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2015, Volume 29 Issue 07 Publication date: 26 July 2015 Previous Issue Next Issue

Research Progress of Synergistic Agents in Intumescent Flame Retardants

2015, 29 (07): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2015.07.001

Abstract ( 574 )

In this paper, synergistic agents were classified into different types, based on their flame retardant mechanism, such as cooperative charing, catalyzing charing, altering carbon layer structure, absorption of free radicals, smoke suppression, suppression of harmful gas release, nanometer synergistic agent, and so on. Research progress had been reviewed for new type of synergistic agent and new mechanisms.

Research Progress of Conductive Polyaniline Composites

2015, 29 (07): 7-12 ; DOI: 10.19491/j.issn.1001-9278.2015.07.002

Abstract ( 520 )

In this paper, research progress was reviewed for conductive PANI composites, including PANI/metal oxide, PANI/salt, PANI/carbon, PANI/polymer, etc. On this basis, the developmenttrend of conductive PANI composites was prospected.

Advanced Progress of High Thermally Conductive Filled Epoxy Composites

2015, 29 (07): 13-15 ; DOI: 10.19491/j.issn.1001-9278.2015.07.003

Abstract ( 754 )

The latest approaches to filled epoxy composites with high thermal conductivity were reviewed. The mechanism of thermal conduction, new type of thermal conductive fillers and the construction of the effective heat conducting network, as well as the design of interface layer between fillers and epoxy matrix were analyzed. Besides, the key techniques and hot research topics of high thermally conductive epoxy composites were summarized.

Melt Flow Behavior of Polysilsesquioxane Microspheres Chain-extended Poly(lactic acid)

2015, 29 (07): 20-27 ; DOI: 10.19491/j.issn.1001-9278.2015.07.004

Abstract ( 522 )

Polysilsesquioxane microspheres (PSQs) with six different functional groups, methyl, thiopropyl, epoxy, vinyl, aminopropyl, and methacryloxypropyl, was synthesized, which was introduced into polylactic acid (PLA) separately through melt processing, with the concentration of PSQs kept at 2 %. It was found that the PSQs could effectively improve the melt flow behavior of PLA. Poly(epoxypropoxy)silsesquioxane (PESQ) possessed the highest reactivity with PLA in the six PSQs. It rendered PLA matrix the smallest melt flow rate, 6.0 g/10min, which contrasted to 14.1 g/10 min of neat PLA. The molecular weight of PLA could be extended to 1.7 folds larger. Thermal decomposition temperature of 5 % weightlost increased by 8 ℃, and thus could inhibit PLA degradation in processing for 35 min. In addition, PESQ could also increase the toughness of PLA matrix, with impact strength increased by one fold.

Enhancement and Damping Property of Polyurethane/Spandex Composites Under Small Deformation

2015, 29 (07): 28-32 ; DOI: 10.19491/j.issn.1001-9278.2015.07.005

Abstract ( 538 )

In this paper, spandex fabric 4,4′-methylene bis (MOCA) and polypropylene glycol (PPG) prepolymer or polytetrahydrofuran ether glycol (PTMG) prepolymer was casting molded forming polyurethane/spandex composites. The effect of spandex fabric on the tensile strength and damping properties of polyurethane matrix under small deformation was studied. It was shown that spandex fabric could strengthen the tensile strength and damping properties of polyurethane matrix under small deformation. After compounding, the modulus of elasticity of PPG and PTMG composites was increased 16.33 % and 11.39 %，and the tensile stress at 100 % deformation of PPG and PTMG composite was increased 55.81 % and 46.51 %. Moreover, the lag rate after 1 time stretchingretraction cycle of these two composites was 55.10 % and 62.83 %, compared with the matrix, the value was enhanced 26.12 % and 14.03 %, respectively.

Molten Chain Extension Technology, Kinetics and Structure Characterization of Poly(lactic acid) Based on Isocyanate Derivatives

2015, 29 (07): 33-39 ; DOI: 10.19491/j.issn.1001-9278.2015.07.006

Abstract ( 652 )

Poly（lactic acid）(PLA) was prepared by ringopening polymerization of D, L-lactide with zinc oxide (ZnO) pillared organic saponite under microwave assistance. The molten chain extension reaction of PLA was investigated with hexamethylene diisocyanate (HDI) and 4, 4-diphenylmethane diisocyanate (MDI) as chain extenders. The effect of reaction time and addition amount of chain extender on the molecular weight of PLA was also studied. The optimum parameters of the chain extending reaction were as follows: the ratio between nNCO to nOH was 2.5：1, the reaction temperature was 180 ℃, the chain extension time of MDI was 45 min, and the chain extension time of HDI was 30 min. Kinetics experiments indicated that the chain extender showed the apparent rate constants of MDI and HDI were 6.081×10^3 g/(mol·min)，6.98×10^3 g/(mol·min), respectively.

Polymerization of Heatresistant ABS Resins Synthesized in a Plug Flow Tube Continuous Reactor

2015, 29 (07): 40-45 ; DOI: 10.19491/j.issn.1001-9278.2015.07.007

Abstract ( 619 )

A heatresistant ABS resin was prepared by a selfdeveloped, fourkettle plug flow reactor tube through bulk polymerization, and Nphenyl maleic (NPMI) was used as the modifier. It was found that the resin containing 3 % NPMI had better tensile strength and higher thermal deformation temperature, and the impact strength was relatively low. In order to improve the thermal deformation temperature while keeping certain impact strength, some contrast experiments were made to research the influence of NPMI and rubber addition on the structure and properties of ABS resin. When the same amount of NPMI was added to the 1st and 3rd reactors at the same time, the tensile strength of ABS resin was 54.3 MPa, and the impact strength was 162.3 J/m, and the thermal deformation temperature was 84.6 ℃, which were much better than those of the product obtained when NPMI was added in the 1st or 3rd reactor separately.

Crystallization and Melting Behavior of sPS/PBA-aPS Blends

2015, 29 (07): 46-52 ; DOI: 10.19491/j.issn.1001-9278.2015.07.008

Abstract ( 582 )

In this paper, syndiotatic polystyrene/polybutylacrylateatactic polystyrene (sPS/PBA-aPS) coreshell latex particles blends were prepared by means of melt blending. The effect of PBA-aPS on the crystallization behavior and crystalline morphology of sPS was investigated using scanning calorimetry (DSC) and polarized optical microscopy (PLM). In addition, DSC and XRD were used to study the effect of cooling rate and isothermal crystallization temperature on melting behavior of sPS/PBA-aPS blends. The experimental results indicated that the addition of PBA-aPS coreshell latex particles hindered the crystallization of sPS. It was obvious that the meltingrecrystallizationremelting processes existed during the melting. Equilibrium melting point of sPS was 293.2 ℃. With increasing amount of PBA-aPS, the equilibrium melting points of sPS decreased and βcrystal became imperfect, the impact strength was obviously improved. When the mass ratio of sPS/PBA-aPS was 75:25, the impact strength was improved by 117 % based on neat sPS.

Study on Melting and Crystallization Behavior of PTT Copolyesters Modified by MPO

2015, 29 (07): 53-58 ; DOI: 10.19491/j.issn.1001-9278.2015.07.009

Abstract ( 597 )

PTT was copolymerizing modified with 2-methy-1,3-propanediol (MPO) through melt esterification, and the melt crystallization behavior was studied by differential scanning calorimetry (DSC). It was found that when the MPO content was 20 %, the melting point of PTT decreased from 226.64 to 201.78 ℃; when the MPO contents was 10 %, the crystallization temperature was decreased from 159.0 to 137.5 ℃, and the half crystallization time (t1/2) increased. With increasing cooling rate, the crystallization temperature of each sample moved to lower temperature and the exothermic peak changed from narrow to wide and t1/2 decreased. In addition, the nonisothermal crystallization behavior of the modified PTT was studied with Jeziorny method, and it was found that the crystallization rate constant (Zc) of the PTT became lower than neat PTT, which indicated that the crystallization ability of PTT after adding MPO became poorer.

In Situ Polymerization and Conductive Properties of Polyaniline/Nanometer Graphite Nanosheets Composites

2015, 29 (07): 59-62 ; DOI: 10.19491/j.issn.1001-9278.2015.07.010

Abstract ( 579 )

Polyaniline (PANI) was a typical conducting polymer while graphite nanosheets (NanoG) are materials of high specific surface. Composites of PANI with NanoG were prepared via an in situ polymerization of aniline (ANI) in the presence of NanoG. Results showed that NanoG had a thickness ranging of 30~90 nm and diameter ranging of 1~20 μm, and diameter to thickness ratio was 300~500. The composites exhibited a high electrical conductivity of 5.16 S/cm when the NanoG content was 2.30 vol %, and the percolation threshold of the composites was as low as 2.30 vol %. This great improvement of conductivity could be attributed to the high aspect ratio of NanoG.

Study on Aging Mechanism of Polypropylene

2015, 29 (07): 63-66 ; DOI: 10.19491/j.issn.1001-9278.2015.07.011

Abstract ( 708 )

The thermal oxygen aging mechanism of polypropylene（PP）was studied using the methods of melt flow rate and infrared spectroscopy. It was found that the thermal oxidative aging degradation rate of PP obeys an exponential function, and the fitting degree was high. This suggested that before thermal oxygen aging degradation, PP needs some additional energy. When the energy was accumulated to a certain degree, the “induction period” appeared and PP began to degrade and the rate of degradation would be accelerated.

Simulation of Film Posting of Instrument Panels of Cars and Optimization of Process Parameters

2015, 29 (07): 67-71 ; DOI: 10.19491/j.issn.1001-9278.2015.07.012

Abstract ( 418 )

The meter shell was decorated with a polypropylene film. And the film thickness and its deforming distribution in x, y direction were obtained through finite element simulation, and the influencing factors of film forming were analyzed. Aiming at the goal of the minimum standard deviation of average film thickness and its deforming distribution in x, y direction, the process parameters were optimized and analyzed using design of experiment method. Optimization gave the maximum film thickness of 0.2013 mm, and the minimum thickness was 0.1883 mm. The maximum deformation of the film in x and y direction were 3.125 and 3.250 mm, respectively.

Research Progress in Nucleating Agents for Plastics Microcellular Foams

2015, 29 (07): 72-79 ; DOI: 10.19491/j.issn.1001-9278.2015.07.013

Abstract ( 536 )

In order to enhance the quality of foaming products, in this paper, the influence of nucleating agent on the foam morphology were introduced. To elucidate the mechanism involving these nucleating agents, relative analysis and comparison were made and the effect of nucleating agents on cellular morphology was explored. The criteria for choosing a proper nucleating agent were particularly emphasized.

Multiobjective Optimization of Injection Molding Process Based on AHP and GRA

2015, 29 (07): 80-85 ; DOI: 10.19491/j.issn.1001-9278.2015.07.014

Abstract ( 545 )

A multiobjective optimization method was proposed through the combination of analytic hierarchy process (AHP) and grey relation analysis (GRA) applying to multiple quality indexes, such as warp, volume shrinkage ratio, and sink index. The normalized weighting value of three quality index was obtained by means of analytic hierarchy process. Injection molding process was simulated by using Moldflow and orthogonal experiment design，and the predicted value of each quality index was obtained. The grey relational coefficient of experiment sequence and each quality index was calculated, and then the grey relational grade was obtained by means of a comprehensive evaluation model which combined the analytic hierarchy process (AHP) with gray relational analysis (GRA) methods, the analysis of means was executed afterwards. Holding pressure of second stage was best significantly effective on the comprehensive quality index, followed by injection time. The optimal process parameters combination of the injection molding was injection time(1.2 s), holding pressure of first stage(120 MPa), holding pressure of second stage(120 MPa), holding pressure of third stage(80 MPa). The feasibility of the proposed method was demonstrated by the project of mobile phone shell.

Properties of Thermally Conductive Polymers Reinforced with Graphite Mixed in a Co-rotating Non-symmetric Twin-screw

2015, 29 (07): 86-91 ; DOI: 10.19491/j.issn.1001-9278.2015.07.015

Abstract ( 575 )

Using flake graphite with particle size 15 μm and alumina with particle size 3 μm as thermally conductive filler, and novel corotating nonsymmetric twinscrew extruder as processing machine, thermally conductive polymers of PP/Al2O3 and PP/Al2O3/graphite were prepared at the filling content of 10 % graphite and 10 %~50 % alumina, respectively. It was found that the addition of a small amount of graphite may increase the tensile, bending, and impact strengths of PP/Al2O3 composites. Melt flow rate of PP/Al2O3/graphite was smaller than PP/Al2O3, and HDT of PP/Al2O3/graphite increased about 15 % based on PP/Al2O3.

Synergism Between Phosphorous Flame Retardant and Zinc Borate on the Flame Retardancy of Polyamide11

2015, 29 (07): 92-95 ; DOI: 10.19491/j.issn.1001-9278.2015.07.016

Abstract ( 635 )

Diethyl aluminum phosphate (DEAP), melamine phosphate (MP) and zinc borate (ZB) was used in polyamide11 (PA11), the limiting oxygen index, vertical burning UL 94 grade, and cone thermos value were characterized. The thermosstability was studied by thermal gravimetric analysis. The char constitution was analyzed by FTIR. The limiting oxygen index value of neat PA11 was only 23 % and without UL 94 rating. The sample containing 20 % DEAP possessed a limiting oxygen index value of 28 % with a V-2 grade in UL 94 test, and the sample containing 13 % DEAP/7 %MP and 12.5 % DEAP/7 %MP/0.5 %ZB gave rise to a limiting oxygen index of up to 29 % with V-1 rating in UL 94. The char was significantly expanded after the addition of 12.5 % DEAP/7 %MP/0.5%ZB.

Preparation and Application of a New Ricinoleic Acid Based Ester and Its Plasticizing Effect on Poly(vinyl chloride)

2015, 29 (07): 96-99 ; DOI: 10.19491/j.issn.1001-9278.2015.07.017

Abstract ( 562 )

A new ricinoleic acid polyol ester was prepared through esterification reaction of ricinoleic acid with pentaerythritol, which was used as a plasticizer in poly(vinyl chloride) (PVC). The chemical structure of prepared plasticizer was characterized with infrared spectroscopy and nuclear magnetic resonance hydrogen spectrum. The torque, thermal stability, and mechanical properties of plasticized PVC characterized. The migration resistance of the plasticizer was tested. The torque, tensile strength, and elongation at break of the plasticized PVC was 14.9 N·m, 23.28 MPa, and 263.13 %, respectively. The new plasticizer had a lower migration rate than that of phthalate plasticizer and epoxidized soybean oil.

Development of PET/PE Alloy Tubes Made of Recycling Polyester Bottles

2015, 29 (07): 100-103 ; DOI: 10.19491/j.issn.1001-9278.2015.07.018

Abstract ( 663 )

A selfmade compatibilizer was used in blends of recycling PET and PE, and the PET/PE alloy tubes was developed. The tube not only has a perfect appearance and low price, but also good properties, including the tensile strength of 33.2 MPa, elongation at break of 151 %, impact strength of 40.3 kJ/m2, Vicat softening temperature(A50) of 81.2 ℃, and ring stiffness of 5.1 kN/m2. In addition, PET/PE alloy pipes could be processed without predrying.

Effect of Screw Configuration on Performance of PA6/PE-LD Blends

2015, 29 (07): 104-111 ; DOI: 10.19491/j.issn.1001-9278.2015.07.019

Abstract ( 594 )

The influence of screw configurations in melt conveying section on PA6/PE-LD blends was studied in a corotating twin screw extruder and the arrangement form and types of distributive mixing and dispersive mixing elements were considered. For PA6/PE-LD blends, experimental study has proved that the blends prepared by distributive arrangement of screw configurations had better mixing and mechanical properties than those by concentrated arrangement of screw configurations.

Two-component Injection Mould Design for Automobile Grilles

2015, 29 (07): 112-116 ; DOI: 10.19491/j.issn.1001-9278.2015.07.020

Abstract ( 561 )

By analyzing the structural process of automobile grilles, the sequence control technology of multiple gate needle valve hot nozzles was used to improve the product’s appearance quality. The mechanism of angle lift, cylinder actuated external slider， and cylinder actuated internal slider were combined to fulfill core pulling of complex car molds. Centering plates, prismatic, and guides were fitted to shorten the dimensions of molds and to ensure accurate positioning in large molds.

Design of Injection Moulds for 45 ° Elbow Pipe Fittings

2015, 29 (07): 117-120 ; DOI: 10.19491/j.issn.1001-9278.2015.07.021

Abstract ( 543 )

Taking the design of injection molds for 45 ° elbow pipe fitting with 8，4， and 2 cavities as the examples, described the number and arrangement of parts in one mold, the structural characteristics and action step of the mold were explored. The best design was found to be: for small size parts, using vertically arranged angle guide pillars; for large size parts, using horizontally arranged sleeve corepulling structure.