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Polymers and Polymer Composites

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Title: OPTICAL TRANSPARENCY CHANGE METHOD FOR CURE MONITORING OF GFRPs
Page Range: p.63-71
Author(s): Akira Todoroki; Norihiko Hana
File size: 261K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
The resin transfer molding(RTM) process is becoming popular for low-cost fabrication of complex commercial products made from GRP. As regards the RTM process for complex components, the optimal fabrication process is found by repeated trial and error. This process is time-consuming and one of the reasons for the high cost of composite products. To overcome this problem, it is useful to monitor the degree of cure of target GRP products. In this study, the luminance change method was used for cure monitoring of polyester-based GRP composites. Polyester resin usually changes its optical transparency during the curing process, which enabled the degree of cure to be monitored by measuring the luminance change of light or reflected light. A system that measured reflected light was developed. The sensing system employed a light-emitting diode as the light source and a photodiode as a light power sensor. This low-cost cure monitoring system was applied to the monitoring of the degree of cure in GRPs and was achieved using commercially-available dielectric sensors. Results were compared with the results of luminance change. The effectiveness of this method was confirmed experimentally. 10 refs.

Title: NUMERICAL SIMULATION BASED PROCESS WINDOW FOR CONSOLIDATION OF THERMOSET COMPOSITE LAMINATES
Page Range: p.73-82
Author(s): Min Li; Yizhuo Gu; Yanxia Li; Zuoguang Zhang
File size: 482K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
Laminate consolidation is very important for continuous fibre-reinforced thermoset resin matrix composites and the degree of consolidation depends on resin rheological behaviour and processing conditions. This study focused on the rheological characteristics of two types of epoxy resins (low temperature- and high temperature-curing) and a bismaleimide resin and developed an evaluating method based on numerical simulation, providing guidelines to ensure consolidation. The rheological characteristics under isothermal conditions were examined and the determination of gel point using viscosity increment rate was adopted. The autoclave process for T700S carbon fibre composite laminates was simulated numerically and the effects of cure cycle, number of plies and lay-up type of fibre bed on consolidation were analysed. A process window was constructed to achieve the required degree of consolidation by adjusting the external pressure and the time of applying external pressure. The results showed that the quantitative impacts of processing conditions on consolidation and the feasibility of processing operations could be obtained from the established process window. 25 refs.

Title: MICROENCAPSULATION OF HYDROPHILIC SOLID POWDER AS A FIRE RETARDANT BY THE METHOD OF IN SITU GELATION IN DROPLETS USING A NON-AQUEOUS SOLVENT AS THE CONTINUOUS PHASE
Page Range: p.83-90
Author(s): Masanori Takahashi; Yoshinari Taguchi; Masato Tanaka
File size: 521K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
Hydrophilic, solid, powdery diammonium bitetrazole(BHT.2NH"3) as a fire retardant was microencapsulated with bisphenol-A epoxy resin by the method of in-situ gelation in droplets to give water resistance. In this method, a non-aqueous solvent was adopted as the continuous phase instead of water to prevent the hydrophilic core material from leaking out. In the experiment, it was mainly the agitation speeds during preparation of droplets containing BHT.2NH"3 and during the microencapsulation process, the gelation temperature, and the oil-soluble surfactant species that were varied. The content of core material could be increased by using a non-aqueous solvent instead of the water phase. The content of core material increased with gelation temperature and independently of the agitation speeds during first droplet preparation and during the microencapsulating process. The leakage ratio increased with agitation speeds and decreased considerably with gelation temperature. 10 refs.

Title: A STUDY OF PU/MMT NANOCOMPOSITES
Page Range: p.91-96
Author(s): Min Qiao; Qianping Ran; Shishan Wu; Jian Shen
File size: 186K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
The polyurethane(PU)/montmorillonite(MMT) composite prepared by in-situ polymerisation was a type of intercalated nanocomposite. The silicate platelets were dispersed in the PU matrix on the nanoscale. The DMF suspension containing the PU/MMT nanocomposite was stable for a long time, and the silicate platelets did not subside. With increasing content of silicate, the tensile and tear strength of the PU/MMT nanocomposite increased, but the rate of increase diminished. Compared with that of pure PU, the temperature of initial weight loss of the PU/MMT nanocomposite in the first step decreased because of the acid catalytic action of the protonated silicate platelets, but the temperature of initial weight loss in the second step increased due to the barrier effect of the silicate platelets and the strong interfacial interaction between silicate platelets and the molecular chains of PU. 27 refs.

Title: STRUCTURE AND PROPERTIES OF PVA/SiO"2 INTERPENETRATING POLYMER NETWORK MATERIALS PREPARED BY THE SOL-GEL METHOD
Page Range: p.97-100
Author(s): Feng-Yu Quan; Li-Li Chen; Yan-Zhi Xia; Quan Ji
File size: 167K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
Organic-inorganic interpenetrating polymer network(IPN) materials were prepared by hydrolysis and condensation of tetraethoxysilane(TEOS) in PVAl solution. The structure and morphology of the IPNs were investigated by FTIR spectroscopy and TEM. The thermal properties were examined by TGA and DSC. FTIR spectroscopy showed the formation of Si-O-C and Si-O-Si bonds in the system. TEM demonstrated a homogeneous dispersion of silica in the PVAl matrix when the amount of TEOS added was appropriate. DSC and TGA revealed that, compared with pure PVAl films, the hybrid films exhibited a higher Tg and high thermal stability. 17 refs.

Title: EVALUATION OF THE MORPHOLOGY AND PERFORMANCE OF POLYETHER SULFONE REVERSE OSMOSIS COMPOSITE AND NON-COMPOSITE MEMBRANES
Page Range: p.101-108
Author(s): Madaeni S S; Barzin J; Jokar Z
File size: 305K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
Reverse osmosis membranes were prepared by the phase inversion technique using polyether sulphone(PES) dissolved in DMAc with and without the addition of polyvinylpyrrolidone(PVP). The effects of the composition of the casting solution on membrane morphology and performance were investigated on the basis of ion removal from treated water. The membrane prepared from 22 wt % PES demonstrated the best ion rejection. Higher flux was accessible by changing the polymer solution composition to 16 wt % PES and 2.5 wt % PVP. For preparation of polyamide composite membranes, the interfacial polymerisation technique was employed. In this procedure, hexamethylenediamine and sebacyl chloride were reacted with each other on the surface of a membrane support. Synthesis conditions, such as the concentration of monomers and the reaction time, significantly affected the performance of the composite membranes. The permeation rate and ion rejection capability of composite polyamide membranes were 40-80 (L/m^2 h) and 28-30% respectively with the initial feed conditions of 400 psi and 25 deg C. 34 refs.

Title: EFFECT OF SWELLING PROCESS ON MONODISPERSITY OF POROUS POLYSTYRENE-DIVINYLBENZENE MICROSPHERES PREPARED BY TWO-STEP SWELLING POLYMERIZATION METHODS
Page Range: p.109-116
Author(s): Xiaoyan Liao; Jiang Cheng; Lu Li; Pihui Pi; Xiufang Wen; Zhuoru Yang
File size: 472K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
Porous polystyrene-divinylbenzene(PS-DVB) microspheres of narrow size distribution in the size range of 3.9-4.4 micrometres were prepared by two-step swelling polymerisation methods. The effects of swelling conditions such as swelling activator, temperature, the dispersion method and dibutyl phthalate(DBP)/seed particle ratio on particle size distribution of the PS-DVB microspheres were investigated in detail. Optimal swelling conditions for the preparation of uniformly sized PS particles were shown to be use of DBP as swelling activation agent, swelling temperature 35 deg C, dispersion by ultrasonic-assisted magnetic dispersion, and DBP/seed particle ratio 1-1.5 ml.g^-^1. It was found that particle size distribution became narrower and swelling time was shortened from more than 24 h to 10 h with the introduction of ultrasonic dispersion, which was attributed to the cavitation effect of ultrasonics and the significant magnetic field action arising therefrom, speeding up the equilibrium of swelling process. Swelling temperature also had a significant effect on the monodispersity and particles with the best uniformity could be achieved with the temperature at 35 deg C. The possible reason was that the process of seed particles absorbing swelling agent through water phase was an equilibrium course of thermodynamics and kinetics. 20 refs.

Title: MECHANICAL PROPERTIES AND FLAME RETARDANCY OF SEBS-BASED COMPOSITES FILLED WITH MAGNESIUM HYDROXIDE
Page Range: p.117-125
Author(s): Wang-Dong Xiao; Kibble K A; Feng Lin
File size: 307K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 17
Issue No: No.2

Abstract
The flame-retardancy and mechanical properties of styrene-ethylene/butylene-styrene block copolymer(SEBS)-based composites, containing SEBS blended with a paraffinic hydrocarbon extender oil, propylene copolymer and magnesium hydroxide(MH) or silane coupling agent surface-treated magnesium hydroxide(m-MH), were investigated. A maleic anhydride-grafted SEBS(MA-SEBS) was used as a polymer modifier for some composites. As the amount of MH or m-MH increased, the flame-retardancy of composites improved, while the TS and EB decreased, and the melt flow property of the composites became poorer. When the oil-filled SEBS(O-SEBS) was partially replaced by MA-SEBS, the TS of the composites increased and EB decreased. Furthermore, replacement of O-SEBS with MA-SEBS and treating MH with silane coupling agent (simultaneously) improved the TS of the composites by a large margin. The phase structure of the composites was characterised using SEM and this revealed that the particle-matrix interfacial bonding was improved through the addition of MA-SEBS. The stability of the composites was investigated by TGA. 21 refs.

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