Rheological Properties Of Blends Research Articles

Impact of Partial Replacement of Wheat Flour with Chickpea Flour on Physico-Chemical and Sensory Properties of Tea Buns

ABSTRACT The present study aimed to identify the optimum substitution ratio of chickpea flour (CF) into ordinary tea buns with intention to improve the nutritional value and the best sensory properties while retaining their shape. Flour blends were prepared in the proportions of wheat flour WF: CF (w/w %) 80:20, 70:30, 60:40, and 50:50 while WF (100:0) as a control. The rheological properties of blends were determined by Brabender farinograph apparatus. The prepared buns were evaluated for color, loaf specific volume, proximate composition, amino acid profile, and the preference towards sensory properties. According to the farinograph results, WF and 20% substitution were strong dough while 30%, 40%, and 50% substitutions were medium-strength doughs. In higher incorporation ratios, the moisture contents of the buns were decreased and the crumb texture gets harder and less porous making the product unacceptable. Buns made with 40% and 50% substitution failed to exceed the minimum requirement of specific loaf volume. The levels of protein in the buns are gradually elevated, making the product more nutritious with complementing amino acid profiles. Although the higher incorporation is more healthy and nutritious, only 20% and 30% CF incorporated buns seem to be practical in the manufacturing industry.

Effect of Ethylene-Ethyl Acrylate Copolymer on the Rheological Properties of LDPE/PLST Blends

The rheological properties of polyethylene/starch blends compatibilized with ethylene–ethyl acrylate copolymer (EEA) were investigated at different temperatures and shear rates. According to the Fourier transform infrared spectroscopy (FT-IR) data, the application of EEA as a compatibilizer did not lead to the significant change in the blends’ band spectra because the concentration of acrylate groups (and consequently that of carbonyl groups) in the blends was low and the degree of hydrogen bonding was small enough. The rheological properties of blends showed that the melts of the blends were pseudoplastic materials. Viscosity of melt for all blends increased with an increase in both EEA and starch content. Power law index measurements showed that the n value increased and was less than one and the K value decreased with the increase in EEA content. Blends with higher content of starch had the lowest value of activation energy (Ea) and the sensitivity of blends to temperature decreased with an increase in starch content.

Structural, Rheological, and Mechanical Properties of Binary Compounds Based on High-Density Polyethylene and Linear Low-Density Polyethylene

Rheological, molecular, thermal, and mechanical properties of binary blends based on bimodal high-density polyethylene (HDPE; ethylene–1-hexene copolymer) and unimodal linear low-density polyethylene (LLDPE; ethylene–1-butene–1-hexene terpolymer) were studied. Six blends with different HDPE/LLDPE weight ratios, 80/20, 70/30, 60/40, 50/50, 40/60, and 20/80, were prepared by blending in a double-worm extruder. The correlation of the rheological properties of the blends, analyzed by the capillary and rotation methods, with the melt flow index and molecular characteristics was demonstrated. LLDPE with increased flowability (MFI = 3 g/10 min) as a polymer additive is an effective plasticizer allowing control of the melt viscosity in a wide range and choice of the optimum target value of the melt flow index of the blend. The activation energy of the melt flow was calculated, and the relationship between this quantity and the content of short-chain branchings in polyethylene blends was revealed. The blends obtained are homogeneous, but an increase in the content of LLDPE in HDPE leads to a change in the polyethylene structure, which is confirmed by a decrease in the crystallinity and in the lamella thickness. The strength values at the yield point and at break decrease with an increase in the fraction of LLDPE in HDPE. Changes in the properties of these blends in their processing into a film by flat-die extrusion were studied.

Effect of Blending Modifications for Phenylethynyl-terminated Polyimides

A reactive diluent (ODA-PEPA) and a flexible phenylethynyl-terminated imide oligomer (PEI-PEPA) were designed and synthesized based on the 2,3,3’,4’-diphenyl ether tetracarboxylic acid dianhydride (a-ODPA), 3,4’-oxydianiline (3,4’-ODA), and 4-phenylethynylphthalic anhydride (PEPA). Solution blended systems with the addition of 5, 10, and 15 wt% ODA-PEPA to PEI-PEPA oligomer and their cured resin systems were prepared. Results showed that ODA-PEPA is semi-crystalline in nature. The Tg values of cured resins were improved from 273 °C to 280 °C by the addition of ODA-PEPA, due to the higher crosslink densities. In addition, rheological properties of blends showed lower melt viscosity and wider processing window, revealing improved melt processabilities for potential application in making advanced composites. The isothermal viscosity in 280 °C of PEI-PEPA containing 15 wt% ODA-PEPA reactive diluent decreased by two thirds, due to the low molecular weight of ODA-PEPA. The cured blends demonstrated high thermal stability and heat resistance. 5 wt% thermal decomposition temperatures (Td5) of the cured blends were above 549 °C and 547 °C in N2 and air atmosphere, respectively. The char yield reported at 800 °C in N2 atmosphere increased from 58.8% to 63.7 % with the addition of ODAPEPA. Meanwhile, the cured polyimides blends possessed good bond strength (> 9.3 MPa).

Evaluation of Physico-chemical and Rheological Properties of Blend of Soy with Standardized Milk

The present investigation was carried out to evaluate the feasibility of fortification of soymilk with standardized milk for the production of fortified nutritive milk formulation. The functional properties of cattle milk can be enhanced by blending of soy milk. The soymilk was obtained by using standard procedure by grinding soaked seeds of soybean with hot water (bean to water ratio, 1: 4 w/v). In the present study three formulations of soy and standardized milk were prepared as follows T<sub>1</sub> (100% soymilk), T<sub>2</sub> (50% soymilk: 50% standardized milk), T<sub>3</sub> (60% soymilk: 40% standardized milk), and T<sub>4</sub> (70% soymilk: 30% standardized milk) and Control as T<sub>0</sub> (standardized milk). The changes in physico-chemical, sensory and rheological properties were recorded. The results revealed that overall organoleptic acceptability scores of formulated milks formulations were 6.9, 8.06, 7.65, 7.04 and 8.49 for the formulation T<sub>1</sub>, T<sub>2</sub>, T<sub>3</sub>, T<sub>4</sub> and T<sub>0</sub>, respectively. Fat, total solids, titratable acidity, pH, ash and solid non fat content were decreased with increasing soymilk proportion, while moisture and protein content were increased. The blending of different ratio of soymilk with standardized milk had significant affect on colour attributes (L*, a* and b*). Yellowness and greenness increased while lightness decreased as the proportion of soymilk increased.

Does nanoclay addition always lead to amelioration? Dual effects of the nanoclay on the PA‐6/EVOH/SEBS ternary blends

This work presents the investigation of properties of polyamide‐6 (PA‐6)/ethylene vinyl alcohol (EVOH)/styrene‐ethylene‐butylene‐styrene (SEBS) ternary blends and related nanocomposites with nanoclays. In this way, the effect of the mixing protocol and nanoclay type on the morphology, mechanical, and rheological properties of the blends was comprehensively studied. Scanning electron microscopy (SEM) observation revealed that, for the neat ternary blends, core‐shell droplets were formed in which SEBS droplets were encapsulated by EVOH phase in the PA‐6 matrix. In this regard, experimental observations were compared and discussed with the predictions of phenomenological models. According to the X‐ray diffraction analysis, the distribution and degree of dispersion of the nanoclays were significantly influenced by mixing protocol. It was demonstrated that competition between the intrinsic effect of the nanoclay on the physical properties and its inhibiting effect on the interactions between PA‐6 and EVOH phases led to some interesting observations for the rheological and mechanical properties of the ternary blends. The results revealed that optimum properties could be obtained by selecting appropriate nanoclay and mixing protocol.

Application of thermal analysis in the selection of polymer components used as a binder for metal injection moulding of Co\u2013Cr\u2013Mo alloy powder

To produce the polymer-powder slurry for injection moulding the thermoplastic polymers such as polypropylene, high-density polyethylene and ethylene-vinyl acetate were used. Depending on skeletal polymers, in every feedstock paraffin wax (PW) was used in the amount of 50% of binder. Application of PW gives the possibility using solvent debinding or thermal debinding at a lower temperature. Then the open porosity into the injected samples reduces the time of thermal debinding of binder residue. Application of one type of skeletal polymer requires using a long isothermal step. The use of a blend of skeletal polymers enables subsequent thermal degradation which consecutively removes skeletal polymers during the heating to the sintering temperature, to minimise the time of isothermal stops. The rheological properties of blends used as a binder and next feedstocks were investigated during mixing in the twin-screw extruder and capillary rheometer. This results gives the information about the possibility to produce feedstocks and then to their injection moulding. Thermal behaviour of samples was determined by differential scanning calorimetry and thermogravimetric analysis to obtain the information about the temperature of mixing the polymers and to propose the thermal debinding cycle.

An experimental study on foaming of linear low-density polyethylene/high-density polyethylene blends

In this research work, foaming behavior of selected polyethylene blends was studied in a solid-state batch process, using CO2 as the blowing agent. Special emphasis was paid towards finding a relationship between foamability and thermal and rheological properties of blends. Pure high-density polyethylene, linear low-density polyethylene, and their blends with two weight fraction levels of high-density polyethylene (10 and 25%wt.) were examined. The dry blended batches were mixed using an internal mixer in a molten state, and then the disk-shaped specimens, 1.8 mm in thickness, were produced for foaming purposes. The foaming step was conducted over a wide range of temperatures (120–170℃), and the overall expansion and cellular morphology were evaluated via density measurements and captured SEM micrographs, respectively. Three-dimensional structural images were also captured using a high resolution X-ray micro CT for different foamed samples and were compared. Rheological and DSC tests for the virgin and blends were also performed to seek for a possible correlation with the formability. Based on the results, blended polyethylene foams exhibited remarkable expansion and highly enhanced cell structure compared to pure polymers. Bulk density, as low as 0.33 g/cm3, was obtained for blends, while for the virgin high-density polyethylene and linear low-density polyethylene, bulk density lower than 0.5 g/cm3 was not attainable. The lowest density was observed at a foaming temperature of 10–20℃ above the melting (peak) temperature obtained via DSC test. Rheological characteristics, including storage modulus and cross-over frequency value, were also found to be the indicators for the materials foaming behavior. Moreover, blends with 25% wt. of high-density polyethylene exhibited the highest expansion values over a wider range of temperature compared with 90% linear low-density polyethylene/10% high-density polyethylene.

Preparation and Characteristic of PC/PLA/TPU Blends by Reactive Extrusion

To overcome the poor toughness of PC/PLA blends due to the intrinsic properties of materials and poor compatibility, thermoplastic urethane (TPU) was added to PC/PLA blends as a toughener; meantime, catalyst di-n-butyltin oxide (DBTO) was also added for catalyzing transesterification of components in order to modify the compatibility of blends. The mechanical, thermal, and rheological properties of blends were investigated systematically. The results showed that the addition of TPU improves the toughness of PC/PLA blends significantly, with the increase of TPU, the elongation at break increases considerably, and the impact strength increases firstly and then falls, while the tensile strength decreases significantly and the blends exhibit a typical plastic fracture behavior. Meantime, TPU is conducive to the crystallinity of PLA in blends which is inhibited seriously by PC and damages the thermal stability of blends slightly. Moreover, the increased TPU makes the apparent viscosity of blends melt decrease due to the well melt fluidity of TPU; the melt is closer to the pseudoplasticity melt. Remarkably, the transesterification between the components improves the compatibility of blends significantly, and more uniform structure results in a higher crystallinity and better mechanical properties.

Rheological and Thermal Properties of Blends of Recycled LDPE and Virgin LDPE

Blends of recycled LDPE and LDPE were prepared by the twin-screw extruder at different ratios. Recycled LDPE was used as matrix in this work, LDPE was used to improve the properties of RLDPE. Thermal and rheological properties of the blends were carefully evaluated and compared with pure LDPE. DSC measurements indicates that the RLDPE/LDPE blends are miscible in the crystalline phase and LDPE can increase the crystallization of the blends. Rheological analysis shows that virgin LDPE will promote the normal flow of RLDPE and improve the mobility of chain segments in flow. Consequently, the rheological and processing properties of the blends have improved compared to RLDPE. The blends show potential applications in high-value products.

Study on the Mechenical Properties of PPC/PLA Blends Modified by POSS

Aliphatic polycarbonate Polycarbonate/poly (lactic acid)/(PPC/PLA) blends were prepared by melt blending, 1,2-propanediol isobutyl POSS (P-POSS) were added into the blends as a compatilizer and reinforcer. The morphologies, mechanical properties and rheological properties of blends were investigated systematically. The results showed that the adding of P-POSS could improve the compatibilization of PPC and PLA obviously. The thermal stability of the blends was enhanced but the crystallization was effected slightly. Moreover, the tensile strength and impact strength of blends exhibited a considerably increase.

Investigation of correlation between rheological properties of rubber compounds based on natural rubber/styrene-butadiene rubber with their thermal behaviors

Rubber compounds are widely used in many applications because of the properties they exhibit. The physical and mechanical properties of these blends are sensitive to small variations in the amount of the individual polymers used. Thermogravimetry is currently gaining wide acceptance as a method for compositional analysis of vulcanizates. Knowledge of the relationship among thermal behavior of rubber compounds with their rheological properties is important for the assessment of the optimum process conditions to produce materials that have required properties. The correlation of rheological properties of rubber compounds based on natural rubber/styrene-butadiene rubber with their thermal behavior has been assessed using thermogravimetry analysis. Thermogravimetric method permits the analysis to be completed in a short time and requires only a small sample. Thermogravimetry derivative profile (DTG) of the uncured blends and their rheological properties were investigated. Differential derivative curves of uncured vulcanizate showed that the degradation of styrene-butadiene rubber takes place at a higher temperature than that of natural rubber. According to DTG curves, two useful factors were demonstrated. These factors were the peak height ratio of natural rubber/styrene-butadiene rubber and a new factor called ‘normalized factor ,’ which could be correlated with the rheological properties of the blends. The result showed that the rheological nature of samples had acceptable correlation with the factors obtained by thermal analysis method. In other words, in this work a simple and reproducible experimental method was developed to efficiently predict the rheological properties of rubber blends.

Phase equilibria in ternary polymer blends

The phase states and rheological properties of blends of three polymers—polystyrene, poly(methyl methacrylate), and the styrene-acrylonitrile copolymer—in the common solvent chloroform are studied. The phase diagrams are constructed and the positions of spinodals are determined via the method of turbidity points. The effect of the third polymer on the compatibility of the binary blend obeys Prigogine’s rule; that is, it is determined by the solubility of the added polymer in the first two components. The extremum composition dependence of rheological properties of ternary polymer systems in the vicinity of the separation point (the metastable region) is found. Through the method of convex-shell construction, the phase diagrams are calculated.

Study on the Thermal and Rheological Properties of Reactive Blending PC/PLA/EVA Blends

EVA was added into PC/PLA blends as a modifier for improving the impact strength of blends, and meanwhile the thermal properties and rheological properties of blends should also be influenced. PC/PLA/EVA blends were prepared by melt blending and the catalyst DBTO was added into the blends in blending process to catalyze the transesterification of PC and EVA for improving the compatibility of blends. The effects of blend composition and transesterification on the thermal and rheological properties of blends were investigated. The results showed that the addition of EVA could improve the crystallinity of PLA in PC/PLA/EVA blends but had little influence on the thermal stability of blends,and the transesterification was beneficial to both the crystallization of PLA and thermal stability of blends. The addition of EVA and the transesterification of PC and EVA increased the apparent viscosity of blends, while the apparent viscosity of blends decreased drastically and the pseudo-plasticity characteristic of blend melts was weakened obviously with increasing PLA content and rising temperature.

Rheological Properties of Chlorinated Polyethylene Blended with Low-cost Grade Natural Rubber

Abstract A low-cost grade natural rubber (STR20 NR) was used for partly substituting elastomeric chlorinated polyethylene (CPE) and then cured by sulfur. Rheological properties of blends with various blend composition ratios under oscillatory and steady shear flows were investigated. Cure behavior is found to be promoted with increasing NR content. The viscoelastic behavior of CPE/NR blends, as determined from the Rubber Process Analyzer (RPA2000), is controlled strongly by blend composition. Uncured blends show relatively poor storage modulus associated with high damping factor probably due to the thermal degradation of NR phase. By contrast, after curing the NR phase in blends, bulk rheological properties change remarkably. Blends with NR as a major component reveal frequency-independent behavior with a broad linear viscoelastic (LVE) region. Flow properties under capillary shear of uncured blends agree well with those under oscillatory shear, i.e., the greater the NR content, the lower the apparent shear viscosity. Surprisingly, even without the elimination of elastic effect by the Bagley correction, it is still possible to superimpose plots of complex viscosity against test frequency over those of apparent shear viscosity against wall shear rate, which are different from the rheological properties of CPE blended with premium grade of NR (STR5L).

Rheological Properties of Blends of Ternary Copolyamide 6/66/610 with Chitosan

The viscosity of melts of a blend of a ternary copolyamide 6/66/610 and polysaccharide (chitosan) used as biodegradable additive was determined by capillary viscometry at 150–170°C.

Carbon black‐filled PET/HDPE blends: Effect of the CB structure on rheological and electric properties

AbstractThe rheological and electric properties of blends of poly(ethylene terephthalate) (PET) and high‐density polyethylene (HDPE) filled with various types of carbon black (CB) were analyzed in detail in this project. Four types of CB samples with available values of surface area, particle size, porosity, density, and maximum packing fraction were considered. Blends were prepared using an internal mixing chamber at two different rotational speeds, prior to mold compression of the samples. The rheological properties of the blends with varying polymer composition and a constant amount of CB were recorded in terms of torque variation with time for two shear rates (in terms of rotational speed). Rheological data were related to the resistivity of blends. Results show that the CB structure (porosity, surface area, apparent bulk density, and particle size) largely determine the resulting equilibrium torque and electrical properties. Furthermore, since CB is preferentially located in the HDPE phase, higher conductivity is observed as the PET content decreases, since the relative CB content in this phase increases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 562–569, 2001

Melt rheological properties of polypropylene-maleated polypropylene blends. I. Steady flow by capillary

Melt rheological properties of blends of polypropylene (PP) and PP grafted with maleic anhydride (PP-g-MA) are studied using a capillary rheometer. A pseudoplastic flow behavior is observed. The pseudoplasticity of the melt reduces with an increase of PP-g-MA content and/or temperature. The PP-g-MA component in the blend acts as decreasing melt viscosity, especially in the lower shear rate region, while the addition of PP-g-MA to PP does not cause obvious increase of die swell ratio. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1641–1648, 1999

Morphological and rheological detection of the phase inversion of PMMA/PS polymer blends

The phase inversion process was investigated from different points of view. First, a reliable on-line and off-line method of morphology detection using light microscopy is established. The method provides fast information that can be used to discriminate between different types of morphologies. Second, TEM images are modelled with Markov Random Fields. For characterization purposes image features are introduced and tested. A combination of features allows classification of different morphologies of PMMA/PS blends. In the third part we show that the rheological properties of blends allow also discrimination between different morphologies.

The Influence of Chemical Topology on Morphology, Elastic and Rheological Properties of Rubber-Reinforced Polymer Blends

Blends of random polystyrene-SBR were prepared first in a co-rotating twin screw extruder and then injected for being used as impact modifiers. Several experiments were realized, changing the chemical composition of SBR. The blends were made with 5% of SBR in a rigid matrix of polystyrene and the SBRs had different compositions. The samples were characterized by different techniques and compared to a sample with 0% SBR content. The tests performed were: a) mechanical: tensile strength, flexion and Izod impact; b) rheological: melt index flow and melt index razor-sharp at 205 °C and c) morphology: studied by scanning electron microscopy (SEM). The results show that the morphology of surfaces and the mechanical and rheological properties of these blends depend on the relation Styrene/Butadiene and on the structure of the SBRs.