Iranian Polymer Journal / Volume 9 Number 4 (2000) 203209           ISSN: 1026-1265/2000

 

IR Laser Surface Modification of Polyethylene

 

Terephthalate as a Biomaterial

 

Mahrokh Dadsetan1, Hamid Mirzadeh2(*) and Naser Sharifi-Sanjani3

(1) Laser Research Center, Atomic Energy Organization of Iran, P. O. Box: 11365-8486, Tehran, I.R. Iran

(2) Department of Polymeric Biomaterials, Iran Polymer Institute, P.O. Box: 14965/159,

Postal code: 14977, Tehran, I.R. Iran

(3) Department of Chemistry, Faculty of Science, University of Tehran, P. O. Box: 14155-6455, Tehran, I.R. Iran

 

ABSTRACT

 

There have been a number of attempts to create a novel surface that reduces the adverse effects of blood interaction with material. Among various techniques, laser-induced surface modification is highly suitable for this purpose. This paper presents surface modification of polyethylene tere-phthalate (PET) using CO2 pulsed laser. The changes in surface properties were investigated by SEM, attenuated total reflectance infrared spectroscopy (ATR-FTIR) and water drop contact angle measurements. The complicated microstructures on the PET surface were observed in SEM micrographs. ATR-IR spectra showed that the crystallinity decreased in the surface region as a result of laser irradiation. The water drop contact angle also decreased with increasing the laser pulses. The haemocompatibility of CO2 laser irradiated PET was examined in vitro, evaluating its capability of inducing platelet adhesion in comparison with the unmodified PET. The number of adhered platelets was determined by platelet-rich plasma method and lactate dehydrogenase activity measurements. Platelet adhesion on the untreated PET was relatively high. Laser irradiation of PET surface reduced the number of adherent platelets and prevented platelet spreading on the surface. The extent of platelet adhesion was correlated to the number of laser pulses.

 


Iranian Polymer Journal / Volume 9 Number 4 (2000) 211220        ISSN: 1026-1265/2000

 

Hydrodynamic Study of the Hydrolytic Polymerization of

 

e-Caprolactam in Industrial Polymerization Units

 

Mihai Rusu1(*), Maria Lungu1, Liviu Bujor2 and Daniela Rusu3

(1) Department of Macromolecules, "Gh. Asachi" Technical University of Iasi, Bd. D. Mangeron no. 71, 6600 Iasi, Romania

(2) S.C. POLIROM S.A., Roman, judetul Neamt, Romania

(3) Biomaterials Department, "Gr. T. Popa" University of Medicine and Pharmacy, 6600 Iasi, Romania

 

ABSTRACT

 

This work presents an experimental study dealing with the deviations from the ideal flow models in the case of the flow of e‑caprolactam and, respectively, of the polymer melt, along an industrial unit for polyamide‑6 synthesis. The flow pattern was determined by analyzing the mean residence time and dispersion criterion, which were obtained from radiotracer measurements. Different flow types were evidenced for different zones of the industrial polymerization unit: plug‑flow with small mixing contribution in the reactor feeding pipe and in the prepolymerizer device and stirred flow with flow defects (stagnant zones and recirculations) for the polymerization column. The analysis of the residence time distribution functions revealed different flow patterns according to different regions of the polymerization column. We estimated the stagnant volume of each polymerization zone by comparing the experimental mean residence time and corresponding nominal residence time, defined as the ratio between the total volume of the zone and the volumetric flow rate. The detection of some important flow anomalies occurring in the 3rd and 4th zones of the polymerization column indicates the positions requiring an improvement of hydrodynamic regime. These experimental results were used and to ameliorate the operating regime of the ε‑caprolactam polymerization unit.

 


Iranian Polymer Journal / Volume 9 Number 4 (2000) 221227        ISSN: 1026-1265/2000

 

The Influence of Different Processing Additives on

 

Biodegradation of Poly(e-caprolactone)*

 

Maria Rutkowska1(**), Katarzyna Krasowska1, Aleksandra Heimowska1,

Maria Śmiechowska1 and Helena Janik2

(1) Gdynia Maritime Academy, 81-225 Gdynia, Poland

(2) Technical University of Gdańsk, 81-952 Gdańsk, Poland

 

ABSTRACT

 

The influence of different processing additives on the biodegradation of poly(e-caprolactone) film in the compost with plant treatment active sludge is described in this paper. Poly(e-caprolactone) was incubated for several weeks in compost in natural and laboratory conditions. The characteristic parameters of plant treatment active sludge such as: temperature, pH, moisture content and activity of dehydrogenases and their influence on degradation of poly(e-caprolactone) are presented and discussed. The loss of weight, intrinsic viscosity, tensile strength and morphological changes were tested during the period of degradation. Results of measurement indicate that the biodegradation of poly(e-caprolactone) without additives was very fast in compost with plant treatment  active sludge and after six weeks the polymer film was completely assimilated. The introducing of processing additives gives better tensile strength of the materials and less vulnerable to microorganisms attack.

 


Iranian Polymer Journal / Volume 9 Number 4 (2000) 229238        ISSN: 1026-1265/2000

 

Transformation of Morphology of As-extrudates of High-density/

 

Linear Low-density Polyethylene Drawn Tapes

 

Suryya K. Rana

Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi: 110 016, India

 

ABSTRACT

 

Drawn tapes were manufactured by mechanical drawing on a hot plate maintained at 82 C from as-extrudates with different crystallinities from high-density polyethylene (HDPE) to small quantity of linear low-density poly-ethylene (LLDPE). The process of drawing was analyzed to understand the effects of the percentage crystallinity of as-extrudates on the mechanical properties of the drawn tapes. Incorporation of LLDPE up to 15 % LLDPE systematically decreases the percentage crystallinity of as-extrudate by 25 %. It was also noticed that the initial differences in crystallinity were not reflected in the drawn tapes. However, the as-extrudate with higher initial percentage crystallinity produced a tape with better mechanical properties than the as-extrudate with lower crystallinity. The coarse fibril formation is seen in the flake- like crystalline bodies of the as-extrudates. This fibrillar formation is quite distinct with HDPE as-extrudate. On drawing, the flake-like crystalline bodies disintegrate to fibrils. The higher inter-planar spacing helps in the formation of uniform and finer fibrils. Finer and uniform fibrils free of branching and discontinuity perhaps are imperative for better mechanical properties. The HDPE as-extrudate with high percentage crystallinity and good fibrillar formation provides a better precursor for the high tenacity and modulus tape.

 


Iranian Polymer Journal / Volume 9 Number 4 (2000) 239248        ISSN: 1026-1265/2000

 

Effects of Cold-drawing and Heat-setting on the Structure and

 

Properties of Medium Speed Spun Polypropylene Filaments

 

Mohammad Haghighat Kish*, Seyed Ahmad Shoushtari and Sima Kazemi

Synthetic Fiber and Textile Research Center, Amir Kabir University of Technology, Tehran, I.R. Iran

 

ABSTRACT

 

Effects of cold-drawing and heat-setting on some aspects of mechanical properties and structural parameters of polypropylene filaments spun at 3500 m/min are examined. Similar to the yarn produced at low speeds, drawing changes the structure and properties of the filaments. Heat-setting increases the compactness and uniformity of micro-fibrilar structure of the filaments. Crystalline fraction as determined by the change in density and molecular orientation as measured by birefringence increase with the increase in draw ratio. True strength does not change considerably, but nominal strength increases and the breaking-extension decreases with draw ratio and heat- setting treatment. The temperature of the onset of melting as indicated by DSC examination does not effect considerably by drawing and heat-setting. The increase of crystalline fraction as measured by density is not in accordance with the results of the crystalline fraction measurement by X-ray diffraction. The trend in increase of crystallinity determined by DSC agrees with the increase of crystalline fraction determined by density.

 


Iranian Polymer Journal / Volume 9 Number 4 (2000) 249254        ISSN: 1026-1265/2000

 

 

Novel Imide-modified Polyurethanes, Synthesis and

 

Thermal Characteristics

 

Hamid Yeganeh*, Mehdi Barikani and Feriedoun Noei Khodabadi

Department of Polyurethane & Special Substances, Iran Polymer Institute, Tehran, I.R. Iran

 

ABSTRACT

 

New (polyurethane-imide)s (PUIs) were synthesized by polyaddition reaction of two different diisocyanates with three different imide containing diols. The reactions were performed in DMAc solvent at 100 ºC using dibutyltin dilaurate as a catalyst. The structure of diols and PUIs were characterized by conven-tional methods including 1H NMR, FTIR, and mass spectroscopies, and physical properties such as solution viscosity, solubility property, thermal stability and thermal behaviour were studied for PUIs. These polymers showed excellent solubility in polar aprotic and chlorinated solvents. Their inherent viscosities were in the range of 0.280.35 dL/g. Also their 10% weight loss were in the temperature range of 323358 ºC.

 


Iranian Polymer Journal / Volume 9 Number 4 (2000) 255261        ISSN: 1026-1265/2000

 

Poly(3‑methoxyethoxythiophene) and its Copolymers with

 

Aniline, Thiophene and Pyrrole: Chemical and

 

Electrochemical Synthesis

 

S. Hossein Hosseini, Faraj A. Gorgani and Ali A. Entezami*

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

 

ABSTRACT

 

We have investigated the chemical and electrochemical polymerization of a thiophene derivative functionalized with a 3‑methoxyethoxy moiety and its copolymers with aniline, thiophene and pyrrole. Chemical polymerization of monomers was carried out in presence of FeCIO4.9H2O/HClO4 oxidant. The electropolymerization by a cyclic voltammetry method was studied under the sufficient concentrations of monomer, 0.1 M tetrabutylammonium hexafluoro-phosphate, 20 mL acetonitrile, GC disk working electrode, Ag/AgCI reference electrode and platinum wire counter electrode conditions. The produced films give highly conducting polymeric materials, some of which are soluble in common organic solvents. The conductivity of polymers was measured by four‑point probe technique. The undoped state of the polymers possessed conductivities of lower than 104103 S/cm. After doping with FeCI3/ nitro-methane or vapour I2, conductivities increased to 103102 S/cm. Properties of the polymers were characterized using UV, IR, NMR, CV and GPC.