Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Cartilage Tissue Engineering for Ear as in Rabbit Model with

 

Perforated Polyurethane Prosthesis: In Vivo Assay

 

Hamid Mirzadeh1(*), M. Ali Mohagheghi2(*), Hossein Ahmadi2, Hamid Mirkhani2,

Saeed Amanpour3 and Pirooz Salehian4

(1) Iran Polymer Institute, P.O. Box 14965/159, Tehran, I.R. Iran

(2) Cancer Institute, P.O. Box 13145-158, Tehran, I.R. Iran

(3) Razi Vaccine and Serum Research Institute, Karaj, I.R. Iran

(4) Iran University of Medical Sciences, Tehran, I.R. Iran

 

Received 14 February 2000; accepted 24 April 2020

 

ABSTRACT

 

Attempts have been done in this study to assay in vivo implantation of the perforated polyurethane prosthesis as ear cartilage in a rabbit model. The suitable prosthesis, compatible with ear cartilage in rabbit (300–400 mm thickness) was synthesized and implanted in the left ear of 18 rabbits as cartilage substitution. Cartilage from the left ear with the same area of the implant was trans‑implanted on the right ear as control. After 1 to 5.5 months en bloc resection of prosthesis and surrounding tissues for histopathological and biocompatibility studies were performed. Of the 18 inserted implants, complete healing was observed in 8 (45%) cases. Four (22%) of the remain-ing 10 implants showed partial healing and remaining six (33%) showed non-healing. It was, therefore, concluded that perforation might improve the cartilage cell ingrowth, when perforated polyurethane used as artificial cartilage for the repair of ear cartilage defects.

 

Key Words: perforated polyurethane (PPU), biocompatibility, ear cartilage, tissue engineering

 

 

Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Effects of Silica on the Cure Properties of Some

 

Compounds of Styrene-butadiene Rubber

 

M. Ali Ansarifar*, Jatinder P. Chugh and Siavash Haghighat

Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough

Leicestershire LE11 3TU, UK

 

Received 13 December 1999; accepted 2 May 2020

 

ABSTRACT

 

The cure properties of some conventional accelerator/sulphur compounds of styrene-butadiene rubber (SBR) with a sulphur to accelerator ratio of ~1.8, containing no filler, and 10, 30, or 50 pphr rubber by weight precipitated amorphous white silica filler type VN3 were studied at 160 ºC by an oscillating disc rheometer curemeter. The optimum cure time, t95, of the compounds was lengthened substantially from 20 to 280 min when silica loading was raised to 50 pphr. The rate of cure calculated from the cure rate index, decreased sharply from 8.3 to 0.37 min–1 when the amount of silica in the mixes reached 50 pphr. Interestingly, the scorch time, ts2, of the compounds was not affected by the addition and increases in the amount of silica, and remained at about 8 min, although, there was some evidence that silica had interfered with the reaction mechanism of sulphur cure and reduced the extent of cure in the rubbers. Our results indicated that the compounds were fully cured when sufficient time i.e., up to 300 min for the mix with 50 pphr filler, was allowed for the reaction in the compounds at elevated temperature to complete.

 

Key Words: silica, styrene-butadiene rubber, accelerator/sulphur cure compounds, cure properties

 

 

Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Use of Rice Husk and Phenols Extracted from it as Filler and

 

Antioxidant Respectively in Vulcanization Studies of NR

 

A.P. Kuriakose* and G. Rajendran**

Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology

Cochin‑682 022, India

 

Received 15 August 1998; accepted 29 November 2020

 

ABSTRACT

 

In the present study, the rice husk is used as filler in natural rubber (NR) to observe its reinforcing effect on the rubber vulcanization. The effect of variation of particle size and of filler loading is investigated. The results of the study indicated that much reinforcement is not obtained by the incorporation of husk in different formulations. When used in smaller particle size, however, some reinforcement effect is noticed. This effect can further be increased by incorporation of resorcinol and hexamine in the compound recipe. In the next part of the study, the mixture of phenols consisting of ferulic, vanillic, p-coumaric, sinapic p‑hydroxy benzoic, salicylic and indoleacetic acid extracted from rice husk has been tried as antioxidant in NR gum and filled vul-canizates. The results obtained were compared with those of control mixes containing styrenated phenol. The cure characterisitics and vulcanizate pro-perties were evaluated. The results indicated that there is not much variation in cure characteristics or tensile properties between control and experimental sets. Further, the antioxidant protection given by phenols from rice husk is comparable with that of styrenated phenol.

 

Key Words: rice husk, phenol, filler, antioxidant, natural rubber

 

 

Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Polyurethanes (III): Polyaddition Products of

 

4,4´‑Bis(2-hydroxyethylenethio)diphenyl Ether and 2,4‑Tolylene

 

Diisocyanate

 

Danuta Wdowicka*, Wawrzyniec Podkościelny and Anna Kultys

Department of Organic Chemistry and Technology, Maria Curie­ Skłodowska University 20‑614 Lublin, Poland

 

Received 8 November 1999; accepted 10 April 2020

 

ABSTRACT

 

New linear polyurethanes derived from 4,4´‑bis(2-hydroxyethylenethio)di-phenyl ether (4‑HETE) and 2,4‑tolylene diisocyanate (TDI) were synthesized by both melt or solution polymerization. Good results were obtained using aprotic solvent: N,N´-dimethylformamide, dibutyltin dilaurate (DLDBT) as a catalyst ~1 wt % concentration and ~30 wt % concentration of monomers and conducting the process at 90–100 ºC for 2 h. Basic physico‑chemical properties of the series of PUs obtained are presented. Thermal properties of the polymers were investigated by means of thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Molecular weight distribution was determined by gel permeation chromatography. The structure of the resulting products was confirmed by elemental analysis, Fourier transform infra-red spectroscopy and X‑ray diffractometry. The properties of copolyurethanes containing variable amounts of poly(oxytetramethylene)diol (PTMO~650 or 1000) synthesized in the conditions established earlier for non-segmented PUs are also presented.

 

Key Words: linear polyurethanes, polyaddition, non-segmented polyurethanes, segmented polyurethanes, characterization

 

 

Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Azo Dyes Based on Resorcinol‑formaldehyde Oligomer

 

Ashish P. Naik1, Kishore R. Desai1(*), Hasmukh S. Patel2

(1) Department of Chemistry, South Gujarat University, Surat‑395 007, Gujarat, India

(2) Department of Chemistry, S.P. University, Vallabh Vidhyanagar, India

 

Received 21 September 1999; accepted 2 April 2020

 

ABSTRACT

 

Resorcinol-formaldehyde oligomer was synthesized by the condensation of resorcinol and formaldehyde in presence of oxalic acid. The mole ratio of reactants employed was 1:0.5, respectively. A series of new oligomeric disperse dyes were prepared by coupling various aromatic diazonium salts to resorcinol‑formaldehyde oligomer. Their dyeing on polyester, nylon and wool resulted in variety of attractive hues on fibres. In this study of oligomeric azo- resorcinol‑formaldehyde dyes, the dyeing of the fibres completed in short time and most important is that no patches were observed on the fibres, while the earlier reported oligomeric dyes form patches on the fibres. They were characterized in terms of their softening points, colour, solubility, IR and UV visible spectra and thermogravimetric properties. Their dyeing on, polyester, nylon and wool resulted in yellow, orange and brown to red shades with good to excellent light fastness and washing fastness properties.

 

Key Words: azo dyes, polyester, nylon, wool, fastness, properties

 

 

Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Synthesis and Characterization of Some New Polyarylates

 

Derived from Two Heterocyclic Monomers

 

Ahmad Banihashemi* and S. Hassan Firoozifar

Department of Chemistry, Shiraz University, Shiraz, I.R. Iran

 

Received 26 June 1999; accepted 6 May 2020

 

ABSTRACT

 

New polyarylates were synthesized by phase‑transfer catalyzed two‑phase polycondensation of benzofuro[2,3‑b]benzofuran 2,9‑dicarbonyl chloride with bisphenols of various derivatives and 2,13‑dihydroxy[7a,14c]dihydronaphtho-[2,1‑b] naphtho[1´,2´:4,5]furo[3,2‑d] furan with various aromatic dicarboxylic acid chlorides. All of these polyarylates dissolve readily in a wide range of organic solvents such as N,N´-dimethylacetamide, N-N´-dimethylformamide, and hexamethyl phosphoramide. These polyarylates have inherent viscosities of 0.14–0.30 dL/g and 10% weight loss between 302.9–455.8 ºC in nitrogen atmosphere.

 

Key Words: polyarylates, polycondensation, benzofuro[2,3‑b]benzofuran-2,9‑dicarbonyl chloride, bisphenols, 2,13‑dihydroxy[7a,14c]dihydronaphtho[2,1‑b] naphtho[1´,2´:4,5]furo[3,2‑d] furan

 

 

Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Study of Crystallinity of High-density Polyethylene by Inverse

 

Gas Chromatography

 

Mousa Ghaemy*, Mohammad Reza Hadjmohammadi and Reza Tabaraki

Department of Chemistry, Faculty of Sciences, University of Mazandaran, Babolsar, I.R. Iran

 

Received 21 June 1998; accepted 14 February 2021

 

ABSTRACT

 

Method of inverse gas chromatography (IGC) has been used for the physico-chemical characterization of polymers for more than two decades. In this method the polymeric stationary phase could be characterized by using probe molecules. The retention volume of probe is a measure of the polymer-probe interaction and show changes in the polymer structure at melting point or glass transition temperature. Crystallinity of high-density polyethylenes (HDPE) of Poliran and Irapol from Iranian petrochemical companies was studied. The effects of the flow rates and the sample size on peak retention volume were investigated. Modified techniques for measurement of flow rate and coating were used. Retention diagram and degree of crystallinity were determined for a sample of low-density polyethylene and the results were compared with those obtained for HDPE. Experimental data of crystallinity and melting points showed that the Iranian HDPE is a polymer with suitable engineering properties.

 

Key Words: high-density polyethylene (HDPE), crystallinity, inverse gas chromatography, retention diagram, soaking method

 

 

Iranian Polymer Journal / Volume 9 Number 2 (2000)                          ISSN: 1026-1265/2000

 

Continuous Melt Impregnation Process: Materials Parameters

 

Zahed Ahmadi1, S. Reza Ghaffarian1(*) and Davood Amiri2

(1) Polymer Engineering Department, Amir Kabir University, Tehran, I.R. Iran

(2) Research Institute of Petroleum Industry, Tehran, I.R. Iran

 

Received 4 December 1999; accepted 3 April 2020

 

ABSTRACT

 

The first step in the manufacturing of long and high fibre volume fraction of thermoplatic composite is the prepreg production with a melt impregnation process. During this process a polymeric matrix is introduced into the fibre tow. In this research an extruder equipped with a specially designed cross- head die was used for producing long and high fibre volume fraction of thermoplastic prepregs and to study the continuous melt impregnation of glass fibre roving with a polypropylene melt. A suitable relation determined from the cross-sectional area of the bundles and prepreg was selected as a proper indication of the impregnation quality. Our study shows that process and material parameters such as melt temperature and melt flow index have positive effect on the impregnation and those like line speed and melt pressure inside the cross-head die having a negative effect on fibre wetting.

 

Key Words: melt impregnation, prepreg, cross‑head die, polypropylene, fibre glass roving