Showing papers in "International Journal of Polymeric Materials in 2004"
TL;DR: In this paper, the tensile strength of the composites increases with increasing oil palm empty fruit bunch loading up to 20% in the presence of 3% (by weight) of acrylic acid and 0.01% of dicumyl peroxide.
Abstract: Oil palm empty fruit bunch (EFB), nowadays, has not been fully utilised economically and is always subjected to environmental concern, whereas its handling in the palm oil mill also consumes unproductive cost and energy. In this work oil palm empty fruit bunch filled polypropylene composites were prepared using solution technique and reactive processing in a screw extruder. Results indicate that in the first technique, tensile strength of the composites increases with increasing oil palm empty fruit bunch loading up to 20% (by weight) in the presence of 3% (by weight) of acrylic acid and 0.01 mol ratio of dicumyl peroxide. However the elongation at break shows decreasing trend. Similar observation was also obtained for composites prepared in a single screw extruder. Results from SEM, GPC and IR spectra show that better compatibility between oil palm empty fruit bunch and polypropylene was achieved in the presence of acrylic acid.
62 citations
TL;DR: In this paper, the effects of varying the chain length of polyethylene glycol (as the soft segment) were investigated to produce lignin-based polyurethanes with variable thermal and mechanical properties.
Abstract: Polyurethane (PU) films were prepared by solution casting using a three-component system, namely a novel semi-rigid solvolytic lignin, soft segment and a co-monomer. In the present study, the effects of varying the chain length of polyethylene glycol (as the soft segment) were investigated to produce lignin-based polyurethanes with variable thermal and mechanical properties. An important objective was to incorporate as much lignin as possible. The polyethylene glycol (PEG) studied included 5 different molecular weights (200, 400, 1000, 1500 and 2000 g/mol). The polyurethane films, prepared by solvent casting, were evaluated for crosslink density, and ultimate mechanical and thermal properties. Results showed that the films derived from the PEG 200 were either too weak or brittle to be tested. It was found that the PEG (400, 1000, and 1500) are better choices for producing polyurethanes from the solvolysis lignin studied. Crosslink densities of PU films using the 400, 1000 and 1500 were determined to be in...
35 citations
TL;DR: In this article, the effect of varying the Hexamethylene N, N′ bis (tert-butyl peroxy carbamate) concentration had a great influence on the rheological behavior as well as the dynamic and tensile properties of the material.
Abstract: Dynamic vulcanization of a soft grade of thermoplastic natural rubber (TPNR) was carried out using several concentrations of Hexamethylene N, N′ bis (tert-butyl peroxy carbamate) (HBTP). The blends were melt mixed in a Brabender plasticorder. The effectiveness of dynamic vulcanization was investigated using the Brabender plastograms, swelling index measurements, rheological behavior by means of a capillary rheometer, dynamic mechanical properties, and tensile testing. It was found that varying the HBTP concentration had a great influence on the rheological behavior as well as the dynamic and tensile properties of the material. The increase of HBTP dosage resulted in an increase of the extent of crosslinking and caused an increase of the elastic modulus and a reduction of the loss modulus. The ultimate tensile strength and elongation at break also increased with increasing HBTP loading. The rheograms indicated that the blends exhibit a pseudoplastic behavior.
34 citations
TL;DR: In this paper, three different castor-oil-based polyester-polyols with aromatic as well as aliphatic isocyanate adducts in different NCO/OH ratios were used for high solids polyurethane coating formulations.
Abstract: High solids polyurethane (PU) coating formulations were developed by reacting three different castor–oil–based polyester–polyols with aromatic as well as aliphatic isocyanate adducts in different NCO/OH ratios. Structure of polyurethane resins was confirmed by FTIR spectroscopy. The molecular weight between two crosslinks (Mc) and solubility parameter of the samples (polymer films) were determined by a swelling method. The polyurethane resins were coated on test panels and tested for their flexibility, scratch hardness, cross-hatch adhesion, impact, pencil hardness and solvent resistance as per standards. The effect of catalyst, structure of isocyanate and flexibility of polyols on the resulting polyurethanes was evaluated. Thermal stability of these polymers was determined by thermogravimetric analysis (TGA).
31 citations
TL;DR: The use of conductive polymers as a substitute for metallic conductors and semiconductors has attracted much attention in the literature as discussed by the authors, and polyfuran has been reported to be much less stable that either polypyrrole or polythiophene.
Abstract: The use of conductive polymers as a substitute for metallic conductors and semiconductors has attracted much attention in the literature. In particular, aromatic heterocyclic polymers constitute an important class because they possess chemical and electrical stability. The properties of these polymers are promising for their many technological uses such as antistatic coatings, solar cells, electronic devises, and so on. Polyfuran is among the least common heterocyclic polymers. Polyfuran has been reported to be much less stable that either polypyrrole or polythiophene. The chemical synthesis of polyfuran using a mild oxidizing agent, pyridinium chlorochromate is described. Also, the preparation of ten co-polymers of polyfuran with one to five percent pyrrole or thiophene is reported. The polymers are characterized by 1H NMR, IR, and ESR spectroscopy, and the electrical conductivity of the synthetic polyfuran and ten co-polymers is provided.
30 citations
TL;DR: In this paper, N-methylpyrrole (NMePy) and carbazole (Cz) copolymerization was conducted in acetonitrile and the properties of the resulting copolymers were investigated by spectroscopic methods (UV-VIS, FT-IR, cyclic voltammetry and four point probe conductometer).
Abstract: Electrocopolymerization of N-methylpyrrole (NMePy) and Carbazole (Cz) was conducted in acetonitrile. Oxidative chemical random copolymerization of NMePy and Cz was also realized by Cerium (IV) ammonium nitrate (CAN) for comparison. The properties of the resulting copolymers were investigated by spectroscopic methods (UV-VIS, FT-IR), cyclic voltammetry and four point probe conductometer, to understand the oligomeric pyrrole ring interaction with carbazole ring where the reactive nitrogen of pyrrole ring was capped (substituted) by methyl group.
21 citations
TL;DR: In this paper, an interfacial polymerization method was used to prepare fragrant microcapsules and the wall material was a polyurea formed by the reaction of triphenyl methane triisocynate (JQ-1) and TDI (2,4-toulene diisocyanate) with amines that were the reaction results of isocyanates with water.
Abstract: The interfacial polymerization method was used to prepare fragrant microcapsules. The wall material was a polyurea formed by the reaction of triphenyl methane triisocynate (JQ-1) and TDI (2,4-toulene diisocyanate) with amines that were the reaction results of isocyanates with water. During the preparation, An emulsifier (GPE2040), protective colloid (PVA) and catalyst (dibutyltin dilaurate) were used. The influences of the phase ratio (organic/aqueous), core/wall ratio, the amounts of emulsifier and protective colloid and the radio of triphenyl methane triisocyanate (JQ-1)/TDI (2,4-toluene diisocyanate) on particle size and size distribution of the microcapsules prepared were studied. A mechanism of the process of wall forming is suggested i.e. it might be that the isocyanate migrates outwards through the forming microcapsule's wall and reacts there with water to form amines, which in turn react with isocyanate groups nearby, resulting in the formation of polyurea and the polyurea formed accumulates on th...
20 citations
TL;DR: In this article, the structural behavior of polyethylene- graft-polystyrene sulfonic acid (PE- g-PSSA) membranes prepared by simultaneous radiation-induced grafting of styrene onto low density polyethylenes (PE) films followed by sulfonation was investigated.
Abstract: Structural behavior of polyethylene- graft-polystyrene sulfonic acid (PE- g-PSSA) membranes prepared by simultaneous radiation-induced grafting of styrene onto low density polyethylene (PE) films followed by sulfonation was investigated. FTIR, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to monitor the changes in the morphology and the crystallinity taking place in the membranes during the applied two step preparation procedure (grafting and sulfonation) and the variation of the degree of grafting. Thermal properties such as melting temperature (Tm) and the heat of melting (ΔHm) were also studied. The membranes showed a chemical structure of strongly hydrophilic nature due to the presence of (SO3 −) groups with their associated water molecules. Both grafting and subsequent sulfonation were found to induce significant structural changes in the PE matrix. The overall crystallinity of the membranes was found to decrease with the increase in the degree of grafting and that is ...
19 citations
TL;DR: In this paper, the silane coupling agents developed in the present investigation were utilized for coupling hydroxyl terminated polydimethylsiloxane with epoxy matrix and cured with hexamethylenediamine and diaminodiphenylmethane.
Abstract: Silane coupling agents, namely 3-[(2–aminoethyl)amino]propyltrimethoxysilane (AETMS), 3-[(2–maleicmonoamido)maleicmonoamido]propyltrimethoxysilane (MMTMS) and 3-[(2–maleicdiamido)maleicdiamido]propyltrimethoxysilane (MDTMS), were synthesized and characterized using FT–IR and viscosity studies. The silane coupling agents developed in the present investigation were utilized for coupling hydroxyl terminated polydimethylsiloxane with epoxy matrix and cured with hexamethylenediamine and diaminodiphenylmethane. The siliconized epoxy system developed using MDTMS and cured with diaminodiphenylmethane yielded higher glass transition temperature, better thermal stability and imparts higher crosslinking density due to its higher functionality (pentafunctional) than AETMS and MMTMS (trifunctional). Diamine–cured siliconized epoxy resins coupled with AETMS, MMTMS and MDTMS can be used for the development of high–performance advanced composites.
19 citations
TL;DR: In this article, it was shown that all components of PMMA/HA composite can be linked together either by ionic bonds or by hydrogen bonding, which significantly enhances the mechanical properties of such bioactive polymer systems and their functionality as an implant material.
Abstract: Chemical modification of HA with PAA and PVP solutions prior to PMMA/HA composite synthesis gave rise to a significant improvement of the bending and impact strength as well as a hardness and emollescence temperature of the final product. Polymer-polymer complexes, formed as a result of chemical interaction of non-reacted (with HA calcium ions) carboxyl group of PAA with PVP at the interface of HA with PMMA, play a key role in this improvement. Using IR spectroscopy and X-ray photoelectron spectroscopy, it was shown that all components of PMMA/HA composite can be linked together either by ionic bonds or by hydrogen bonding. This significantly enhances the mechanical properties of such bioactive polymer systems, and their functionality as an implant material.
19 citations
TL;DR: In this paper, a copolymer of polypropylene with maleic anhydride has been employed as compatibilizer agent, by previous mixing with PP matrix, which improved fiber/matrix adhesion, as shown by changes of the free surface energy of fibers.
Abstract: Fique fibers reinforced polypropylene (PP) composites have been investigated for different fiber lengths and contents. Fiber/matrix interfacial adhesion has been modified by fiber treatments such as mercerization, esterification with maleic anhydride, and adding of an isocyanate compound. A copolymer of polypropylene with maleic anhydride has been employed as compatibilizer agent, by previous mixing with PP matrix. Both compatibilization ways improve fiber/matrix adhesion, as shown by changes of the free surface energy of fibers and also by SEM analysis. Addition of the compatibilizer agent leads to higher flexural properties than those obtained for composites where the fibers were treated. Dynamical mechanical properties of composites seem to indicate that movement in the crystalline PP phase, possibly occurring on the fiber/matrix interphase, takes place in between the glass transition and the melting temperatures of PP matrix.
TL;DR: A series of novel crosslinked copolymers based on the monomers acrylamide, calcium acrylate, and sodium methacrylate were prepared by aqueous solution polymerization using ammonium persulfate (APS) as initiator and N, N-methylene-bis-acrylamides (MBA) as crosslinking agent.
Abstract: A series of novel crosslinked copolymers based on the monomers acrylamide (AM), calcium acrylate (CA), and sodium methacrylate (SMA) were prepared by aqueous solution polymerization using ammonium persulfate (APS) as initiator and N, N-methylene-bis-acrylamide (MBA) as crosslinking agent. The synthetic variables monomer concentration, crosslinker concentration, initiator concentration were also studied. The experimental results of SAPs show good absorbency in both water and NaCl solutions. The copolymers were characterized by IR spectroscopy. The water retention of SAPs was studied in an oven at 60 and 100°C.
TL;DR: In this paper, an electrochemical oxidative polymerization of 2-amino-4-phenylthiazole on platinum electrode in acid medium was carried out and different reaction parameters were investigated such as current density, acid concentration, monomer concentration, and temperature with duration of time.
Abstract: Electrochemical oxidative polymerization of 2-amino-4-phenylthiazole on platinum electrode in acid medium was carried out. Different reaction parameters were investigated such as current density, acid concentration, monomer concentration, and temperature with duration of time. The orders of the electropolymerization reaction were found to be 1.06, 1.10, 1.16 with respect to current density, acid concentration, and monomer concentration, respectively. The apparent activation energy (Ea) was found to be 61.04 kJ mol−1. The obtained polymer films were characterized by IR, UV, 1H-NMR, elemental analysis, thermogravimetric analysis, and cyclic voltammetry. The mechanism of the electrochemical polymerization reaction has been also discussed. Surface morphology of the obtained polymer film was characterized by X-ray diffraction and scanning electron microscopy.
TL;DR: Alanine/EPR rods (3 × 10 mm) for routine use in high-dose radiation applications have been prepared by a simple technique in the laboratory where alanine powder was mixed with molten mixture of paraffin wax and ethylene vinyl acetate copolymer (EVA).
Abstract: Alanine/EPR rods (3 × 10 mm) for routine use in high-dose radiation applications have been prepared by a simple technique in the laboratory where alanine powder was mixed with molten mixture of paraffin wax and ethylene vinyl acetate copolymer (EVA). The binding mixture EVA/Paraffin does not present interference or noise in the EPR signal before or after the irradiation. The rods show good mechanical properties for safe and multi-use handling. The rods can be used with good precision in the dose range from 1 to 125 kGy. The overall uncertainty for calibration of the EVAPA rod dosimeters at 2σ was found to be 4.56%. The dose response, influence of humidity and temperature during irradiation, energy dependence as well as post–irradiation storage at different conditions are discussed.
TL;DR: In this article, the effect of choice of reactants and their relative proportions on the properties of unsaturated polyester resins is investigated, including tensile strength, tensile modulus, elongation at break, toughness, impact strength, surface hardness, abrasion resistance, and water absorption.
Abstract: Unsaturated polyesters are synthesized in the laboratory by the condensation of saturated and unsaturated anhydrides with glycols. The condensate obtained is mixed with styrene monomer to get an unsaturated polyester resin formulation. The properties of the polyester resin synthesized are affected by the synthesis parameters. In this study, the parameters investigated are the effect of choice of reactants and their relative proportions. Properties such as tensile strength, tensile modulus, elongation-at-break, toughness, impact strength, surface hardness, abrasion resistance, and water absorption were tested after curing the resin. Various combinations of (a) maleic anhydride and phthalic anhydride, (b) propylene glycol and ethylene glycol, and (c) propylene glycol and diethylene glycol were used to investigate the effect on the properties of the synthesized resin. The combinations of the anhydrides and glycols that give optimum properties are identified. The results show that most of the properties are m...
TL;DR: In this paper, the kinetics of free radial polymerization of methyl methacrylate (MMA) using potassium peroxydisulfate as initiator in the presence of prophenonebenzyldimethylammonium chloride as phase transfer catalyst were studied.
Abstract: The kinetics of free radial polymerization of methyl methacrylate (MMA) using potassium peroxydisulfate as initiator in the presence of propiophenonebenzyldimethylammonium chloride as phase transfer catalyst were studied. The reactions were carried out under inert and unstirred conditions at constant temperature of 60°C in cyclohexanone/water biphase media. The dependence of the rate of polymerization on various experimental conditions, such as different concentrations of monomer, initiator and phase transfer catalyst (PTC) and different ionic strength, temperature and volume fraction of aqueous phase was studied. The order with respect to monomer, initiator and phase transfer catalyst was found to be 1, 0.5 and 0.5 respectively. The rate of polymerization (Rp) is independent of ionic strength and pH. However, an increase in the polarity of solvent and volume fraction of aqueous phase has slightly increased the Rp value. Based on the results obtained, a mechanism has been proposed for the polymerization r...
TL;DR: In this article, white rice husk ash (WRHA) and BRHA were incorporated as filler in natural rubber compounds and a conventional vulcanization system (CV) was chosen and cure studies were carried out on a TI-100 Curometer at 150, 160, 170 and 180°C.
Abstract: White rice husk ash (WRHA) and black rice husk ash (BRHA) were incorporated as filler in natural rubber (NR) compounds. A conventional vulcanization system (CV) was chosen and cure studies were carried out on a TI-100 Curometer at 150, 160, 170 and 180°C. From the rheometric data obtained at 150°C, a specific constant related to the filler structure was evaluated that allowed predictions on how the presence of filler would affect mechanical properties such as tensile and tear resistances, and hardness. Swelling behavior and examination of the fracture surface, which was carried out on a Scanning Electron Microscope (SEM), were used to get some idea on the interaction between the rubber matrix and the filler. WRHA showed a good reinforcing potential for NR compounds and catalytic effect upon vulcanization.
TL;DR: In this paper, the effect of the adhesion system components HRH (hydrated silica, resorcinol and hexamethylenetetramine) on the physico-mechanical properties of EPDM mixes was studied.
Abstract: The effect of the adhesion system components HRH (hydrated silica, resorcinol and hexamethylenetetramine) on the physico-mechanical properties of EPDM mixes was studied. The effect of different volume fractions of nylon–6 short fibers on these properties of EPDM vulcanizates was also studied before and after ageing. The results showed that the shorter the length of the fibers, the greater would be their efficiency in EPDM vulcanizates. The experimental results revealed that the best concentration of reinforcing fibers that leads to high stress at low strain was 25 phr. The presence of reinforcing fibers and the adhesion system greatly improve the ageing resistance of the rubber composites. This may be attributed to further formation of crosslinked resin, which balances the degradation that occurs during ageing.
TL;DR: In this paper, the melting-blending of poly(ethylene terephtalate) (PET) and polypropylene (PP) as well as polyamide 66 (PA66) and PP in wt. ratio 70/30, 50/50 and 30/70 was studied by X-ray diffraction, scanning electron microscopy (SEM), and static mechanical testing.
Abstract: Nanostructured polymer composites (NPC) are obtained by melt-blending of poly(ethylene terephtalate) (PET) and polypropylene (PP) as well as polyamide 66 (PA66) and PP in wt. ratio 70/30, 50/50 and 30/70, followed by cold drawing of the extruded bristle and compression molding of the drawn bristles in form of film. The blends are studied by X-ray diffraction, scanning electron microscopy (SEM), and static mechanical testing. SEM and X-ray reveal different blend morphologies created during the stages of NPC manufacturing: isotropic blend after extrusion, fibrillization of both components after drawing, izotropization of the PP matrix with preservation of the PET- or PA66 fibrils after hot pressing. Also observed was a strong epitaxial effect of the nanostructured microfibrils of PET or PA66 on the non-isothermal crystallization of PP during cooling after compression molding at 215°C. Thus, the cold drawn and thermally treated PET/PP and PA66/PP blends represent anisotropic transcrystalline structures. The ...
TL;DR: In this paper, the nonisothermal crystallization kinetics of polypropylene (PP)/nano-SiO2 composites were studied by means of differential scanning calorimetry (DSC).
Abstract: The nonisothermal crystallization kinetics of polypropylene (PP)/nano-SiO2 composites was studied by means of differential scanning calorimetry (DSC). The modified Avrami theories by Jeziorny, Ozawa, and Mo were used to analyze the data of DSC. The results showed that both the Jeziorny and Mo methods could describe this system very well, but the Ozawa analysis failed. The activation energy was evaluated by the Kissinger method. It was found that the crystallization activation energy of PP was higher than that of PP/nano-SiO2 composites. The determined results of mechanical properties showed that the addition of nano-SiO2 increased the mechanical properties of the PP. Micrographs of Polarized optical micrograph (POM) further demonstrated that nano-SiO2 could toughen the PP.
TL;DR: In this article, the effect of elevated temperatures on the release kinetics of heparin from polyurethane (PU) and ethylene vinyl acetate copolymer (EVA) was examined.
Abstract: The objectives of this study were to examine the effect of elevated temperatures on the release kinetics of heparin from polyurethane (PU) and ethylene vinyl acetate copolymer (EVA), and on the biological activity of heparin released from the polymer matrix. Monolithic samples, prepared by dispersing heparin in solutions of PU and EVA, were fabricated and evaluated for in vitro release rates. Comparisons were made on the release rate of heated and non-heated samples. Heating at 120°C had little effect on the release kinetics from PU and an increase on release from EVA. Bioactivity of pure heparin and heparin released from PU was also evaluated and were found to remain stable up to 210°C.
TL;DR: In this article, copolymers of N-ethyl carbazole (ECZ) with N-methyl Pyrrole (N-MPy) and 3-Methyl Thiophene (3-MTh) were synthesized on platinum substrate and electrochemical investigation of polymeric films was performed.
Abstract: Copolymers of N-ethyl Carbazole (ECZ) with N-Methyl Pyrrole (N-MPy) and 3-Methyl Thiophene (3-MTh) were synthesized on platinum substrate and electrochemical investigation of polymeric films was performed. The characterization of homopolymer and copolymer films was performed by electrochemical methods (i.e. polarization curves and cyclovoltammetric measurements), solid-state conductivity measurements and spectrophotometric methods comparatively. A possible scheme for the copolymerization has been suggested. Solid state conductivity of PECz can be improved by inclusion of 3MTh and NMPy into chain. The ionization potentials, Ip, electron affinity, Ea, optical band gap, Eg, peak potentials, Ep, and doping degrees, y, of copolymer electrodes were calculated from these measurements. Copolymer electrodes have lower Ip, Eg, Ep values and better switching properties in accordance with homopolymer electrodes. Presence of alkyl group gives solubility to copolymers obtained both chemically and electrochemically.
TL;DR: An intercrosslinked network of varying percentages of N,N′-bismaleimido-4,4′-disphenyl methane (BMI), vinyl ester oligomer (VEO) modified unsaturated polyester (UP) matrices have been developed.
Abstract: An intercrosslinked network of varying percentages of N,N′-bismaleimido-4,4′-disphenyl methane (BMI), vinyl ester oligomer (VEO) modified unsaturated polyester (UP) matrices have been developed. Vinyl ester oligomer was prepared by reacting commercially available epoxy resin GY 250 (Ciba-Geigy) and acrylic acid was used as toughening agent for unsaturated polyester resin. BMI-VEO-UP matrices were characterized for their mechanical properties, viz tensile strength, flexural strength and unntoched Izod impact test as per ASTM standards. The dielectric strength and water absorption measurements were also performed according to ASTM standards. Data obtained from mechanical studies, dielectric strength and water absorption indicate that the introduction of VEO into unsaturated polyester resin improves mechanical properties and affects the moisture resistance according to its percentage concentration. The incorporation of BMI into the VEO modified unsaturated polyester system improves mechanical properties, die...
TL;DR: In this article, the effects of wood fiber content on the void fraction, cell morphology, and notched Izod impact strength of microcellular foamed HDPE/PP blend composites with wood fiber were studied.
Abstract: The effects of wood fiber content on the void fraction, cell morphology, and notched Izod impact strength of microcellular foamed HDPE/PP blend composites with wood fiber were studied. The influence of wood fiber content on the carbon dioxide adsorption and desorption in the samples was also examined. Adsorption of carbon dioxide decreased with increased wood fiber content. Gas diffusion rates were faster as wood fiber content increased. The void fraction decreased dramatically when wood fiber was introduced in the blend. Environmental scanning electron microscopy (ESEM) was used to investigate the effects of wood fiber content on cell morphology. The 30:70 HDPE/PP polymer blend without wood fiber resulted in a high void fraction, with a uniform and well-developed microcellular structure, but when wood fiber was introduced, a uniform and well-developed microcellular structure could not be produced. The effects of foaming on Izod impact strength were dependent on wood fiber content.
TL;DR: In this paper, polymers containing s-triazine rings in the main chain were synthesized by interfacial polycondensation reaction of 2,4-dichloro-6-[4′-hydroxy-1′-naphthyl]-triazine with various aromatic diols such as BPA, bisphenol-s, and phenolphthalein (PH) using cationic emulsifier (CTMABr) and NaoH as acid acceptor.
Abstract: Polymers containing s-triazine rings in the main chain were synthesized by interfacial polycondensation reaction of 2,4-dichloro-6-[4′-hydroxy-1′-naphthyl]-s-triazine with various aromatic diols such as bisphenol-A (BPA), bisphenol-s (BPS), and phenolphthalein (PH) using cationic emulsifier (CTMABr) and NaoH as acid acceptor. Polymers were obtained in good yield and were characterized by solubility, intrinsic viscosity, and FT-IR spectral analysis. The relative solubilities of these polymer samples were determined in a variety of solvents. Thermal stability was studied by TGA technique.
TL;DR: In this paper, the formation of hexagonal modification of isotactic polypropylene (iPP) matrix, induced by motion of embedded natural fibers (NF) has been investigated by WAXS method.
Abstract: The formation of hexagonal modification (β) of isotactic polypropylene (iPP) matrix, induced by motion of embedded natural fibers (NF) has been investigated by WAXS method. Untreated and chemically modified flax as well as hemp fibers were used as NF. The motion temperature of NF was found to strongly influence the content of hexagonal modification. If the temperature of motion of NF is lower, then the amount of β-iPP significantly increases. The content of β-iPP also depends on the rate of motion of NF; however, the chemical modification of NF surface reduces the content of this form.
TL;DR: In this paper, the authors examined the effect of time duration of bacterial cellulose (BC) biosynthesis as well as the culture medium composition on molecular parameters of the obtained polymer and found that the degree of polymerization of BC increases as the duration of biosynthesis is prolonged up to 6 days.
Abstract: The aim of the present study was to examine the effect of time duration of bacterial cellulose (BC) biosynthesis as well as the culture medium composition on molecular parameters of the obtained polymer. It was found that the degree of polymerization of BC increases as the duration of biosynthesis is prolonged up to 6 days. A further prolongation of the process to 28 days lowers the degree of polymerization (DP) value and increases polydispersity. An examination of the effect of culture medium composition on the biosynthesis pointed out that the course of the process is mainly influenced by the chemical nature of the carbon source. The best results for molecular parameters were obtained for a medium containing 4% of glucose.
TL;DR: In this article, the incorporation of pre-characterized hexagonal ferrites, namely barium ferrite (BaFe12O19), into natural rubber matrix is carried out according to a suitable recipe for various loadings of the filler.
Abstract: Rubber ferrite composites (RFC) are magnetic polymer composites and have a variety of applications as flexible magnets, pressure/photo sensors, and microwave absorbers. The mouldability into complex shapes is one of the advantages of these magnetic elastomers. They have the potential of replacing the conventional ceramic materials, due to theire flexible nature. In the present study, the incorporation of pre-characterized hexagonal ferrites, namely barium ferrite (BaFe12O19), into natural rubber matrix is carried out according to a suitable recipe for various loadings of the filler. The processability of these compounds was determined by evaluating the cure characteristics: scorch time, cure time, and minimum and maximum torque. It has been found that the addition of magnetic fillers does not affect the processability of the composites, whereas the physical properties are modified. The magnetic properties of these composites containing various loadings of the magnetic filler were also investigated. The ma...
TL;DR: In this paper, a cold drawn blend of poly(ethylene terephthalate) (PET) and polyethylene (PE) (50/50 by wt.) was investigated during heating, melting and subsequent crystallization upon cooling of PE by means of wide-angle X-ray scattering (WAXS) of synchrotron radiation.
Abstract: A cold drawn blend of poly(ethylene terephthalate) (PET) and polyethylene (PE) (50/50 by wt.) was investigated during heating, melting, and subsequent crystallization upon cooling of PE by means of wide-angle X-ray scattering (WAXS) of synchrotron radiation. Strong epitaxial effects of the highly oriented PET on the very first stages of non-isothermal crystallization of PE during cooling of the cold drawn blend from 160°C to room temperature were found. WAXS shows that transcrystalline PE layers are formed around the PET fibrils. Within these layers, the PE crystallites are partly oriented at 90° with respect to their initial orientation (draw direction).
TL;DR: In this article, an interfacial polymerization method was employed for micro encapsulation, and the wall material was polyurea and the core materials were diethyl (o-) phthalate, dibutyl (O)-phthalate and dioctyl(o-) polysilicon.
Abstract: In this article, an interfacial polymerization method was employed for micro encapsulation. The wall material was polyurea and the core materials were diethyl (o-) phthalate, dibutyl (o-) phthalate and dioctyl (o-) phthalate. Poly (vinyl alcohol) (PVA) was used as protective colloid and GPE2040 was used as emulsifier. The effects of catalyst in different phases and core materials with different hydrophobicities on the morphology and particle size were studied. It was found that the surface of microcapsules form catalyst in aqueous phase were smoother and the average size was smaller than that with the catalyst in the organic phase and higher hydrophobicity gave smoother morphology.