Search

Elastomeric chlorosulfonated polyethylene (Hypalon) and thermoplastic polypropylene (PP) based thermoplastic Vulcanizates (TPVs) were prepared in presence of different doses of partial methyl ester of styrene-maleic anhydride copolymer (PMES-MA) as compatibilizer employing dynamic vulcanization technique. The mechanical analysis of the prepared TPVs exhibited significant improvements in stress at 25% modulus, ultimate tensile strength (UTS), and hardness values. FTIR studies revealed that a chemical interaction had taken place between hypalon and compatibilizer during the process of dynamic vulcanization which led to an enhancement of interfacial adhesion between them. The two-phase morphologies were clearly observed by scanning electron microscopic studies. The Tg values of hypalon were modified in the TPVs as exhibited by differential scanning calorimetric studies. TGA studies indicated the increase in thermal stability of all TPVs with respect to the elastomeric hypalon. Rheological properties showed that the compatibilizer reduces the melt viscosity of TPVs and thus facilitates the processibility of the same. [ABSTRACT FROM AUTHOR]

Generally speaking, various seaweed resources, if properly managed, can be a renewable resource with the ability to be sustainably and commercially exploited on a global basis, according to the species available, for a variety of products of industrial importance. In recent times, agar, derived from certain red seaweeds, is the only phycocolloid to have registered a surge in demand and value. However, little emphasis has been given to this emerging opportunity in India, which to our best judgment has the potential to be a significant commercial success. This review reports on steps taken to ensure Indian self-reliance on the production of agarophytes, their resource availability, management, agar characterization, and various methods of extraction. Historically fluctuating landings have reported the availability of different agarophytes of which maximum biomass of 982 dry t for Gracilaria edulis was harvested during 1990–1991 along with 665 dry t of Gelidiella acerosa during 2002–2003. Meanwhile, data for the industrial production of agar reported ca. 197 t of food-grade agar and ca. 92 t of bacteriological grade agar annually, which is very low in quantity as opposed to domestic requirements. Despite this, farming of agarophyte holds considerable promise. A model is proposed here whereby productivity of 1 t agarophyte per day (TPD) could realize US$827,22–287,440 as net profit. Technical interventions are required in order to improve the growth and yield of commercial open-water farming of agarophytes. During the last two decades, agar imports to India increased ca. 7 times in volume and ca. 42 times in value, while export figures were ca. 198 times and ca. 149 times, respectively. This review examines the existing policies and legislations acting as constrains for the agarophyte trade and products which would provide a framework for improving the overall prospects of agar producing red seaweeds in India. [ABSTRACT FROM AUTHOR]

ABSTRACT Polyvinylpyrrolidone (PVP) grafted sulfated polysaccharide of the seaweed Cystoseira indica (CIsps) (CIsps- graft-PVP) was synthesized in aqueous medium under microwave irradiation in the presence of potassium persulfate (KPS), as a free radical initiator. Varying the reaction parameters, e.g., concentration of PVP and KPS, reaction time and temperature, optimum grafting condition was identified as the one having the highest grafting ratio (Gr 2.30) and grafting efficiency (Ge 0.92). The grafted copolymer was characterized by FT-IR, 13C-NMR and thermo gravimetric analysis (TGA). The 5% (w/v) dispersion of the new material CIsps- graft-PVP in water exhibited comparable binding properties with papers, polyethylene sheets, and wood pieces as against that of a commercial adhesive. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42383. [ABSTRACT FROM AUTHOR]

ABSTRACT Elastomeric Chlorosulfonated polyethylene (Hypalon®) and thermoplastic Polypropylene (PP) based thermoplastic vulcanizates (TPVs) were prepared in presence of different doses of compatibilizer, maleic anhydride grafted PP (PP-g-MA) by employing dynamic vulcanization technique. The effect of incorporation in different proportions of compatibilizer on mechanical, spectral, morphological, thermal, and rheological properties of such TPVs was studied and the same were compared to that of virgin PP and amongst themselves. The mechanical analysis of the prepared TPVs exhibited significant improvements in stress at 25% modulus, ultimate tensile strength (UTS), and hardness values. FTIR studies revealed that a chemical interaction had taken place between Hypalon® and functionalized compatibilizer during the process of dynamic vulcanization which led to an enhancement of interfacial adhesion between them. The two-phase morphologies were clearly observed by scanning electron microscopic studies. The Tg values of Hypalon® was modified in the TPVs as exhibited by differential scanning calorimetric studies. TGA studies indicated the increase in thermal stability of all TPVs with respect to the elastomeric Hypalon®. Rheological properties showed that the compatibilizer reduces the melt viscosity of TPVs and thus facilitates the processibility of such TPVs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40312. [ABSTRACT FROM AUTHOR]

Different thermoplastic vulcanizate (TPV) blends were prepared from elastomeric chlorosulfonated polyethylene (CSM) and thermoplastic polypropylene (PP) by employing dynamic vulcanization technique. The mechanical properties of such blends were compared in respect of their stress at 25% modulus (25%M), ultimate tensile strength (UTS), percent elongation at break, and hardness to those of pure CSM. The mechanical analysis showed substantial improvement in stress at 25%M, UTS, and hardness values with the incorporation of 15-40 parts of thermoplastic contents (PP) (per hundred parts of blend). The two-phase morphologies were clearly observed by scanning electron microscopy studies. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC studies showed a decreasing trend in glass transition temperature ( Tg) and TGA studies indicated the increase in thermal stability of all TPV blends with respect to the elastomeric CSM. Rheological studies showed that there is an increasing trend in shear melt viscosity of TPV blends with the increase in PP amount as the higher content of isotactic PP used in the present case increases the melt viscosity. The TPVs obtained after the rheotron studies displayed identical shear stress/strain pattern when further subjected to the same study. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Polypropylene (PP) and Vectra A950, a thermotropic liquid crystalline polymer (LCP), blends were prepared in a single-screw extruder with the variation in Vectra A950 content in presence of fixed amount (2%, with respect to PP and LCP mixture as a whole) of ethylene-acrylic acid (EAA) copolymer as a compatibilizer. Mechanical analysis of the compatibilized blends within the range of LCP incorporations under study (2-10%) indicated pronounced improvement in the moduli, ultimate tensile strength (UTS), and hardness. Fourier transform infrared (FTIR) spectroscopy studies revealed the presence of strong interaction through H-bonding between the segments of Vectra A950 and the compatibilizer EAA. Morphological studies performed by scanning electron microscopy (SEM) manifested the development of fine fibrillar morphology in the compatibilized PP/Vectra A950 blends, which had large influence on the mechanical properties. Differential scanning calorimetry studies showed an initial drop of the melting point of PP in the presence of EAA followed by enhancement of the same in presence of Vectra A950. TGA showed an increase in the thermal stability for all blends with respect to matrix polymer PP. Rheological studies showed that a very small quantity of Vectra A 950 was capable of reducing the melt viscosity of PP particularly in the lower shear rate region and hence facilitated processibility of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Polypropylene/Vectra A 950 blends were prepared in a single screw extruder in presence of different doses of ethylene acrylic acid copolymer (EAA), as a compatibilizer. The effect of incorporation in different proportions of EAA at a fixed dose of 5% Vectra A 950, on different properties of such blends was studied. Mechanical analysis exhibited improvements in tensile properties of polypropylene matrix with the incorporation of EAA. The prepared such blends were further characterized by FTIR spectroscopy, SEM, DSC and TGA studies. Rheological studies showed that both Vectra A 950 and EAA drop down the melt viscosity of polypropylene. [ABSTRACT FROM AUTHOR]

SUMMARY Galactans containing methylated galactan moieties were extracted from Indian agarophytes, namely, Gracilaria millardetii and Gracilaria textorii growing naturally along the west coast of India. The galactans were treated with α-amylase to remove floridean starch. These were characterized by Fourier Transform-Infrared (FT IR), 13C-Nuclear Magnetic Resonance (C NMR), Gas Chromatography-Mass Spectrometry (GC MS), Inductively Coupled Plasma spectroscopy (ICP) and Gel Permeation Chromatography (GPC) and were found to be composed of d-galactose, 6- O-methyl-D-galactose and 3,6-anhydro-L-galactose. Methylation analyses revealed that both the polysaccharides consisted of 3-, 2,3-, 4,6-linked galactose as well as four-linked 3,6-anhydro galactose residues. Both the Gracilaria species produced low gelling (<100 g cm−2) and highly sulfated (2.1% to 4.8%) galactans containing very low heavy metal contents (ICP). These galactans may be of potential utility in food and biological applications. [ABSTRACT FROM AUTHOR]

The effect of alkali pre-treatments on the properties of agar obtained from Gelidiella acerosa and Gelidium pusillum growing along the West and South coast of India was studied in order to evaluate its potential for industrial use. Agar samples were extracted by hot water extraction and termed native agar, and alkali pre-treatment was carried out with various NaOH concentrations e.g. 4%, 6%, 8%, 10% and 15%, to optimise the alkali concentration for preparation of alkali-treated agar. Gelidiella acerosa and Gelidium pusillum produced superior quality agar polymers having greater gel strengths 2,000 ± 50 and 1,400 ± 50 g cm and lower sulphate contents ≤0.30% and ≤0.50%, respectively, as opposed the low gel strength and high sulphate content agars reported in the literature. Furthermore, the physicochemical properties of agars were identical with the commercially available agars. The results of this study revealed that Indian agarophytes may be used for production of superior quality agar and agaroses, which may be used for food and biological applications. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) was melt blended with Vectra B-950 [a thermotropic liquid crystalline polymer (LCP)], in a single screw extruder in presence of different doses of ethylene acrylic acid (EAA) copolymer, as modifier. The effect of incorporation in different proportions of EAA at a fixed dose of 5% LCP, on mechanical, thermal, morphological, and rheological properties of such blends was studied and the same were compared with that of pure PP and amongst themselves. Mechanical analysis (tensile properties) of the prepared blends exhibited improvements in ultimate tensile strength (UTS), modulus, toughness, hardness, and impact strength of PP matrix with the incorporation of EAA. The improvement in mechanical properties is associated with the formation of LCP fibrils as evidenced by scanning electron microscopy (SEM). A strong interaction through H-bonding between the segments of Vectra B-950 and EAA was established by FTIR study. Differential scanning calorimetry (DSC) studies indicated substantial increase in melting point of the blends, and thermogravimetric analysis (TGA) showed that the thermal stability of PP was improved with the addition of LCP and EAA. Rheological properties showed that LCP and EAA drop down the melt viscosity of PP and thus facilitate processibility of blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Superior quality non-methylated and low-sulphated galactans were extracted from two Indian agarophytes namely Gracilaria debilis and G. salicornia growing naturally along the west coast of India, using an eco-friendly method developed in our laboratory. The galactans were characterised by FT-IR, C NMR, GC-MS, ICP, GPC and rheological measurements. G. debilis produced exclusively non-methylated galactan exhibiting the greatest gel strength of 650±25 g cm and lowest sulphate of 0.21±0.06%. On the contrary, G. salicornia polysaccharide was composed of non-methylated galactose (major) and mannose (minor), having gel strength of 510±25 g cm and sulphate of 0.45±0.06%. Very low heavy metal contents were determined in both the galactan samples, which may thus be potentially useful in food and biological applications. [ABSTRACT FROM AUTHOR]

A hybrid material was prepared from the hot water soluble sulphated polysaccharide of the green seaweed Chaetomorpha antennina (CMsps) and polymethyl methacrylate (PMMA) by radical polymerization in aqueous medium under microwave irradiation. An insoluble material was formed with the progress of the polymerization. The product was characterized by the IR spectrum and elemental analysis, as well as by acid hydrolysis followed by mass spectrum of the hydrolysate of the hybrid CMsps–PMMA for confirming the insertion of PMMA. Comprehensive characterization of the product included TGA, XRD, ESI-MS and BET surface analysis. The hybrid material was porous, and formed gel in water–DMSO mixture. It had the crystallinity index of 0.122, and had BET pore diameter of 3.71 nm, a size which is far larger than the molecular diameters of common natural gases and zeolites (0.5–1.0 nm). This material may be useful in the domain of certain adsorption and catalytic applications. [ABSTRACT FROM AUTHOR]

In vitro somatic embryogenesis and regeneration of somatic embryos to whole plants through micropropagules was successfully demonstrated from pigmented uniseriate filamentous callus of Kappaphycus alvarezii (Doty) Doty in axenic cultures. More than 80% of the explants cultured on 1.5% (w/v) agar-solidified Provasoli enriched seawater (PES) medium showed callus development. The callus induction rate was consistently higher for laboratory-adapted plants. The excised callus grew well in subcultures and maintained its growth for prolonged periods if transferred to fresh medium in regular intervals. Some subcultured calli (<10%) did undergo transformation and produced densely pigmented spherical or oval-shaped micropropagules (1–5 mm in diameter) that subsequently developed into young plantlets in liquid PES medium. The micropropagule production was further improved through somatic embryogenesis by a novel method of culturing thin slices of pigmented callus with naphthaleneacetic acid (NAA) or a mixture of NAA and 6-benzylaminopurine. Transfer of embryogenic callus along with tiny somatic embryos to liquid medium and swirling on orbital shaker facilitated rapid growth and morphogenesis of somatic embryos into micropropagules that grew into whole plants in subsequent cultivation in the sea. The daily growth rate of one tissue cultured plant was monitored for seven generations in field and found to be as high as 1.5–1.8 times over farmed plants. The prolific somatic embryogenesis together with high germination potential of somatic embryos observed in this study offers a promising tool for rapid and mass clonal production of seed stock of Kappaphycus for commercial farming. [ABSTRACT FROM AUTHOR]

An electrodialysis process is proposed to achieve efficient separation of sodium sulfate from its mixture with p-toluene sulfonic acid. In this process, interpolymer type ion-exchange membranes were used due to their higher chemical stability and durability. Experiments were conducted in laboratory scale electrodialysis unit with an effective area of 65 cm2 and 10 cell pairs, at different compositions of sodium sulfate and p-toluene sulfonic acid in its mixture, to see the effect of their concentration on the process efficiency. Batchwise electrodialysis experiment in four stages was also conducted to separate 12% (w/v) sodium sulfate from 2% (w/v) p-toluene sulfonic acid. Observations indicate that at higher sodium sulfate concentration, energy consumption increases while current efficiency decreases due to enhanced back diffusion from concentrate to treated compartments. Dialytic rate of sodium sulfate is also estimated under different experimental conditions. It is concluded that p-toluene sulfonic acid adsorbed or masked the surface of anion-exchange membrane, which is responsible for the increased reduction in the ionic transportation with the increase in concentration of p-toluene sulfonic acid. Adsorption/masking is completed up to its critical micelle concentration and beyond this concentration; further increase in p-toluene sulfonic acid has no more effect on ionic transportation. [ABSTRACT FROM AUTHOR]

The water-soluble antithrombotic polysaccharide sulfate fraction designated GI-1 was isolated from the marine red alga Grateloupia indica. It consists mainly of D-galactose (Gal), L-Gal, 3,6-anhydro-D-galactose (D-AnGal) and 3,6-anhydro L-galactose (L-AnGal). On the basis of the results from 13C NMR and methylation analysis of completely desulfated GI-1, we assigned a typical agarocolloid-carrageenan hybrid type of the backbone consisting of both disaccharide repeating units, [→3)β-D-Gal(1→4)α-D-Gal(1→] and [→3)β-D-Gal(1→4)-L-Gal(1→]. In addition, two repeating units, [→3)β-D-Gal(1→4)α-D-AnGal(1→] and [→3)β-D-Gal(1→4)α-L-An-Gal(1→],were also suggested for the native GI-1 from partial methanolysis and 13C NMR studies. [ABSTRACT FROM AUTHOR]

Polysaccharides of marine origin, for example, agarose (Ag) and alginic acid (Alg)‐based new nano‐size monoamido amino acid derivatives are synthesized and their protein‐like characteristics are evaluated. Two new agarose‐based nanosize amino acid derivatives are obtained by partial amidation of agarose succinate half‐ester (Ag‐SA; DS 0.95) employing aliphatic acyclic and cyclic diamines, for example, 1,6‐hexamethylenediamine (HDA) and trans‐1,4‐cyclohexanediamine (CHDA), named Ag‐SA‐hexamethylene‐monoamido (AEAm) and Ag‐SA‐cyclohexanemonoamido (AECAm) amines (DSs 0.47, 0.35), recording isoelectric points (pIs) 7.9 and 6.4, respectively. Alginic acid, extracted from the Indian seaweed species, Sargassum tenerrimum, is functionalized with ethylene diamine (EDA) affording a nanosize alginic‐acid‐based monoamido amino acid (Alg‐EDA; DS 0.47; pI 3.40). All of these three nanosize monoamido amino acids (DLS; (nm) AEAm 0.65, 80.9; AECAm 0.65, 7.54, and 107.4; Alg‐EDA 0.89, 2.0, 50, and 61.0) exhibit protein‐mimicking functions interacting with Salman testes DNA and bovine serum albumin (BSA), displaying different complexation and decomplexation profiles in a varying pH regime. These nanobody polysaccharide‐based protein‐like large molecules may be of potential utility in the domains of pH‐responsive drug delivery, separations as well as chiral sensing applications. [ABSTRACT FROM AUTHOR]