Iranian polymer journal
Volume:14 Issue: 11, 2005

Acellulose fibre (e.g., cotton) and a protein fibre (e.g., silk), after under going pretreatment and activating stages, were coated by conductive polymers such as pyrroleby two Vapour and liquid phases. The value of penetration of conductivepolymer into fibres by scanning electron microscope (SEM) was determined.Then assessments were made on physical properties and optimization of the value andpercent of coating by these properties. Electronic images of SEM showed that vapour orgas coating is more desired, as gas penetration into fibres realized better. Electrical properties of produced fibres are by a four- probe method and optimized value on properties and suitable conductivity were obtained. The polymer conductivity of fibres after several washings for cotton and silk fibres were measured to be 6.4×10-4 S/cm and 3.2×10-4 S/cm, respectively. Heat studies of differential scanning calorimetry (DSC) also showed an increase of heat resistance of both coated fibres

The syntheses of a novel telechelic polymer and a polyfunctional dendrimeric copolymer were achieved. For the synthesis of telechelic polymer, first a diacid of poly(ethylene glycol) was chlorinated using thionyl chloride. Then 5-aminosalicylic acid (5-ASA) was reacted with diacyl halide poly(ethylene glycol). The resulting polymer containing drug molecule (5-ASA) (1) reacted with dicyclohexyl carbodiimide (DCC) in dichloromethane and a polyfunctional copolymer (2) was obtained. The GPC measurements confirmed the formation of a pentamer containing telechelic blocks type compound.The thermoreversible behaviours of the prepared hydrogels of both telechelicpolymer and the polyfunctional dendrimeric copolymer have been investigated. The thermoreversible behaviour of telechelic polymer 1 in water was almost in contrast to the thermoreversible behaviour of compound 2. The structure definition and analysis of thesynthesized new compounds was carried out using NMR, FTIR, UV-Vis spectrometry, optical microscopy and viscosimetry methods.

The aim of this study is to investigate and apply two approaches of fuzzy regression as well as statistical regression for modelling the colour yield in polyethylene terephthalate (polyester) high temperature (HT) dyeing as a function of disperse dyes concentration, temperature, and time. The two approaches of fuzzy regression modelling were triangular coefficients and exponential coefficients. The statistical models obtained, did not meet the required conditions to be accepted. However, after applying modification to the original fuzzy regression models with triangular coefficients, acceptable models were obtained. The modification was carried out by means of enabling the centre of coefficients to take positive and negative values as well as dispersing fuzziness in the coefficients. The models obtained with exponential fuzzy coefficients showed weak interaction for the above mentioned variables and hence it seems that for modelling cases such as the one considered in this paper, fuzzy regression with triangular coefficients may be preferred.

Poly(amic acid) grafted silica nanoparticles (PAA-SNs) were successfully prepared by the grafting polymerization of poly(amic acid)s based from the in-situ condensation polymerization of pyromellitic dianhydride (PMDA) and three diamines (4,4ídiaminodiphenyl ether (DDE), 4,4í-diaminodiphenyl methane (DDM) and 4,4í-diaminodiphenyl sulphone (DDS)) from the surfaces of the γ-aminopropyl silica nanoparticles (APSNs) with N,N-dimethyl acetamide (DMAc) as solvent. The products were characterized by elemental analyses (EA), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The percentage of grafting (PGs) (the weight ratios of the PAA grafted and the charged silica nanoparticles) of PAADDE-SNs, PAADDM-SNs, PAADDS-SNs, calculated from the results of C elemental analyses (EA), were 56.77%,38.97% and 46.05%, respectively. The TEM analysis showed that they could be dispersed in organic solvents. Therefore, the systems could be used as reactive nanofillersor nano-cross-linkers for polymer nanocomposites because of their better organic solubilities and the large numbers of carboxyl acid groups on their surfaces.

Trimellitic anhydride (1) was reacted with L-isoleucine (2) in acetic acid and the resulting imide-acid [N-trimellitylimido-L-isoleucine] (4) was obtained in high yield. The direct polycondensation reaction of this diacid with several aromatic diols such as bisphenol A (5a), phenolphthalein (5b), 4,4í-dihydroxybiphenyl (5c), 4,4í-dihydroxydiphenyl sulphide (5d), 4,4í-dihydroxydiphenyl sulphone (5e) and 1,4-dihydroxyanthraquinone (5f) was carried out in a system of tosyl chloride (TsCl), pyridine (Py) and N,N-dimethylformamide (DMF). The reactions with TsCl were significantly promoted by controlling alcoholysis with diols in the presence of the catalytic amounts of DMF to give a series of optically active poly(ester-imide)s (PEI)s with good yield and moderate inherent viscosity ranging 0.18-0.28 dL/g. The polycondensation reactions were significantly affected by the amounts of DMF, molar concentration of monomers, TsCl and pyridine, aging time, addition time of diols, temperature and the reaction time. All of the above polymers were fully characterized by 1H NMR, IR, elemental analysis and specific rotation. Some structural characterization and physical properties of these optically active poly(ester-imide)s are reported.

Unbleached and hydrogen peroxide bleached bagasse chemimechanical pulp were acetylated in liquid phase in order to investigate the change in paper properties due to chemical modification. The acetylation treatment was carried out on paper sheets and pulp samples. Effect of liquid phase acetylation on optical and mechanical properties of bagasse chemimechanical paper sheets was evaluated. The obtained results also indicated that acetylation is a reliable method to eliminate phenolic hydroxyl groups. Paper made from unbleached CMP increased in brightness (up to 10 percentage units) on acetylation, while the hydrogen peroxide bleached paper decreased in brightness. The acetylation treatment removed or inactivated some chromophores originally present in the unbleached CMP but not in the hydrogen peroxide bleached samples. The results showed that partial acetylation even for short period of times could cause considerable increase in wet strength of paper, due probably to lower equilibrium moisture content. Also, other mechanical properties such as tear resistance and tensile strength were not affected to any great extent by acetylation in liquid phase providing that the paper sheet is acetylated instead of pulp. Present study proved that active phenolic hydroxylfunctional groups present in pulp could be modified without losing mechanical srengthsand optical behaviour of the paper.

In this study, the various combinations of low- and high-decomposition temperature initiators and dual promoters were used to cure an unsaturated polyester resin. Methylethyl ketone peroxide (MEKP) and acetyl acetone peroxide (AAP) solutions were used as low-temperature initiators. Benzoyl peroxide (BPO) and t-butyl perbenzoate (TBPB) were used as medium and high-temperature decomposition initiators, respectively. Gel time and pseudo-adiabatic exotherm measurements have been used to study the curing behaviour. It is demonstrated that the low-temperature initiator decomposition does not interfer with the high-temperature initiator decomposition. It is also found that theexotherm peak and cure rate have been affected by the decomposition rate of low temperature initiator at different ways. It is shown in this study that for cobalt naphthenate and dimethyl aniline (DMA) dual promoters systems, with the increasing of DMA concentration, namely high reactive promoter, causes the exotherm parameters sharply change. It might be due to the more reactive nature of DMA in comparison with the cobalt naphthenate reactivity. Now we can say, a judicious choice of a dual initiator or a dual promoter can avoid short time exothermic reactions, so a dual system can be much more effective han a single one.

Critical pigment volume concentration (CPVC) is a fundamental transition charac-teristics at which properties of a coating changes significantly. At this point voids begin to introduce through the film. Many methods have been proposed to deter- mine the CPVC of indoor latex paints based on the change of a film property. These methods are mostly time consuming. In this research, a new method has been proposed based on permeability of coating and it is compared with wet scrub resistance method which is a mechanical one. Wet scrub test is based on the void contents and the strength of the interfaces of latex particles existing in the film. In contrast, permeation test is only based on the void contents through the film and therefore it is more consistent with the definition of CPVC. It was observed that this new method is several times faster and less sensitive to aging or annealing.

Polymeric ligand-bridged metal chelates of VO(II), Cr(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) were prepared on interaction of 4,4í-(4,4í-biphenylylenebisazo)-disalicylaldehyde phenylhydrazone with metal salts in N,N-dimethylformamide (DMF). All the polychelates are dark coloured powders, insoluble in water and common organic solvents. They have very poor solubility in DMF. All the polychelates are found to be noncharged chelate polymers from their conductivities in DMF. Their probable structures were determined from reflectance electronic spectral and magnetic measurements in conjunction with infrared spectroscopy. The diffuse reflectance spectra of VO(II), Cr(III), Mn(II), Co(II), Ni(II) and Cu(II) polychelates have been analyzed in terms of ligand-field theory. Infrared spectra have been obtained to determine coordination sites of the ligand. The thermal, magnetic and conductivity measurements are discussed in light of the proposed assigned structure. All the polychelates are believed to have an octahedral stereochemistry. The semi-empirical AM1 calculation was also performed on ligand structure.