Iranian polymer journal
Volume:20 Issue: 1, 2011

Poly(butylene succinate) (PBS), with similar physical properties to those ofpolyethylene, is degradable and can be used as a common material. However,it is not adopted widely in industry and domestic applications due to its high cost.In this work, to improve the performances and wide applicability of PBS, a newbiodegradable blend has been prepared by incorporating alkaline lignin (AL) filler intoPBS as a matrix. First, the AL and PBS, where the weight percentage of the former inthe blends varied between 5 and 30%, were mixed at a rotating speed of 78 rpm for10 min at 120°C; and then, the resultant mixture was compression-moulded into asheet at 120°C under 20 MPa pressure for 5 min. Moreover, methylenediphenyldiisocyanate (MDI) was used as coupling agent to further modify new PBS/AL blends,and the weight percentage of MDI was regulated from 0.5 to 2%. The structure andproperties of the resultant blends were investigated by Fourier transform infraredspectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electronmicroscopy, swelling, tensile and water absorption tests. The results showed that theaddition of AL inhibited the crystallization of PBS matrix, and enhanced the Youngsmodulus of the blends. In addition, it was found that the addition of MDI favouredfurther enhancements in tensile strength and Young's modulus, and reduced the waterabsorption of the blends.

The role of carbon black (CB) in the viscoelastic behaviour of rubber compoundswas investigated to better understand the reinforcing mechanism. The influenceof CB nanoparticles on the strain-dependency and relaxation phenomena ofseveral styrene butadiene rubber (SBR) compounds was evaluated using rubberprocess-analyzer (RPA). Rheological results of uncured samples showed that reducedcomplex modulus with strain strongly depend on CB-rubber interactions. Filled mastercompounds showed greater modulus compared to raw SBR, which dropped ratherabruptly; meaning more noticeable non-linear viscoelastic behaviour. The observedtrend of damping factor recognized the linear viscoelastic behaviour for strain <15%,however, at higher strains a large positive deviation was noticed. In the strain regionunder 15%, CB-filled rubber showed more elastic behaviour than gum; more elastic asthe CB loading increased while in the non-linear zone, the reverse trend was observed.Torsion relaxation modulus based on standard linear solid (SLS) model was plotted andfound disputable changes regarding to varied factors. Both values of relaxed modulusand the relaxation slope increased as the functions of CB surface area and content,and also the relaxation time (τ) shifted to higher values. In addition, CB affected thecure characteristics and after cure relaxation. In the cured compounds, the slope ofrelaxed modulus was steeper at starting time (~0.01 s) and less steep at longer timethan those of the master compound, reaching a considerable set at the end of relaxationwhich was dependent on CB level and size

Two series of poly(oxadiazole-imide)s based on naphthalene-containinganhydrides and aromatic diamines having preformed oxadiazole rings have beensynthesized. One series contains four polymers: two of them are based onnaphthalene-1,4,5,8-tetracarboxylic dianhydride and the other two are based onbis(ketonaphthalic-anhydride). The other series contain four copolymers based onmixtures of these dianhydrides with hexafluoroisopropylidene-diphthalic anhydride.Most of these polymers are easily soluble in polar amidic solvents and even in lesspolar and convenient solvents, allowing them to be processed in thin films andcoatings. These polyimides and copolyimides show high thermal stability, with initialdecomposition temperature being above 430°C and glass transition temperature in therange of 190-318°C. Conformational rigidity parameters of these polymers have beencalculated by Monte Carlo method and discussed in relation with thermal properties.The values found experimentally for glass transition temperature correlate well withthose calculated by using the conformational rigidity parameters. The dependence ofglass transition temperature of these polymers on Kuhn segment can be described bylinear equations, with a very good factor of convergence.

Thermoplastic elastomer nanocomposites based on polypropylene (PP) andethylene-propylene diene monomer (EPDM) and Cloisite 15A were prepared viadirect melt mixing in a co-rotating twin-screw extruder. The formulation forpreparation of nanocomposites was fixed with the ratio of 75/20/5 for PP/EPDM/organoclay©15A, expressed in mass fraction. The objective of the present study wasto investigate the effects of processing conditions on the formation of TPE(PP/EPDM/nanoclay) nanocomposites. The parameters under study included thefeeding rate, screw speed and barrel temperature, which were varied independently,from 0.2 to 1.0 kg/h and from 50 to 150 rpm and 180 to 200°C, in the order given.Design of experiments was carried out by Expert Design software (Taguchi AnalysisMethod) on the basis of three different levels of the above processing parameters. Thestate of dispersion was quantified by X-ray diffraction, transmission electronmicroscopy and rheological measurements. X-Ray diffraction results show that thenanocomposites obtained in different conditions have an intercalated structure and theproportion of exfoliation, estimated by rheological measurements, depend on theoperating conditions. The exfoliated layers increase when the feed rate and barreltemperature decrease and the screw speed increases. The study of linear viscoelasticproperties also shows that the storage modulus, G’, is very sensitive to the microstructureof the nanocomposite. A Carreau-Yasuda model with a yield stress isproposed to describe the rheological behaviour of these materials. The yield stress ofnanocomposites increases when the barrel temperature and feed rate are reduced andthe screw speed is increased.

Polyacrylamide (PAM) and its copolymers are of important polymeric materials inpetroleum industry, for example in drilling fluids and enhanced oil recovery. Highmolecular weights of these polymers are needed to have optimum efficiency inthe above given applications. High molecular weight polyacrylamide nanoparticleswere prepared by inverse-emulsion polymerization of aqueous acrylamide solution inxylene as a continuous phase under various conditions in the presence of a mixture ofnon-ionic emulsifiers (Tween 85 and Span 80). Monomer conversion, particle size andits distribution in the final emulsion and molecular weight of the polymer product wereanalyzed appropriately by gravimetry, dynamic light scattering (DLS) and capillaryviscometry techniques. The effect of variables such as stirrer speed, temperature,initiator concentration and type, emulsifier concentration and hydrophilic-lipophilicbalance (HLB) value of the emulsifier system on the viscosity-average molecularweight, particle size and its distribution and reaction kinetics were investigated.Depending on the reaction conditions, PAM particles with average particle sizesgenerally smaller than 200 nm in diameter and particle size distribution in the range of50-400 nm and viscosity-average molecular weights as high as 8×106 g.mol-1 wereobtained.

The synthesis of vinylic derivatives of 2,3:5,6-di-O-isopropylidene-α-D-mannofuranose1a as polymerizable glycomonomer moieties was accomplished. Firstly,in order to carry out the selective reactions on polyhydroxylic carbohydratemolecules, all of the hydroxyl groups of D-mannopyranose 1 except one of thehydroxyl groups in anomeric centre (C1-OH) were protected with the formation of acetalcompound. Then the acetal protected derivative 1a was reacted with acryloyl chloride,methacryloyl chloride, methacrylic anhydride and ρ-(chloromethyl)styrene in thepresence of triethylamine and sodium hydride to give the vinyl saccharide monomericcompounds 2a, 2b and 2c. Then monomers 1-O-acryloyl-2,3:5,6-di-O-isopropylidene-α-D-mannofuranoside 2a, 1-O-methacryloyl-2,3:5,6-di-O-isopropylidene-α-D-mannofuranoside2b and ρ-(2,3:5,6-di-O-isopropylidene-α-D-mannofuranose-1-oxymethyl)styrene 2c were isolated with column chromatography method using a gradient ofhexane and ethyl acetate as eluant. The homopolymerization of above mentionedsugar-protected glycomonomers led to poly(1-O-acryloyl-2,3:5,6-di-O-isopropylidene-α-D-mannofuranoside) P3a, poly(1-O-methacryloyl-2,3:5,6-di-O-iso-propylidene-α-Dmannofuranoside)P3b and poly[ρ-(2,3:5,6-di-O-isopropylidene-α-D-mannofuranose-1-oxymethyl)styrene] P3c in the presence of benzoyl peroxide by heating at 60°C usingsolvent. The obtained glycopolymers were purified through solvent and non-solventsystems. The structure of all purified glycomonomers and glycopolymers wereconfirmed using 1H, 13C and 2D NMR and FTIR. The molecular weights of the obtainedglycopolymers were determined using gel permeation chromatography (GPC).

The synthesis of vinylic derivatives of 2,3:5,6-di-O-isopropylidene-α-D-mannofuranose1a as polymerizable glycomonomer moieties was accomplished. Firstly,in order to carry out the selective reactions on polyhydroxylic carbohydratemolecules, all of the hydroxyl groups of D-mannopyranose 1 except one of thehydroxyl groups in anomeric centre (C1-OH) were protected with the formation of acetalcompound. Then the acetal protected derivative 1a was reacted with acryloyl chloride,methacryloyl chloride, methacrylic anhydride and ρ-(chloromethyl)styrene in thepresence of triethylamine and sodium hydride to give the vinyl saccharide monomericcompounds 2a, 2b and 2c. Then monomers 1-O-acryloyl-2,3:5,6-di-O-isopropylidene-α-D-mannofuranoside 2a, 1-O-methacryloyl-2,3:5,6-di-O-isopropylidene-α-D-mannofuranoside2b and ρ-(2,3:5,6-di-O-isopropylidene-α-D-mannofuranose-1-oxymethyl)styrene 2c were isolated with column chromatography method using a gradient ofhexane and ethyl acetate as eluant. The homopolymerization of above mentionedsugar-protected glycomonomers led to poly(1-O-acryloyl-2,3:5,6-di-O-isopropylidene-α-D-mannofuranoside) P3a, poly(1-O-methacryloyl-2,3:5,6-di-O-iso-propylidene-α-Dmannofuranoside)P3b and poly[ρ-(2,3:5,6-di-O-isopropylidene-α-D-mannofuranose-1-oxymethyl)styrene] P3c in the presence of benzoyl peroxide by heating at 60°C usingsolvent. The obtained glycopolymers were purified through solvent and non-solventsystems. The structure of all purified glycomonomers and glycopolymers wereconfirmed using 1H, 13C and 2D NMR and FTIR. The molecular weights of the obtainedglycopolymers were determined using gel permeation chromatography (GPC).