Structural investigation of anionic functional poly(vinyl alcohol) doped polypyrrole nanospheres

This article reports on a facile route for the preparation of polypyrrole nanospheres with improved water solubility, ordering and conductivity in the presence of a polyelectrolyte, such as phosphorylated polyvinyl alcohol. The phosphorylated polyvinyl alcohol (PPVA) was used as both the stabilizer and the dopant in the chemical oxidative polymerization of pyrrole. The resulting PPVA doped polypyrrole (PPy) nanocomposites (PPy-PPVA) were characterized with FTIR, TGA, SEM and AFM techniques. The electrical conductivity of polymer was measured by four-point probe method. Our observation and results suggest a plausible formation mechanism of PPy nanospheres, PPVA micelle might have functioned as ‘template’ during the polymerization of pyrrole monomers, meanwhile, the PPy chains doped with phosphate group. It was found that the size decreased and their dispersion stability in water increased with the increasing feeding ratio of PPVA. The conductivity of PPy with different morphologies was also measured and compared. When the PPVA: pyrrole feeding ratio ranged from 20 to 50 wt%, the PPy-PPVA nanoparticles showed spherical shape with excellent uniformity, good electrical conductivity (up to 33.1 S·cm^?1), and weakly temperature dependent conductivity. It’s worth mentioning that the PPy-PPVA nanocomposite prepared in high PPVA feeding ratio has been well-dispersed for more than 24 months, which indicates its significant dispersion stability.     

The enhanced electrical conductivity of cotton fabrics via polymeric nanocomposites

Enhanced electrical conductivity of cotton fabrics coated with polyaniline (PANI) and PANI/carbon coated Fe (Fe@C) and carbon coated Co (Co@C) metal nanoparticles (NPs) composites were investigated. PANI/metal nanoparticle (NP) composites were fabricated with a surface initialized polymerization method and silanization helped with chemical bonding to cotton. The volume resistivity of the samples and structural characterizations were assessed by relevant methods. The results showed that enhanced electrical conductivity, thermal stability and magnetization were obtained via polymeric nanocomposites (PNC) and all these findings revealed that PANI/metal NP PNC coated cotton fabrics would exhibit good level electromagnetic shielding performance as a function of combined electrical conductivity and magnetization which is the objective of our future studies.     

Synthesis and characterization of electrically conductive composite films of polypyrrole/poly(acrylonitrile-co-styrene)

Homogeneus Polypyrrole (PPy)/poly(acrylonitrile-co-styrene) (SAN) composite thin films were prepared by chemical polymerization of pyrrole on poly(acrylonitrile-co-styrene) matrix. Ce (IV) is used as an oxidant for in-situ polymerizion of pyrrole on SAN matrix, having an advantageous over the impregnation method. The formation and incorporation of PPy in the copolymer matrix were confirmed by FTIR-ATR and UV-Visible spectrophotometric measurements. Thermal analyses showed that after polymerization of Py in copolymer matrix, thermal behavior of SAN was changed and derivative of weight loss at this temperature was increased by increasing of PPy content. XPS and FTIR-ATR analysis of composite films indicated cerium salt with nitrate ion acted as a dopant. The increase in the AC electrical conductivity of the PPy/SAN composites over pure SAN was observed. At lower frequency up to 10⁵ Hz, conductivity was shown an independent behavior from frequency; but at high frequencies (10⁵–10⁷ Hz), dependence on frequency was explained by polaron and bipolaron formations of PPy. The dispersion of PPy particles in copolymer matrix was proven by SEM, AFM and digital camera. By the increase of PPy content in the composite films, increase in AC conductivities, and decrease in dielectric constants and loss were observed.     

Effects of poultry manure on soil solution electrical conductivity and early growth of Monochoria vaginalis

We investigated the effect of poultry manure (PM) on the occurrence and early growth of Monochoria vaginalis in relation to soil solution electrical conductivity (SSEC). PM was applied at rates corresponding to 0 g of nitrogen (N) m^?2 (PM-0), 1 g N m^?2 (PM-1), 3 g N m^?2 (PM-3), and 5 g N m^?2 (PM-5). At 7 d post-seeding, the soil solution was sampled to measure EC, and also the emergence and growth of M. vaginalis were evaluated. The emergence rate of M. vaginalis decreased with increasing application rate of PM and SSEC. SSEC was significantly negatively correlated with the emergence rate of M. vaginalis seedlings. The average leaf number and length of M. vaginalis did not differ between PM-0, PM-1, and PM-3, but were significantly lower in PM-5. In summary, PM would allow to better control the emergence and early growth of M. vaginalis.     

Spatial variability of bulk soil electrical conductivity in a Malaysian paddy field: key to soil management

On-the-go EC sensor is a useful tool in mapping the apparent soil electrical conductivity (EC_a) to identify areas of contrasting soil properties. In non-saline soils, EC_a is a substitute measurement for soil texture. It is directly related to both water holding capacity and cation exchange capacity (CEC), which are key ingredients of productivity. This sensor measures the EC_a across a field quickly and gives detailed soil features (1-s interval) with few operators. Hence, a dense sampling is possible and therefore a high resolution EC_a map can be produced. This paper presents experiences in acquiring detailed EC_a information that is correlated to other soil properties for precision farming of rice. The study was conducted on a 9 ha rice plot in MARDI Seberang Prai Station, Penang. The VerisEC3100 was pulled across the field in a series of parallel transects spaced about 15 m apart. The study showed that shallow and deep EC_a had high correlation and shallow EC_a had significant correlation to P. Deep EC_a had significant correlation to P, K and yield. Regression equations showed that N and P could be estimated by shallow EC_a but, pH, K and yield were better estimated by deep EC_a. This study was able to draw some basic ideas of nutrient zone management according to precision farming technique.     

Antibacterial efficacy of polypyrrole in textile applications

This paper describes application and evaluation of polypyrrole as an antibacterial polymer. Polypyrrole was produced embedding two doping agents: chloride and dicyclohexyl sulfosuccinate ions. Stability of the antibacterial efficacy of polypyrrole deposited on cotton fabrics was assessed before and after three different kinds of washing (namely, laundering with anionic and non-ionic detergents and dry-cleaning). Polypyrrole showed excellent antibacterial properties (100 % of bacterial reduction) against Escherichia coli for both doping agents. Treated fabrics were further characterised by scanning electron microscopy, energy dispersive X-ray analysis and infrared spectroscopy. The antibacterial efficacy diminished after launderings with anionic and non-ionic detergents because of two different mechanisms: the neutralisation of positive charges under alkali conditions (dedoping), and a partial removal of polypyrrole by abrasion and surfactant action. After dry-cleaning, polypyrrole embedding chloride and dicyclohexyl sulfosuccinate ions still showed excellent antibacterial efficacy. Moreover, scanning electron microscopy investigations were used to intuitively explain the bactericidal mechanism of polypyrrole on Escherichia coli bacteria.     

Morphology and electrical conductivity of PS/PMMA/SMMA blends filled with carbon black

An alternative strategy to reduce the percolation threshold of carbon black (CB) in polymer blends was investigated using random copolymer ternary blends of polystyrene (PS), poly(methyl methacrylate) (PMMA), and a styrene-methyl methacrylate random copolymer (SMMA). The target morphology was to selectively locate CB particles in the encapsulating layer of SMMA during melt mixing. The CB used in this study is BP-2000 from Cabot and has a strong selective affinity to PS. Even when the CB was premixed with SMMA, it moves to the PS phase during the melt mixing. However, we also observed the CB particles located at the interface between SMMA and PS phases. Through this study it is found that the interaction between polymers and CB particles is critical for selectively localizing CB particles in multi-component polymer blends. Although appropriate processing condition may retard the movement of CB particles to the polymer phase with affinity, it cannot prevent it completely and locate them to the SMMA phase, which is not thermodynamically favored. To locate CB particles in an encapsulating layer of ternary polymer blends, first of all, polymers forming it should have selective affinity to CB.     

Influence of the draw ratio on the mechanical properties and electrical conductivity of nanofilled thermoplastic polyurethane fibers

Electrically conducting textile fibers were produced by wet-spinning under various volume fractions using thermoplastic polyurethane (TPU) as a polymer and carbon black (CB), Ag-powder, multi-walled carbon nanotubes (MWCNTs), which are widely used as electrically conducting nanofillers. After applying the fiber to the heat drawing process at different draw ratios, the filler volume fraction, linear density, breaking to strength, and electrical conductivity according to each draw ratio and volume fraction. In addition, scanning electron microscopy (SEM) images were taken. The breaking to strength of the TPU fiber containing the nanofillers increased with increasing draw ratio. At a draw ratio of 2.5, the breaking to strength of the TPU fiber increased by 105 % for neat-TPU, 88 % for CB, 86 % for Ag-powder, and 127 % for MWCNT compared to the undrawn fiber. The breaking to strength of the TPU fiber containing CB decreased gradually with increasing volume fraction, and in case of Ag-powder, it decreased sharply owing to its specific gravity. The electrical conductivity of the TPU fiber containing CB and Ag-powder decreased with increasing draw ratio, but the electrical conductivity of the TPU fiber containing MWCNT increased rapidly after the addition of 1.34 vol. % or over. The moment when the aggregation of MWCNT occurred and its breaking to strength started to decrease was determined to be the percolation threshold of the electrical conductivity. The heat drawing process of the fiber-form material containing the anisotropic electrical conductivity nanofillers make the percolation threshold of the electrical conductivity and the maximum breaking to strength appear at a lower volume fraction. This is effective in the development of a breaking to strength and electrical conductivity.     

Effect of solvent and blended polymer on electrical conductivity of PEDOT:PSS/polymer blended nanofibers

Poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) and polyethylene oxide (PEO) (or polyvinyl alcohol (PVA)) blended electrospun nanofibers were prepared in the presence of dimethyl sulfoxide (DMSO) and ethylene glycol (EG). The effects of added solvents (DMSO and EG) and blended polymers (PEO and PVA) on electrical conductivity and current-voltage (I-V) response were investigated. Electrical conductivity was dependent on both the additional solvent and blended polymers. PEDOT:PSS/PEO blended nanofibers showed a much higher electrical conductivity than PEDOT:PSS/PVA. EG blended PEDOT:PSS/PEO blended nanofibers showed much higher electrical conductivity than DMSO. The PEDOT:PSS/PEO/EG blended nanofibers web showed the highest value in I-V response.     

Microstructures and electrical properties of composite films based on carbon nanotube and para-aramid containing cyano side group

We report the microstructures and electrical properties of poly(2-cyano-1,4-phenylene terephthalamide) (cyPPTA)-based composite films including pristine multi-walled carbon nanotube (MWCNT) of 0.3-10.0 wt%, which were manufactured by ultrasonication-based solution mixing and casting techniques. FT-IR spectra of the composite films revealed the existence of specific interaction between cyPPTA and MWCNT. Accordingly, the pristine MWCNTs were found to be dispersed uniformly in the cyPPTA matrix, as confirmed by TEM images. The electrical resistivity of the composite films decreased considerably from ~10¹⁰ Ω cm to ~10⁰ Ω cm with the increase of the MWCNT content by forming a conductive percolation threshold at ~0.525 wt%. The composite films with 3.0-10.0 wt% MWCNT contents, which have sufficiently low electrical resistivity of ~10²-10⁰ Ω cm, exhibited excellent electric heating performance by attaining high maximum temperatures and electric power efficiency under given applied voltages of 10-100 V. Since the thermal decomposition of the composite films took place at 520-600 °C under air atmosphere, cyPPTA/MWCNT composite films could be used for high performance electric heating, antistatic, and EMI shielding materials.     

砖茶氟的防龋功效及其应用

龋齿是世界性疾病,通过对青砖茶的防龋试验,表明它有明显的防龋效果,且价廉味浓,便于普及推广。     

Structure,electrical and mechanical properties of polyamide 66/acid-treated MWCNT composite films prepared by solution mixing in the presence of nonionic surfactant

Two different sets of polyamide 66(PA66)-based composite films containing 2.0-10.0 wt% acid-treated multiwalled carbon nanotubes (MWCNT) were manufactured by solution mixing and casting method in the presence or absence of a nonionic surfactant. For the improved dispersion and interfacial interaction of MWCNTs in the PA66 matrix, carboxylic acid-functionalized MWCNTs were prepared by the acid-treatment of pristine MWCNTs. The uniform dispersion of the acidtreated MWCNTs in the PA66 matrix was confirmed from FE-SEM images of the fractured composite film surfaces. DSC thermograms supported that the acid-treated MWCNTs served as nucleating agents for the melt-crystallization of PA66 in both composite films prepared with/without the addition of the surfactant. The electrical and tensile mechanical properties of the composite films prepared with the surfactant were ~20 % higher than those of the composite films manufactured without the surfactant. For both composite films, sheet resistivity and tensile mechanical properties were found to be highly decreased and increased, respectively, with the increment of the acid-treated MWCNT content.     

Spatial variability of soil saturated hydraulic conductivity in paddy field in accordance to subsurface percolation

Insufficient puddling with inappropriate implements or imprecise time/intensity may alter saturated water flow in paddy soil spatially or temporary due to change in aggregate size distribution, dry bulk density, saturated hydraulic conductivity, and percolation rate of the soil. In this study, spatial variability of saturated hydraulic conductivity (K _s), a key parameter of the saturated water flow, in Fuchu Honmachi paddy plot (100 m × 28 m) was characterized based on dielectric or ADR dry bulk density (ρ_b-ADR) with help of non-similar media concept (NSMC) and geostatistics model to meet its correlation to subsurface percolation. A 100 cc core and an ADR data were sampled from each sub-plot (7 m × 7.5 m), and then were used for measuring and predicting ρ_b and K _s. The predicted data agreed with the measured ones, in which they fitted well the x = y line with RMSE of 0.029 cm³ cm⁻³ (R ² = 0.68), 0.027 g cm⁻³ (R ² = 0.71) (ρ_b), and 0.098 cm d⁻¹ (R ² = 0.45) for θ, ρ_b, and K _s, respectively. The predicted ρ_b and K _s had similar trend in spatial variability to the measured ones particularly within the distance of 46.3–51.9 m and 26.2–27.9 m, respectively. The spatial variability of the predicted K _s coincided to that of the subsurface percolation rate, in which they had similar distance of dependence. The results indicated that the presenting method can be reasonably accepted.     

Effect of initial water content on saturated hydraulic conductivity in desalinization with slaking and drying

Soil slaking is an environment-friendly technique that is gaining importance in restoring saline soils. The objective of this article is to evaluate the effect of initial water content (IWC) on saturated hydraulic conductivity (K _s) in desalinization with slaking and drying. Accordingly, a slaking test was carried out during February, 2009 for evaluating the effects of slaking and drying on K _s, sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP) under various IWC. We prepared natural and air-dried soils of paddy field in Kojima Bay Polder, Japan to give different pre-drying, air-dried, and not dried (natural). The air-dried soils were resaturated. Each soil was well mixed, then dried to different initial moisture contents (60, 50, 40, 30, 20, and 10% by weight). The specimens were immersed into water in the pot for 24 h. The K _s was measured, and cations in slaked and unslaked soils were analyzed. The K _s was high under the water content below 30% in both the natural and the air-dried soils. But the effects were more pronounced in the natural soil. The air-dried soil showed far smaller K _s than the natural soil. In outer solution, the highest SAR was noted at 30% in the natural and 30 and 20% in the air-dried soils. Significant decrease in ESP of the soils (slaked + unslaked) was also observed at the same water content. Lower water content was more effective in decreasing the soil ESP after desalinization from saline soil. The natural soil showed lower ESP and higher porosity, which was considered as a reason for higher K _s of natural soil than that of air-dried soils. The results indicated that lower water content (10–30%) had no hazardous effect on K _s by slaking and drying of soil.     

Evaluation of infiltration models and field-saturated hydraulic conductivity in situ infiltration tests during the dry season

Paddy and Water Environment - Field-saturated hydraulic conductivity (Kfs) is an important parameter used to estimate field water requirements in irrigation systems, although it is widely...     

Reinforcement of wet milled jute nano/micro particles in polyvinyl alcohol films

Textile industry generate significant amount of waste fibres in form of short lengths during mechanical processing. However these short fibres possess excellent properties suitable for many other applications. The objective of this work was to use them for the preparation of nanoparticles/nanofibres as fillers in biodegradable composite applications such as food packaging, agriculture mulch films, automotive plastics, etc. The present paper concerns with jute fibres as a source of nanocellulose for reinforcement of PVA mulch films. Jute fibres were first refined to micro/nanoscale particles in form of nanofibrillar cellulose (NFC) by high energy planetary ball milling process in dry and wet condition. Wet milling was observed more efficient than dry milling in terms of unimodality of size distribution with reduction in size below 500 nm after milling for 3 hours. Later the obtained particles were used as fillers in Poly vinyl alcohol (PVA) films and their reinforcement evaluated based on thermal properties. It was observed that glass transition temperature (T_g) of PVA films improved from 84.36 °C to 95.22 °C after addition of 5 % jute particles without affecting % crystallinity and melting temperature (T _m) of PVA. Dynamic mechanical analysis of composite films with 5 % jute particles showed higher value of 14×10⁸ Pa for storage modulus in comparison to 9×10⁸ Pa of neat composite film. The percolation effect was observed more above glass transition temperature which consequently resulted in improved transfer of stiffness from jute particles to PVA matrix above 50 °C. The percolation phenomena also explained the improvement in thermal stability by 10 °C for every increased loading of jute particles due to formation of hydrogen bonds with PVA matrix.     

The effect of Rosa damascena essential oil on the amygdala electrical kindling seizures in rat

We investigated the effect of Rosa damascena Mill, essential oil on the development of induced amygdala kindling seizures. Male Wistar rats were implanted with one tripolar and two monopolar electrodes in right basolateral amygdala and dura surface, respectively. The control group was injected solvent of essential oil and two experimental groups were injected 750 and 1000 mg kg(-1) of essential oil (ip), 30 min before a daily kindling stimulation. The number of stimulations required for the first appearance of seizure stages was significantly larger in two experimental groups than in control group. Mean after discharge duration was significantly different and essential oil reduced the increase of after discharge duration. Mean after discharge amplitude was also shorter in the groups treated with essential oil than in control group. Duration time for 5th stage of seizure at fully-kindled rats was significantly shorter in two experimental groups than control group. These results suggest that Rosa damascena essential oil significantly retarded the development of seizure stages and possesses the ability to counteract kindling acquisition. The flavonoids of Rosa damascena may act via GABAA receptors as previous studies have proposed for flavonoids of other medicinal plants. More detailed studies are recommended to define the effective component(s) of Rosa on different types of epilepsy.     

Development of biodegradable films based on blue corn flour with potential applications in food packaging. Effects of plasticizers on mechanical,thermal, and microstructural properties of flour films

In the present study, blue corn flour films were developed. The cereal grain’s total composition (excluding the pericarp) is used to obtain the films. The plasticizing effects of two different polyols such as glycerol and sorbitol on the mechanical, thermal, and microstructural properties of flour films were researched. The results showed that films plasticized with sorbitol had better mechanical properties and less affinity for water than those plasticized with glycerol. The sorbitol-plasticized films were more rigid and did not lose their integrity when immersed in water. The ATR-FTIR spectra of blue corn flour plasticizer with sorbitol showed the presence of the additional band at 1745 cm⁻¹ characteristic of the vibrational carbonyl peak, which confirms the chemical linkages between sorbitol and a polymeric matrix. The effect of the plasticizer on the glass transition temperature (T_g) was characterized using differential scanning calorimetry (DSC). T_g decreased as the plasticizer content increased. Plasticized glycerol films showed lower T_g values than those with sorbitol. SEM observations showed that it was necessary to add plasticizer to maintain film integrity. The sorbitol-plasticized flour films revealed better adhesion between phases, and these films showed a compact structure.     

Properties of polyacrylonitrile/single wall carbon nanotube composite films prepared in nitric acid

Nanocomposite films were prepared by casting the solution of polyacrylonitrile (PAN) and single wall nanotube (SWNT) in nitric acid subsequent to sonication. Even though SWNT shows good dispersion visually, the reinforcing effect was not satisfactory. The G-band Raman spectra of the drawn film clearly demonstrated that SWNTs in the film are well-oriented along the drawing axis of the film. The electrical resistivity of the film prepared using nitric acid was lower than that of the film using DMF. Thus, nitric acid is presumably more effective in dispersing nanotubes than DMF.