جستجوی مقالات مرتبط با کلیدواژه « acrylonitrile butadiene styrene » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Research subject:

 Polycarbonate/acrylonitrile butadiene styrene alloy is one of the most widely used polymer alloys in the world, which has become very widespread due to the excellent properties and characteristics of these alloys as well as other advantages. However, it seems that strengthening the properties and efficiency of these alloys can increase their scope of application. Typically, polymers have a high resistance to the passage of electricity. In recent years, increasing the electrical conductivity or reducing the electrical resistance of polymers by using conductive nanoparticles has received much attention.

Research approach:

 For this purpose, first, alloys of polycarbonate and acrylonitrile butadiene styrene were prepared by melt mixing method and were tested and evaluated in terms of physical and mechanical properties, thermal properties and behavior of the melt. Next, by adding nanographene to the best alloy, the electrical, mechanical and morphological properties of nanocomposites were investigated. In order to increase the electrical conductivity of nanocomposites, different amounts of nanographene (1, 2 and 3%) were used.

By increasing the amount of polycarbonate, tensile strength and modulus, flexural strength and modulus, and HDT of the alloys increased. The results showed that the alloy with 68% polycarbonate generally has better properties than other alloys, so this alloy was considered as the polymer base of nanocomposites. The results of the mechanical test show an increase in the tensile strength and tensile modulus of the samples with an increase in the percentage of nanoparticles. Also, the examination of the electrical resistance of nanocomposites showed that in all samples, nanographene has been able to reduce the electrical resistance of the polymer to a very significant extent. By examining the mechanical and electrical properties of the samples, it was determined that the Percolation threshold of nanoparticles is equal to 2%. The FE-SEM images of the nanocomposites showed that the graphene nanoparticles were well dispersed in the polymer matrix and no traces of clumps or clusters resulting from the accumulation of nanoparticles were observed.

Hypothesis: 

Using glass fiber in acrylonitrile-butadiene-styrene (ABS) composites has its limitations by increasing the final price (cost) of the product, abrasions in processing machines, the environmental and health problems during recycling as well as the reduction in impact strength of the composite. This study was carried out to evaluate the effect of silane-treated wollastonite, with a needle structure similar to glass fiber, as an alternative to glass fiber in order to eliminate the drawbacks of ABS/glass fiber composites, on the mechanical properties of ABS/wollastonite composites and compared with ABS/glass fiber composites.

The ABS composites were produced using two types of wollastonite with different geometrical specifications. Dispersion of wollastonite in ABS matrix was evaluated using the SEM micrographs, and the mechanical properties of the composites were determined based on tensile and Izod impact testes. Then, the suitable wollastonite was selected and the ABS/wollastonite composites properties such as tensile, impact strength, thermal and dynamic-mechanical properties were compared with the ABS/glass fiber composites properties at similar percentage of reinforcement phase.

The experimental results showed that the geometrical specification, especially the length/diameter ratio of wollastonite has a significant effect on the impact strength of the ABS composite as a result of good interfacial interaction between the filler and polymer matrix. The results showed significant improvement in the impact strength of ABS/wollastonite composites compared with that of ABS/glass fibers, while the modulus and strength as well as the Vicat softening temperature were acceptable compared with those of ABS/glass fibers composites. According to the results, ABS/wollastonite composites can be a good alternative to ABS/glass fiber composites in many applications.

Hypothesis:

 Due to the nature of a fused deposition modeling (FDM), by which the parts are fabricated layer by layer, many defects are developed during printing of the products. Therefore, a few efficient solutions are required to minimize the defects and other shortcomings. The increase in the physical and mechanical properties of the fabricated parts using nanoparticles seems to be one of the methods.

To improve the mechanical properties of acrylonitrile-butadiene-styrene (ABS), which is one of the most common materials employed in FDM technique, various amounts (1, 3 and 5 wt%) of multi-walled carbon nanotubes (MWCNTs) were added to the matrix through a melt mixing process. The filaments containing different MWCNTs contents, required for fabricating of the samples, were then prepared by extrusion. Next, the samples were printed with the layer thicknesses of 0.05, 0.1 and 0.2 mm and raster angles of +45/-45° and 0/90°. Several experiments such as the tensile and rheological tests as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations were carried out to examine the nanocomposite samples.

The SEM and TEM studies revealed that the nanoparticles were reasonably well dispersed throughout the matrix. The results of the tensile tests indicated that by addition of MWCNTs, the tensile strength and Young's modulus were increased by 21% and 103%, respectively, in comparison to those of the pristine material. It was also found that at a constant layer thickness, the maximum value of the tensile strength was obtained for the nanocomposite containing 3 wt% MWCNTs, however, the modulus progressively increased with the increase of the nanoparticles content. In addition, the change in raster angle showed no significant effect on the tensile properties, and the increasing of the layer thickness had an adverse effect on the properties for all the materials examined.