Iranian Journal of Polymer Science and Technology
Year:2001 | Volume:14 | Issue:4 (ISSUE NO.54)|Papers Count:6

The effect of mixing-ratio of polypropylene (PP) and nylon 6 (N6) (10-50 wt%) in presence of different amount of polypropylene grafted maleic anhydride (PP-g-MAH) (0-10 wt%) as a compatibilizer on rheological, morphological and thermal properties of alloys were investigated. The alloys were prepared by using an internal batch mixer (Haake Rheocord 90). Rheological properties of the alloys in low and high shear rates were dependent on the amount and the size of the dispersed phase. With increasing the amount of compatibilizer in the 80/20 PP/N6 alloys, viscosity of alloys increased due to increasing interactions between phases. Numbers and sizes of dispersed phase (N6) increased with increasing the amount of N6, co-continuious morophology was observed for the alloy containing 50 wt% N6. Size of dispersed-phase-particles in the presence of PP-g-MAH decreased. The results of the measurements crystallinity by DSC showed that the percent of crystallinity of N6 decreased with increasing amount of compatibilizer. FTIR spectrum, indicated the formation of bond between N6 and PP-g-MAH in alloys.

The applications of melamine-formaldehyde resin for house wares applications have decreased nowadays. However, Due to the excellent properties of this resin for example hardness, whiteness, heat resistance and electrical resistance, it can be used for the structural application. In this paper, therefore, the effect of glass fiber on the properties of melamine-formaldehyde moulding compounds has been investigated. The effect of glass fiber from 10 to 60 weight percent on the mechanical and physical properties has been studied; Results show that the mechanical of glass fiber reinforced compounds are much higher than the commercial melamine-formaldehyde moulding compounds that are being reinforced with  a-cellulose fiber. Results also indicate that a compound that are reinforced with 50 weight percent of glass fibers have optimum mechanical properties.

Depending on their chemical constitution, disperse dyes mayor may not be affected in alkaline, reducing and alkaline-reducing solutions. In clearing of reduction type, a solution of a reducing agent (sodium dithionite) and an alkaline (caustic soda) is used. The removal of the dye molecules which are not absorbed by polyester after fixation, dissolve the polyester oligomers and brightening shades constitute the task of reduction clearing. In this study, experiments were carried out for 11 disperse dyes of different chemical constitutions. The results showed that according to their behaviour in the solutions of sodium dithionite, caustic soda and their mixture, these dyes can be classified in 5 groups. This classification may be used as a means of identifying disperse dyes.

Melt fracture causes surface disorder in extrusion process of some thermoplastic polymers. A number of researchers have endeavored to inhibit or postpone the occurrence of the phenomenon by using additives, designing suitable dies and employing special alloys as die construction material. In the present research the occurrence of melt fracture in extrusion of LLDPE was studied, and it was elucidated that at the onset of the phenomenon the actual pressure of the melt at the die departure, called exit pressure, is unstable and fluctuates permanently. In addition, by using a laboratory extruder equipped with a slit die, the rheological properties of LLDPE at different output rates were investigated. The results disclose that the measurement of exit pressure in extrusion process can be used as a procedure to determine the onset of melt fracture occurrence.

The radiation grafting of maleic anhydride onto polypropylene wax by a mutual irradiation method has been studied in xylene. The effect of y-irradiation dose and mole fraction on the grafting was investigated. The effect of benzoyl peroxide, choice of solvent and molecular mobility was also studied. Efficiency of the grafting has been determined by two different methods and found that results are comparable. One of these methods is the acid-base titration that it has based upon counting acid number of MAH-g-PP after converting it to diacid by hydrolysis reaction. Other method is based upon FTIR spectroscopy and determining absorbance of carbonyl (1716 cm-1) and double bond (1645 cm-1) of maleic anhydride grafted onto PP, and mapping comparison between them.

In short fiber reinforced composite, fiber orientation plays a key role on composite part's mechanical properties resulting in higher reinforcing effect along the orientation direction. It is therefore important to be able to predict and analyze orientation variation during the processing time. A comprehensive mathematical model and eventually a computer program has been developed enabling the analysis of factors such as fiber shape variations, half rotation time and slippage along and across streamline in non-Newtonian fluid flow. The program is used here to study the variations in power fluid flow field in a pipe with uniform circular cross section. The results provide a good basis for a quantitative study of a physical behaviour, which is qualitatively approved.