A new cationic surfactant N,N′-dimethyl-N-acryloyloxyundecyl piperazinium bromide and its pH-sensitive gels by microemulsion polymerisation

A piperazine-based cationic surfactant, N,N′-dimethyl-N-acryloyloxyundecyl piperazinium bromide (DAOUPB) was synthesised by a two-step procedure. The monomer was polymerised in two new microemulsion systems: (i) DAOUPB/water/methyl methacrylate (MMA):hydroxyethylmethacrylate (HEMA) and (ii) DAOUPB/water/acrylonitrile with ethyleneglycol dimethacrylate (EGDMA) as the crosslinking agent. Transparent solid polymeric materials were obtained by photo-initiated polymerisation of some of these microemulsion compositions. Most of the bicontinuous microemulsions investigated gelled within 10 min resulting in transparent solid polymers. The electron micrographs of the polymers obtained from microemulsion compositions containing MMA:HEMA did not show any micropores, while those obtained using acrylonitrile revealed the existence of open-cell type micropores and also of the bicontinuous nature of the system. The width of the bicontinuous structure (micropores) was about 33 nm in the dry state, with long and winding channels of random distribution. The swelling of the gels was highly sensitive to pH.     

Nanocarbon in Polymeric Nanocomposite Hydrogel—Design and Multi-Functional Tendencies

ABSTRACT

Polymeric hydrogels are three dimensional polymeric networks. Incorporation of nanoparticle in polymers has led to emerging class of nanocomposite hydrogel having hierarchical 3D nanostructured mesh. This review scrutinizes the effect of nanomaterials on design, structure, functional properties, and applications of polymeric nanocomposite hydrogels. Herein, current state of the art in different types of polymeric nanocomposite hydrogels with graphene, carbon nanotube, nanodiamond, and fullerene has been highlighted. The polymeric nanocomposite hydrogels have gained considerable recognition for battery electrode, shape memory material, absorbent, oil/water separation, and biomedical application. Current challenges and opportunities in the field of polymeric nanocomposite hydrogel have also been discussed.     

Binary Adsorption Isotherms of Water and Ethyl Acetate Vapor for Materials Contained in a Box of a Tobacco Product

ABSTRACT

An experimental study has been carried out on the characteristics of binary adsorption isotherms of water and volatile flavor for typical materials used in a box of a tobacco product or cigarettes. Ethyl acetate chosen as a model for water–soluble volatile flavor. Binary adsorption isotherms for the tobacco, papers, filters, and activated carbons were measured with a flow–type multi–component adsorption system under the canstant conditions of temperature a t 303 K and vapor pressure of water a t 2.5 kPain the vapor pressure range of ethyl acetate from 0 to 4.2 kPa. A linear equation was applied to express the binary adsorption isotherms for the tobacco, papers and filters, while a Dubinin–Astakhov equation was applied for the activated carbons. The binary adsorption was characterized into three groups, depending on the selectivity as well as the mechanism of adsorption; i.e.(l) for tobacco and papers, water was adsorbed much greater rather than ethyl acetate, (2) for filters, ethyl acetate was adsorbed on the surface as great as water, (3) for activated carbons, ethyl acetate was adsorbed much greater onto their micropores rather than water. The results showed that ethyl     

Sorption Equilibrium in Relation to the Spatial Distribution of Molecules — Application to Desorption of Potato

ABSTRACT

An analysis of desorption isotherms for potato shows the following probable qualities in the water-potato system. In the natural state the water is bound rather strongly due to loss of rotational degrees of freedom in the sorbed molecules, which is caused by small molecular voids in the cellulose structure. This structure therefore is formed as a uniformly cross bound state of the OH-groups. This state prevails up to a certain temperature, above which a reaction sets in, where OH bonds are successively broken, giving possibility for a partial rotation of sorbed molecules. In the range of lower moisture content the cellulose structure is changed into a crystalline state as in wood, although the degree of crystallinity is lower, which is the probable reason why the statistical fluctuations in the isotherms are greater for potato than for wood.     

Adsorption of Radon and Water Vapor on Commercial Activated Carbons

Abstract

Equilibrium adsorption isotherms are reported for radon and water vapor on two commercial activated carbons: coconut shell Type PCB and hardwood Type BD. The isotherms of the water vapor were measured gravimetrically at 298 K. The isotherms of radon from dry nitrogen were obtained at 293, 298, and 308 K while the data for the mixture of radon and water vapor were measured at 298 K. The concentrations of radon in the gas and solid phases were measured simultaneously, once the adsorption equilibrium and the radioactive equilibrium between the radon and its daughter products were established. The shape of the isotherms was of Type III for the radon and Type V for the water vapor, according to Brunauer's classification. The adsorption mechanism was similar for both the radon and the water vapor, being physical adsorption on the macropore surface area in the low pressure region and micropore filling near saturation pressure. The uptake capacity of radon decreased both with increasing temperature and relative humidity. The heat of adsorption data indicated that the PCB- and the BD-activated carbons provided a heterogeneous surface for radon adsorption. The equilibrium data for radon were correlated with a modified Freundlich equation.     

Silylcellulose Acetate Membrane for Desalination of Water

Abstract

Commercial cellulose acetate (39.9% acetyl) was partially modified with different proportions of Trimethylchlorosilane. The physical properties of modified polymers were studied. The membranes prepared from these polymers were evaluated for desalination of water by reverse osmosis. The thermal stability of modified cellulose acetate was also investigated.     

WATER SORPTION ISOTHERMS AND GLASS TRANSITION PROPERTIES OF GELATIN

ABSTRACT

The water sorption isotherms of gelatin of different molecular weights (317,700, 228,900, and 197,400) were determined at 50°C using an isopiestic method. The sorption isotherms were modeled using the Brunauer–Emmett–Teller (BET) and Guggenheim–Anderson–deBoer (GAB) equations. The BET and GAB equations were able to predict the equilibrium moisture content (EMC) with a mean relative error of 5.2 and 5.0%, respectively. The BET monolayer moisture content varied from 4.81 to 5.70% (d.b.) while modeling with the GAB equation predicted monolayer moisture content of 6.14–7.58% (d.b.) depending upon molecular weight. The monolayer moisture content increased with increasing molecular weight. Studies on the effect of moisture content on the “rheological glass transition temperature” (T _g ) showed a smooth increase in the value of T _g as a function of increasing concentration of gelatin solids. This varied from 7 to 35°C at 75% and 97% solids, respectively for the protein sample with MW = 317,700. Pinpointing of the T _g was implemented with the technique of small deformation dynamic oscillation. It was proposed that the “rheological” T _g is the point between the glass transition region and the glassy state. It acquires physical significance by identifying the transition from free volume phenomena of the polymeric backbone in the glass transition region to an energetic barrier to motions in the glassy state involving stretching and bending of chemical bonds.     

Gel Permeation Chromatography and Thermodynamic Equilibrium

Abstract

Although gel permeation chromatography is firmly established as a technique for investigating heterogeneity in synthetic polymers, the character of the chromatographic process-whether it is dominated by diffusion, by flow effects, or by an equilibrium partitioning of polymer between the mobile phase and the micropores in the column packing-is still disputed. General chromatographic theory supports the idea that under ordinary experimental conditions the equilibrium distribution of a solute determines the position of its elution peak in the chromatogram. Statistical mechanical calculations of distribution coefficients for linear and branched polymer chains and idealized pores of simple geometry lead to predictions in good accord with some experimental findings.     

ELECTRICAL-RESISTANCE ELEMENT ARRAYS OPERATING AT HIGH VOLTAGES FOR HEATING AND DRYING IN INDUSTRIAL APPLICATIONS

Abstract

Drying using ambient subzero temperatures is of potential interest for thermosensitive products. Existing theoretical drying models have been used to predict the response of the system to different aeration systems. The model is based on enthalpy balances and includes water freezing and deposition of water on the surface of the commodity. It uses thermophysical properties of the commodity (i.e., maize in this study) and ambient weather data collected from northeastern China. Water within the grain is modelled as bound, free or frozen. The physical state of water under subzero temperatures has been investigated using a differential scanning calorimeter and nuclear magnetic resonance spectrometry. It has been established that the quantity of bound water was around 17%. Thermophysical properties characterizing the drying behavior of maize kernels cv. Huangmo 417, the most common variety grown in northeastern China, were determined under a wide range of moisture contents and drying temperatures. Those were: particle and bulk density, porosity, thermal conductivity, specific heat, thin layer drying, and sorption isotherms. It could be established that the thermal conductivity and specific heat were strongly dependent on temperature and relative humidity and that the sorption isotherms followed the 5-term Guggenheim-Anderson-de-Boer model. The industrial-scale in-store drying experiments in northeastern China have demonstrated the feasibility of in-store drying under subzero conditions. Advantages in terms of reduced susceptibility of maize to mould formation have been established, resulting in improved quality and financial returns to the processor.     

Synthesis and Characterization of Glycidyl Azide Polymer with Enhanced Azide Content

ABSTRACT

The present study reports the preparation of glycidyl azide polymer with enhanced azide content. This process involves the cationic ring-opening polymerization of epichlorohydrin (ECH) using borontrifluoride etherate (BF₃-etherate) and 2,2-bis(bromomethyl)1,3-propane diol (BMPD) as initiator and co-initiators, respectively, followed by subsequent azidation of the product. For both the products, poly(epichlorohydrin)s (PECHs) and glycidyl azide polymers (GAPs) the substituted 1,3-propane diol units were characterized by spectroscopic as well as thermal analysis. Vapor pressure osmometer studies indicated that as the diol concentration increased in the polymerization the formed PECH molecular weight decreased. The spectral analysis indicates the presence of corresponding diol units in their polymeric chains. The differential scanning calorimetry and elemental analysis of the GAPs developed in this investigation indicated the presence of higher azide content in the polymer.     

Surface Activity of Monomeric and Polymeric (3-alkyloxy aniline) Surfactants

ABSTRACT

The adsorption and micellization processes of 3-alkyloxy aniline namely [3-decyloxy aniline (C10M), 3-dodecyloxy aniline (C12M) and 3-cetyloxy aniline (C16M)] and their polymers [C10P, C12P and C16P] have been investigated using surface tension (γ) measurements at different temperatures. The synthesized monomers and polymers have been characterized by IR and elemental analysis. The surface and thermodynamic parameters of these monomeric and polymeric surfactants are investigated. The results show that the critical micelle concentration (CMC) of the polymeric surfactants is lower than that of monomers. The CMC values decreases as the hydrophobic chain lengthens for both monomeric and polymeric surfactants. The surface parameters show the ability of monomeric and polymeric surfactants to adsorb at the air/water interface and decrease the surface tension. The thermodynamic parameters reveal that the micellization process is spontaneous for all investigated surfactants. The specific conductance measurements show that the specific conductance increases with increasing chain length of the substituted alkyl groups, the synthesized polymeric surfactants have higher values of specific conductance than the corresponding monomers and the specific conductance increases with rising solution temperature.     

Physical Properties of Polymeric Solids

Abstract

Progress in physical properties of polymeric solids in Japan is reviewed.     

Comparison of water permeation behaviour in poly(dimethylsiloxane), poly(ether ether ketone), and glass fibre reinforced composites using dielectric spectroscopy

Abstract

This paper describes the use of dielectric spectroscopy to characterise the absorption of water by three different classes of polymeric materials: an elastomer, poly(dimethylsiloxane); a thermoplastic, poly(ether ether ketone); and two composites, polyester and vinyl ester glass fibre reinforced laminates (GRP). Novel approaches have been used to assess water absorption by the elastomer and the GRP and the results are critically assessed. The data for all the materials are discussed in the context of their molecular structures. The applicability and limitations of these dielectric methods for the assessment of water absorption in polymeric materials that have considerably different physical properties is demonstrated.     

Elastomeric Multiphase Systems Consisting of IPN-Domain Latex Particles

A. Multiphase Polymeric Materials

The unique properties of multiphase polymeric materials resulting from their phase-separated morphology are becoming increasingly important due to the potential synergistic effects of combining two polymers with different properties. Multiphase polymeric materials can result from incompatible or semi-incompatible blends, block copolymers, graft copolymers, and interpenetrating polymer networks (IPNs). There are many examples of the superior properties of elastometic and rigid multiphase polymers [1, 2].     

Effect of Molecular Weight on the Strength of Nylon 6 and PET Fibers

Abstract

The mechanical properties of polymers depend on their morphological characteristics. With many systems and especially with semicrystalline polymers, it is possible to achieve significant changes in structure and properties by varying their thermal and stress histories. Considering the broad range of polymer applications it would, therefore, be desirable to have a quantitative understanding of the effects of structure on the properties of polymers in the solid state. The morphology of polymers is, however, often so complex that the interpretation of the mechanical responses must be restricted to qualitative considerations. In particular, the analysis of strength of un-oriented semicrystalline polymers is quite complex because of large plastic deformations which usually precede the rupture. However, by orienting the polymers in the form of fibers, it is possible to achieve structures which can be ruptured in tension with minimum plastic deformation. Under these conditions, the analysis of mechanical properties is greatly facilitated for fibers. Nevertheless, we still lack a quantitative understanding of the mechanical responses of polymeric fibers mainly because their structure has not yet been described with a precision allowing rigorous treatments.     

THE INFLUENCE OF TEMPERATURE ON SORPTION ISOTHERMS OF PROTEIN-CONTAINING MIXTURES

ABSTRACT

This paper presents a method for calculation of water sorption isotherms for multicomponent mixtures at different temperatures from mass fractions and sorption isotherms of components at a reference temperature. Additionally, Krischer's coefficients are required for the components. To compare experimental and calculated data, investigations on whey protein concentrates were carried out.     

Development of Cu- and/or phosphonium-based polymeric biocidal materials and their potential application in antifouling paints

The synthesis and characterization of a series of biocidal polymeric materials for potential antifouling submarine applications are presented. The polymeric backbone of these materials contains anionic units, such as styrene sulfonate, and/or acrylate or maleate units. The hydrophobic/hydrophilic nature of these polymers was, furthermore, tuned through copolymerization with hydrophobic units, such as vinyl acetate or styrene. The biocidal species, Cu²⁺ ions and/or phosphonium cations, were incorporated through electrostatic and/or coordination interactions, depending on the nature of the polymeric backbone. It was observed that the release of Cu²⁺ ions in water from the Cu²⁺-containing materials is controlled by the hydrophobic/hydrophilic balance of the polymeric backbone. The prepared biocidal polymeric materials were incorporated into two paint formulations, based on a rosin or a vinylic matrix. The erosion properties of the biocidal paints under accelerated laboratory conditions were evaluated using scanning electron microscopy. It is found that the antifouling performance is related to the release of biocidal species. The most efficient materials are those containing Cu²⁺ ions or combining both Cu²⁺ and phosphonium cations.     

Physical Properties of Polymer Solids and Control of Supermolecular Structure

Abstract

Linear crystalline polymers can be processed to produce high degrees of orientation, sufficient to produce drastic increases in tensile strength and modulus. Ultra high modulus and strength fibers are produced from a high molecular weight polymer employing a variety of techniques, such as meltspinning, super-drawing, solid-state extrusion, etc. Long polymer chains can be fairly well aligned and extended only after the polymeric chains are disentangled. Gel spinning is one of the preparation techniques of disentangled high molecular weight polymer with sufficient drawability.     

Removal of lead ions from wastewater using novel Schiff-base functionalized solid-phase adsorbent

ABSTRACT

This article discusses the synthesis, characterization and lead ions sorption capability of a novel recyclable Schiff-base anchored cross-linked polyacrylamide. The synthesized polymeric adsorbent was characterized by FT-IR technique, XRD and SEM analysis. Sorption parameters, such as solution’s pH, contact time, polymer dose, lead ions initial concentration, etc., were studied and optimized. Experimentally, the optimum sorption pH was around 5.0 and the sorption equilibrium was attained after 30 min. Under the optimal conditions, the maximum sorption capacity was found to be 355 mg/g, which is considered high when compared with different adsorbents. Effect of interfering ions on the sorption capacity was explored. Sorption isotherms, kinetic and thermodynamic studies were considered to identify the sorption behavior of the new polymeric adsorbent. Sorption isotherm studies showed that the maximum sorption capacity was attended as a result of homogeneous monolayer sorption of lead ions on the surface of the synthesized polymeric adsorbent. The mechanism of lead ions sorption by the synthesized polymeric adsorbent was found to be chemisorption complexation mechanism. Moreover, kinetic studies revealed that the sorption process followed a pseudo second order kinetic model. Thermodynamic data depicted that the sorption process is spontaneous, reversible and exothermic in nature. Experiments on elution and reusability of the synthesized polymeric adsorbent were executed and the results showed its validity for reuse for at least four cycles with 11% loss in its original capacity. Finally, the applicability of the synthesized Schiff-base anchored solid phase adsorbent for the removal of lead ions from industrial wastewater was explored and the results indicated its good removal efficiency.