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2011, Volume 25 Issue 08 Publication date: 26 August 2011 Previous Issue Next Issue

Research Progress in Carbon Nanotubes Reinforced Polymer Nanocomposites

Guozhi Xu

2011, 25 (08): 1-9 ; DOI: 10.19491/j.issn.1001-9278.2011.08.001

Abstract ( 1928 )

In this article, the recent progress in mechanical properties of carbon nanotubes(CNT) reinforced polymer composites were reviewed, with particular attention to polyurethane and polyimide based composites. Various functionalization methods in the modification of CNT were discussed, and the effectiveness of different processing techniques were compared. Finally, a future outlook for the development of CNT reinforced polymer composites were given

Progress in the Studies on PET/PTT Blending System

WANG Liyan

2011, 25 (08): 10-13 ; DOI: 10.19491/j.issn.1001-9278.2011.08.002

Abstract ( 1426 )

The development of PET/PTT blending system at home and abroad is reviewed. The compatibility, structures and morphology, behavior of melting crystallization, crystallization kinetics, and crystalline melting behavior of blends are emphasized, especially the prospect of the development of the blends is predicted.

Development and Models for Numerical Simulation of Flow-induced Crystallization

2011, 25 (08): 14-18 ; DOI: 10.19491/j.issn.1001-9278.2011.08.003

Abstract ( 1647 )

The research works on flow-induced polymer crystallization were reviewed. A number of mathematical models for the effects of flow on crystallization dynamic, morphology, and rheology were introduced. The simulated performance by various models were compared.

Macro Properties of Polyurethane Elastomers Based on Different Polyols

2011, 25 (08): 19-23 ; DOI: 10.19491/j.issn.1001-9278.2011.08.005

Abstract ( 1567 )

Four kinds of polyurethane (PU) elastomers were synthesized from polytetrahydrofuran polyols (PTMG), polycaprolactone polyol (PCL), and 4, 4′- diphenylmethane diisocyanate with 1,4 - butanediol as a chain extender and trihydroxy polyether polyols as a crosslinker. The effects of the alteration of the PTMG and PCL molecular weight on the mechanical, thermal, and rheological properties of the PU elastomers were studied by means of unversal testing machine, dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), and ARES rheometer. It was revealed that PCL-based PU elastomers had higher tensile strength, hardness, plateau modulus, soft segment glass transition temperature, and the apparent viscosity of reaction system than PTMG-based PU elastomers, while PTMG- based PU elastomers showed higher hysteresis loss. It was also found that the above properties denpent on the molecular weight of polyols in PU elastomers synthesized from the same kind of polyols.

Influence of Hybrid Nucleating Agents on the Crystallization Rate and Intrinsic Viscosity of PET

LIU Bo

2011, 25 (08): 24-27 ; DOI: 10.19491/j.issn.1001-9278.2011.08.006

Abstract ( 1726 )

The influence of different nucleating agents on the crystallization rate and intrinsic viscosity of poly (ethylene terephthalate) was studied using differential scanning calorimetry (DSC) and Ubbelohde viscometer, respectively. It showed that hybrid nucleating agents（half-crystallization time was 32.3~45.3 s） had advantages over single nucleating agents(half-crystallization time was 42.9~57.9 s) in promoting crystallization, and a few hybrid nucleating agents performed well in reducing the decrease of intrinsic viscosity.

Aminofunctional Modification of Graphene Oxide Sheets and Its Composite with Epoxy Resin

2011, 25 (08): 28-33 ; DOI: 10.19491/j.issn.1001-9278.2011.08.007

Abstract ( 1626 )

Research on aminofunctional modification of graphene oxide sheets and its epoxy composite was carried out. Using flake graphite as a raw material, graphite oxide was prepared by Hummers method, and obtained graphene oxide sheets by ultrasonic process. Triethylenetetramine and ethylenediamine was introduced to the surface of graphene oxide sheets by shrink mixture method, and then epoxy/aminofunctional modified graphene oxide sheets composite was prepared. The characterization with XRD, TGA, FTIR, Raman, SEM showed the partial reduction of graphene oxide sheets after the aminofunctional modification. Besides, the introduction of modified graphene oxide sheets into epoxy composite increased the elastic modulus and tensile strength of composite by 100 % and 60 %, respectively.

Study on Direct Esterification of Terephthalic Acid and 1,4-Cyclohexanedimethanol

2011, 25 (08): 34-37 ; DOI: 10.19491/j.issn.1001-9278.2011.08.008

Abstract ( 1679 )

In this research the effects of the molar ratio of TPA/CHDM and the mass ratio of catalyst on the esterification extent and reaction time were studied. Based on the systematic experiments, the esterification kinetics equation and activation energy were obtained. For comparison, the esterification of TPA and EG were also studied at the same conditions. It showed that the best recipes were TPA/CHDM=1:1.6, and the content of catalyst was 3.5/104. It also found that the activation energy, reaction time of the reaction between TPA and CHDM was lower than those of TPA and EG, and the effect of temperature on the reaction between TPA and CHDM was also moderate.

Preparation and Properties of Dialkyl Phosphinates Aluminum Flame Retarded Epoxy Resin Composites

2011, 25 (08): 38-41 ; DOI: 10.19491/j.issn.1001-9278.2011.08.009

Abstract ( 1447 )

In this paper, flame retarded epoxy resin (EP) composites containing diethyl phosphinate aluminum (OP930) was prepared and the mechanical properties, morphologies of fracture surfaces, thermal stability, and flame retardancy of EP/OP930 composites with different contents of OP930 have been studied. Results showed that EP/OP930 composite with only 15 wt % OP 930 can achieve the optimal flame retardancy (limiting oxygen index was 28.8 % and reach UL 94 V-0 rating). The composites exhibited satisfying thermal properties as well as good compatibility with the matrix. Compared to neat resin, the mechanical properties of composites were also on a very good level.

Study on P(AA/AM)-g-AT Water Absorbent Polymer

2011, 25 (08): 42-47 ; DOI: 10.19491/j.issn.1001-9278.2011.08.010

Abstract ( 1348 )

Water absorbing polymer-P(AA/AM) brushes on attapulgite were prepared by aqueous solution polymerization using a redox system [potassium persulfate(K2S2O8), potassium persulfate(Na2SO3)] and zaodiisobutyronitrile(AIBN) as initiators, N，N'-methylene-bis-acrylamide as a crosslinker. The grafting of poly(AA/AM) on the attapulgite was confirmed by FTIR. In this work , the water-absorbing property of the resin reached 125 g/g in distilled water, and 23 g/g in salt-water(0.9 wt %). Scanning electron microscopy (SEM) observation on the resin showed that a uniform dispersion of AT was obtained. The thermal stability of Poly(AA/AM)-g-AT was better than that of pure resin. The existence of AT and the use of AIBN reduced the of monomer residue.

Preparation of PTFE/ZrO₂ Composite Microporous Membrane by PTFE Resin Emulsion and Investigation on Performance

2011, 25 (08): 48-51 ; DOI: 10.19491/j.issn.1001-9278.2011.08.012

Abstract ( 1294 )

This paper used polytetrafluoroethylene (PTFE) emulsion as a matrix phase, micro-nanozirconium dioxide（ZrO2）powder as a reinforcer to prepare. PTFE/ZrO2 composite membranes via mechanical stretch, and the tensile strength of the membranes was tested. Single-factor method to analyze the effect of ZrO2 powder content, draw ratio, heat-treatment temperature, and heat-treatment time on the tensile strength of the composite membrane. PTFE/ZrO2 membranes were post-treated by low-temperature plasma to study the effect of the plasma treatment time and ZrO2 power on the hydrophility of the membranes. It showed that the tensile strength of PTFE/ZrO2 composite membranes increased with increasing ZrO2 content, but decreased with increasing of draw ratio. When heat-treatment temperature was 310 ℃, heat-treatment time was 10 min, the tensile strength gave rise to a maximum. The best post-treated time of low-temperature plasma was 30 s.

Preparation of Polypropylene Anti-corrosion Jacket Material

2011, 25 (08): 52-56 ; DOI: 10.19491/j.issn.1001-9278.2011.08.013

Abstract ( 1315 )

Polypropylene anticorrosive jacket layer material was prepared by means of cross-linking-blending process in a twin-screw extruder. The effects of kneading blocks in extruder, screw speed, content of crosslink agent on the mechanical property of the product were evaluated. When the number of kneading blocks was 12, screw speed was 130 r/min, and loading of crosslink agent was 0.10 % optimal mechanical properties were achieved. In addition, Vicat softening point reached 146 ℃, notch impact strength reached 91.5 kJ/m2 at room temperature, and 15.2 kJ/m2 at 0 ℃. Melt flow rate of the products was in the range of 0.9~1.1g/10 min.

Toughening Modification of PP Outer Cap Composite Used in Combinational Closures of Plastic Infusion Containers

2011, 25 (08): 57-61 ; DOI: 10.19491/j.issn.1001-9278.2011.08.014

Abstract ( 1314 )

Polypropylene (PP) composite for outer-cap ring of plastic infusion containers was prepared via melt extrusion blending of polyethylene (PE), elastomer, PP, and other additives. The ratio of PP, PE, and elastomer was optimized by orthogonal factorial design. The mechanical properties of the composite and the open force of outer-cap ring were studied. It showed that the most important factor affecting the mechanical properties and the open force of outer-cap ring was the content of elastomer. The impact strength of the composite increased first and then decreased, the tensile strength and open force of outer cap ring decreased with increasing elastomer. SEM observations revealed that elastomer was finelydistributed in composite when the content of elastomer was less than 25 mass%. It could be concluded that the optimized recipe was: PP 65 mass%, PE 20 mass%, elastomer 25 mass%, and antioxidant and other additives 5%.

Test Research on Water Resistant Performance of Hot Melt Adhesive in Plastic Pipe Reinforced by Cross-Winding Steel Wires

2011, 25 (08): 62-65 ; DOI: 10.19491/j.issn.1001-9278.2011.08.016

Abstract ( 1350 )

Combined with sorption test, tensile test and peeling test, the properties of water resistance of EP252 hot melt adhesive (HMA) were researched. Research indicated that plastic-coated steel wires were not corroded except the end of them at 25℃, so steel wires were well protected by HMA. Compared with HMA at 25℃, the yield stress and Young's modulus of treated HMA at 60℃ significantly decreased by 12% and 7%, respectively. Cohesive failure of HMA is the main failure mode in the peeling test of steel-HMA bonding system after water absorption under different temperature, because there still remained a very thin HMA layer on the surface of steel wires after peeling test, which demonstrated steel-HMA bonding system has a very high cohesive strength.

Influence of Modified Conditions on Impact Property of Polyurethane Rigid Foam

ZHOU Xiao-qian Guo-kuo ZHENG Juan DU Yun-ting LU Xin Huang

2011, 25 (08): 66-68 ; DOI: 10.19491/j.issn.1001-9278.2011.08.017

Abstract ( 1221 )

Polyurethane rigid foam was prepared by introducing nano-SiO2 and basalt fiber into polyurethane matrix. The effects of isocyanate index, contents of water, nano-SiO2 and basalt fiber, length of basalt fiber on the impact property were studied. When the isocyanate index was 1.05, of nano-SiO2 was 3.0 %, and of 5.0 mm basalt fiber was 3.0 %, the best value of impact strength was obtained.

Rheological and Foaming Behaviors of Plasticized Poly（vinyl alcohol）

2011, 25 (08): 69-74 ; DOI: 10.19491/j.issn.1001-9278.2011.08.018

Abstract ( 1373 )

The rheological properties of plasticized polyvinyl alcohol (PVA) were investigated with capillary rheometer. The effect of cooling rate on crystallization propertities of PVA was studied with differential scanning calorimetry analyzer (DSC). The PVA foams were fabricated by filling chemical foaming agent through melt extrusion, and the cell morphology and the density of the foams were investigated with scanning electron microscope (SEM) and density tester. PVA was sensitive to the shearing effect. At low shear rate, the melt viscosity of PVA was high, leading to the homogeneous distribution of the cells and a low density; at high shear rate, the melt viscosity of PVA was low and the gas was easy to escape, leading to the break or combination of the cells. At low cooling rate, the melt viscosity was low, leading to the combination or collapse of the cells; at appropriate cooling rate, the distribution of cell diameter was homogeneous; with further increase of cooling rate, the cell combined due to the excessive gas pressure, resulting in the high density of the foams.

Research on Properties and Applications of XPS Boards

2011, 25 (08): 75-80 ; DOI: 10.19491/j.issn.1001-9278.2011.08.019

Abstract ( 1921 )

Main properties of extruded polystyrene foam(XPS) were reviewed including thermal conductivity,compression strengh,long-term thermal resistance, moisture-proofing,etc.XPS boards could be applied in thermal insulation for building and cold store, as well as geofoam for road, railway and channel. The necessity of imprving flame retardancy of XPS boards was discussed. Developing trend of XPS foam sector was put forward in the background of phase-out of HCFCs.

Preparation of Encapsulated Ammonium Polyphosphate and Its Applications in SEBS

Feng Shen

2011, 25 (08): 81-85 ; DOI: 10.19491/j.issn.1001-9278.2011.08.020

Abstract ( 1458 )

Encapsulated ammonium polyphosphate coated with melamine-formaldehyde resin (MFAPP) was prepared by in situ polymerization, and characterized by SEM and TGA. Water resisting properties and flame retardant properties of MFAPP and Dipentaerythritol (DPER) in SEBS were also studied. SEM results confirmed that APP could be finely encapsulated. The weight loss of MFAPP between 50 ℃ and 250 ℃ was only 1.629 %, which indicated well thermal stabilities. Samples of SEBS/ MFAPP/DPER composites did not turn white in hygrothermal condition for 4 days, which exhibited much better water resisting properties than samples of SEBS/APP/DPER composites. When using MFAPP and DPER as intumescent flame retardant (IFR), 30 % fill amount was enough to reach FV-0 level without decreasing mechanical properties.

Mechanisms of Action and Development of Antioxidants

2011, 25 (08): 86-90 ; DOI: 10.19491/j.issn.1001-9278.2011.08.021

Abstract ( 1895 )

The antioxidation mechanisms, development trend, and relationships between structure and antioxidation property of several main kinds of antioxidants were reviewed. The antioxidation mechanisms including chain termination, peroxide decomposition and metal ion deactivation. The chain terminator including hydrogen donor, free radical scavengers, and electron donor. The work on multi-functional, reactive, and natural antioxidants constituted the developing trend.

Influence of Sample Preparation Methods on Tensile Test Results of Plastic Film

HUANG Wei

2011, 25 (08): 91-93 ; DOI: 10.19491/j.issn.1001-9278.2011.08.022

Abstract ( 1782 )

Through the microscopic observation, preparation principle analysis, and comparison between samples prepared by punching or cutting methods, it was concluded that the cutting methods was not suitable for tensile test of plastic film.

Effect of Backflow on the Distributive Mixing Performance of Incompatible Polymer Blends

2011, 25 (08): 94-98 ; DOI: 10.19491/j.issn.1001-9278.2011.08.023

Abstract ( 1415 )

The flow fields of six different screw configurations at melt conveying section in an intermeshing co-rotating twin-screw extruder were simulated and in the meantime the corresponding experiment was carried out. The results showed that increasing the backflow coefficient can enhance the distributive mixing effect of polymer blend, and the greater the backflow coefficient is, the better the distributive mixing performance will be.

Two-color Injection Molding of a TV Front Cabinet on an General Machine

2011, 25 (08): 99-102 ; DOI: 10.19491/j.issn.1001-9278.2011.08.024

Abstract ( 1381 )

A technical scheme of double-color injection molding was presented, aimed to produce TV front cabinets on a regular injector. An auxiliary screw was added on the regular injector and the injection mold was improved. A movable core was introduced into the structure double-color mold. With a special ejector plate, dozens of bosses with varying heights inside a double-color cabinet could be injected smoothly. Although the skin layer of the cabinet was molded with transparent material, no optical defect was detectable with naked eyes. The scheme has been adopted in mass production and has gained good effects.