Iranian Polymer Journal / Volume 8 Number 1 (1999) 3–8 ISSN: 1026-1265/1999
Synthesis and Characterization of Novel Aromatic Polyamides
and Polyimides by In-situ Silylation of Trimethoprim
Sh.M. Ataei1 and M. Barikani2
(1) Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran, I.R. Iran
(2) Iran Polymer Institute, Tehran, I.R. Iran
2,4-Diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine known as trimethoprim was activated by in-situ silylation and used as an activated diamine in the synthesis of aromatic polyamides and polyimides. The reactions of silylated trimethoprim with terephthaloyl chloride and isophthaloyl chloride for preparation of polyamides were investigated. Polyimides were also prepared by reaction of silylated trimethoprim with pyromellitic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic dianhydride. All polymers were characterized by conventional methods including IR and NMR spectroscopies. Thermal stability and thermal behaviour of polymers were studied using simultaneous thermal gravimetry and differential scanning calorimetry methods. The resulting polymers showed good thermal stability of T10 between 260 and 335 °C; glass transition temperature (Tg) of around 200 °C was observed for polyimides, but no glass transitions were detected for polyamides. The obtained polymers showed excellent solubility in common organic solvents. The inherent viscosities were in the range of 0.336-0.432 (dL/g) which indicated suitable molecular weights.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 9–15 ISSN: 1026-1265/1999
Phase Transfer Catalysis in Polycondensation Processes (XIX):
Thermal Behaviour of Some Polyesters Containing Oxetanic
Rings in the Main Chain with Potential NLO Properties
C. Foia1, V. Toader2, N. Hurduc1 and N. Hurduc2
(1) Department of Physical Chemistry, Al.I. Cuza University, 71 Bd. Mangeron, Iassy-6600, Romania
(2) Macromolecular Department, Gh. Asachi Technical University, 11A Bd. Copou, Iassy-6600, Romania
The synthesis of a set of polyesters by phase transfer polycondensation of a mixture based on potassium isophthalate and various dyes and 3,3-bis (chloromethyl)oxetane is reported. All obtained structures were characterized by 1H NMR spectroscopy and thermogravimetric analysis. The thermal behaviour of the synthesized samples with that of a physical mixture (homopolymer and dye) are comparatively discussed. The thermal stability is generally good, their decompositions do not occur at temperatures beyond 220 °C, while the pure dye degradation process starts at about 100 °C. So, it is shown that the presence of dye decreases the thermal stability of the physical mixtures, while the degradation of chemically modified polymers is found to be non-dependent. In the case of chemical structure, however, the dye insertion promotes the obtainment of non-linear optical (NLO) thermosets by opening of oxetanic rings in the presence of diamines. Therefore, such compounds might be used as precursors for coloured NLO networks.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 17–23 ISSN: 1026-1265/1999
Synthesis of Symmetrical and Unsymmetrical Dialkyl and Alkyl
Aryl Trithiocarbonates Using Polymer Supported Systems
B. Tamami and A.R. Kiasat
Department of Chemistry, Shiraz University, Shiraz, I.R. Iran
Symmetrical and unsymmetrical dialkyl and alkyl aryl trithiocarbonates are readily synthesized as exclusive and virtually pure products in considerably short reaction times and excellent yields by the reaction of primary or secondary alkyl, benzyl or allyl halides with hydroxide form of an anion exchange resin, or polymer supported thiolate in carbon disulphide, under mild reaction conditions, respectively. In addition, this procedure provides excellent yield of 1,3-dithiolane-2-thione from the 1,2-dibromoethane as a cyclic alkyl trithiocarbonate in comparatively very short reaction time without formation of any polymeric by-product. It is observed that the nature of halide ion has considerable effect on the reaction rate and the order of reactivity for different alkyl halides are RI>RBr>RCl. The polymer supported thiolate is very stable and can be stored without any loss of reactivity. The polymeric system is easily regenerable.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 25–30 ISSN: 1026-1265/1999
Acetone-formaldehyde-m-cresol Based IPNs for Glass Fibre
Reinforced Composite Application
H.S. Patel, B.C. Dixit and R.B. Dixit
Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar - 388 120, Gujarat, India
Acetone-formaldehyde (AF) resin having dihydroxy functionality (-CH2OH) has been prepared and polycondensed with m-cresol (mC) at equimolar ratio of AF:mC to produce acetone-formaldehyde-m-cresol (AF-mC) resin. The three component IPNs have been prepared from this acetone-formaldehyde-m-cresol (AF-mC) resin, diglycidyl ether of bisphenol-A (a commercial epoxy resin) and methyl methacrylate using simultaneous mode of IPN synthesis. The curing catalyst, hexamethylenetetramine, for AF-mC, radical initiators such as 2,2'-azobisisobutyronitrile for methyl methacrylate and curing catalyst, 4,4'-diamino diphenylmethane, for the epoxy resin were employed. The various proportions of three components were employed. All the IPNs were characterized in terms of their thermal stabilities with DSC, TGA. The glass fibre reinforced composites of produced IPN syrups have been fabricated and their chemical resistivity and mechanical properties were evaluated.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 31–36 ISSN: 1026-1265/1999
The Effect of Temperature, Concentration of Catalyst and
Reactants on Yield of BPA Synthesized from
Industrial Starting Materials
A. Rahimi, S. Farhangzadeh and F. Ziaee
Iran Polymer Institute, Tehran, I.R. Iran
Bisphenol A (BPA) is the product of condensation reaction of phenol with acetone in the presence of an acid catalyst. BPA is a major raw material for the manufacture of relatively new high-temperature polycarbonate resins and epoxy resins. These two applications consume over 90% of the BPA output. So, we decided to investigate its different preparation methods to find the optimum industrial production conditions which satisfy the economy, and operational conditions of Iran Industry. With this aim, we synthesized BPA from industrial grade starting materials, with high degree of purity(92%) and high yield (90%). In this article we discuss the effect of different parameters such as temperature, concentration of catalyst, reactants, and the presence of a promoter on yield of BPA and report the optimum conditions to obtain the 90% yield of BPA with high degree of purity.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 37–42 ISSN: 1026-1265/1999
Studies on Dynamic Vulcanization of PP/NBR Thermoplastic
G. Naderi, M. Razavi Nouri, M. Mehrabzadeh, and G.R. Bakhshandeh
Iran Polymer Institute, P.O. Box: 14965/115, Tehran, I.R. Iran
Thermoplastic elastomeric materials have become important because they have many properties of vulcanized rubbers and can be rapidly fabricated as thermoplastics. In this work, selected grade of polypropylene (PP) was modified with dimethylol-phenolic resin and then it was melt-mixed with acrylonitrile-butadiene rubber (NBR) for several weight ratios. After sufficient mixing time additional phenolic resin was added to mixing chamber and the blends were dynamically vulcanized. In order to study the effects of the compositions and dynamic vulcanization on the physical and mechanical properties, simple blends of unmodified polypropylene and NBR were also prepared. The results show that dynamically vulcanized blends have higher tensile strength, elongation at break, solvent and oil resistance.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 43–50 ISSN: 1026-1265/1999
Copolymerization of p-Benzoquinone with 9-Vinylcarbazole
N.A. Yunis oglu
Institute of Polymer Materials of the Azerbaijan Academy of Sciences, S. Vurgun St.124, Sumgait, 373204
Republic of Azerbaijan
Copolymerization of p-benzoquinone and 9-vinylcarbazole has been firstly realized in the presence of triethylamine in ethanol and pyridine medium. The regularities, compositions and structures of products of this process have been studied. It has been established that the basic reaction product is the copolymer with hydroquinone and 9-vinylcarbazole units. Along with copoly-mer 5-10% hydroquinone and 15-20% homopolymer of quinone are formed. Molecular weight distribution has been studied by gel-chromatographic method and values of molecular weights (Mw=4120-8010 and Mn=3960-6400) of copolymers have been determined. The formation of weak intermolecular complexes between p-benzoquinone and 9-vinylcarbazole has been fixed by UV method. Thus, the mechanism of formation of copolymer and side products in interaction of p-benzoquinone and 9-vinylcarbazole has been suggested.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 51–59 ISSN: 1026-1265/1999
Synergistic Effects of Some Phosphites Antioxidants
Used in Polypropylene Stabilization
M. Ghaemy and S. Fruzandeh
Department of Chemistry, University of Mazandaran, Babolsar, I.R.Iran
Inhibition of thermal oxidation of polypropylene (PP) by three synthesized aliphatic and aromatic phosphites containing two different antioxidant functional groups in the same molecule was observed in an air-circulating oven at 115 °C. The stabilizing effect increases with increasing concentration of antioxidants. Long-term heat aging of PP is more efficiently reduced by the prepared phosphites than two available commercial phenolic antioxidants. It was shown that besides the chemistry of trivalent phosphorus, the reactions of the secondary structure of the aromatic and aliphatic phosphites also influence the overall performance. Phosphites containing substituents, compound (III), able to form non-propagating species, such as hindered phenols, are able to perform through chain-terminating mechanism as well.
Iranian Polymer Journal / Volume 8 Number 1 (1999) 61–66 ISSN: 1026-1265/1999
Synthesis and Characterization of Novel Polyureas with 4-
Phenylurazole Moieties in the Chain
Sh.E. Mallakpour and B. Sheikholeslami
Organic Polymer Chemistry Research Laboratory, College of Chemistry, Isfahan University of Technology
Isfahan, 84156, I.R. Iran
The reaction of 4-phenylurazole (PHU) 1 with n-isopropylisocyanate 3 was performed at room temperature and the resulting bis-urea derivative 4 was obtained in high yield and it was finally used as a model compound for the polymerization reaction. The step-growth polymerization reactions of monomer 1 with hexamethylene diisocyanate (HMDI) 5, isophorone (IPDI) 6 and toluene-2,4-diisocyanate (TDI) 7 were performed in DMAc in the presence of pyridine or triethylamine as a catalyst. The resulting novel polyureas have an inherent viscosity in a range of 0.04-0.23 g dL-1 in DMF at 25 °C. These polyureas were characterized by IR, 1H NMR and elemental analysis.The resulting polymers are soluble in most organic solvents. Some physical properties and structural characterization of these novel polyureas are reported.