Iranian polymer journal
Volume:17 Issue: 1, 2008

Microwave irradiation (2.46 GHz, 300 W) was utilized to produce salicylic acidformaldehyde- resorcinol (SFR-M) chelating resin in DMF media at 80±2ºC with ecofriendly approach involving shorter time as compared to conventional ethod. The resulting resin was characterized by FTIR, 1H NMR, and elemental nalysis. The investigation of the surface characteristics of the resin was carried out y examination of resin morphology using scanning electron microscopy (SEM) at ifferent magnifications. Broido and Horowitz-Metzger methods were used to calculate the energy of activation (Ea) from TGA. The chelating properties of synthesized resin such as total ion-exchange capacity, effect of pH, concentration and time for different metal ions Ni (II), Cu (II), Zn (II), Cd (II) and Pb (II) were also studied by employing batch equilibrium method. The quantitative separations of metal ions from binary Ni(II)-Cd(II)] and ternary [Ni(II)-Zn(II)-Cd(II)] synthetic mixtures were performed by column chromatography at 25±2ºC. The constituents of brass were also analyzed by selective sorption on column at optimized distribution coefficient (Kd) values. Microwave assisted chelating resin is specific for transition metal ions rather than selective as compared with the resin synthesized by conventional method.

This article presents an extensive survey of the current knowledge in the field of a recently emerged linear aromatic polyester, poly(trimethylene terephthalate) (PTT), as a promising thermoplastic polymer for engineering applications currently ddressed by linear polyamides, as well as two other linear aromatic polyesters,. e., poly(ethylene terephthalate) (PET), and poly(butylene terephthalate) (PBT). To ffset relatively high cost and further improve the physical properties, tailoring PTT to pecific performance-cost profile taking advantage of blending with other polymers as received substantial interest. Critical results of the published papers available ithin the literature on PTT-based blends are cited in this article. From the standpoint f integrating the features of both polymers and nanoparticles into composite materials, he impressive technology of nanocomposites has been increasingly drawing academic nd scientific attraction where the polyester nanocomposites, including those ased on PTT matrix in particular, have also been successfully delivered with desired roperties. The recent advances in the area of PTT-based nanocomposites are then reviewed in this survey. A concise discussion on the future trends in the aforementioned ields is lastly presented.

The homopolymer of glycidyl methacrylate (GMA) and its random copolymers رwith 2-ethyl hexyl acrylate (EHA) and isoprene (IP) were synthesized under vacuum using azobis (isobutyronitrile) (AIBN) as initiator at 70±1ºC. Tris (trimethylsilyl) methyl group (trisyl= Tsi) was then covalently attached to the obtained homopolymer and copolymers as side chain. The polymers were characterized by 1H NMR, IR, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). In the case of poly (GMA) modification, limitation in conversion is observed and it has been attributed to the steric hindering effect of the previously grafted moieties. This modification increases the rigidity of polymers and, subsequently, their glass transition temperature as shown by DSC and DMTA analyses. The results show that, with the incorporation of the tris (trimethylsilyl) methyl group in the polymer side chains, a series of novel modified polymer containing new properties are obtained, that can find some applications in polymer industry.

Sheets of poly(3-hydroxylbutyrate-co-4-hydroxylbutyrate)[P(3HB-co-4HB)] with various 4HB contents and triethyl citrate (TEC) plasticization are prepared by melt mixing and compression moulding. The thermal, crystalline and mechanical properties of these sheets are evaluated. Furthermore, fracture surfaces of samples plasticized by TEC are examined by scanning electron microscope (SEM). The results show that the increase of 4HB content can lead to the decrease of thermal parameters of samples such as melting temperature, glass transition temperature, crystalline temperature and crystallinity. However, the elongation-at-break of samples increases with the 4HB content increasing, and the strength-at-break decreases as a whole. The incorporation of 4HB units can improve the thermal stability of copolymer. The effect of TEC on the thermal and mechanical properties of samples is similar with that of 4HB unit. In contrast to 4HB unit, the increase of TEC content can worsen the thermal stability of samples. In addition, the copolymer of P(3HB-co-4HB) is compatible with TEC and its ductility can be improved by incorporation of TEC.

Polyurethane elastomers with improved crystallinity and hydrophilicity were synthesized by step growth polymerization techniques using poly(ε-caprolactone) (PCL) and 4,4′-diphenylmethane diisocyanate (MDI), extended with α,ω alkane diols (hydroxyl group attached with first and last methylene unit of an alkane chain). Structural characterizations were performed using FTIR, 1H NMR and 13C NMR techniques. Crystallinity of the polyurethane (PU) films was studied and discussed by using X-ray diffraction technique. For all the samples, the crystallinity and hydrophilicity were found to increase with increasing of the chain extender length. Optimum crystallinity and hydrophilicity were obtained from elastomer extended with 1,10-decane diol (DDO) in comparison to elastomers extended with 1,2-ethane diol (EDO). Contact angle measurement, water absorption and swelling behaviour of the synthesized polyurethane were affected by number of methylene units in the chain extenders in the resulted PU. Investigation of structure-property relationship for prepared elastomers showed that the main determining factors for observed properties were degree of crystallinity, hydrophilicity and chain extender length in the PU backbone.

Amild acidic dioxane extraction procedure was used to isolate lignin from hardwood bleached chemimechanical pulp (BCMP). The isolated lignin was impregnated on Whatman filter paper and irradiated with ultraviolet (UV) light under various exposure times. Then, photodegraded lignin was recovered and characterized by FTIR spectroscopy and high pressure size exclusion chromatography (HPSEC). Loss of lignin aromatic content induced by syringyl and guaiacyl nuclei degradation, reduction in Caryl-O ether bond caused by demethoxylation and β-O-4 bond cleavages, and formation of carbonyl and/or carboxyl groups with slight increase in phenolic hydroxyl group, were some of structural changes observed by FTIR spectroscopy studies. Analysis of lignin samples with HPSEC indicated that formation of high molecular condensed structures by radical coupling during 4 h irradiation time, caused to increase lignin molecular weight. However, with continuing irradiation time of up to 120 h, the molecular weight of lignin decreased by 23% of its original value due to predominating photodegradation mechanisms. The results are discussed in relation to the reaction pathways leading to the breakdown of the lignin macromolecular structure.