فهرست مطالب محمدحقیقت کیش

The unwanted discharge of oil from different types of reservoirs into sea water has brought many environmental and economic difficulties in the world. In the past، attempts have been made to remove the floating oil from water surface in the oceans using synthetic and natural adsorbents such as polypropylene، cotton، and wool fibers. In the present work، nonwoven fabrics made from the blend of solid and hollow polyester (PET) fibers (0، 25، 50، 75، and 100% hollow fibers) were examined for oil retention and pickup capacities. Four types of oils were used in the experiments. The sorption capacity and oil retention capability of 100%-hollow fiber was found to be superior among the samples tested. The results showed that the replacement of solid fibers with the hollow fibers increased oil pickup capacity and prevent fibers from sinking into deep water. These advantages of hollow fibers are attributed to the higher specific surface area and larger apparent volume of this type of fibers.

Production of polypropylene is growing for applications in different types of textiles. The main limitations in some of their applications are attributed to its low photostability and related property changes. There are several factors that have considerable effects on the process of photo-oxidation and the resulting photostability. From polymer production up to its usage the recognition of these parameters is necessary in order to control the degradation and to improve the useful life period of the products. In this paper، first the photo-oxidation mechanism of polypropylene in the presence of air is reviewed and then the effects of different factors including additives are examined. The incorporation of additives and light stabilizers in polymers are important in order to preserve their long-term use in the environment. Besides the complex mechanisms of photostabilization، this review presents an in-depth account of the behavior of the additives with respect to the photochemical oxidation of polypropylene and the interactions involved. Stabilization of polypropylene was improved in the presence of a mixture of photostabilizers، exhibiting an enhanced irradiation resistance. It would appear that the origin and composition of the pigment and its interaction with photostabilizers are all important factors. Several analytical techniques were employed to evaluate the stabilization effectiveness of the additives and degradation process; finally the techniques and the experimental methods for evaluation of photo-oxidation level and photo-oxidation products are introduced. Thedifferences in the views are highlighted and the shortcomings are explained.

Atechnical feasibility study has been conducted on production of nano- andmicro-fibrils from nylon 6/polypropylene grafted with maleic anhydride/polypropylene blended films. Fibrils are prepared in four consecutive steps.In the first step the polymers melt blended in an extruder with and without compatibilizersto produce chips; in the second step films are extruded from polymer blends chips,in the third step films are cold drawn with different draw ratios at room temperature andin the forth step fibrils are extracted by Soxhlet extraction with formic acid as solventfor nylon 6. The films and fibrils were examined by scanning electron microscope andFTIR spectroscopy. It is found that the polypropylene dispersed phase deforms and coalescesinto elongated fibrils during drawing operation. The fibrils’ diameters in theblends containing compatibilizer are more uniform and are smaller than those from filmswithout compatibilizers. The thinnest polypropylene fibril observed has a diameteraround 300 nm with the aspect ratio above 150. The stress-elongation curves show threedistinctive regions, elastic, yield and hardening-leading to breakage. The elastic regionis short and follows by necking and yield, i.e., elongation without increase in load. Thehardening region is accompanied by the increase in the slope. The deformations of thepolypropylene particles are noticed during the last regions of the extension; the fibrildeformations seem to be more severe during breakage.

In this study a pad-steam process for alkali treatment of polyester/cotton fabric has been developed and the effect of alkali on polyester/cotton fabric has been investigated. Caustic soda has been used as a main chemical for alkaline hydrolysis. In order to reach the required percentage of weight reduction without damaging the fiber structure and optimizing the chemicals and treatment time, certain auxiliary product such as quaternary ammonium salt which can be considered as a hydrolysis accelerating agent, besides caustic has been used. Some characteristics of alkali-treated fabric such as tenacity,crease recovery angle, bending length and water absorbency have been measured. Finally the best process, giving the best result as far as water absorbency, handle with the lowest damaging to the physicochemical properties of the fabric has been evaluated. J. Color Sci. Tech. 2(2008), 141-149.© Institute for Colorants, Paint and Coatings.

The existing standards for measuring carpet properties consider carpet behavior after loading while its dynamic and instantaneous behavior is neglected. To investigate the dynamic behavior of under loading carpets, an INSTRON machine equipped with a developed system was used. The reliability of the system was verified by testing different materials. Different samples of hand-knitted carpet with 30, 40, 50, 60 and 70 Raj (rows/6.5cm), with specific structural and physical characteristic and raw material, were tested to obtain the curves of their pressure resistance versus time. The relation between features derived from the load/time curves and carpet structural and physical characteristics and raw materials were defined. Measuring the Pearson coefficient correlation, the linear correlations were studied and analyzed. The results indicate that with increase in knot density (Raj), the rate of decreasing thickness during loading, the resilience of carpet pile after loading, the total work exerted to carpet for reaching to jamming phase and the work returned by carpet during recovery phase decrease; while with increase in carpet thickness, the resilience and the total work increase. In addition, the load/time curves of different materials and hand-knitted carpets were compared. The similarities and differences between their behaviors were derived and the desirable compressibility behavior of a carpet is accordingly suggested.

Photooxidation as an important process, which significantly affects the service life of the polypropylene products, has been the subject of much theoretical and experimental study. Pigments used often change the light stabilities of polypropylene. Out-door applications of pigmented polypr-opylene are now increasingly developed in products such as artificial grass. The aim of this work is to examine the effect of photo-oxidation on the structure of isotactic polypropylene (iPP) in film and filament forms, where phthalocyanine pigment is used. For production of films and filaments, iPP granules with MFI 25 g/10min were used, with and without phthalocyanine pigment. Samples were exposed to xenon lamp for various time lengths. The extent of the changes in chemical and structural parameters was examined by differential scanning calorimetry, Fourier transform infrared spectroscopy and wide angle x-ray diffraction. The results show that carbonyl and hydroperoxide indices increase during the exposure to the radiation. The changes in melting points of the samples were not significant after irradiation process. The effects of phthalocyanine pigment in the photooxidation of film and filament were different. Crystalline fractions of the non-pigmented filament samples decreased during the irradiation time while increased in film samples. Build up of hydroperoxide and carbonyl group in filament was higher than in film samples; that could be due to the differences in structural parameters. Crystallinity variations during photooxidation are related to the nucleation effect of the pigment, chemical crystallization and phase transformation.