Linear Expansion Ratio Research Articles

Development of BPPO-based anion exchange membranes for electrodialysis desalination applications

In this article, the fabrication of anion exchange membranes from brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) and N-methylmorpholine (NMM) has been reported. The prepared membranes were characterized in terms of ion exchange capacity (IEC), water uptake (WR), linear expansion ratio (LER), thermal stability, tensile strength (TS), alkaline stability, transport number and membrane area resistance. The ion exchange capacity, water uptake and linear expansion ratio of the prepared membranes are found to be increased with the increasing amount of NMM content in the membrane matrix. The membranes NMM-15 and NMM-18 are much more stable than QPPPO membrane in 2M NaOH at room temperature. Fourier transform infrared spectroscopy was employed to confirm the functional groups in the membrane. The surface morphology of fabricated membranes was studied by scanning electron microscopy. The membranes were used in electrodialytic removal of NaCl from aqueous solution at constant applied voltage. The membrane NMM-18 with higher hydrophilicity (IEC=1.74mmol/g & WR=27.40%) and lower membrane area resistance (1.5Ω·cm2) showed good ED performance than commercial membrane Neosepta AMX under the same experimental conditions.

Porous BPPO-based membranes modified by aromatic amine for acid recovery

Abstract This study reports novel triphenylamine based porous anion exchange membranes (AEMs) with brominated poly(2,6-dimethyl-1,4-phenyleneoxide) (BPPO) acting as a polymer backbone for acid recovery via diffusion dialysis. Physiochemical properties and electrochemical performance of prepared membranes were tuned by varying the dosage of triphenylamine and concentration of gelatin medium. Thermal property like thermogravimetric analysis (TGA) was investigated along with water uptake (WR), ion exchange capacity (IEC), linear expansion ratio, etc. The effect of triphenylamine content inside BPPO backbone was discussed in brief relation with acid recovery. The porous AEMs showed the water uptake (WR) values of 159.3–243.5%, ion exchange capacity (IEC) of 0.97–1.49 mmol/g and linear expansion ratios of 3.23–6.45%. The acid dialysis coefficients (UH) for different AEMs were found to be 0.0056–0.0104 m/h while the separation factors (S) between HCl and FeCl2 varied from 21.9 to 38.8 at 25 °C. The obtained values are comparable to those of commercial membrane DF-120B (0.004 m/h for UH, 24.3 for S at 25 °C). The effect of gelation medium on the morphology and DD performance of the selected membrane has also been investigated. The membranes reported in this manuscript are promising candidate for acid recovery via diffusion dialysis.

Facile and cost effective PVA based hybrid membrane fabrication for acid recovery

A new route for a hybrid anion exchange membrane was proposed for diffusion dialysis (DD) using polyvinyl alcohol (PVA) and glycidyl trimethyl ammonium chloride (EPTAC) as starting materials and aminopropyltriethoxysilane (KH550) as crosslinking agent. A series of membranes were prepared by varying the content of EPTAC. The obtained membranes were characterized with ion exchange capacity (IEC), water uptake (WR), linear expansion ratio (LER), tensile strength (TS), elongation at break (Eb), thermal decomposition temperature (Td) and initial decomposition temperature (IDT), etc. Their diffusion dialysis (DD) performance was conducted with a simulated feed containing 0.81M HCl+0.18M FeCl2. The results show that the membranes not only have good chemical/thermal stability, but possess high DD performance. The dialysis coefficients (UH) are in the range of 0.011–0.018m/h and the separation factors (S) are in the range of 18.5–21 at 25°C, both are higher than those of the commercial DF-120 membrane (0.009m/h for UH, 18.5 for S) determined at the same conditions. Considering its low cost and easy fabrication, the route for hybrid anion exchange membranes provides better candidates in DD process for acid recovery.

Effect of curing conditions on the hydration and performance of CFBC ash cementitious system

Circulating fluidized bed combustion (CFBC) ash can be used as supplementary cementitious material for concrete production for its high pozzolanic activity. We investigated the effect of curing conditions on the hydration and performance of CFBC ash-Portland cement system (30: 70, by mass) including hydration products, paste microstructure, linear expansion ratio, chemically combined water content and compressive strength. The results show that tobermorite rather than ettringite is generated under the condition of autoclaved curing. The expansion and mortar strength of the system cured in water is higher than those cured in air at a given age, and the strength and bulk volume may retract under the condition of air curing. In addition, autoclaved curing facilitates the increase of strength gain at early curing ages (the increase rate lowers down in the following ages) and the improvement of system volume stability. It is suggested that sufficient water is necessary for the curing of CFBC ash cementitious system, and autoclaved curing may be considered where volume stability is a primary concern.

Synthesis of a Biglucoside and Its Application as Montmorillonite Hydration Inhibitor

A biglucoside (BG) was synthesized with glucose and epichlorohydrin as raw materials. The inhibition of BG against montmorillonite swelling was investigated by various methods including montmorillonite linear expansion test, mud ball immersing test, thermogravimetric analysis, and scanning electron microscopy. The results show that the BG has good inhibition ability to the hydration swelling and dispersion of montmorillonite. Under the same condition, the linear expansion ratio of montmorillonite in BG solution is much lower than that of MEG. The particle distribution measurement, thermogravimetric analysis, FT-IR, and scanning electron microscopy results all prove the efficient inhibition of BG.

Methods for the control of volume stability of sulfur-rich CFBC ash cementitious systems

The destructive expansion of circulating fluidised bed combustion (CFBC) ash is the bottleneck problem for its utilisation in building materials. The effect of mixing pulverised-coal combustion (PCC) fly ash or clinker as well as autoclave curing on the expansion of a sulfur-rich CFBC ash cementitious system was investigated. It was found that the linear expansion ratio of CFBC ash–PCC fly ash–clinker mortar with no more than 3·5% SO3 is close to that of cement mortar. Moreover, the linear expansion ratio of CFBC ash–clinker–water paste dropped to less than 0·5 mm/m after autoclave curing. This study suggests that the volume stability of a CFBC ash cementitious system can be controlled effectively through autoclave curing or limiting the content of total SO3 to below 3·5%.

A simple and green preparation of PVA-based cation exchange hybrid membranes for alkali recovery

Here, a novel and green route for preparing cation exchange hybrid membranes is presented via polyvinyl alcohol (PVA) and 3-trihydroxysilyl-1-propanesulfonic acid (THOPS), during which aqueous media instead of organic solvents is used and sulfonation process is avoided. The resulting hybrid membranes have the water uptake (WR) of 38–86%, ion exchange capacities (IECs) of 0.70–1.56mmol/g, initial decomposition temperature (IDT) of 224–231°C, tensile strength (TS) of 13.3–40.7MPa, and favorable elongation at break (Eb) of 177–571%. The linear expansion ratio (LER) is in the range of 15–25% in water, while in the range of 18–27% in 1.0M alkali solution. Diffusion dialysis (DD) of NaOH/Na2WO4 system shows that the dialysis coefficients of NaOH (UOH) are in the range of 0.011–0.022m/h, with the separation factors (S) of 11.6–20.6. Consequently, apart from endowing the resulting hybrid membranes with desirable DD performances, the method employed herein is simple and environment-friendly particularly due to the avoidance of organic solvents and hazardous sulfonation agents.

Cation exchange hybrid membranes prepared from PVA and multisilicon copolymer for application in alkali recovery

Cation exchange multisilicon copolymer with a long main chain and many branched chains as well as high content of cation exchange and Si(OR)3 groups has been developed from sodium allylsulfonate (SAS) and vinyltrimethoxysilane (VTMS). The corresponding PVA/SiO2 cation exchange hybrid membranes have been prepared via the sol–gel process of the copolymer with poly(vinyl alcohol) (PVA).The hybrid membranes have the water uptake (WR) 84–106%, ion exchange capacity (IEC) 0.14–0.45mmol/g, initial decomposition temperature (IDT) 225–233°C and tensile strength (TS) 23.9–44.0MPa. They are stable in 1M NaOH solution with a linear expansion ratio (LER) of 17.7–18.3% and a weight loss percent of 4.3–5.5% for 30 days. The diffusion dialysis (DD) process for the alkali mixture indicates that the dialysis coefficients of NaOH (UOH) are around 0.0065–0.0086m/h and the separation factors (S) are in the range of 24.4–51.6 for the NaOH/Na2WO4 system and 13.9–9.6 for the NaOH/NaAlO2 system. Hence, the hybrid membranes can be potentially applied in the DD process for the alkali recovery.

Synthesis and Properties of Quaternary Phosphonium‐based Anion Exchange Membrane for Fuel Cells

AbstractQuaternary phosphonium‐based polyelectrolyte was synthesized from bromomethylated poly(2,6‐dimethyl‐1,4‐ phenylene oxide) (BPPO) by functionalization with tris(2,4,6‐trimethoxyphenyl) phosphine (TTMPP). Typically, excellent solubility of the polyelectrolyte in polar solvents, such as NMP and DMSO, allowed a solution‐casting strategy for preparation of anion exchange membrane (AEM) with properly ordered hydrophilic/hydrophobic nano‐scale phase separation morphology, which was visible in atomic force microscopic phase images. Accordingly, the optimized ionmeric AEM exhibited excellent hydroxide conductivity of 110 mS/cm at 70°C, but extremely restricted linear expansion ratio of below 7% at the same temperature. Additionally, such membrane could maintain flexibility and conductivity after an immersion treatment in 1 mol/L NaOH solution at 60°C for about 100 h, implying its potential in alkaline fuel cells.

Study on the Effect of Curing Condition on the Performance of FBC Ash

The cementitious system containing FBC ash is usually associated with volume expansion when cured in the normal temperature, due to its relatively high SO3 content. This paper presents a further study on the effect of different curing conditions on the flexural and compressive strength of FBC ash-Portland cement clinker mortar and linear expansion ratio of FBC ash-Portland cement clinker paste. The results show that autoclaved curing is more beneficial to increasing mortar strength in early days than standard curing, but with slow strength development in later period. Moreover, autoclaved curing could decrease the expansion of FBC ash greatly. This study confirms that the expansion of FBC ash can be significantly inhibited by autoclaved curing.

Influence of green banana flour substitution for cassava starch on the nutrition, color, texture and sensory quality in two types of snacks

Green banana flour (GBF), as a functional ingredient, was used to partially substitute cassava starch in two types of snacks, viz. fish cracker (FC) and cassava cracker (CC). It is observed that use of GBF increased the nutritional value including enhancement of dietary fiber, essential minerals, polyphenol content, antioxidant capacity and decreased oil content to varying degrees depending on the substitution level in these two crackers. However, its use compromised the textural properties in terms of the linear expansion ratio, crispness, bulk density, porosity and color. Sensory evaluation showed that the products with not more than 40 g substitution level by GBF from 100 g cassava starch in CC and not more than 15 g in FC were acceptable by the panelists.

Inhibition of the Expansion of CFBC Ash

The destructive expansion of CFBC ash is the bottleneck problem for its utilization in building materials. The addition of chemical substances and autoclave curing were used to inhibit the expansion in the paper. The results show that the addition of 1% CaCl2 or 1% Na2CO3 can decrease the 28 d linear expansion ratio of CFBC ash-water mortars by about 19%, with no disadvantage influence on the compressive strength. Moreover, the linear expansion ratio of CFBC ash-clinker-water pastes was below 5×10-4 after autoclave curing. The work confirms that the expansion of CFBC ash can be inhibited effectively by the way of autoclave curing.

Synthesis and properties of side-chain-type sulfonated poly(phenylene oxide) for proton exchange membranes

To obtain side-chain-type proton exchange membranes, bromomethylated poly(phenylene oxide) (BPPO) was modified via etherification reaction under mild conditions to introduce pendant naphthalene sulfonic acid groups. The reaction has been proved facile and efficient, and more than 70% of benzyl bromide groups of BPPO could be substituted. Their solution-cast membranes showed potential application as proton exchange membranes. The membranes had acceptable proton conductivity ranging from 38 to 71 mS/cm (25 °C, 100% relative humidity) in spite of relatively low ion exchange capacity ranging from 0.93 to 1.62 mmol/g. Meanwhile they exhibited outstanding dimensional stability in water (i.e., no more than 32% water uptake and no more than 11% linear expansion ratio in water at 80 °C), which was supposed to be ascribed to unique π–π interaction between pendant naphthalene rings.

Dilatometry and high-temperature X-ray diffractometry study of La 0.6Sr 0.4Ti 0.1Fe 0.9O 3 − δ and La 0.6Sr 0.4Ti 0.3Fe 0.7O 3 − δ oxygen-permeable membranes

The thermal expansion behavior of La 0.6Sr 0.4Ti 1 − x Fe xO 3 − δ (x = 0.7 and 0.9) was investigated by dilatometry and in situ powder X-ray diffractometry at 25 and 1000 °C under controlled oxygen partial pressures in air and at reducing atmosphere, P O2 = 0.21 and 1 × 10 − 20 atm, respectively. The sintered samples of x = 0.7 and 0.9 showed positive thermal expansions, i.e., 12.4 and 14.4 × 10 − 6 K − 1 , respectively, in air up to 1000 °C, and also larger expansions at lower partial oxygen pressures, with a linear thermal expansion ratio factor of 0.10 and 0.40%. The change in the crystal lattice parameters analyzed by XRD Rietveld refinement showed that the crystal lattice volume increased with an increase in temperature and a decrease P O2. The linear thermal expansion rates estimated from volume change of the XRD data for the oxides of x = 0.7 and 0.9, were 0.13 and 0.27%, which corresponds to those of estimated from the dilatometry.

Solvent induced transition from wrinkles to creases in thin film gels with depth-wise crosslinking gradients

We investigated solvent induced transition of surface instability from wrinkles to creases in poly(2-hydroxyethyl methacrylate) (PHEMA) gels with depth-wise crosslinking gradients. The mode of surface instability and morphology of surface patterns was found to be dependent on the equilibrium linear expansion, which was a function of crosslinker concentration and the solvent–polymer interaction. The maximum linear expansion was obtained when the PHEMA film was swollen in a good solvent, which had the Hildebrand solubility parameter (δs) close to that of PHEMA gels, 26.6 to 29.6 MPa1/2. In a relatively poor solvent (e.g. water), wrinkling patterns were obtained and the morphoplogy was determined by the concentration of the crosslinker, ethylene glycol dimethacrylate (EGDMA). In a good solvent, such as alcohol and alcohol/water mixture, the equilibrium linear expansion ratio increased significantly, leading to the transition from wrinkling to creasing instability. In an ethanol/water mixture, we systematically varied the ratio between ethanol and water and observed the transition from wrinkling to creasing when gradually adding ethanol to water, and the reverse transition when adding water in ethanol. The onset of the linear expansion ratio for creasing (αc,c) was again found dependent on EGDMA concentration: αc,c ≈ 2.00 and 1.3, respectively, for gels with 1 and 3 wt% EGDMA. Finally, we demonstrated confinement of the creases by combining swelling and photopatterning.

Cassava starch snack formulation using functional shell fish by‐products: mechanical, sorption and geometric properties

AbstractUtilisation of by‐products of the shrimp industry, namely shrimp head protein and chitosan, could lead to a functional snack with substantial market in Asia. Produced on a cassava starch base this would lead to a product with shrimp flavour and chitosan's lipid adsorption capacity. The characteristics of such a mixture with 82% deacetylated chitosan and salt was investigated by Rapid Visco Analyser and instrumental Texture Profile Analyser using the Doehlert Uniform Shell experimental design. Polynomial models explained more than 88% of variability of responses. A significant effect of salt, shrimp head proteins and chitosan was observed on cassava starch gelling characteristics. A corresponding heat and shear stress resistance ability was observed while there was a reduction in its specific swelling power. Snacks prepared in the form of chips and extruded product confirmed their good potential for added value to snack foods in respect of their 90–94% linear expansion ratio, up to 1.1 kg maximum breaking force and up to 4.5 radial expansion ratio. Adsorption isotherm of extrudates had a maximum water content target of 115 g kg−1 dry matter at 25 °C for a later formulation and extrusion optimisation, in order to guarantee consumer texture acceptability. Corresponding shelf‐lives of extrudates were calculated at three storage conditions. Copyright © 2005 Society of Chemical Industry

ADT 43- A high yielding short duration rice variety for Tamil Nadu

Rice culture AD 93013, a derivative of IR 50/ Improved White Ponni was released as ADT 43 during January 1998 for general cultivation in Tamil Nadu. It recorded a mean yield of 5933 kg ha' in 110 days with 6.0, 6.2 and 6.5% higher yield than those of IR 50. ADT 36 and ASD 18 respectively. The biological yield of ADT 43 was 14.5 t ha¹ (5.9 t of grain and 8.6 t of straw) and its potential grain yield was 10.0 t ha. It is semi dwarf in stature with medium slender white rice finer than improved White Ponni. ADT 43 is resistant to Green leaf hopper and field tolerant to stem borer and Gallmidge. The rice possess high amylose content (> 25%) with good linear elongation (1.72 times) and high volume expansion ratio (4.6) after cooking. It is suitable for growing in the first crop season (Sornavari/Kar/ Kuruvai) of Tamil Nadu except Kanyakumari and Tuticorin districts.

A comparison of theoretical and empirical expansion of coals in the high pressure sorption of methane

Empirical data on coal expansion due to high pressure sorption of methane were compared with the linear expansion ratio predicted on the basis of the theoretical dual sorption model. The model is based on a thermodynamical treatment of the sorption process, viewed as consisting of absorption and adsorption subprocesses, with a submicroporous and heterogeneous copolymeric nature of coal being assumed. While regarding the expansion of coal as a result of the absorption subprocess only, this model may be used to evaluate the theoretical linear expansion ratio. Three coal-methane systems have been examined. Coals with different degrees of metamorphism (wt% C (daf): 80.9, 86.5, 92.4) were used. Sorption and expansion measurements were carried out at 298 K, over the pressure range 0.5–4.5 MPa. Very good agreement of theoretical and empirical values was found in the lower pressure range. Differences observed in the higher pressure range suggest compression of pores was significant.