Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 1–5                                                             ISSN: 1017-6020/1992

 

Determination of Crosslink Density by Swelling in the Castable

 

Polyurethane Elastomer Based on 1/4-Cyclohexane Diisocyanate

 

and p-Phenylene Diisocyanate

 

M. Barikani and C. Hepburn

Loughborough University of Technology, Loughborough, Leicestershire, LE 11 3 TU, UK

 

ABSTRACT

 

Five different series of castable polyurethane elastomers, based on the system polycaprolactone /trans 1,4‑cyclohexane diisocyanate or p-phenylene diisocyanate and various types of chain extenders, were synthesized to study the effect of using excess diisocyanate and three functional chain extender on crosslink density and swollen volume. Crosslink density was measured by swelling in toluene at room temperature for one week. It was found that the crosslink density significantly increases with increasing amounts of excess diisocyanate in the original gel. It was also found that a higher value of crosslink density is observed on changing from diol chain extenders to a diamine system.

 

 


 Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 7–10                                                          ISSN: 1017-6020/1992

 

Electrochemical Behaviour of Electroactive/Conductive

 

Poly(a-naphthylamine) in Aqueous Media

 

A. Entezami, S.M. Golabi and J. Raof

Electroanalytical Chemistry Laboratory, Faculty of Chemistry, University of Tabriz, Tabriz, I.R. Iran

 

ABSTRACT

 

The electroactive poly(a‑naphthylamine) was prepared in 0.2 M perchloricacid solution by sweeping potential at the range of .5 to + 0.6 V/vs SCE, on the surface of various solid electrodes such as Pt disk, Au disk,Gc disk and pt foil (O. 5 cm2). Electrochemical behaviour was characterized during polymer chain growth and after chain formation by cyclic voltametry. The effects of temperature, the nature of the working electrode, and the sweeping rate of applied potential were studied during the electropolymerisation of the monomer.

 

 

 

 

 


Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 11–14                                                         ISSN: 1017-6020/1992

 

Investigation on Photochemical Reactions of Sensitized Novolac

 

Resin Composition as Positive Working Lithographic and

 

 Microlithographic Application

 

H. Mivehchi

Chemistry Group of Jahad Daneshgahi, Sharif University of Technology, Tehran, I.R. Iran

 

ABSTRACT

 

Photosensitive formulations comprising diazonaphthoquinone novolac resins have been widely used as positive working lithographic and microlithographic materials [1–3]. To enhance the light sensitivity of the formulations, ester adducts of photosensitive agents based on diazonaphthoquinone sulfonic acids are currently being employed. It has been found that the composition based on the esters of the sensitive agents with cyclic alcohols, and phenols, including novolac resins responds well to the requirements of the positive printing plates, namely high image resolution upon ultraviolet radiation, adhesion and coatability to the aluminium plates.

* Present address: Iran Polymer Institute, Tehran.

 


Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 15–20                                                         ISSN: 1017-6020/1992

 

Radiation Modification of EPDM Rubber: Evaluation of

 

Wettability and Biocompatibility

 

A.A. Katbab, R.P. Burford and J.L. Garnett

School of Chemical Engineering and Industrial Chemistry, The University of New South Wales, Kensington, NSW, Australia

 

ABSTRACT

 

Surface modification of rubber vulcanizates based on ethylene‑propylene terpolymer (EPDM) is carried out by 60Co-radiation induced graft copolymerization of N‑vinylpyrrolidone(NVP), 2‑hydroxyethylmethacrylate(HEMA)and acrylamide (MM) using the simultaneous method. The wettability and biocompatibility of the modified samples are evaluated by the water drop contact angle and cell culturing technique, respectively. Although wettability increases with increasing graft level, this property shows a nonlinear relationship with biocompatibility, particularly for the samples modified with acrylamide. On the basis of the technique employed, samples grafted with NVP and HEMA show better cell attachment and biocompatibility than those modified with AAM. The graft degree of each monomer is influenced by the monomer concentration and EPDM structural factors. The addition of 1.0% multifunctional acrylates to the grafting system of each monomer produced a profound effect on graft degree and biocompatibility of the modified samples.

 

 

 

 

 


Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 21–24                                                         ISSN: 1017-6020/1992

 

Internal Heat Generation and Fatigue Life Behaviour of

 

Polyurethane Elstomer Based on Trans 1,4-Cyclohexane

 

Diisocyanate

 

M. Barikani and C. Hepburn

Loughborough University of Technology, Loughborough, Leicestershire, LE 11 3 TU, UK

 

ABSTRACT

 

Internal heat generation of castable polyester polyurethane elastomers based on the system polycaprolactone diol(Capa 225)/trans 1,4‑cyclohexane diisocyanate(CHDI)/1,4‑butane diol(1,4‑BD) and 1,4‑cyclohexane dimethanol(1,4‑CHDM) was measured on the De mattia‑machine by using a contact flat thermocouple head during the flex cracking resistance measurements. It was found that the heat generation of these polymers increased with excess percentages of diisocyanate and applied strain. It was also found that both crack initiation and crack propagation resistance decreased with increasing crosslinking due to the excess diisocyanate.


Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 25–31                                                         ISSN: 1017-6020/1992

 

Reduction of Molecular Chain Ends in Natural Rubber

 

Vulcanizates

 

G.R. Bakhshandeh and J.E. Stuckey

The University of Aston in Birmingham, Gosta Green, Birmingham B4 7ET, England

 

ABSTRACT

 

It is necessary to reduce the molecular weight of natural rubber by mastication so that its plasticity is high enough to accept compounding ingredients. This increases the number of elastically ineffective chain ends in the vulcanizate and causes a decrease in physical properties. If this mastication process is carried out in the presence of specific radical acceptors which combine with the polymeric free radicals so formed to give end groups that are capable of producing cross‑links during the vulcanization process, then the number of free chain ends are reduced and there is a marked improvement in physical properties. Suitable radical acceptors include: 2 ‑ mercaptobenzthiazole, mercaptobenzthiazole disulphide, alkyl thiuram di‑, and polysulphide and dialkyl phosphoryl di‑, tri‑, and tetrasulphides. To reduce competition from other radical acceptors, it is necessary to use acetone extracted natural rubber and masticate in the absence of oxygen. A quantitative assessment of the reduction of free chain ends based on changes in the C1 constant of the Mooney Rivlin equation is described.

 


Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 33–35                                                         ISSN: 1017-6020/1992

 

Electrosynthesis of Highly Conducting Polythiophene Thin Film

 

in Perchloric Acid

 

A. Entezami and N. Arsalani

Department of Organic Chemistry, Faculty of Chemistry, Tabriz University, Tabriz, I.R. Iran

 

ABSTRACT

 

Electroactive/conductive polymer film can be generated on an electrode surface by the oxidation of thiophene in highly concentrated perchloric acid. The mechanism of electropolymerization has been proposed in perchloric acid solution.

 

 

 


Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 36–44                                                         ISSN: 1017-6020/1992

 

Polymer Electrolytes Based on Poly(oxyethylene)

 

M. Nekoomanesh and C. Booth

Chemistry Department, Manchester University, Oxford Road, Manchester, M13 9PL UK

 

ABSTRACT

 

The chemistry of the published works on polymer electrolytes is briefly reviewed.The preparation of poly(oxyethylene) prepared from PEG400 and uniform EG with m=3 to 6 is represented. The structural (NMR and GPC), thermal (DSC) and conductivity properties of the polymers are discussed. It is shown that the Tg of the electrolytes increases linearly with increasing salt concentration. However the melting behaviour of electrolytes from PEG400 is different from those with uniform EG’s. The conductivity of all the samples is compared and it is elucidated that the electrolyte of PEG400 is the best ion conductor in the series studied with conductivity of < 10–5 Scm–1 at room temperature.

 


Iranian Journal of Polymer Science and Technology / Volume 1 Number1 (1992) 45–54                                                         ISSN: 1017-6020/1992

 

Starch as a Filler in HDPE

 

G.J.L. Griffin and S.A. Hashemi

Ecological Materials Research Institute of Brunel University, Department of Material Technology, Uxbridge, UB8 3PH, UK

 

ABSTRACT

 

Emphasis is placed in this paper on experiments designed to elucidate the mechanisms by which starch‑polymer interactions result in composites with properties markedly different from the unfilled polymer properties. In particular, attention has been directed towards increasing our understanding of the thermal and mechanical properties of starch filled HDPE.