Iranian Polymer Journal / Volume 6 Number 4 (1997) 227233 ISSN: 1026-1265/1997
Cure Kinetics of Novel Tetrafunctional N‑Glycidyl Epoxy
Resin and their Glass‑Fibre‑Reinforced Composite
Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar-388 120
The curing reactions of tetrafunctional epoxy resin N,N,Nī,Nī‑tetraglycidyl-1,1ī ‑bis[4‑p‑aminophenoxy)phenyl]phenylmethane using different amine curing agents are studied by differential scanning calorimetry. The kinetics of the thermal degradation of cured epoxy resins are studied by thermogravimetry at a heating rate of 10 ºC min1. The overall activation energy for the curing reactions are observed to be in the range 76.0‑386.1 kJ.mol1. The glass‑fibre‑epoxy‑resin composites are fabricated using the said tetrafunctional N‑glycidyl epoxy resin with the conventional epoxy resin DGEBA in the ratio 20:80 using different amine curing agents and evaluating for their physical, mechanical, chemical and electrical properties.
Iranian Polymer Journal / Volume 6 Number 4 (1997) 235241 ISSN: 1026-1265/1997
Acylation of Polybutadiene Containing 4‑Phenyl Urazole
Organic/Polymer Chemistry Research Laboratory, College of Chemistry
Isfahan University of Technology, Isfahan 84156, I.R.Iran
Polybutadiene with a narrow molecular weight is synthesized by anionic polymerization of butadiene monomer in cyclohexane at 20 ºC using n‑butyllithium as initiator. This polymer is statistically functionalized with 4‑phenyl-1,2,4‑triazoline‑3,5‑dione by hydrogen abstraction addition reaction (ene reaction) in an extent of 5, 10, and 15%. These functionalized polymers are reacted with acetyl chloride as well as benzoyl chloride in presence of pyridine at room temperature. These reactions lead to the replacement of N‑H with acetyl and benzoyl groups. The amount of urazole and acyl incorporation are determined by 1H NMR technique. Some physical properties of these modified polybutadienes are reported.
Iranian Polymer Journal / Volume 6 Number 4 (1997) 243252 ISSN: 1026-1265/1997
Oxidation of Polypropylene Homopolymer in Presence of an
Aqueous Solution of Phenyltrimethyl
Chemistry Department, Faculty of Science, University of Tehran, Tehran, I.R. Iran
The oxidation of polypropylene homopolymer film and powder (film grade) in presence of an aqueous solution of phenyltrimethyl ammonium permanganate (Ph.TMAP) at room temperature would be desirable if the original morphology of the polymer must be maintained. The oxidation process leads to the formation of polar groups (such as, alcoholic, hydroperoxide, etc.) mainly carboxylate ions and quaternary ammonium hydroxides liberating MnO2 as a by‑product from the decomposition of the Ph.TMAP. The treated surfaces are studied by scanning electron microscopy (SEM), Fourier Transform IR and electron spectroscopy for chemical analysis (ESCA). The analyses show an increase in the number of oxygen atoms absorbed as compared to the molar concentration of the oxidizing agent and time. As a result of the decomposition of Ph.TMAP the polypropylene surface was covered with MnO2 and it was corroded. The MnO2 formed was analyzed by ESCA analysis as well as by chemical tests. The oxidation reaction of polypropylene homopolymer and Ph.TMAP as an effective oxidant system produce interesting products, which can be used as compatibilizer in some industries. A reaction mechanism of the polypropylene oxidation, at room temperature and in an aqueous solution of Ph.TMAP, is proposed.
Iranian Polymer Journal / Volume 6 Number 4 (1997) 253260 ISSN: 1026-1265/1997
Polyurethanes (II): Products of Polyaddition of
Bis(4‑hydroxyethylenethio)diphenyl Ether with
Depatment of Organic Chemistry and Technology, Maria Curie-Sklodowska University
20-614 Lublin, Poland
We report new linear polyurethanes synthesized by polyaddition reaction of bis(4‑hydroxyethylenethio)diphenyl ether with 1,6‑hexane diisocyanate. Two synthetic variants are applied, in solution or in melt, with or without a catalyst. Good results are obtained using aprotic solvent, N,Nī‑dimethylformamide, Ca. 25% weight concentration of monomers, dibutyl tin dilaurate as a catalyst, and conducting the process at 90‑100 ºC for 3.5‑4.0 h. Basic physico‑chemical properties of polyurethanes obtained are presented. Thermal behaviour of the polymers is analyzed by means of thermogravimetry and DSC. The structure of resulting products is characterized by elemental analysis, FTIR spectrum and X‑ray analysis. Effect of partial replacement of bis(4‑hydroxyethylenethio)diphenyl ether by 20‑70 mol% 1,6‑hexanediol on the properties of polyurethanes obtained in the optimal conditions established earlier has been investigated.
Iranian Polymer Journal / Volume 6 Number 4 (1997) 261268 ISSN: 1026-1265/1997
(1) Polymer Group, Chemical Engineering Department, Tarbiat Modarres University, Tehran, I.R. Iran
(2) Institute of Petroleum Research, NIOC, Ray, Tehran, I.R. Iran
The polymerization of vinyl acetate in methanol, ethyl acetate and acetic acid is studied and the conversion‑times are reported. Due to the importance of molecular weights of polymers from the solution and bulk methods, and their uses in optimization of polymerization, specially in controlling the properties of the polymer, the viscosity, molecular weight and molecular weight distributions are measured and reported. Statistical calculations and curve fittings of the data on the molecular weights and the solvent (methanol‑monomer ratio) indicate a very low mathematical residues. The conversions are compared with bulk, and the effect of temperature on solution polymerization in ethyl acetate is used to show the importance of high activation energy of the initiator (benzoyl peroxide). Triethyl amine, being used as catalyst in solution polymerization of vinyl acetate (ethyl acetate and acetic acid), indicate a faster conversion.
Iranian Polymer Journal / Volume 6 Number 4 (1997) 269272 ISSN: 1026-1265/1997
Studies on Recycling of Poly(ethylene terephthalate)
(1) Department of Chemical Engineering, Sharif University of Technology, Tehran, I.R. Iran
(2) Iran Polymer Institute, Tehran, I.R. Iran
Effect of reprocessing on poly(ethylene terephthalate), PET, is studied. While mechanical properties show slight decrease, the weight‑average molecular weight,`Mw, drops more notably. Blends of 20 w/w % recycled PET with virgin PET show practically the same mechanical properties with its`Mw slightly lower than virgin PET. The results suggest that mechanical blending can be used for recycling purposes without sacrificing useful properties of the virgin PET, and to reduce raw material cost in bottle fabrication.
Iranian Polymer Journal / Volume 6 Number 4 (1997) 273279 ISSN: 1026-1265/1997
Synthesis and Application of Quaternized Polyvinylpyridine
Supported Dichromate As a New Polymeric Oxidizing Agent
Department of Chemistry, Shiraz University, Shiraz, I.R. Iran
Cross‑linked poly(n‑butyl‑4‑vinylpyridinium)dichromate is easily synthesized and used as a versatile and effective oxidizing agent for the oxidation of different organic compounds. This reagent oxidizes primary and secondary alcohols (benzylic and aliphatic) to their corresponding aldehydes and ketones in an appropriate solvent, respectively. With this oxidant the oxidation of thiols to disulphides, hydroquinones to quinones, acyloins and allylic alcohols to the corresponding carbonyl compounds, have also been investigated under reflux condition. Functional groups such as phosphines, oximes, sulphides and aromatic hydrocarbons are unaffected. The reagent can be easily regenerated.
Iranian Polymer Journal / Volume 6 Number 4 (1997) 281286 ISSN: 1026-1265/1997
Poly(p‑styrenesulphonamide) as a New and Selective Catalyst
for Bromination of Various Aromatic Compounds
A. Khazaei, H. Hosseini, and M. Sadri
Department of Chemistry, Faculty of Science, Bu-Ali Sina University, Hamadan, I.R. Iran
The objective of the present work was preparation of poly(p‑styrenesulphonamide) that can be used as a catalyst for bromination of aromatic rings, such as benzene, toluene, isopropyl benzene and bromobenzene. Poly(p-styrenesulphonamide) can be synthesized from radical polymerization of p‑styrenesulphonamide with the use of azobisisobutyronitrile (AIBN) as an initiator. p‑Styrenesulphonamide was prepared from commercial 4‑vinylbenzene sulphonic acid sodium salt (CH2=CH.C6H4SO3Na+), phosphorus pentachloride, and ammonia. Poly(p‑styrenesulphonamide) synthesized can be used in equimolar amounts as a polymeric catalyst, and it catalyzes a wide range of bromination reactions. Then the brominated product is separated and the polymer is recovered, which can be used in another process for bromination of other aromatic rings. One of the advantages of this polymer is that the bromination of aromatic rings takes place without brominating the alkyl substitution on aromatic ring. Also in comparison with catalysts which so far have been applied for bromination of aromatic compounds, this polymer, as catalyst, has many advantages, e.g. high recovery, reuseability, selectivity and stability when exposed to moisture and air.