The effects of some factors, i.e., long chain branches on EPDM and PP backbone and short side chain branches of HDPE on melt extensibility and melt elasticity were studied and compared with those of ternary blends of linear PPs. Long chain BRANCHED EPDM, long chain BRANCHED PP, and linear PE with small side chains were used to increase the molecular entanglements and melt drawability and to improve melt elasticity. Using three linear PP in the blends, showed a synergistic effect on melt elasticity in a certain percentage of composition. The experimental results have been indicated that both ternary blends of linear PPs and ternary blends containing a BRANCHED PP increased molecular entanglements and affected on melt elasticity. HDPE as a polyolefin with short side chains showed better effect on melt elasticity and melt drawability than ternary linear PP blends. Long chain branches of EPDM considerably improved its damping factor (tan d) and steady state creep compliance (Je0). The effect of long chain BRANCHED EPDM and high molecular weight linear PE with small branches, on melt tension force and damping factor of blends were measured and compared with those of blends containing a long chain BRANCHED PP. Long chain BRANCHED PP(LCB-PP) showed a distinct effect on melt extensibility of blends. The most significant effect is observed by using the PE and long chain BRANCHED PP, both.

polypropylenes loaded with different alkyl ammonium-modified montmorillonite are prepared to utilize a melt-mixing technique in various ways. Two types of polypropylene and compatibilizer are incorporated to improve the dispersion of various types of nanoclay and the dyeing behavior of the nanocomposites with various disperses, acid and basic dyes were studied. For the first time, the aim of this study was to investigate the effect of operational and material parameters in dyeing behavior and color buildup of producing nanocomposite due to better understanding of the dyeability mechanism of PP/nanoclay composite. The extent of exfoliation and dispersion of the nanoclay in PP was analyzed by XRD and TEM analytical techniques and the dyeability was studied through color build up and spectrophotometric measurement. The results showed that the mixing condition had no significant effect on dyeability. The lower the molecular weight of polypropylenes and compatibilizer caused the better the dyeability. The most intercalated nanocomposite also showed better dyeability and within various types of dye, disperses dye showed better dyeability. All things considered, it is appeared that between the two mechanisms suggested for dyeing improvement in the PP/nanoclay composite, the dominant mechanism is creating the path. Prog. Color Colorants Coat. 10 (2017), 73-84© Institute for Color Science and Technology.

In this research the effect of both calcium carbonate nanoparticles and PP-g-MA ones on impact strength and Young's modulus of Polypropylene (PP) are investigated experimentally. Two kinds of CaC03 nanoparticles (monolayer-coated and uncoated) are used to investigate the effect of surface treatment of nanoparticles on the mechanical properties of these composites. All samples are mixed in a co-rotating twin screw extruder and are formed ninto standard tensile and impact bars using the injection molding method. The effect of surface modification of nanoparticles and presence of PP-g-MA on the dispersion of calcium carbonate nanoparticles in polypropylene matrix are studied by field emission scanning electron microscopy (FESEM). The results show a good agreement between the TGA analysis and the related theory. The results also show that surface modification of calcium carbonate nanoparticles and also the PP-g-MA are affective in improving the distribution and dispersion of nanoparticles in the PP matrix. Increasing of the calcium carbonate nanoparticles improves both the impact strength and the Young's modulus of polypropylene. The more the PP-g-MA is added to PP matrix the more the impact strength of the samples increases and the less their Young's modulus decreases.

Blend of PP/PET is an immiscible composition because of the difference between solubility coefficient and lack of attraction between polar/non-polar polymers. For inducing required miscibility in the blend, various compatibilizers are used. In this research, PP-g-MA is being employed. This copolymer is produced from the chemical reaction and grafting between maleic anhydride (MA), dicumyl peroxide (DCP) and polypropylene (PP) The effect of adding DCP concentration (at constant MA) increases the grafting efficiency on PP and on the other hand, enhancing MA concentration (at constant DCP) decreases grafting efficiency. The results indicate that PP-g-MA makes PET fibrillar to become smaller and it also makes the phases to become closer. It is found however that using this compatibilizer, specially in large amount, decreases the mechanical properties of the blend.

Polypropylene (PP) as a linear resin has low melt strength. The melt strength of polymer is the main feature for the success of low density extrusion foam. Use of a high melt strength such as BRANCHED PP (Br-PP), is required to achieve large volume expansion by preventing cell coalescence and gas loss. In this paper, the effects of long chain BRANCHED polypropylene on melt elasticity and volume expansion in the extrusion process of PP ternary blends are investigated. The equilibrium creep compliance (Je0) and damping factor (tan d) of melts were evaluated as melt elasticity index by oscillation rheometry. To setup the extrusion foaming process, the Haake 25 L/D single-screw extruder was improved by design and manufacturing to a special 38 L/D screw with a long mixing zone. Extrusion temperatures were optimized to reach a stable foaming process. The consistency of process pressure as a measure of foam extrusion system stability was evaluated. The cell population density and expansion ratio were determined for foam samples. The effects of the blowing agent (BA) on the amount of pressure build-up were measured at various BRANCHED PP levels in the blend. The experiments showed that, by increasing the BRANCHED PP, Je0 increases, and tan d decreases, which is an evidence of improved melt elasticity. The maximum expansion ratio for the blends was achieved at about 55% of BRANCHED PP resins and 20% of B.A. The results also showed that, by increasing the BRANCHED PP, the cell population density increases to a maximum of 7.5×106 (cell/cm3) and no significant increase was observed at higher BRANCHED PP levels.

A fully coupled formulation of thermo-fluid shape design problems has recently been developed in which the unknown nodal coordinates appear explicitly in the formulation of the problem. This \direct design" approach is, in principle, generally applicable and has been successfully applied in the context of potential and Euler flow models. This paper focuses on the direct design of ducts using the ideal flow model and may be considered as an addendum to the paper entitled \Direct Design of Ducts" [1]. However, a cell-vertex finite volume method is used and a different boundary condition implementation technique is applied, as compared to the method presented in the previous paper. The other new feature is that a non-linear algebraic method is used for grid generation. The method is also proved to be capable of designing complex flow passages, such as BRANCHED ducts.

An experimental apparatus has been developed for observing interfacial stability and deformation of multilayer pressure driven channel flows. The interface instability of a co-extrusion flow of polyethylene and polypropylene is studied experimentally in a slit geometry. This is performed by introducing disturbances of controlled wavelength and amplitude on three-layer symmetric (A-B-A) polymer melts and followed by a series of extrudate mechanical testing. In this study variations of mechanical properties as well as wave interlocking have been related to the conformation of the interfacial waves. By investigating the growth of interfacial waves and tensile stress of extrudate samples, a relationship between interfacial instability and mechanical properties of polypropylene (PP) and high density polyethylene (HDPE) systems has been established. It is shown that instabilities are associated with interfacial waves, and it turns out that its amplitude is known as a mechanism for controlling the strength of three-layer polymer products. It is also demonstrated that the mechanism of interfacial strength is related to interfacial instabilities as well as the interfacial wave interlocking. By considering that the instability is controlled by modal wave it may be possible to forecast the quality of final products in the co-extrusion process.

Melt strength of polymer is one of the main primaries for the success in producing low-density extrusion foam and thermoforming process. Polypropylene (PP) as a linear polyolefin has low melt strength for bubble stabilization and sagging. Large molecules and long chain branches of PP cause higher molecular entanglements and increase elongational strength of PP melt. In this paper rheological behavior, melt elasticity, mechanical properties, and crystallinity of linear PP blends are studied and compared with blends containing a long chain BRANCHED PP resins. It is found that ternary blends of Linear PP improve the melt elasticity in a certain composition, comparing to binary blends. BRANCHED PP resins increase molecular entanglements, which leads to higher melt elasticity. The results of this study help to understand the effects of chain size and chain architecture in increasing the melt strength and melt drawability of PP blends. These are the most important factors for producing low density PP foam and high quality thermoformed products.

The non-isothermal crystallization kinetics of pure polypropylene (PP) and AB3 hyper-BRANCHED polymer (HBP)/PP blends (with 5% HBP content) were investigated with various cooling rates by differential scanning calorimetry (DSC) method. The Avrami analysis modified by Mandelkern and a method combined with Avrami and Ozawa equations were employed to describe the non-isothermal crystallization kinetics of the samples. The conclusion showed that at the same cooling rate, hyper-BRANCHED polymer could accelerate crystallization effectively. Furthermore, in the blends, the crystallization rate decreased when the higher molecular weight of HBP was added. An increase in the Avrami exponent showed that the addition of HBP influenced the mechanism of nucleation and the growth of PP crystallites. The possible reason and explanation could be attributed to the fractal structure of hyper-BRANCHED polymer which has an influence on the diffusion mode of crystallizable segments towards the growing nuclei. The polarized micrographs showed that the number of effective nuclei increased obviously in the HBP/PP blends where, HBP acts as a heterogeneous nucleation agent during the crystallization of the blends. In addition, the activation energy of crystallization was also obtained according to the Kissinger method and the results showed that the crystallization activation energy decreased remarkably in HBP/PP blends.