Iranian polymer journal
Volume:18 Issue: 3, 2009

Polymer supported reagents have become the subject of considerable and increasing interest as insoluble materials in the organic synthesis. The attachment of the reagents to the insoluble macromolecular matrix can solve the problems of tedious work-up, lability, toxicity, or unrecyclability often experienced with nonpolymeric low-molecular weight reagents. A literature survey shows that a review on poly(vinylpyridine)-supported reagents is not available yet. This review will focus on the implementation of methodologies for polymer supported reagents based on poly(vinylpyridine) (PVPy), in the organic synthesis appeared in the literature until the year of 2009. The aim is to distill the literature into three categories and to present each as a short table listing the functionalized polymers involved, along with their relevant applications as reagents. In the text, discussions on the structural and transformation of some typical polymeric reagents are given, although there is not detailed procedure provided in the text about the synthesis of the polymers or their transformations. When appropriate, comparison between the behaviour of supported reagents versus non-supported reagents is attempted. This review does not include the patent literature.

Waste management is a major concern in petrochemical plants. Almost all types of wastes are used to modify bitumen. Following this concept polymer and non-polymer wastes of petrochemical production lines were used to modify bitumen. It was found that incorporation of the wastes separately or as a combination of some high performing polymer-modified bitumens are obtained. Almost all modifiers did not improve the low temperature properties of the modified bitumen and in some cases deteriorated this property. The low molecular weight polyethylene (LMP) and Nmethylpyrrolidone (NMP) wastes increase high temperature performance of bitumen, whereas styrene-butadiene rubber (SBR) waste improves low temperature performance at moderate concentrations. The best performance grades (PG) obtained by introducing these modifiers are PG = 106-10, PG = 76-22 and PG = 94-16 at a rate of 5% modification, respectively. The best performance grades obtained with mixtures of NMP and SBR were PG = 82-16 and PG = 76-22. The most useful performance grades resulted form incorporation of mixtures of LMP and SBR in bitumen were PG = 94-16 and PG = 100-10. In fact, mixtures of LMP and SBR wastes were found to be the most beneficial compositions for bitumen modification.

Five new polythioamides were prepared by polycondensation of a mixture of sulphur and various diamines with a dicarbonyl compound [4,4’- methylenebis(cinnamaldehyde)] (MBC). The used diamino compounds were ethylenediamine, 1,3-propylenediamine, meso-stilbenediamine, semicarbazide, and thiosemicarbazide. The polythioamides formed were characterized by elemental microanalysis, FTIR, UV, Vis, and 1H NMR spectroscopies, thermal analysis and viscosity measurement. All the polythioamides indicated a characterized band within 1230-1260 cm-1 due to νC=S vibrations. The synthesized polythioamides indicated better thermal stability up to 600ºC. The dialdehyde (MBC) and polythioamides were soluble in number of organic solvents including tetrahydrofuran, dimethyl formamide, dimethyl acetamide, and dimethyl sulphoxide. The intrinsic viscosities of these polythioamide ranged within 0.393-0.5201 dL/g as compared to 0.174-0.249 dL/g for dialdehyde (MBC) in THF.

Interactions within a package system refer to the exchange of mass and energy inside the packaged food, the packaging material and the external environment. Absorption of flavours into packaging material causes the loss of aroma or changes in the mechanical properties of package. Therefore, it results in reduced perception of the product quality. In this research, the effect of menthol absorption by polyethylene terephthalate (PET) bottles on mechanical properties of the PET bottles was investigated through tensile test. The PET samples containing yogurt drinks with 100 ppm initial concentration of menthol were stored for about three months at 4ºC, 25ºC, and 45ºC and the mechanical properties (tensile strength, modulus of elasticity and elongation) of PET bottles were measured periodically during the storage time. A new technique, dispersive liquid-liquid microextraction (DLLME), was used before GC analysis for concentrating the acetone extraction solution containing menthol. The effect of menthol on mechanical properties of PET bottles was compared through tensile test results of the PET bottles containing yogurt drinks with 100 ppm menthol against PET bottles containing yogurt drink without initial concentration of menthol solution. Maximum effect of menthol on mechanical properties of PET bottles was observed on the samples stored at 45ºC that could be due to the high amount of absorbed menthol at higher storage temperatures. It was also found that tensile strength and modulus of elasticity of PET bottles decreased with the absorption of menthol, while the elongation increased.

In this research, a new model is established based on progressive fatigue damage and critical element models to simulate fatigue behaviour and predict the fatigue life of composite laminates with stress concentration. This model, called the “regional elements” model, has three major parts: stress analysis, failure analysis, and material property degradation. A critical region of the analyzed composite laminate is considered and the elements of this region are divided into critical and sub-critical layers. Using 2- dimensional stress analysis, failure modes of these regional elements are investigated and material properties in the critical and sub-critical layers are changed according to sudden and gradual material property degradation rules. Gradual material property degradation is performed on the longitudinal tensile strength of critical layers and the longitudinal tensile stiffness of sub-critical layers. By the iteration of the aforementioned loop, fatigue damage modelling is completed and an estimate of the fatigue life of acomposite laminate is obtained. The finite element method is used to assess the capabilities of the current model through a user-friendly computer programme. The modelpredicts initial and final failure loads to within 20% of experimental results for the caseof static failure analysis. However, 3-dimensional stress and failure analyses arerequired to improve the model for fatigue failure analysis for all the configurations.

Novolac type resin was prepared by liquefaction reaction of oil palm empty fruit bunch (EFB) in the presence of phenol at various reaction conditions. This polymer later is known as phenolated EFB (PEFB). PEFB-base board was made using PEFB as a polymer matrix phase and EFB as a filler. The effect of various liquefaction conditions and filler content on water absorption and thickness swelling of PEFB-base board was studied. The hardness of these samples also was examined before and after water absorption. The result clearly showed that the major part of water absorption and thickness swelling were due to water absorption of EFB filler. It was found that the water absorption in the PEFB-base board is slightly higher than the commercial novolac resin board. The result of hardness test showed a substantial decrease in hardness after water absorption test at higher filler content (80%). It was also found that the reduction of hardness in PEFB-base board after water absorption is lower than the commercial novolac-base board.

Dendritic polyamidoamine (PAMAM) is one of the first synthesized and commercializeddendrimers, and because of its peculiar properties it is widely used in many fields. In this paper, the first generation polyamidoamine dendrimer (G1.0 PAMAM) with primary amine terminal groups was synthesized by the Michael additio reaction of ethylenediamine and acrylic acid ester in the divergent approach. The first grade mass molecule ions [M+H+]+, m/z 518 in mass spectra indicated that the molecular weight of G1.0 PAMAM was 517 g.mol-1, which was in accordance with the theoretical molecular weight. The characteristic structure of the products was corroborated by FTIR spectra. Moreover, thermal behaviours of G1.0 PAMAM were investigated by DSC and TG-DTG techniques. It was suggested that G1.0 PAMAM had a two-stage thermal weight loss curve between 150ºC and 450ºC, the intersection temperature 282.32ºC divided the weight loss curve into two stages, the normalized heat was -485.48 J.g-1, and the heat flow values at the intersection temperature of two stages reached a maximum. The weight loss ratio to the total weight ratio was 55.71% at the first temperature stage between 150ºC to 282.32ºC, and at the same stage the integral heat area to the total heat ratio was about 53.93%. Standard MS and the second order MS spectra of G1.0 PAMAM showed that the decomposed structure at the low temperature stage would be the fragment ion, m/z 289. A possible formation mechanism of the fragment ion was also proposed as that the primary amine terminal of G1.0 PAMAM was decomposed from terminal tetra-amino structure to bi-amino structure.

The aim of this study is to investigate electrospinning of polycaprolactone (PCL)- blend chlorophyllin sodium copper salt (CSC) to prepare biodegradable nanofibrous mats for fabricating tissue engineering scaffold. For a suitable biofunctional tissue engineering scaffold, one of the most important factors was that the scaffold should provide enough space for the living cells. Therefore, by adding a non-toxic salt into the nanofibrous mats it was possible to attain this goal. In this study, PCL/CSC nanofibrous mats were tested by scanning electron microscopy (SEM); and the mechanical properties of nanofibrous mats with or without CSC were tested by a universal mechanical testing machine. The crystallized property was investigated by an Xray diffraction (XRD) instrument. The degradation property and CSC released behaviour were also tested in this study. SEM examinations revealed that the PCL/CSC nanofibres with 20% CSC lose their fibrous structure. For evaluation of the performance of PCL/CSC nanofibrous mats as scaffolds which could provide sufficient space for the cells, the mats were examined for weight loss and CSC release tests. The results demonstrated that the PCL/CSC nanofibrous mats could lose most of the CSC in the first several hours, which may provide more space for cells anchorage and proliferation. We conclude that combination of CSC into PCL nanofibrous mats is feasible for fabricating a novel tissue engineering scaffold.