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Polymers and Polymer Composites

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Title: MODIFIED PF RESINS FOR COMPOSITE STRUCTURES WITH IMPROVED MECHANICAL PROPERTIES
Page Range: p.297-306
Author(s): Cardona F; Aravinthan T; Moscou C
File size: 232K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.6

Abstract
Novel composites resins for civil engineering structures were synthesised. Resol phenolic resins were modified by the copolymerisation of phenol with cardanol (obtained from CNSL). The modified PF resins were synthesised at different proportions of phenol to cardanol and also of the total phenol to formaldehyde. The synthesis was carried out under alkaline conditions and with a maximum content of 40 wt.% of cardanol. The effect of the partial substitution of phenol by cardanol on the thermal and mechanical properties of the CPF resins was investigated. An increase in the content of cardanol resulted in a proportional increase in the flexibility and in the fracture toughness together with a decrease in the flexural modulus of the cured CPF resins. The higher toughening effect of replacing phenol with cardanol was obtained with the total P:F molar ratio of 1.0:1.25. Also a direct proportionality between the amount of cardanol content and the decrease in crosslink density of the resins was observed. Simultaneous TGA-FTIR studies of the resins were carried out and the emitted gases were identified. The results confirmed that the thermal stability and the temperature of degradation of the cured CPF resins decreased as the amount of cardanol content increased. Gas emissions during the pyrolysis of the CPF resins also increased. 44 Refs.

Title: ISOTHERMAL CRYSTALLIZATION KINETICS OF TRICOMPONENT BLENDS OF POLYCARBONATE, POLY(TRIMETHYLENE TEREPHTHALATE) AND POLYBUTYLENE TEREPHTHALATE
Page Range: p.307-313
Author(s): Al-Mulla A; Al-Omairi L; Mathew J; Bhattacharya S
File size: 253K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.6

Abstract
The isothermal crystallisation kinetics of two different types of linear aromatic polyesters, namely poly(trimethylene terephthalate) (PTT), poly(butylene terephthalate) (PBT) and their blend with polycarbonate (PC) has been investigated using differential scanning calorimetry (DSC). The blend composed of PTT25/PBT25/PC50 (wt/ wt.%) was synthesised using a twin screw extruder. Isothermal studies for PTT were conducted between 129 and 159 C. The temperature ranged between 168-177 C for PBT and between 170 and 183 C for the blend. Avrami, Tobin and Malkin models were used to estimate the crystallisation kinetic parameters, such as crystallisation rate order (n), crystallisation rate constant (k) and half time of crystallisation (t0.5). The values of average sum of square of errors (ASE) of all models were comparable. This detailed study indicates that the models investigated are suitable for describing the crystallisation kinetics of the blend and the neat polymers. 46 Refs.

Title: THE INVESTIGATION OF MELAMINE CYANURATE-ENCAPSULATING MAGNESIUM HYDROXIDE FLAME RETARDED POLYAMIDE-66
Page Range: p.315-320
Author(s): Liu Y; Wang Q
File size: 192K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.6

Abstract
Inorganic flame retardant, magnesium hydroxide (MH), was surface-modified through in-situ encapsulation of an organic nitrogen flame retardant, melamine cyanurate (MCA) by making use of the self-thickening effects during melamine-cyanurate self-assembly process. The obtained MH encapsulated by MCA (MCA-MH) was applied for the flame retardance of polyamide-66 (PA66). As compared to MH modified by silane coupling agent (MH-SC), MH-MCA had much better compatibility and dispersion in PA66 matrix due to replacing MH-PA66 interface by MCA-PA66, As a result, MCA-MH flame retarded PA66 showed obviously enhanced the flame retardancy and mechanical properties. Additionally, the relationship between the MCA/MH ratio and the flame retardancy, as well as the mechanical properties was investigated, and the corresponding synergistic effects between MCA and MH were researched. 10 Refs.

Title: THE STUDY OF EPOXY METHACRYLATE/SILICA HYBRID
Page Range: p.321-327
Author(s): Ou C-F; Shiu M-C
File size: 247K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.6

Abstract
A series of epoxy methacrylate/silica hybrids, containing 0.5, 1, 3, 5, 7, 10, and 15 wt.% tetraethyloxysilane (TEOS), were synthesised by sol-gel process. Differential scanning calorimetry (DSC) indicated that the glass transition temperatures (Tg) of the hybrids were higher than that of the pure epoxy methacrylate, the maximum increase of 26.7 C being achieved with the addition of 3 wt.% TEOS. The decomposition temperatures (Td) of the hybrids were higher than that of the pure epoxy methacrylate (EMA) and rose as the TEOS content increased. The light transmittance of the hybrids was still higher than 80% with up to 15 wt.% TEOS. The water permeability of the hybrids decreased with increasing TEOS content to 7 wt.%, and then increased to 15 wt.%. The hybrid with 7 wt.% TEOS exhibited a maximum permeability decrease of 54.0%. Scanning electron microscopy (SEM) showed that the number of dispersed droplet of silica increased as the content of TEOS increased. 32 Refs.

Title: MECHANICAL AND SURFACE PROPERTIES OF E-BEAM IRRADIATED POLYTETRAFLUOROETHYLENE-SILICONE RUBBER COMPOSITES
Page Range: p.329-336
Author(s): Dadbin S; Kashcooli Y; Frounchi M
File size: 225K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.6

Abstract
Compounding electron beam irradiated polytetrafluoroethylene (PTFE or Teflon) powder with silicone rubber produced silicone rubber/PTFE composites with desired physical properties. PTFE powder was exposed to electron beam irradiation at various doses and characterized by FTIR, DSC and contact angle measurements. Irradiation of PTFE with high energy electron beam induced chain scission reactions. Irradiated PTFE showed higher degree of crystallisation and lower melting point with increasing absorbed dose. Number average molecular weight of irradiated PTFE was reduced significantly at higher absorbed doses. Formation of polar groups on the surface of irradiated PTFE powder was detected by FTIR spectroscopy. The latter was also verified by measurements of water-drop contact angle, which decreased with increasing absorbed dose. Mechanical and surface properties of the composites of silicone rubber and PTFE were characterized by tensile strength, abrasion resistance and water drop contact angle measurements. All the composites containing 5-15 phr PTFE showed higher tensile strength compared to the silicone rubber. Irradiation of PTFE powder had a significant effect on improving the abrasion resistance of the silicone rubber upon addition of only 5 phr irradiated PTFE. Similar abrasion resistance was obtained with the addition of higher amounts of non-irradiated PTFE (15 phr). Water drop contact angle of the composites decreased slightly with increasing the absorbed dose of PTFE. 17 Refs.

Title: THE EFFECTS OF WEATHERING ON MECHANICAL PROPERTIES OF KENAF UNSATURATED POLYESTER COMPOSITES (KFUPC)
Page Range: p.337-343
Author(s): Rashdi A A A; Sapuan S M; Ahmad M M H M; Khalina A
File size: 256K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.6

Abstract
Exposure to natural weathering changes the mechanical properties of unsaturated polyester composites. These changes can negatively affect the mechanical properties of natural fibre composites, through UV radiation and relative humidity. The idea of this study was to determine the durability of kenaf unsaturated polyester composites (KFUPC) in natural conditions, and in addition, to determine the effects of weathering on the performance of these composites and the biodegradability possessed by the composite when exposed to natural weather. KFUPC composites were exposed to the atmosphere for four months. Humidity up-take tests were performed on composite specimens containing (10%, 20% and 30%) weight percentage of fibre content. The tensile properties of exposed specimens were evaluated, and compared alongside dry composite specimens. A decrease in tensile properties of the weather exposed composites was demonstrated, compared with the dry samples. The percentage of moisture uptake increased as the weight percentage of fibre increased, due to the high cellulose content. 22 Refs.

Title: SOLAR AND ENVIRONMENTAL DEGRADATION EFFECT ON TENSILE STRENGTH AND GLASS TRANSITION TEMPERATURE OF GLASS FIBRE REINFORCED PLASTIC LAMINATES
Page Range: p.345-349
Author(s): Sevim C; Varhkh C
File size: 187K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 18
Issue No: No.6

Abstract
In this study, solar and environmental degradation were performed for glass fibre/epoxy and glass fibre/vinyl ester composites. Tensile and differential scanning calorimetry (DSC) tests were applied before and after degradations. Considering tensile strength, it is concluded that vinyl ester composite samples used in this study were more durable against environmental degradation compared to the epoxy based samples. On the contrary, epoxy based samples seemed to be more durable than those of the vinyl ester under solar degradation. Moreover, the glass transition temperature loss % of both two resins was very low after solar degradation. It was observed that the destructive effect of environmental degradation was more dominant than solar degradation, according to measurements of tensile strength and glass transition temperature values. 14 Refs.

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