Grewia gum is a polysaccharide derived from the inner stem bark of the edible plant Grewia mollis. Juss (family Tiliaceae). It is a savanna shrub that grows wildly but is usually cultivated in Nigeria and Northern part of Cameroon. The main goal of the present study was to investigate the effect of aqueous extraction conditions on the extraction yield and physicochemical properties of the Grewia mollis. The studied aqueous extraction variables were water/powder (W/P) ratio (10&#x2009;:&#x2009;1&#x2013;80&#x2009;:&#x2009;1&#x2009;w/p), temperature (25.0&#x2013;85.0&#x2218;C), time (1&#x2013;3&#x2009;h), and pH (4.0&#x2013;10.0). The results indicated that the aqueous extraction variables exhibited the least significant (<svg style="vertical-align:-0.1638pt;width:58.712502px;" id="M1" height="11.375" version="1.1" viewBox="0 0 58.712502 11.375" width="58.712502" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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</svg>) effect on the yield and the viscosity of the gum. The result shows that the ratio of extraction is the main factor affecting the extraction of gum. The optimized extraction condition for higher viscosity was at the powder/water ratio of 1&#x2009;:&#x2009;55.4, pH of 7, time of 1&#x2009;h, and temperature of 50&#x2218;C. However, the optimized extraction condition for higher yield was at the powder/water ratio of 1 : 80, pH of 4, time of 3&#x2009;h, and temperature of <svg style="vertical-align:-0.20473pt;width:32.787498px;" id="M2" height="13.1875" version="1.1" viewBox="0 0 32.787498 13.1875" width="32.787498" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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</svg>.

Emmanuel Panyoo Akdowa

Thaddee Boudjeko

Alice Louise Woguia

Nicolas Njintang-Yanou

Claire Gaiani

Joel Scher

Carl Moses F. Mbofung

Optimization of Variables for Aqueous Extraction of Gum from Grewia mollis Powder

Starch was isolated from T. leontopetaloides tubers, chemically modified by acetylation with varying amounts of acetic anhydride. Monolayer of the ten acetylated and control starch powders was exposed on roof top for five weeks and pastes of both exposed and unexposed (control) samples were prepared with distilled water (1&#x2009;:&#x2009;3 w/w). The effects of acetylation, degree of substitution (DS), and exposure to sunlight were investigated to evaluate the retrogradation tendency of the adhesive pastes from changes in syneresis, tack strength, optical clarity, viscosity, gelation time, and drying time. The results obtained showed that all the adhesive properties studied were affected by both DS and exposure to sunlight. While tack strength, viscosity, and drying time were found to increase with increase in DS, syneresis, optical clarity, and gelation time were found to decrease with increase in DS. Increase in tack strength and reduction in syneresis imply that the acetylation treatment has made T. leontopetaloides starch more suitable for use in remoistenable adhesive applications. The reduction in syneresis, optical clarity, and gelation time with increase in DS was attributed to the strengthening of the bonds between the amylose and amylopectin molecules, preventing water leaching out of the starch granules.

Hamza Abba

Abdulqadir Ibrahim

Gideon A. Shallangwa

Sani Uba

Yakubu A. Dallatu

Effect of Acetylation on Stability to Retrogradation of Starch Extracted from Wild Polynesian Arrowroot (Tacca leontopetaloides (L.) Kuntze) for Utilization as Adhesive on Paper

We reported a well-defined amphiphilic fluorescent polymer bearing indole repeating units with naphthalimide pendants obtained by ATRP followed by chemical modification. The obtained polymer poly (N-allyl indole-2-(4-hydroxybutyl)-1, 8-naphthalimide) (PAIHN) was characterized by 1H NMR, FTIR, and GPC. The polymer showed a specific fluorescence emission maximum at 538&#x2009;nm excited at 435&#x2009;nm in aqueous solution. The amphiphilic nature of the polymer was investigated in aqueous solution using two spectroscopic methods, namely, absorption and emission spectroscopy. The Critical Miceller Concentration values obtained by UV-visible and fluorescence are in good agreement with each other. The micelles were characterized by TEM at concentration of 0.014&#x2009;mg/mL. The polymer PAIHN prepared after tweaking exhibits green fluorescence at 538&#x2009;nm due to the significant effect of naphthalimide moieties, whereas before tweaking the polymer poly (1-allyl indole-3-carbaldehyde) (PAIC) exhibits blue fluorescence at 425&#x2009;nm due to indole repeating units of the polymer.

Ambika Srivastava

Pooja Singh

Arti Srivastava

Rajesh Kumar

Amphiphilic Fluorescent Well-Defined Living Polymer from Indole-3-Carboxaldehyde and 4-Bromo-1, 8-Naphthalic Anhydride: Synthesis and Characterization

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends.

Emi Govor&#x10d;in Bajsi&#x107;

Vesna Rek

Ivana &#x106;osi&#x107;

Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

Poly(azophenyleneazo-2,4-diamino-1,5-phenylenes) were synthesized via diazotization of m- and p-phenylenediamine and azocoupling with m-phenylenediamine. It is found that, simultaneously, dihydrobenztriazolic units were formed as a result of cyclization reaction between amino and azo groups located in ortho position to each other. Oxidation of poly(azo-p-phenyleneazo-2,4-diamino-1,5-phenylene) was carried out and new polymer with benzotriazolic units in the main polymer chain was obtained. The conductivities of obtained polymers doped with iodine were increased with doping levels increase from 10&#x2212;9&#x2013;5 &#xd7; 10&#x2212;8&#x2009;S/m to 0,1&#x2013;0,6&#x2009;S/m.

A. H. Durgaryan

R. H. Arakelyan

N. A. Durgaran

E. E. Matinyan

Synthesis, Characterization, and Electrical Properties of Poly(azophenyleneazo-2,4-diamino-1,5-phenylenes)

Polymer composites of ZnO and WO3 nanoparticles doped polyvinyl alcohol (PVA) matrix have been prepared using solvent casting method. The microstructural properties of prepared films were studied using FTIR, XRD, SEM, and EDAX techniques. In the doped PVA, many irregular shifts in the FTIR spectra have been observed and these shifts in bands can be understood on the basis of intra/intermolecular hydrogen bonding with the adjacent OH group of PVA. The chemical composition, phase homogeneity, and morphology of the polymer composites of the polymer film were studied using EDAX and SEM. These data indicate that the distribution of nanosized ZnO and WO3 dopants is uniform and confirm the presence of ZnO and WO3 in the film. The crystal structure and crystallinity of polymer composites were studied by XRD. It was found that the change in structural repositioning and crystallinity of the composites takes place due to the interaction of dopants and also due to complex formation. The mechanical studies of doped polymer films were carried out using universal testing machine (UTM) at room temperature, indicating that the addition of the ZnO and WO3 with weight percentage concentration equal to 14&#x25; increases the tensile strength and Young&#x2019;s modulus.

N. B. Rithin Kumar

Vincent Crasta

Rajashekar F. Bhajantri

B. M. Praveen

Microstructural and Mechanical Studies of PVA Doped with ZnO and WO3 Composites Films

The present work is an investigation of AC impedance behaviour of poly(meta-aminophenol). The polymer was prepared by oxidative chemical polymerization of meta-aminophenol in aqueous HCl using ammonium persulfate as an oxidant at 0&#x2013;3&#xb0;C. The synthesized polymer was characterized by GPC, Elemental analysis, UV-VIS-NIR, FT-IR, 1H NMR, XRD, SEM, and TGA-DTA. The AC conductivity and dielectric response were measured at a temperature range from 303 to 383&#x2009;K in the frequency range of 20&#x2009;Hz to 106&#x2009;Hz. The AC conductivity data could be described by the relation <svg style="vertical-align:-3.39064pt;width:80.512497px;" id="M1" height="20.4375" version="1.1" viewBox="0 0 80.512497 20.4375" width="80.512497" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,16.162)"><path id="x1D70E" d="M548 455q-32 -77 -74 -77q-37 0 -103 10l-3 -2q36 -30 48.5 -62t12.5 -80q0 -103 -75 -179.5t-175 -76.5q-70 0 -113 45t-43 128q0 115 83.5 200.5t209.5 85.5q31 0 77.5 -4t67.5 -4q36 0 62 30zM350 274q0 54 -17 86q-19 35 -57 35q-50 0 -90 -37.5t-59 -91.5t-19 -109&#xA;q0 -61 24.5 -96.5t65.5 -35.5q51 0 87.5 46.5t50.5 100.5t14 102z" /></g>

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			<g transform="matrix(.017,-0,0,-.017,20.55,16.162)"><path id="x1D714" d="M615 290q0 -148 -114 -245q-65 -57 -125 -57q-39 0 -62 27t-29 70q-31 -41 -72 -69t-74 -28q-49 0 -82.5 43t-33.5 124q0 97 55 174.5t148 124.5l15 -24q-59 -45 -94 -113t-35 -146q0 -58 19.5 -88.5t48.5 -30.5q33 0 62 34.5t45 101.5q16 73 20 135l80 17l5 -6&#xA;q-11 -37 -23.5 -100t-12.5 -92q0 -47 16.5 -71.5t44.5 -24.5q62 0 95.5 67t33.5 160q0 107 -63 152l1 9q14 14 45 14q29 0 57.5 -44t28.5 -114z" /></g><g transform="matrix(.017,-0,0,-.017,36.104,16.162)"><path id="x3D" d="M535 323h-483v50h483v-50zM535 138h-483v50h483v-50z" /></g><g transform="matrix(.017,-0,0,-.017,50.808,16.162)"><path id="x1D434" d="M716 28l-8 -28h-254l8 28q55 5 66 17.5t5 47.5l-30 145h-232l-74 -138q-21 -43 -11 -54.5t72 -17.5l-6 -28h-235l8 28q53 7 73.5 21t53.5 70l319 540l33 8q6 -43 33 -176l80 -381q10 -49 26.5 -63t72.5 -19zM495 281l-49 264h-2l-149 -264h200z" /></g><g transform="matrix(.017,-0,0,-.017,63.268,16.162)"><use xlink:href="#x1D714"/></g>

			<g transform="matrix(.012,-0,0,-.012,74.112,8)"><path id="x1D446" d="M457 488l-30 -3q-17 148 -131 148q-53 0 -84.5 -34.5t-31.5 -82.5q0 -42 25.5 -72t74.5 -62l33 -22q63 -42 95 -85t32 -102q0 -84 -67 -137t-163 -53q-58 0 -113 22t-70 43l-4 152l27 4q4 -32 15 -62.5t31 -59.5t53.5 -47t76.5 -18q56 0 92 35t36 96q0 39 -25 70t-78 68&#xA;l-31 22q-32 23 -53.5 41.5t-45 57t-23.5 77.5q0 82 58 132.5t156 50.5q46 0 101 -17l18.5 -6t17 -6t8.5 -3q-4 -55 0 -147z" /></g>

		
	
</svg>, where the parameter &#x201c;<svg style="vertical-align:-0.23206pt;width:8.2875004px;" id="M2" height="11.75" version="1.1" viewBox="0 0 8.2875004 11.75" width="8.2875004" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,11.4)"><use xlink:href="#x1D446"/></g>

		
	
</svg>&#x201d; and <svg style="vertical-align:-3.39066pt;width:17.275px;" id="M3" height="15.4" version="1.1" viewBox="0 0 17.275 15.4" width="17.275" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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</svg> values decrease in the entire range of study and hence follow Correlated Barrier Hopping conduction mechanism. Both dielectric constant and dielectric loss increase with the decrease of frequency exhibiting strong interfacial polarization at low frequency and the dissipation factor also decreases with frequency. Complex electric modulus and dissipation factor exhibit two relaxation peaks, indicating two-phase structure as indicated by a bimodal distribution of relaxation process. The activation energies corresponding to these two relaxation processes were found to be 0.07 and 0.1&#x2009;eV.

Thenmozhi Gopalasamy

Mohanraj Gopalswamy

Madhusudhana Gopichand

Jayasanthi Raj

Poly Meta-Aminophenol: Chemical Synthesis, Characterization and Ac Impedance Study

Solid films of pure chitosan, chitosan-LiCF3SO3, chitosan-NaCF3SO3, and chitosan-AgCF3SO3 were prepared using solution cast technique. The influence of cation size on the chitosan structure has been investigated by X-ray diffraction technique. The interaction between the alkali metal ions and the donor atoms of chitosan polymer is a strong hard-acid/hard-base interaction. It was found that the intensity of crystalline peaks of chitosan decreases with increase of cation size. The impedance analysis shows that ionic transport is high for the high amorphous system. The second semicircle in <svg style="vertical-align:-0.0pt;width:17.2875px;" id="M1" height="20.725" version="1.1" viewBox="0 0 17.2875 20.725" width="17.2875" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,20.663)"><path id="x5A" d="M561 176l29 -6q-25 -130 -36 -170h-517l-8 15l420 599h-173q-77 0 -102 -7t-39 -29q-19 -29 -35 -87l-29 1q9 111 12 183h24q9 -16 19 -20.5t34 -4.5h399l7 -14l-413 -594q48 -6 163 -6q94 0 131.5 7.5t58.5 29.5q28 29 55 103z" /></g><g transform="matrix(.008,-0,0,-.008,10.312,6.8)"><path id="x2032" d="M227 744l-123 -338l-31 15l73 368q12 3 41.5 -8t36.5 -20z" /></g><g transform="matrix(.008,-0,0,-.008,13.457,6.8)"><use xlink:href="#x2032" /></g></svg>-<svg style="vertical-align:-0.0pt;width:14.15px;" id="M2" height="20.725" version="1.1" viewBox="0 0 14.15 20.725" width="14.15" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,20.663)"><use xlink:href="#x5A" /></g><g transform="matrix(.008,-0,0,-.008,10.312,6.8)"><use xlink:href="#x2032" /></g></svg> plots and the surface plasmonic resonance (SPR) peaks in chitosan-AgCF3SO3 sample system reveal the formations of silver metal nanoparticles. It was found that the high amorphous sample exhibits the high dielectric constant and dielectric loss values. The increase of dielectric constant and dielectric loss with temperature for chitosan-salt membranes indicated an increase of charge carrier concentration.

Shujahadeen B. Aziz

Zul Hazrin Z. Abidin

Role of Hard-Acid/Hard-Base Interaction on Structural and Dielectric Behavior of Solid Polymer Electrolytes Based on Chitosan-XCF3SO3 (X = Li+, Na+, Ag+)

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Journal of Polymers