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Stoyko Fakirov - One of the best experts on this subject based on the ideXlab platform.
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oxygen permeability analysis of microfibril reinforced Composites from pe pet blends
Composites Part A-applied Science and Manufacturing, 2008Co-Authors: R J Shields, Debes Bhattacharyya, Stoyko FakirovAbstract:Abstract Polymers, their blends and Composites are the most widely used types of barrier materials in the world today. This study uses an experimental design technique to investigate the oxygen permeability of a new type of microfibril reinforced polymer–polymer Composite (MFC). It is based on blends of polyethylene (PE) and poly(ethylene terephthalate) (PET) in the ratio of 70/30 (wt%) to create Composites without sophisticated processing techniques or expensive coatings, but with oxygen barrier properties superior to those of neat PE. Microfibril reinforced films of 150–200 μm thickness were produced using a variety of manufacturing conditions, cooling conditions and fibre orientations. All films have been shown to possess superior oxygen barrier properties compared to the plain PE films, with the best allowing just over one quarter of the oxygen permeation that was observed through standard PE. Scanning electron microscopy of these films revealed significant differences in microstructure and reinforcement morphology of the films made using different manufacturing parameters. It has been noted that the films allowed to cool slowly, while they remained under pressure in the press decrease permeability significantly, in part due to increases in crystallinity. Statistical analysis has evaluated the impact of each manufacturing parameter on permeability. Generally, manufacturing and cooling conditions appear to have greater influence on barrier properties than the fibril orientation. Many of the MFC films also had tensile strength and modulus well in excess of that of neat PE, with the best film having triple the modulus and nearly double the strength of the unreinforced matrix polymer.
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recycling of poly ethylene terephthalate as polymer polymer Composites
Polymer Engineering and Science, 2002Co-Authors: M Evstatiev, Stoyko Fakirov, B Krasteva, K Friedrich, J A Covas, A M CunhaAbstract:Microfibrillar reinforced Composites (MFC) comprising an isotropic matrix from a lower melting polymer reinforced by microfibrils of a higher melting polymer were manufactured under industrially relevant conditions and processed via injection molding. Low density polyethylene (LDPE) (matrix) and recycled poly(ethylene terephthalate) (PET) (reinforcing material) from bottles were melt blended (in 30/70 and 50/50 PET/LDPE wt ratio) and extruded, followed by continuous drawing, pelletizing and injection molding of dogbone samples. Samples of each stage of MFC manufacturing and processing were characterized by means of scanning electron microscopy (SEM), wide-angle X-ray scattering (WAXS), dynamic mechanical thermal analysis (DMTA), and mechanical testing. SEM and WAXS showed that the extruded blend is isotropic but becomes highly oriented after drawing, being converted into a Polymer-Polymer Composite upon injection molding at temperatures below the melting temperature of PET. This MFC is characterized by an isotropic LDPE matrix reinforced by randomly distributed PET microfibrils, as concluded from the WAXS patterns and SEM observations, the MFC dogbone samples show impressive mechanical properties-the elastic modulus is about 10 times higher than that of LDPE and about three times higher than reinforced LDPE with glass spheres, approaching the modulus of LDPE reinforced with 30 wt% short-glass fibers (GF). The tensile strength is at least two times higher than that of LDPE or of reinforced LDPE with glass spheres, approaching that of reinforced LDPE with 30 wt% GF. The impact strength of LDPE increases by 50% after reinforcement with PET. It is concluded that: (i) the MFC approach can be applied in industrially relevant conditions using various blend partners, and (ii) the MFC concept represents an attractive alternative for recycling of PET as well as other polymers.
Wenyen Chiu - One of the best experts on this subject based on the ideXlab platform.
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synthesis and physical properties of the crosslinking poly butyl acrylate polystyrene core shell Composite latex
Polymer Journal, 2000Co-Authors: Chiafen Lee, Yuhsia Chen, Wenyen ChiuAbstract:Butyl acrylate and styrene were used as monomers in the first stage and second stage respectively, and potassium persulfate (K 2 S 2 O 8 ), as the initiator to synthesize the polymer/polymer Composite latex by two-stage soapless emulsion polymerization. In the first stage, the poly(butyl acrylate) with crosslinking structure (PBA(XL)) was synthesized to be the seed latex. In the second stage, the styrene was polymerized in the presence of PBA(XL) seeds to form the PBA(XL) / PS Composite latex. The morphology of the Composite latex was observed by transmission electron microscopy (TEM) and showed that Composite latex particles were with core-shell structure. The particle size distribution of the Composite latex was very uniform. The kinetics of reaction of the second stage polymerization were investigated. The results showed that the reaction rate would be influenced by the degree of crosslinking of the PBA(XL) seeds, initiator concentration and agitation speed. The components of the PBA(XL)/PS Composite polymers were measured by thin-layer chromatographic (TLC) analysis. The results showed a thin layer of PBA-graft-PS copolymer between the core (PBA) and shell (PS) region. The morphology of the PBA(XL)/PS Composite polymers, processed under heat and pressure, was observed by transmission electron microscope (TEM). The morphology may change gradually with increase of processing time. The mechanical properties and rheological properties of the Composite polymers were investigated.
Madhavi Srinivasan - One of the best experts on this subject based on the ideXlab platform.
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plastic crystalline semi crystalline polymer Composite electrolyte based on non woven poly vinylidenefluoride co hexafluoropropylene porous membranes for lithium ion batteries
Electrochimica Acta, 2014Co-Authors: Nageswaran Shubha, Raghavan Prasanth, Hng Huey Hoon, Madhavi SrinivasanAbstract:Abstract The advantageous properties of both solid soft matter electrolytes and polymer gel electrolytes (PGEs) are combined to develop a electrospun polymer Composite electrolyte (PCE) for lithium ion batteries , based on addition of butanedinitrile (BDN, the plastic crystal) to poly(vinylidenefluoride- co -hexafluoropropylene) {P(VdF- co -HFP)} (semi crystalline polymer). Polymer Composite electrolytes are prepared by activating the fibrous membrane with 1 M LiPF 6 in EC/DEC. The electrochemical characterization shows that the addition of BDN significantly improves the ionic conductivity of Composite electrolytes even at lower temperatures due to the active role played by BDN in ion conduction. Also the compatibility of the polymer Composite electrolyte with lithium electrode improves by incorporation of BDN. Galvanostatic cycling test demonstrates the suitability of these polymer Composite electrolytes for lithium ion batteries in both Li/PCE/LiFePO 4 (half cell) and LTO/PCE/LiFePO 4 (full cell) configurations. The addition of BDN improves the charge discharge performance and cycling stability of the polymer Composite electrolytes.
A M Cunha - One of the best experts on this subject based on the ideXlab platform.
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recycling of poly ethylene terephthalate as polymer polymer Composites
Polymer Engineering and Science, 2002Co-Authors: M Evstatiev, Stoyko Fakirov, B Krasteva, K Friedrich, J A Covas, A M CunhaAbstract:Microfibrillar reinforced Composites (MFC) comprising an isotropic matrix from a lower melting polymer reinforced by microfibrils of a higher melting polymer were manufactured under industrially relevant conditions and processed via injection molding. Low density polyethylene (LDPE) (matrix) and recycled poly(ethylene terephthalate) (PET) (reinforcing material) from bottles were melt blended (in 30/70 and 50/50 PET/LDPE wt ratio) and extruded, followed by continuous drawing, pelletizing and injection molding of dogbone samples. Samples of each stage of MFC manufacturing and processing were characterized by means of scanning electron microscopy (SEM), wide-angle X-ray scattering (WAXS), dynamic mechanical thermal analysis (DMTA), and mechanical testing. SEM and WAXS showed that the extruded blend is isotropic but becomes highly oriented after drawing, being converted into a Polymer-Polymer Composite upon injection molding at temperatures below the melting temperature of PET. This MFC is characterized by an isotropic LDPE matrix reinforced by randomly distributed PET microfibrils, as concluded from the WAXS patterns and SEM observations, the MFC dogbone samples show impressive mechanical properties-the elastic modulus is about 10 times higher than that of LDPE and about three times higher than reinforced LDPE with glass spheres, approaching the modulus of LDPE reinforced with 30 wt% short-glass fibers (GF). The tensile strength is at least two times higher than that of LDPE or of reinforced LDPE with glass spheres, approaching that of reinforced LDPE with 30 wt% GF. The impact strength of LDPE increases by 50% after reinforcement with PET. It is concluded that: (i) the MFC approach can be applied in industrially relevant conditions using various blend partners, and (ii) the MFC concept represents an attractive alternative for recycling of PET as well as other polymers.
Chiafen Lee - One of the best experts on this subject based on the ideXlab platform.
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synthesis and physical properties of the crosslinking poly butyl acrylate polystyrene core shell Composite latex
Polymer Journal, 2000Co-Authors: Chiafen Lee, Yuhsia Chen, Wenyen ChiuAbstract:Butyl acrylate and styrene were used as monomers in the first stage and second stage respectively, and potassium persulfate (K 2 S 2 O 8 ), as the initiator to synthesize the polymer/polymer Composite latex by two-stage soapless emulsion polymerization. In the first stage, the poly(butyl acrylate) with crosslinking structure (PBA(XL)) was synthesized to be the seed latex. In the second stage, the styrene was polymerized in the presence of PBA(XL) seeds to form the PBA(XL) / PS Composite latex. The morphology of the Composite latex was observed by transmission electron microscopy (TEM) and showed that Composite latex particles were with core-shell structure. The particle size distribution of the Composite latex was very uniform. The kinetics of reaction of the second stage polymerization were investigated. The results showed that the reaction rate would be influenced by the degree of crosslinking of the PBA(XL) seeds, initiator concentration and agitation speed. The components of the PBA(XL)/PS Composite polymers were measured by thin-layer chromatographic (TLC) analysis. The results showed a thin layer of PBA-graft-PS copolymer between the core (PBA) and shell (PS) region. The morphology of the PBA(XL)/PS Composite polymers, processed under heat and pressure, was observed by transmission electron microscope (TEM). The morphology may change gradually with increase of processing time. The mechanical properties and rheological properties of the Composite polymers were investigated.