Iranian Journal of Polymer Science and Technology
Year:2006 | Volume:19 | Issue:1 (ISSUE NO. 81)|Papers Count:9

Inulin, the polysaccharide constituent of asphodel is soluble in cold water and forms gels in the presence of borate ions. Cross-links in inulin gel are not permanent and can change their position under shear forces. An inulin gel is formed via an equilibrium reaction which is temperature independent. Meanwhile, the inulin and cross-linking agent contents extensively affect the rheological properties of the gel formed. It is found that the rheological properties of the water-based gel increases with inulin content, whereas a complex behavior for the gel strength is observed with increase in borax (cross-linking agent) content. It is also observed that the complex viscosity of these gels presents a shear-thinning behavior. The asphodel (inulin) gel is a special water-based one which its gel properties remain unchanged in a wide range of temperature. The deGennes model was tested for this gel and a better fitting was observed at high asphodel contents.

In this work, pp grafted with maleic anhydride (PP-g-MA) and diparamethyl dibenzylidene sorbitol (MDBS) were both added as nucleating-clarifying agents into different grades of polypropylene in order to investigate their effects on nucleation and transparency of PP. Nucleation and clarifying effects have been studied by measuring the crystallization temperature (Tc) by using differential scanning calorimetry (DSC) and transparency obtained from DVNis spectrophotometer, respectively. The effective factors on these properties were determined by using Taguchi experimental design. It was found that MOBS content and the type of PP grade used are the most effective factors on increasing Tc and transparency, respectively.

Actuators are the controllable work-producing devices with an input of thermal, electrical or magnetizing stimuli and an output of mechanical energy. Regarding their widespread use, smart polymers have recently been used in producing actuators. Smart polymers are a group of neat or composite materials, which have inherent smartness along with self-adaptive capabilities against external stimuli. Shape memory polymers which are also a group of smart polymers, can recover their initial and permanent shape under external stimuli. In this work an actuator was made of a shape memory cross-linked polyethylene and the effects of different factors such as the content of cross-linking agent, deformation temperature, strain ratio, strain rate, type of cooling and heating rate on final shape recovery, recovery speed and the actuator behavior between 10% and 90% of final recovery were investigated. The results show that the actuator made of cross-linked polyethylene has a controllable behavior in this range.

Recently, silicone elastomeric coatings have been considered as foul release coatings in marine vessels due to their surface properties (low surface energy and non-polarity) and other properties such as low modulus. One of the problems of these coatings is their poor adhesion to primer which results in a low performance of the coating. In this research various silane compounds and different inclusion methods have been used to improve the adhesion of silicon top coat to primer. Adhesion strength was measured by pull-off adhesion method. An increase of 65% in adhesion strength was observed when 1% aminosilane A-1170 was used in a 50/50 mixture of epoxy primer/silicon top coat. SEM results showed an improved compatibility of the components in organosilane containing specimens and FTIR-ATR revealed interactions between some functional groups.

Applying of the extensional flow on poly (vinylidene fluoride) while it is in the molten state is a specific method for converting α to β forms as wellas increasing the amount of β crystallinef orm. In this paper, the effect of extensional flow during film extrusion on the β crystalline phase content and piezoelectric properties of extruded PVDF films has been investigated. The PVDF films were extruded at different draw ratios by using the designed two-channel die having converging walls which can apply high extensional flow to the PVDF melt and also an ordinary slit die. The amount of β crystalline structure and piezoelectric properties of the films produced by these two dies were compared using wide angle X-ray diffract meter (WAXD), differential scanning calorimeter (DSC) and d33-tester. The results revealed that while the d33 value for the samples prepared by the slit die was zero at all draw ratios. The d33 value for the films prepared using a two-channel die equivalent to be 21 pC/N for samples drawn in the molten state was found to have a draw ratio of 9. The samples prepared from the two dies were also drawn under optimum conditions (80-90°C, strain of 400-500% and strain ratio of 5 min-1) and their β-phase contents and d33 values compared with each other at equal draw ratios. Using Fourier transform infrared spectrometer (FTIR), a maximum β-phase content of 83% was found for the films produced using the two-channel die which was 8% higher than what was found from the samples prepared by a slit die. The d33 value for the films produced from the designed die was also found to be 35pC/N which was 5pC/N higher in value than that of the samples prepared by a slit die.

In this study, extractive materials were taken from the bark of Alder (Alnus Subcordata) and Oak (Quercus Castanifolia) using water and 1% NaOH solution (with and without sulfonation) at 90°C temperature and 60 min extraction time. Sulfonation effects were studied by the obtained yield and polyphenolic compounds. Data were statistically analyzed with SPSS software. Multifactor analysis was used (α =0.05 and α =0.01) to test for significance between factors and levels. A multiple comparison of the means was performed employing a Dancan test to identify which groups were significantly different. Results showed that there is not a significant difference between the yield of both methods of extraction at sulfonation and unsulfonation conditions. But there is a significant difference in polyphenolic compounds. Sulfonation increases the solubility of Alder and Oak extractive materials 8% and 10 %, respectively. In general, according to Stiasny number of Alder (91.21%) and Oak (69.74%) their reactive polyphenolic compounds can react with formaldehyde and replace phenol in phenol-formaldehyde resin.

The fabric dyed with bifunctional reactive dyes has a higher durability during laundering and dry cleaning than the fabric dyed with monofunctional reactive dyes. However, this cannot be satisfied by the consumer and the problems of colour changing and staining still remained. The existence of oxidizing agent in the laundry detergent formulation can be affected on the dye-fibre bonds and as consequences causes colour bleeding and also staining of the other clothing. To overcome these problems, new products introduced by the powder producers to prevent the dye hydrolysis, dye-fibre bonds breakage and staining on the adjacent fabrics. In this research work, a copolymer of vinyl imidazol and vinyl pyrrolidone (polymer 1) and polyguanidine (polymer 2) were used as an additive to prevent bleeding of the dye from fabric and protecting the hydrolyzed dyes from redeposition on the fabrics. The results showed that polymer 1 in the detergent formulation causes a reduction in the dye bleeding and staining. The polymer 2 indicated a better performance regards dye bleeding and staining. However, these polymers cannot prevent the breakage of dyefibre bonds completely. The results of this study also illustrated that a reactive dye with the functional groups of FCP/vs has a lower wash fastness than a reactive dye containing MCT/VS reactive groups.

Ethylene-vinyl alcohol (EVOH) copolymers were prepared by the hydrolysis of ethylene-vinyl acetate copolymers. The conversion of acetoxy groups to hydroxy groups was performed using methanol and isopropanol as transesteri fication agents and sodium hydroxide and potassium hydroxide as basic catalysts. The Products of hydrolysis during the reaction including terpolymers of ethylene-vinyl acetate-vinyl alcohol were analyzed by FTIR spectroscopy. Changes in the absorptions of acetoxy, methylene, and hydroxy groups in vinyl acetate and vinyl alcohol units of ethylene- vinyl acetate copolymer and the products of the hydrolysis were followed by measuring the height or area of these peaks and their ratios as a tool to investigate the hydrolysis reaction. The results showed that the hydrolysis with methanol/sodium hydroxide system has a higher rate than that of isopropanol/potassium hydroxide and the final product has a higher degree of hydrolysis. Degree of hydrolysis of 99.8 and 93 percent were obtained using methanol/sodium hydroxide and isopropanol/potassium hydroxide media, respectively.