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2014, Volume 28 Issue 03 Publication date: 15 March 2014 Previous Issue Next Issue

Research Progress in Toughening and Flame Retardation of Phenolic Foams

2014, 28 (03): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2014.03.003

Abstract ( 1874 )

In this paper, recent advances on toughnening methods of physical mixing and chemical modification of phenolic foams, as well as use of flame retardant toughnening agents in the foams were reviewed, the physical mixing agents included some rubbers, flexible polymer resins and some fibers. We also point out some problems relating to the toughnening of phenolic foams.

Research Progress in Fully Biodegradable PLA/PBAT Blends

Yuxia ZHANG Xue LIU

2014, 28 (03): 7-15 ; DOI: 10.19491/j.issn.1001-9278.2014.03.004

Abstract ( 2004 )

Research progress in fully biodegradable PLA/PBAT blends was reviewed. Their compatibility, phase morphologies，melting and crystallization behavior，mechanical properties，and processing ability etc. were introduced.

Development of Microcapsule Self-healing Polymeric Materials

DONG Jinhu

2014, 28 (03): 16-22 ; DOI: 10.19491/j.issn.1001-9278.2014.03.005

Abstract ( 1576 )

In this paper the research progress of microcapsule-based polymer self-healing in recent years was reported, including the development course of polymer self-healing, applications of fluorescent digital image and photoelastic measure, and the polymer self-healing based on microcapsule and microvascular.

Morphology and Properties of Poly(butylene succinate)/ Ethylene-vinyl Acetate Blends

XING Xiao Piming Ma

2014, 28 (03): 23-27 ; DOI: 10.19491/j.issn.1001-9278.2014.03.006

Abstract ( 1501 )

In this article, ethylene-vinyl acetate rubber(EVM) is used to toughen poly(butylene succinate) (PBS) and dicumyl peroxide (DCP) was added to enhance the compatibility of PBS and EVM. With increasing DCP content the tensile property and shore-D hardness were increased first and then decreased. The tensile strength was between 7 and 17 Mpa, the tensile stress at 100 % elongation was between 2 and 10 MPa. The added DCP turned PBS from a dispersed phase to a continuous phase. The optimal content of DCP was 0.3 phr.

Preparation of Polyurethane Foams with Castor Oil Phosphate Flame Retardant Polyols and Expanded Graphite

ZHANG Li-Qiang

2014, 28 (03): 28-32 ; DOI: 10.19491/j.issn.1001-9278.2014.03.007

Abstract ( 1348 )

In this paper, polyurethane foam (PUF) were prepared from glycerolysized castor oil and castor oil phosphate polyol, and MDI, expanded graphite was introduced as a flame retardant. The mechanical behavior and flame resistance of PUF was studied by universal testing, limiting oxygen index, thermogravimetric analysis, and scanning electron microscope. The expanded graphite improved the flame retardant, thermostability, and mechanical strength of polyurethane foam. The synergistic effect between expanded graphite and triethyl phosphate caused the formation of a dense char layer, which inhibited the transfer of heat and combustible gas, and the limiting oxygen index of PUF increased to 29.7 %.

Study on Non-Isothermal Crystallization Kinetics of PTFE/POB Composites

Zheng Zhen-Chao

2014, 28 (03): 33-39 ; DOI: 10.19491/j.issn.1001-9278.2014.03.008

Abstract ( 1841 )

Polytetrafluoroethylene/polybenzoate (PTFE/POB) composites, in which POB particles filled PTFE matrix, were prepared by cold molding and sintering in the air. The non-isothermal crystallization behavior of PTFE/POB composites was studied by differential scanning calorimetry (DSC), and the Jeziorny equation was used to analyze the non-isothermal crystallization kinetics. As the cooling rate increased, peak temperature shifted to a lower temperature, crystallinity temperature the peak became wider, and crystallinity reduced. The addition of POB increased crystallinity and the crystallization rate of PTFE.

Effect of Surface Modification of Walnut Shell on Properties of Poly(lactic acid)/Walnut Shell Powder Composites

2014, 28 (03): 40-45 ; DOI: 10.19491/j.issn.1001-9278.2014.03.009

Abstract ( 1339 )

Walnut shell powder (WSP) was treated with a silicane coupling agent KH550 and was introduced into poly(lactic acid) (PLA) forming composites through melt blending. The effect of the surface treatment of WSP was studied. When the dosage of KH550 was 6wt% of the walnut shell, all the tensile, bending, and impact strengths of PLA/WSP composites were increased by 1.2 times, reached 42.09, 63.89 MPa, and 1.69 kJ/m2, respectively. SEM images indicated the compatibility between WSP and PLA was improved after surface modification. When the contents of WSP were 5 wt % and 40 wt %, the thermal degradation activation energies (Ea) of composites were 13.1 and 29.8 kJ/mol lower, respectively, than those of neat PLA. The surface treatment depressed the decrease in degradation activation energy.

Study on the Behavior of Melting and Non-Isothermal Crystallization of PE-LLD/GB Composites

2014, 28 (03): 46-53 ; DOI: 10.19491/j.issn.1001-9278.2014.03.010

Abstract ( 1263 )

Crystal morphology, melting and non-isothermal crystallization behavior of linear low density polyethylene/glass bead (PE-LLD/GB) composites were investigated by X-ray diffraction, polarization microscope, and differential scanning calorimeter. Jeziorny and Mo methods were applied to analyze the non-isothermal crystallization kinetics of PE-LLD and PE-LLD/GB composites and the activation energy (ΔE) was estimated based on Kissinger method. Upon addition of GB, the size and crystallites was decreased. GB acted as a nucleating agent for the non-isothermal crystallization of PE-LLD, and increased the crystallization onset temperature (To). At a GB content of 8 wt %, the crystallization rate reached the highest value. In addition, the presence of GB increased the crystallization activation energy when the GB content was below 5 wt %.

Research on the Modification of Poly(lactic acid) by Bacterial Cellulose Grafted with Maleic Anhydride

2014, 28 (03): 54-58 ; DOI: 10.19491/j.issn.1001-9278.2014.03.011

Abstract ( 570 )

Bacterial cellulose (BC) was grafted with maleic anhydride (MAH) and the product (BC-g-MAH) was mixed with poly(lactic acid) (PLA) by solvent casting forming composites. The structure and properties of the composites were studied by FTIR, DSC, tensile tester, and TGA analysis. It was found there was a good interfacial compatibility between the BC-g-MAH and PLA. When the content of BC-g-MAH was 20 wt %, the crystallinity, tensile strength, and tensile modulus of the composite increased by 17.1 %, 69.4 %, and 428.4 %, based on neat PLA, respectively. In addition, the composites showed a high thermal stability.

Vinyl Polysiloxane Surface-modified Ammonium Polyphosphate and Its Application in Epoxy Resin as Flame Retardants

Xiaowei Liu Cuicui Wu QU Hongqiang

2014, 28 (03): 59-64 ; DOI: 10.19491/j.issn.1001-9278.2014.03.012

Abstract ( 1393 )

Ammonium polyphosphate (APP) was treated with tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTOS) by a sol-gel method leading to vinyl modified APP (VMAPP), which was introduced into an epoxy resin (EP). The surface vinyl groups could be used as reaction sites for further modification. Fourier transform infrared spectrum (FTIR) analysis confirmed the presence of the vinyl in the epoxy coating film. Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) analysis indicated that a dense protective film was present on the surface of APP. On the film, the content of P, N elements was significantly decreased, and the content of C element increased significantly. The water resistance of VMAPP was better than unmodified APP. The Si element present on the surface of APP synergized with APP to generate more compact and stable char layer and thus promoted the flame retardant performance of EP.

Properties of Poly（propylene carbonate）/Organic Layered Double Hydroxide Composites

2014, 28 (03): 65-70 ; DOI: 10.19491/j.issn.1001-9278.2014.03.013

Abstract ( 1477 )

In this paper, maleic anhydride (MAH) was used as active agents for the end-capping of poly（propylene carbonate）（PPC）. The PPC/organic layered double hydroxide （OLDH） composites was prepared by melt blending. Compared with the pure PPC , When the content of OLDH in the composites is up to 4 %, the 5 % weight loss temperature, the 95 % weight loss temperature and the maximum rate of weight loss temperature was increased by 49.1、70.2、49.3 ℃, respectively. And the glass transition temperature（Tg）was increased from 18.3 ℃ to 22.7 ℃. The addition of a small amount of OLDH particle can both improve the mechanical properties of polymers and barrier properties.

Research of Molding Formability of Product with Microstructure Based on Ultraviolet Radiation

2014, 28 (03): 71-74 ; DOI: 10.19491/j.issn.1001-9278.2014.03.014

Abstract ( 1756 )

The microstructure of a trilateral product was studied by experiment for its formability and replication fidelity through a "light chemical manufacturing" approach. The integrity of the edge was set as a measure of the formability, and the height of the edge was set as a measure the replication fidelity. It was found that the ultraviolet radiation had a significant impact on the formability and replication fidelity of the microstructure of the product. Mould and temperature had no effect on formability of the fine structure, however, had a significant influence on replication fidelity of the microstructure.

Numerical Simulation and Analysis of Variotherm Injection Molding Technique by Using Steam Heating

2014, 28 (03): 75-80 ; DOI: 10.19491/j.issn.1001-9278.2014.03.015

Abstract ( 1375 )

A variotherm injection molding technique with steam heating and coolant cooling was simulated by Moldflow. Pressures at injection location and frozen layer of part at different heating time were studied, and the thermal response at surface and cavity of the mold waqs analysed using constructed models. Compared with traditional injection molding, in the variotherm injection molding the mold temperature was increased to a designed value, the melt could easily fill into the cavity under a low injection pressure, and the frozen layer was appeared after the filling stage. As the mold heating time increased from 10 to 15, 25, 40 s, the maximum pressure at injection position was reduced from 87.1 to 84.61, 79.7, 74.4 MPa, respectively. The surface temperature of the part and the mold could be changed through different heating time, and the part surface temperature was simultaneously affected by the heat transfer coefficient.

Study on the Foaming Behavior of Biodegradable Poly (lactic acid) / Poly (butylene adipate-co-terephthlate) Blends

LIU Wei

2014, 28 (03): 81-86 ; DOI: 10.19491/j.issn.1001-9278.2014.03.016

Abstract ( 1429 )

Poly (lactic acid)/poly (butylene adipate-co-terephtlate) (PLA/PBAT) blends were prepared using multi-functional epoxy compound as a reactive compatibilizer. The effects of the compatbilizer content on the crystallization and rheological behavior of PLA/PBAT blends were characterized and discussed. Results showed that the addition of compatibilizer greatly improved the rheological properties and affected crystallization behaviors of PLA/PBAT blends. Subsequently, PLA/PBAT blends with various compatibilizer contents were foamed with supercritical CO2. The foaming structure, cellular size, and cellular density were investigated. Results showed that the cellular structure was improved with the increasing compatbilizer content due to the enhanced rheological properties.

Polycarbonate Slender Pen Rod Axial Deformation Prediction Combined RSM with GA-BP

谭 小红

2014, 28 (03): 87-92 ; DOI: 10.19491/j.issn.1001-9278.2014.03.017

Abstract ( 1320 )

Four process parameters, mold temperature, melt temperature, holding time, and holding pressure, in injection molding of slender polycarbonate (PC) parts were optimized using GA-BP and RSM methods. The RSM method resulted in the optimal parameter combination of [A3, B3, C1, D1]. The GA-BP method predicted that the minimum axial deformation was 0.0064 mm, very close to the Moldflow simulated value of 0.0063 mm. For 9 groups of random trials, the maximum absolute errors of prediction by GA-BP and RSM were 5.48 % and 7.41 %, and the relative errors were 2.76 % and 3.13 %, respectively. It showed that the combination of GA-BP and RSM provided a high prediction accuracy.

The synthesis of a new type of phosphorus and nitrogen compound bromide flame retardants and the study of flame retardant polypropylene

王小芬

2014, 28 (03): 93-96 ; DOI: 10.19491/j.issn.1001-9278.2014.03.018

Abstract ( 1457 )

In this paper, a novel flame retardant was prepared by compositing melamine hydrobromide (MHB), ammonium polyphosphate (APP), and 2,3-dimethyl-2,3-diphenyl butane (DMDPB). The flame retardant was tested in polypropylene and the optimal weight ratios of MHB:APP:DMDPB were found being 10:10:1. When loading of the flame retardants was 2.0 wt %，the limited oxygen index value increased to 30.8 %,and combustion grade achieve UL 94 V-1.

Storage Characterization and Quality Control on Prepreg Tape of Carbon Fiber(T700)/Polytriazole

2014, 28 (03): 97-100 ; DOI: 10.19491/j.issn.1001-9278.2014.03.019

Abstract ( 1792 )

The physicochemical behavior of prepreg tape of carbon fiber(T700)/polytriazole resin at different storage time and conditions was studied by IR and GPC. With injcreasing storage time, the molecular weight of the resin, insoluble species content, and triazole ring content increased, but the volatile component decreased. The prepreg tape should be refrigerated or frozen in order to extend the use period for large scale preparation.

Design of Injection Mould for Three Different Shapes of Shutter

2014, 28 (03): 101-105 ; DOI: 10.19491/j.issn.1001-9278.2014.03.020

Abstract ( 1593 )

A injection mold was designed which could mold three different shutter parts in one injection run. An inclined pillar slide block core-pulling mechanizm, inserted and core and cavity structure, and a side flow gate were employed. Practice use showed that the mold was reasonably designed, and worked smoothly and reliably. Using this mold, the manufacture cost was reduced, the quality of the product was guaranteed.

Forming Process Optimizing for Injection Molding of the Thin-walled Plastic Parts Based on Warping Deformation

Liang-Hong XIAO

2014, 28 (03): 106-111 ; DOI: 10.19491/j.issn.1001-9278.2014.03.021

Abstract ( 1988 )

The warping deformation of three back-cover of keyboards made from PC, ABS, and PC/ABS were numerically simulated with Moldflow software. A orthogonal simulation experiment was designed and performed. The optimal process parameters were obtained by range analysis. For injection molding of PC, ABS, and PC/ABS, the mold temperature being 100, 40，and 50 ℃, melt temperature being 290, 260，and 240 ℃, injection time being 2.0, 1.0，and 2.5 s, pressure holding time being 25, 15，25 s, respectively. The holding pressure was 110 % the corresponding injection pressure for all three materilas.

Design of Injection Mold for 32 Inch LCD TV Shell

2014, 28 (03): 112-116 ; DOI: 10.19491/j.issn.1001-9278.2014.03.022

Abstract ( 1546 )

According to the size and structure characteristics of the 32 inch LCD TV shell，a mold structure was designed, in which a direct injection system, a push mechanism with rod and tube, a custom semi-finished mold, and a pneumatic side core-pulling institution were adopted. The structure and working principle of the mold were satisfactory for the fully filling of plastic melt and plastic parts with high quality were obtained.