heat resistance and crystallization behavior of the composites were investigated. The results indicated that the modification effect of KH570modified SiO2 particles on PP is better than that of OAmodified ones. The composites achieved the optimum comprehensive properties with the addition of 4 wt % KH570modified SiO2 particles. Their tensile strength kept a stable value in comparison with pure PP, whereas their elastic modulus, flexural strength, flexural modulus and impact strength increased by 46 %, 15 %, 23 % and 14 %, respectively.

Study on Microcellular Foam Properties of PLA/PBAT Blends

2017, 31 (10): 55-60; DOI: 10.19491/j.issn.1001-9278.2017.10.010

Abstract ( 572 )

Poly(lactic acid) (PLA)/poly(butyleneadipatecoterephthalate) (PBAT) blends were prepared by melt blending with the aid of chain extender (CE) and nucleating agent (PPZn). Dynamic rheological characterization and differential scanning calorimetry analysis indicated that the melt strength and crystallization of PLA were improved by addition of CE and PPZn, respectively. Microcellular foams based on PLA/PBAT blends were prepared under the optimal condition developed by this work, and the foams obtained a cell size of 1~4 μm and a cell density of 109~1011 cells/cm3.

Preparation and Properties of Polyurethane Foam Flame Retarded by DMMP and Al(OH)₃

2017, 31 (10): 61-65; DOI: 10.19491/j.issn.1001-9278.2017.10.011

Abstract ( 524 )

This study focuses on flame retardanting effects of dimethyl methylphosphonate (DMMP) and Al(OH)3 as two reprehensive types of organic and inorganic halogenfree flame retardants. The experimental results indicated that the flameretardant effect of DMMP is more effective than that of Al(OH)3 when being used alone. A combination of the organic and inorganic flame retardants could generate a gradient synergistic effect on flame retardancy when the mass ratio of DMMP and Al(OH)3 was set to 4:2. The resulting flameretardant polyurethane foam achieved an oxygen index of 28.5 %, and its thermal stability was much better than that of pristine polyurethane foam.

Study on Curing Kinetics of Dicyclopentadiene Cyanate/Phosphorus-containing POSS

2017, 31 (10): 66-72; DOI: 10.19491/j.issn.1001-9278.2017.10.012

Abstract ( 386 )

Dicyclopentadiene cyanate (DCPDCE) was chemically modified by a novel phosphoruscontaining polyhedral oligomeric silsesquioxane (P-POSS). Curing kinetics of DCPDCE/P-POSS composite system and pure DCPDCE were studied by a nonisothermal differential scanning calorimetry method, and chemical structures of POSS/DCPDCE composite system at different curing stages were monitored by Fouriertransform infrared spectroscopy. The results indicated that both DCPDCE/P-POSS composite and pure DCPDCE could be completely cured by a programmed temperature method. In addition, hydroxyl groups in P-POSS enhanced curing reaction of DCPDCE and thus improved curing degree of the composite system.

Application of Environmentally Friendly Cellulose Acetate for 3D Printing Materials

2017, 31 (10): 73-77; DOI: 10.19491/j.issn.1001-9278.2017.10.013

Abstract ( 598 )

In this paper, ecologically friendly cellulose acetate (ECA) as a 3D printing material was prepared by melt extrusion. By selecting plasticizer content, printing height and aliphatic peroxide (AP) content as three factors, effects of these factors on anchoring strength among the 3D printing melting lines of ECA were investigated by orthogonal experiment, and an optimal combination of these factors was adopted for processing and performance characterizations of 3D printing parts. The results indicated that the maximum anchoring strength of the parts was around 10 MPa, and an optimal combination included a plasticizer content of 35 wt %, a printing height of 0.2 mm, and an AP content of 0.1 wt ‰. This combination results in a flexural modulus of 1166 MPa and tensile strength of 26.1 MPa for the 3D printing parts.

Effect of PLA/Metal Powder Mixture on 3D Printed Products

2017, 31 (10): 78-82; DOI: 10.19491/j.issn.1001-9278.2017.10.014

Abstract ( 629 )

Effects of printing temperature and filling density on molded parts are studied by powder feed of poly(lactic acid) (PLA) in 3D printing process. For preparation of the 3D printing materials, PLA was mixed with different amounts of metal powders for the 3D printing molding process, and the mechanical performance of the molded specimens were measured. Experimental results indicated that increase of contents of the metal powder led to a decrease in tensile strength of the composite materials. In addition, thermal conductivity of the composite material was improved with an increase of the content of the metal powders, but the material expansion coefficient was reduced. This study provides a solution for the deformation problems of large parts in the 3D printing process.

Effect of Formation Methods on Impact Performance and Microstructures of Crosslinked Polyethylene

2017, 31 (10): 83-88; DOI: 10.19491/j.issn.1001-9278.2017.10.015

Abstract ( 620 )

In this work, crosslinked polyethylene samples were prepared by compression molding and rotational molding methods, and then effects of molding methods on dropweight impact strength at different temperature, crystal size, crystallinity degree and gel content at different thickness gradients of crosslinked polyethylene were investigated. The results indicated that the dropweight impact strength of the compressionmolded sample increases from 29 J/mm to 35 J/mm when test temperature was reduced from 25 ℃ to -40 ℃, but the sample kept an identical microstructure in different gradient thicknesses. For the rotational molded sample, the dropweight impact strength at -20~25 ℃ and -40~-30 ℃ is about 29 and 1 J/mm, respectively. There is a ductilebrittle transition between -20 and -30 ℃, and the microstructures also kept an identical microstructure in different gradient thicknesses except for the innermost surface layer around 0.2 mm. The inner surface layer has a lower gel content, higher crystal size and higher crystallization degree in comparison with other gradient thicknesses. Moreover, the microstructures of the innermost surface layer dominated the dropweight impact performance at low temperature.

Effects of Parameters on Dimension of an Injection Molded Part

2017, 31 (10): 89-93; DOI: 10.19491/j.issn.1001-9278.2017.10.016

Abstract ( 655 )

The research focuses on specific dimension of an injectionmolded plastic cover for miniature circuit breakers. Effects of five major parameters on the dimension were analyzed based on an orthogonal method. A comparative investigation was performed on results obtained from the simulation by a Moldflow software and exact experiments. The results indicated that there is a significant overall increasing trend in the pack and hold parameters on the dimension. A mathematical model between the pack and hold pressures and the specific dimension was established by a singlefactor experiment, which provided a valuable reference for parameters adjustment during manufacturing and also supplied a necessary condition for automatic control of dimensions of injectionmolded parts.

Comparison of Properties of Polypropylene Modified by Xylitol Nucleating Agent and Sorbitol Nucleating Agent

2017, 31 (10): 94-98; DOI: 10.19491/j.issn.1001-9278.2017.10.017

Abstract ( 518 )

1,3-2,4-Di(3,4-dimethylbenzylidene) xylitol (DMDBX) was synthesized by using xylitol and (3,4-dimethyl) benzaldehyde as raw materials. The resulting product was characterized by element analysis, Fouriertransform infrared spectroscopy, 1H-NMR, 13C-NMR and differential scanning calorimetry. The haze of PP decreased to 17.6 % with the addition of DMDBX as a nucleation agent, while the haze of pure PP reached 36.3 %. However, its impact strength and tensile strength were improved to 5.083 MPa and 36.90 MPa compared with 4.527 MPa and 34.90 MPa of pure PP, respectively. Moreover, its Vicat softening point decreased from 158.6 ℃ to 157.0 ℃, respectively. It is evident that DMDBX can improve the optical property of PP significantly, slightly enhance mechanical properties, but has little on thermal stability.

Thermal Stability of Stearic Acid Intercalated Ca/Zn Rare-earth Hydrotalcitelike in PVC

2017, 31 (10): 99-104; DOI: 10.19491/j.issn.1001-9278.2017.10.018

Abstract ( 532 )

A series of stearic acidintercalated Ca/Znrareearth hydrotalcitelike compounds were synthesized by a coprecipitation method. Structures of the resultant products were characterized by powder Xray diffraction and Fouriertransform infrared spectroscopy. Thermal stability of poly(vinyl chloride) (PVC) compounds containing different contents of the hydrotalcitelike compounds was evaluated by means of Congo red test, thermal aging oven and conductivity methods. Rheological and mechanical properties were investigated on the optimized PVC compounding system. The results indicated that this type of hydrotalcitelike compounds enhanced the thermal stability of PVC due to a synergetic effect, and therefore, the PVC compounds achieved a dramatic increase in thermal stabilization time. Moreover, the colors of PVC compounds were effectively restrained in early thermal aging stages. The optimal weight ratio of calcium hydrotalcitelike and zinc hydrotalcitelike compound was 2.25:0.75. Compared with normal Ca/Zn stearate, the hydrotalcitelike compounds can more effectively enhance the thermal stability, and rheological and mechanical properties of PVC.

Research on Factors Influencing Photo-aging of Polypropylene Materials

2017, 31 (10): 105-112; DOI: 10.19491/j.issn.1001-9278.2017.10.019

Abstract ( 411 )

Degradation behaviors of freespraying polypropylene (PP) were investigated under three typical conditions of artificial accelerated weathering, and aging effects on weatherability of freespraying PP were evaluated in terms of size and contents of aluminum powders, talcum content and sample color. The results indicated that weather resistance of the freespraying PP was reduced at first and then recovered with an increase of the size of aluminum powders, suggesting that the addition of aluminum powders improve the weather resistance of freespraying PP. This improvement shows a complex fluctuation with the content of aluminum powders. However, there is little influence found on the weatherability with a variation of talcum content. Samples with a black color exhibited an optimal weather resistance, whereas those with a blue color presented the poorest weather resistance.

Design Optimization of Multi-cavity Injection Mould Based on HsCAE and Nastran

2017, 31 (10): 113-122; DOI: 10.19491/j.issn.1001-9278.2017.10.020

Abstract ( 505 )

Integrated optimization of eyebrow pencil fixtures based on mold flow and structural analyses was performed by orthogonal experiments using HsCAE and Nastran softwares. Filling solidification process of the materials used for multicavity injection layout was simulated by HsCAE software. Mold structure and dimension parameters were determined preliminarily. The designs cover gating systems, exhaust systems, cooling systems, the structures of injectionmolded parts, and some possible defects were analyzed. Then, processing parameters upon a certain mold structure were optimized by a Taguchi orthogonal test under a fourfactor threelevel condition, and both of Nastran and Moldflow softwares were employed to deduce an optimum combination of melt temperature, mold temperature, injection time and holding pressure. These results provided a more comprehensive reference for the design and modification of moulds.

Dynamic Stability of Clamping Hydraulic Control Systems of Two Color Injection Molding Machines

2017, 31 (10): 123-131; DOI: 10.19491/j.issn.1001-9278.2017.10.021

Abstract ( 508 )

This paper established a clamping hydraulic system in two different color injection molding machines. The stabilities of different hydraulic systems were analyzed and optimized by means of experimental and simulating methods. The results indicated that, after a modification was performed up on the clamping hydraulic system of IA1600Ⅱbj new color injection molding machine, the mold positioning accuracy was improved from 1.87% to 0.67%. Moreover, the model repeatability also in-creased from 0.096% up to 0.052%, and the response time of new mold oil hydraulic insurance was shortened by 28%. The oil hydraulic safety performance of the updat-ed IA1600Ⅱbj new insurance clamping was improved significantly.