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2013, Volume 27 Issue 03 Publication date: 26 March 2013 Previous Issue Next Issue

Development of Planetary Roller Extruder

Jing Liu XUE Ping Shuxun Xu

2013, 27 (03): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2013.03.001

Abstract ( 1475 )

This paper introduced the structure, application, merits, and progress of planetary roller extruder. Nowadays, the theory study in this field mainly concentrated on the calculation of PRE' parametric and the exploration of PRE' plasticizing efficiency. The improvement of the structure included extending the length of planetary section, the combination of PRE and other extruders. PRE had not been used in processing of PVC only, but also used in the field of wood-plastic composite material, PET, silicon rubber, food and so on.

Recent Development on Flame Retardancy of Polymer/Carbon Nanotubes Composites

2013, 27 (03): 7-18 ; DOI: 10.19491/j.issn.1001-9278.2013.03.002

Abstract ( 1519 )

The research work on the flame retartant behavior of polymer/carbon nanotubes(covalently and noncovalently modified) composites was reviewed. The heat release rate, mass loss rate, time to ignition, limiting oxygen index, and UL94 of the composites were discussed. The key points which need further study and directions for future work were given in conclusion remarks.

Research Progress in Wear Resistance Modification of Ultrahigh Molecular Weight Polyethylene

2013, 27 (03): 19-24 ; DOI: 10.19491/j.issn.1001-9278.2013.03.003

Abstract ( 1475 )

The research progress in wear resistance modification of ultrahigh molecular weight polyethylene(UHMWPE) in recent years was reviewed in this paper. The modification could be divided into two categories: physical blending modification including adding inorganic fillers and/or other polymers; and chemical modification including crosslinking and plasma processing. The modification mechanism and effect of different modifying techniques were discussed. The development trend of wear resistance modification on PE-UHMW was also prospected.

Toughening and Reinforcement of Halogen-free Flame Retarded Polyamide 66/Glass Fiber Composite with Core-shell Structure Silicone Rubber

2013, 27 (03): 25-30 ; DOI: 10.19491/j.issn.1001-9278.2013.03.004

Abstract ( 1352 )

In this study, flame-retardant composites were prepared with polyamide 66 (PA66) as a matrix, silicon rubber with core-shell structure as a toughening agent, glass fibers with round or flat cross-section as a reinforcing phase. The tensile properties, notched impact strength, and flame retardancy of the composites were characterized via universal test machine, Charpy impact tester, and UL 94 test system, respectively. It showed that the impact strength of the composites experienced a continuous increase with increasing rubber content. Moreover, the composites with flat glass fiber had better impact property than that with round glass fiber, regardless the rubber content. The composites demonstrated the best comprehensive performance when the rubber content was 6 wt.%: the notched impact strength increased by 10 % based on those without rubber at a cost of decrease in tensile properties only 15 %. More importantly, the composites passed UL 94 V-0 rating.

Crystallization Behaviors and Mechanical Properties of Polypropylene Grafted by Vinyl Silane/Styrene

2013, 27 (03): 31-36 ; DOI: 10.19491/j.issn.1001-9278.2013.03.005

Abstract ( 1123 )

The crystallization behavior of and the mechanical properties of long chain branching polypropylene(LCBPP-g-VS/St) grafted by vinyl silane and styrene were investigated in this paper. The results indicated that the crystallization peak temperature and the melting peak temperature of PP-g-VS/St increased 10℃ and 2℃ respectively, and the spherulite size of PP-g-VS/St dramatically decreased based on neat LCBPP. Furthermore, the crystallites of PP-g-VS/St composed of γ and α forms when the cooling rate was 10℃/min，while the crystal of PP-g-VS/St composed of α and β form when the polymer crystallized on the injection-molding condition. The non-isothermal crystallization kinetics of PP-g-VS/St indicated that the LCB structure acted as a heterogeneous nucleating agent at the beginning of crystallization and hindered the crystal growth in the latter stage. Compared to virgin iPP, the tensile strength, flexural modulus and impact strength of PP-g-VS/St increased by 28%, 40% and 453%, respectively.

Effect of Compatibilizer on Properties of EVA/ Halogen-free Flame Retardant Copolyester Alloy

ZHOU Hao

2013, 27 (03): 37-41 ; DOI: 10.19491/j.issn.1001-9278.2013.03.006

Abstract ( 1435 )

A high melt flow index polymer 150-W was introduced into an alloy of ethylene-vinylacetate (EVA)and halogen-free flame retardant copolyester (P-PET) as a non-reactive compatibilizer during melt extrusion. The effect of 150-W on properties of EVA/ P-PET alloy was evaluated by mechanical property test, limiting oxygen index, melt rheological behavior test, and dynamic mechanical analysis (DMA). When EVA/ P-PET/ 150-W was 60/30/10, the tensile strength and elongation at break were increased 148.4 % and 283.1 %, respectively, based on neat alloy. The processing properties were also improved. Adding a small amount of 150-W (≤10 %) had no significant effect on the flame retardant performance of the blending system. SEM showed the addition of 150-W promote the formation of the interfacial layer and enhance the bonding at the interface. DMA indicated that 150-W induced the glass transition temperature of P-PET shifting towards lower temperature.

Preparation and Properties of PAPI Modified Soy Protein Isolate Composites

2013, 27 (03): 42-46 ; DOI: 10.19491/j.issn.1001-9278.2013.03.007

Abstract ( 1225 )

Soy protein isolate(SPI) and polyaryl polymethylene isocyanate(PAPI) were mixed, the mixture was introduced into polycaprolactone(PCL) forming composites via hot press-molding. The structure, morphology and properties of the composites were investigated using differential scanning calorimeter analyzer, universal electronic tensile testing machine, dynamic mechanical analyzer, Fourier transform infrared spectroscopy, and scanning electron microscopy. FTIR analysis indicated that the reaction of PAPI and SPI changed the structure of soy protein isolate resulted in tighter compacting and thus affected the properties of composites. Upon adding PAPI, the tensile strength of soy protein plastic increased from 9.65 to 32 MPa, impact strength increased from 1.36 kJ/m2 to 11.7 kJ/m2. With increasing PAPI content, the 24 h water absorption of SPI/PAPI/PCL composites decreased from 33.89 % to 9.77 %.

Accelerating Effect of Urea Derivatives on Epoxy/Dicyandiamide System

2013, 27 (03): 47-52 ; DOI: 10.19491/j.issn.1001-9278.2013.03.008

Abstract ( 1188 )

The accelerating effect of different ureas [3 - (3 - chloro-4 - methyl-phenyl) -1, 1 - dimethylurea (A); 3 - (3, 4 - dichlorophenyl) -1, 1 - dimethylurea (B); 3 - (4 - chlorophenyl) -1, 1 - dimethylurea (C)] on the epoxy/dicyandiamide system were compared. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were utilized to study the reactivity and curing reaction kinetics of three epoxy/ icyandiamide/urea systems. It was showed that the best ratio for system A was 100:6:4 (Epoxy: dicyandiamide: urea A). The system needed 40 min to be cured completely at 130 ℃. The activation energy Ea for system A, B, C was 64.66, 71.68, 71.03 kJ/mol and the reaction order for the three systems was 0.897, 0.930 and 0.928, respectively. All the shear strengths of the three adhesive systems at room temperature were higher than 20 MPa, in which the system A provided the highest value of 24.98 MPa.

Application of Polypropylene Grafted Maleic Anhydride in Intumescent Flame Retardant Polypropylene

2013, 27 (03): 53-57 ; DOI: 10.19491/j.issn.1001-9278.2013.03.009

Abstract ( 1283 )

Composites were prepared from polypropylene (PP), an intumescent flame retardant(IFR), and maleic anhydride grafted polypropylene (PP-g-MAH) via melt blending. The effect of PP-g-MAH on the flame retardancy and mechanical properties was researched by limiting oxygen index, thermal analysis, etc. The limiting oxygen index of composites reached 30 %, and the burning grading reached to UL 94 V-0, when 5 % of PP-g-MAH was introduced. With increasing contents of PP-g-MAH, the interfacial bonding between flame retardant and PP was enhanced and the tensile, bending strength of composites increased while the impact strength decreased. The carbon residue increased obviously with the addition of PP-g-MAH.

Research on Unsaturated Poly(ester-amide) Resin/Calcium Phosphate Fibers Composites and Its Properties

2013, 27 (03): 58-62 ; DOI: 10.19491/j.issn.1001-9278.2013.03.010

Abstract ( 1086 )

A unsaturated poly(ester-amide) resin was synthesized via melt polycondensation. Into the poly(ester-amide) calcium polyphosphate fiber (CPPF), a crosslinking agent and an initiator-accelerant agent was introduced, cured at room temperature, the system was transformed to a cross-linked composite. Thus obtained composite could be completely degraded. With increasing CPPF content, strength, especially impact strength was greatly improved, however, when the CPPF content exceeded 60 %, the mechanical strength of the composite showed some decrease. Soaked the composite in a simulated body fluid environment, the pH and Ca2+ concentration could maintain constant values for 7 weeks. After degradation in above body fluid for 3 months, the composites containing 30 % and 50 % CPPF still maintained 143 and 148 MPa, respectively, of bending strength.

Research on the Toughening Modification of Epoxy Resin Coating

2013, 27 (03): 63-67 ; DOI: 10.19491/j.issn.1001-9278.2013.03.011

Abstract ( 1160 )

The toughening of epoxy resin (EP) with amino silicone oil (AS) was studied. Chemical structure and thermal stability of cured EP with or without AS was compared. In a preferred process, 6 % AS was introduced into EP, stirred for 1 h at 50 °C, after cooled down to room temperature, a curing agent was added and cast to a film and cured for 24 h at room temperature. Thus obtained film gave rise to the optimal comprehensive properties: impact strength was 41 kg.cm, the adhesion strength was 6.800 MPa，he initial decomposition temperature of the EP skeleton in the air was 332.1 °C. During the curing process, AS was bonded with EP in the form of the C-N-C bond because the primary amine of AS reacted with the epoxy groups of EP to generate a secondary amine.

Thermal behavior of Polyvinyl Alcohol/Polypropylene Grafted Maleic Anhydride Blends

2013, 27 (03): 68-72 ; DOI: 10.19491/j.issn.1001-9278.2013.03.012

Abstract ( 1393 )

Polyvinyl alcohol(PVA)/polypropylene grafted maleic anhydride (PP-g-MAH) blend films were prepared by melting process. The differential scanning calorimetry (DSC) was adopted to develop the crystallization and melting behavior of the blends. Results showed that with the increasing of PP-g-MAH content （less than 50 %）, the crystallization and melting temperature of PVA phase increased, the crystallization rate rose,but crystallinity decreased. While with the increasing of PVA content（more than 30 %）, the crystallization and melting temperature of PP-g-MAH phase decreased, crystallinity decreased, but the crystallization rate increased. The nonisothermal crystallization kinetics of PVA phase in the blend was studied according to Ozawa′s theory. Results showed that the primary crystallization of PVA phase was in a temperature range of 191~197 ℃，secondary crystallization was in a temperature range of 173~189 ℃.

Study on Properties Difference of Homo-polypropylene and Co-polypropylene in Modification

2013, 27 (03): 73-76 ; DOI: 10.19491/j.issn.1001-9278.2013.03.013

Abstract ( 1358 )

In this paper, various behavior of homo-polypropylene and co-polypropylene were studied, including thermo-oxidant aging, stress white, post shrinkage after different treatment conditions, and dyeing. After thermo-oxidant aging, the impact strength of homo-polypropylene decreased remarkably, however, that of co-polypropylene increased up to 200 % at first, and then decreased slowly. The resistance to stress whitening of homo-polypropylene was better than that of co-polypropylene; After heat treatment and boiled in water, the post shrinkage of polypropylene with high crystallinity was lower than that of polypropylene with low crystallinity. When the blackness of polypropylene was larger, the hue was more bluish.

Research on Application of Novel Liquid Na/Zn Thermal Sstabilizer in Poly(vinyl chloride)

Liu Peng JIANG Ping-Ping

2013, 27 (03): 77-81 ; DOI: 10.19491/j.issn.1001-9278.2013.03.014

Abstract ( 1197 )

A highly efficient and low cost novel liquid Na/Zn thermal stabilizer was developed in this work. Its application in poly(vinyl chloride)(PVC) was investigated by Heat aging test and conductivity test. In comparison with blank PVC, the thermal stability time of PVC films was extended to 50 min though adding Na/Zn thermal stabilizer at a Na/Zn mass ratio of 1/1. The dynamic thermogravimetric analysis also confirmed that the Na/Zn stabilizer presented an obvious improvement of stability on thermal degradation. Besides, the Na/Zn stabilizer provided soft PVC with excellent mechanical properties.

Analysis on Stress of Injection-molded Parts with Weld Lines from Process Parameters

2013, 27 (03): 82-86 ; DOI: 10.19491/j.issn.1001-9278.2013.03.015

Abstract ( 1193 )

The paper analyzed mechanical properties of injection molded parts by introducing results of Moldflow into ANSYS software based on finite element method. The results showed that the maximum von Mises stress decreased with increasing mold temperature, packing time, and packing pressure, and melt temperature, provided the external loads was the same. Meanwhile, the von Mises stress in the parts with the weld lines was significantly higher those without weld lines in the same conditions. The presence of weld lines also affected the relationship between the process parameters and the maximum von Mises stress of injection molded parts.

Improvement of Air Traps Defects of Power Buttons Based on Flow Simulation of Moldflow

Hong Jian-Ming

2013, 27 (03): 87-91 ; DOI: 10.19491/j.issn.1001-9278.2013.03.016

Abstract ( 1253 )

Taking the design of TV power button as an example, the formation of air traps defect was analyzed with the help of Moldflow software in simulating the region of air traps generated in the flow process. The runner system of the injection mould was improved so as to eliminate the air traps defect in the surface of the button. As a result, the molding was improved and the mass production of the injection was enhanced.

Preparation and Application of A New Reactive-type Flame Retardant Containing P-N Elements

2013, 27 (03): 92-95 ; DOI: 10.19491/j.issn.1001-9278.2013.03.017

Abstract ( 1145 )

A new type of phosphorus and nitrogen containing flame retardant ---β-（N-phenyl carboxamide)ethyl methyl phosphinic acid (CEMP) was synthesized by the reaction of 2-methy-2,5-dioxo-1,2-oxaphospholane(OP) with aniline. The structure of CEMP was characterized with FTIR and 1H-NMP. The flame retarding performance and glass transition temperature (Tg) of CEMP filled epoxy resin was investigated. The composite containing 20 % CEMP reached the UL 94 V-0 rating with limiting oxygen index value of 29.4 %. The flexural strength of the composite was increased by adding the CEMP, while the flexural modulus and Tg of system were reduced with increasing CEMP.

Study on Thermal Conductivity of Polypropylene Composites Filled with Hybrid Particles Exfoliated Graphite

Hongwu Wu Xiaoqiang Xu Han Liu

2013, 27 (03): 96-99 ; DOI: 10.19491/j.issn.1001-9278.2013.03.018

Abstract ( 1285 )

Polypropylene (PP) composites filled with exfoliated graphite (EG) were prepared by roll mixing and hot press method. The effects of filler content, particle sizes, and hybrid filling on the thermal conductivity of the composites were investigated. The thermal conductivity of composites was improved with increasing EG filler contents. When the filling rate was over 30%, the thermal conductivity increased faster, achieving percolation threshold. When the filling rate was 50%, the thermal conductivity of composite material reached 1.791 W/(m·K). The large size filler particles were more beneficial to improve the thermal conductivity of composites than small size particles. If the mixture of hybrid particles was at a preferable mass ratio, the composites exhibited the highest thermal conductivity.

Investigation on Density Balance Method Testing the Density of Polyethylene Resin

2013, 27 (03): 100-103 ; DOI: 10.19491/j.issn.1001-9278.2013.03.020

Abstract ( 1513 )

The repeatability and accuracy of density balance test of polyethylene resin density was investigated and compared with density gradient method. Both methods met the requirements in accuracy and precision of density determination. The difference between the two methods were ≤0.0005 g/cm3 for high density polyethylene and ≤0.0003 g/cm3 for low density polyethylene. As a result, the two methods could be used alternatively. The factors influencing the density balance method were also discussed.

Injection Mold Design for L/R Cover of Level Instrument

张维合 allenzhang

2013, 27 (03): 104-109 ; DOI: 10.19491/j.issn.1001-9278.2013.03.021

Abstract ( 1202 )

According to the structural characteristics of level instrument's L/R cover, an injection mould with side core-pulling and hot runner was designed. analysis and study were made on the mold parting surface, gating system, forming parts, exhaust system, side parting, core pulling mechanism. Through the use of needle valve type hot nozzle and a variety of side core-pulling mechanism, such as inclined core-pulling, composite core pulling, time-delay and forced core pulling, the moud fully met the requirements of above level instrument.

Mold Design and Injection Moulding of Small Wind Turbine Blades Manufactured by Long Glass Fiber Reinforced Polypropylene Composites

2013, 27 (03): 110-116 ; DOI: 10.19491/j.issn.1001-9278.2013.03.022

Abstract ( 1328 )

This paper summarized the comparison of performance between long fiber reinforced polypropylene (LFT-PP) and short fiber reinforced polyamide (SFT-PA6) according to the test result. It showed that at room temperature (23 ℃), the Izod impact strength of LFTPP was 3.44 % enhanced than SFT-PA6; water absorption of SFT-PA6 was twice of LFT-PP; mold shrinkage of LFT-PP was 10 % lower than SFT-PA6. At low temperature (-30 ℃), impact strength of LFT-PP was 16 %~24 % enhanced.The max static load (test value) of fatigue crack of LFT-PP blades manufactured with the optimal injection processing parameters could be up to 150 kg.