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Long term creep assessment of room-temperature cured epoxy adhesive by time-stress superposition and fractional rheological model
Appl. Rheol. 28:6 (2018) 64796 (10 pages) ►
The creep behavior of a new type epoxy resin adhesive which is room-temperature cured and used for reinforcing engineering structures was studied. The tensile strength of the adhesive has reached the desired values for the structural adhesive used for bonding concrete as the base material with steel. The short-term creep tests were conducted under four different stress levels. The generalized curve for reference stress was obtained by utilizing the time-stress equivalent principle. Moreover, compared with traditional Burgers model, an improved fractional KBurgers model obtained by replacing the Newton derivative with the fractional derivative element (Abel component) in the traditional Burgers model can capture the creep behavior of this epoxy adhesive with high precision in the condition of the room-temperature and tensile stress of 36 MPa.► Cite this publication as follows:
Li H, Luo Y, Hu D: Long term creep assessment of room-temperature cured epoxy adhesive by time-stress superposition and fractional rheological model, Appl. Rheol. 28 (2018) 64796.
Abdulwahab S. Almusallam, T.B. Bini
Scaling Law AccompLi.Hed through Correlation of Large Amplitude Oscillatory Shear of Immiscible Polymer Blends with Jackson and Tucker Model
Appl. Rheol. 28:4 (2018) 46039 (10 pages) ►
In the current research, focus is on the comparison of Jackson and Tucker (JT) theoretical model to experimental results of large amplitude oscillatory shear (LAOS) of immiscible polymer blends. The field of rheology of immiscible polymer blends is currently very deficient in LAOS results, especially at moderate to low viscosity ratio values. In addition, most of the theoretical modeling that was carried out on LAOS of immiscible polymer blends used the small deformation theory of Maffettone and Minale. The current work adds further knowledge in the field of modeling of immiscible polymer blends by testing the predictions of the large deformation theory of Jackson and Tucker against LAOS experimental behaviour. LAOS experiments were carried out for a model immiscible blend composed of two Newtonian components (polybutadiene and polydimethylsiloxane) at viscosity ratios 1.34 and 0.39 and at volume fraction value 0.2. Data for the first, third and fifth harmonics of the sinusoidal stress response were recorded by FT-Rheological experimental set up. Validation of Jackson and Tucker model was carried out and the experimental results were compared to the JT model. Furthermore, the theoretical predictions of the JT code were compared to the experiments of Almusallam for two blends at viscosity ratio values of 0.1 and 4.4 at volume fraction value 0.21. The experimental results were plotted in terms of the scaling parameters of Reinheimer et al to test the scaling law. The Reinheimer scaling law was developed for viscosity ratio values larger than 2.5 and hence a new scaling law was developed in the current study taking into consideration the viscosity ratio values less than 2.5.► Cite this publication as follows:
Almusallam AS, Bini TB: Scaling Law Accomplished through Correlation of Large Amplitude Oscillatory Shear of Immiscible Polymer Blends with Jackson and Tucker Model, Appl. Rheol. 28 (2018) 46039.
Delegates of the national rheological societies
Society's Site Mar 2018 - Aug 2018
Appl. Rheol. 28:1 (2018) 50-54 ►
► Cite this publication as follows:
Rheological Societies: Society's Site Mar 2018 - Aug 2018, Appl. Rheol. 28 (2018) 50.
Rheology and stability of Li.Htweight polymer-modified self-consolidating concrete
Appl. Rheol. 27:2 (2017) 25807 (11 pages) ►
Limited information exists in literature regarding the effect of styrene-butadiene rubber (SBR) latexes on rheology and stability of Li.Htweight self-consolidating concrete (LWSCC) intended for repair and precast works. Four series of LWSCC mixtures prepared with various Li.Htweight aggregate (LWA) and SBR concentrations were considered in this project: The free water was adjusted to secure compressive strength of 40 ± 3.5 MPa. The slump flow remained fixed at 700 ± 25 mm, while unit weight varied from 1790 to 2280 kg/m3. Test results have shown that SBR additions lead to reduced concrete flow rate and passing ability. However, improved static stability such as bleeding, segregation, and floating of LWA. The rheological properties including yield stress and plastic viscosity increased for higher SBR additions, reflecting increased cohesiveness resulting from coalescence of water-soluble latexes and binding of cementitious matrix. Three categories of LWSCC classes specified in the European Guidelines were proposed with respect to rheological properties. A Ψ-factor was developed along with series of regression models to predict the combined effect of free water, viscosity-modifier, LWA, and SBR on rheology and stability of polymermodified LWSCC.► Cite this publication as follows:
Assaad J: Rheology and stability of lightweight polymer-modified self-consolidating concrete , Appl. Rheol. 27 (2017) 25807.
Evgeni Ivanov, Hristiana VeLi.Hkova, Rumiana Kotsilkova, Silvia Bistarelli, Antonino Cataldo, Federico Micciulla, Stefano Bellucci
Rheological behavior of graphene/epoxy nanodispersions
Appl. Rheol. 27:2 (2017) 24469 (9 pages) ►
Graphene/polymer nanocomposites are the latest trends in materials science in the recent years, but the technology of their preparation plays a crucial role in obtaining reliable materials with repeatable and enhanced properties. Up to now, there are many unresolved problems in controlling the dispersion of the graphene filler and the corresponding influence on the properties of the final nanocomposite materials. In the present study, we apply rheological methods for controlling the quality of the graphene dispersion. We prepare and characterize epoxy/graphene nanodispersions with graphene contents varying from 0.05 to 1 wt% and explore the effect of different mixing regimes on the dynamic moduli and viscosity, thus assessing the degree of the dispersion. The rheological percolation threshold and relaxation time spectra are determined, in order to evaluate the internal structure of the nanodispersions. The relaxation spectrum is highly efficient to probe the effects of interfaces and interconnections on the relaxation dynamics of molecules in nanodispersions. Rheological results combined with transmission electron microscopy (TEM) observations confirm that the low frequency dynamic viscosity and moduli strongly increase, with increasing the degree of dispersion due to the exfoliation of graphene sheets. The rheological percolation threshold was found at very low concentration depending from the processing conditions. The weight of the relaxation spectra is strongly shifted to higher values, compared to the neat epoxy resin and this effect is much stronger around and above the rheological percolation threshold.► Cite this publication as follows:
Ivanov E, Velichkova H, Kotsilkova R, Bistarelli S, Cataldo A, Micciulla F, Bellucci S: Rheological behavior of graphene/epoxy nanodispersions, Appl. Rheol. 27 (2017) 24469.
Katja A. FröhLi.H, Eleni Mitrentsis, Frank Clemens, Botho Hoffmann, Véronique Michaud, Thomas Graule
Assessment of the Dispersion Quality of refractive index-matched nanodispersions
Appl. Rheol. 26:6 (2016) 65050 (10 pages) ►
Dispersion quality has a large influence on the resulting properties of filled polymers, hybrids and nanocomposites in general. Reducing the van der Waals forces and therefore, matching the refractive index between the filler and the matrix should improve dispersion in hybrid materials. However, in this case the usual Li.Ht-based techniques cannot be used to assess dispersion quality. In this work, dispersions containing silica nanoparticles and a solvent mixture of 1-butanol and benzyl alcohol were analysed by rheological methods. The refractive index of the solvent was changed by varying the mixing ratio, and thus the effect of index difference on the filler-matrix interaction was investigated. In agreement with theory, a stronger gel network was observed when the refractive index of filler and solvent were matched. If the difference in refractive index of the two materials became too large, particles and solvent interaction was reduced, and agglomerates were formed. This resulted in a weaker gel network.► Cite this publication as follows:
Frohlich KA, Mitrentsis E, Clemens F, Hoffmann B, Michaud V, Graule T: Assessment of the Dispersion Quality of refractive index-matched nanodispersions, Appl. Rheol. 26 (2016) 65050.
Hoseini Maryam, Haghtalab Ali, Family Navid
Influence on compounding methods on rheology and morphology of linear low density polyethylene/poly(lactic acid)
Appl. Rheol. 26:6 (2016) 64746 (8 pages) ►
Linear low density polyethylene (LLDPE)/poly lactic acid (PLA) blends were prepared via different melt mixing methods. The effects of various blend compositions and two mixing methods on morphological and rheological behavior of the blends were studied. Scanning electron microscope (SEM) was used to investigate morphology behavior of the blends. The rheological studies illustrated that all samples presented shear thinning behavior and the PLA-rich blends exhibited a Newtonian region. It was found from the rheological measurements that the LLDPE/PLA (75/25 w/w) prepared by batch mixer exhibited higher values of storage modulus and complex viscosity, which is in agreement with the morphology results. In addition, using the different mixing methods, significant differences in the morphological results for the LLDPE/PLA (50/50 w/w) blend were observed. Finally, the results showed that the blends prepared by batch mixer exhibited better morphology, higher storage modulus, and complex viscosity.► Cite this publication as follows:
Maryam H, Ali H, Navid F: Influence on compounding methods on rheology and morphology of linear low density polyethylene/poly(lactic acid), Appl. Rheol. 26 (2016) 64746.
HighLi.Hts from the 24th Nordic Rheology Conference (NRC 2015)
Appl. Rheol. 26:1 (2016) 53-54 ►
► Cite this publication as follows:
Jarnstrom L: Highlights from the 24th Nordic Rheology Conference (NRC 2015), Appl. Rheol. 26 (2016) 53.
Tom C. B. McLeish (Ed.)
Obituary Alexei Li.Htman (1971-2015)
Appl. Rheol. 25:6 (2015) 53-54 ►
Alexei Li.Htman, a leading scientist in Theoretical Soft Matter Physics, has died aged 44
Born in 1971 into a family with strong scientific tradition, Alexei was educated in Moscow. He was awarded a Diploma in Physics with honours from the Physics Department of Moscow State University (MGU) in 1994. He remained at MGU for his PhD research, supervised by Professor Alexander Semenov. The topic, his first foray into polymer physics, was the calculation of the extraordinary ordered nanoscale patterns of chemical separation that are spontaneously generated within polymer melts whose molecules contain extended regions of different chemistry but joined together. These systems maintained a lifelong fascination for Alexei, as did the collaboration with the experimental group in Crete that the Russians worked with closely. The relationship with Crete remained strong and close until the end of Alexei's life. A more important lifelong partnership also began in Moscow - it was as students there that Alexei and Katrina met and married in December 1990. The family grew after their daughters Sonya and Asya were born while Alexei was working on his PhD thesis. Helping to look after two little girls however did not stop him from producing a high quality piece of work. Till the end of his days Alexei remained a loving, committed, hands on dad, always reliable and extremely loyal to his family. The family stayed in Moscow for two more years, with Alexei as a Scientific Fellow at Moscow State University, before moving to the U.K, in 1998, where he took up a position as a Research Assistant in the Department of Applied Mathematics at Leeds University, where Semenov, now his colleague, had also moved. That initial one year position marked the beginning of family's long life in the UK
Alexei stayed at Leeds from 1998 until 2007: in 1999 he moved to the Department of Physics and Astronomy, where he worked on theories of fast flow of entangled polymer melts, including theory and simulations of the convective constraint release model, supervised by Professor Tom McLeish, and working collaboratively with Prof. Scott Milner at an ex tended international workshop at the Kavli Institute of Theoretical Physics in Santa Barbara. In 2002, Alexei’s research had developed to the point where he was awarded an Advanced EPSRC Fellowship, which he held from 2002-2005 in the School of Physics and Astronomy. In this period, Alexei worked on developing new models of polymer dynamics, simultaneous description of rheology, neutron spin-echo, neutron scattering, diffusion, dielectric spectroscopy and NMR experiments, the theory of chemical reactions in polymers and computer simulations. This work has been recognized in many ways, including the best paper award of the Journal of Rheology (2006). From 2005-2007 Alexei held his Fellowship in the Department of Applied Mathematics, also as University Fellow, supervising a team of three postdoctoral researchers working on molecular simulations of polymer melts, slip-links model of entanglements and experimental rheology. Although a theoretician, he worked with experimental colleagues in different laboratories and performed experiments himself, learning and questioning every single detail. As a result, he personally developed the most reliable experimental protocol for measuring the flow properties of polymer melts yet found by the Leeds lab. For an experimentalist, it was a treat to interact with Alexei in this context, a unique experience that led to improved experiments. Co-supervising a PhD student, Richard Graham, the two formulated a now-celebrated non-linear but easily-computable mathematical model for the flow of linear polymers of well-defined length (the ROLiE-Poly model).
He worked hard not only on brilliant new theoretical science, but on making this accessible to others. For example, his foresight and energy led to the creation, with long-time colleague Jorge Ramirez, of a free software tool (called REPTATE) that enabled experimental scientists in universities and industry to sort their polymer flow data and compare it quickly and efficiently to theoretical models, greatly accelerating fundamental research and its application.
In May 2007, Alexei moved to the Department of Mathematics and Statistics at the University of Reading, as Professor of Mathematical Physics. There, together with Prof. Mark Matsen, he created a new group of theoretical polymer physics and within a few years had put Reading ‘on the map’. The group focused on the microscopic foundations of the tube theory and using a blend of theory and multi-scale simulation to dig deeper, and with more care, into the underlying physics than any other group in the world. A testimony of Alexei’s brilliance is his unique ability to bridge concepts and methodologies from different fields. He did so in his recent simulation work by using concatenated ring polymers to study polymer entanglements.
Alexei achieved enormous academic distinction, and his achievements came remarkably quickly – testament to his brilliance as a scientist. Several theoretical works on the linear and non-linear viscoelasticity of entangled polymers carry his name, including the famous Li.Htman-McLeish model (2002) for slow flows (which was 90% Li.Htman) and the GLaMM model (2003) for fast flows (with Graham and Milner). His Advanced EPSRC Fellowship came at the age of 31, and he was appointed Professor of Mathematical Physics in Reading at the age of just 35. Yet while undoubtedly successful himself, Alexei was equally proud of the many achievements of the group he developed. For example, in September this year he spoke glowingly of how two poster prizes out of three available at the Institute of Physics Polymer Physics Biennial Conference were won by post-doctoral researchers from his team. In the same month, he was appointed as the first Mercator Fellow of the Freiburg-Strasbourg-Basel-Mulhouse International Research Training Group on 'Soft Matter Science'. He enjoyed a productive visit to Strasbourg, during which he described himself as "feeling like a PhD student again" (possibly partly due to the position that his former PhD supervisor, Semenov, now holds there!). This is typical of his modesty and enthusiasm.
Alexei was one of those wonderful scientists who remind us that just because something is obvious, doesn't make it true. Alexei would challenge every idea that we had at Leeds – including the ones that we thought were obviously true. But the way in which he demoLi.Hed your ideas was so kind and so surgically precise that it always felt good somehow. He was a particularly vociferous critic of the bad habit that much of the polymer rheology community had got into, of presenting theory together with data from just one technique, then subtly altering the parameters when data from a different technique was brought into comparison. A wonderful paper from 2005 compared his remarkable ‘slip-link model’ to data on rheology, NMR and diffusion measurements simultaneously. He leaves us a permanent reminder that you learn more from theory when it disagrees with experiment and that an experimentalist should have a good grasp of theory and vice versa.
Alexei was a wonderful colleague, and all those who were lucky enough to work with him benefitted immensely from his enthusiasm, support and wisdom. Alexei was an intellectual powerhouse, a truly curious mind, a wonderfully creative thinker, a brilliant teacher at undergraduate and graduate levels, with academic gravitas way beyond his years, yet completely ap proachable, modest and always friendly in a natural way that charmed anybody who met him. The superb group he built in Reading and the quality of people he brought in reflect his vision and sense of commitment.
He was hugely supportive of those for whom he felt he had a responsibility. His dedication to his PhD students and his research team went well beyond professional duty. He sought to provide a family-like environment for the group, especially supportive for those who were far from home. He presented himself as an exemplary reference figure for all the young people in his group, full of energy and full of life. In this continuous work of hospitality and welcome he was supported by his family, to whom he was utterly devoted as husband and father.
Alexei was so much more than an academic and an intellectual. He truly enjoyed life and always managed to combine professional activities with hobbies and family activities. He did so last summer when he visited friends with his family following a workshop and seminar. He had a passion for so many things ranging from sports (especially swimming and hiking) to photography. A truly happy, free spirited man, full of energy and passion for things he did, he had as infectious a love of life as a tireless desire to find scientific truth. He was a great admirer of nature and outdoors with real care about the world and people around him. He was a great friend, a funny, spirited, yet always serious person, and his daily passionate presence, his enthusiasm for science, his warm friendship, will be sorely missed.
Alexei died on 11 October 2015 following a fall while hiking in Maryland, USA. He is survived by his wife Katrina, and their two daughters, Sonya and Asya.
► Cite this publication as follows:
McLeish TCB: Obituary Alexei Likhtman (1971-2015), Appl. Rheol. 25 (2015) 53.
Alexander Ya Malkin, Valery KuLi.Hikhin
Spatial-temporal phenomena in the flows of multi-component materials
Appl. Rheol. 25:3 (2015) 35358 (14 pages) ►
Measuring the rheological properties of multi-component (and multi-phase) systems meets with many special problems which are absent in flows of homogeneous materials. Such complex fluids have inherent structure and all the peculiarities of their behavior are determined by stress-induced temporal-spatial structure rearrangements. This paper is a review devoted to the physical origin and classification of problems encountered in the flow of multi-component materials. Stress-driven phenomena can be related to phase transformations (the formation of a new phase in polymerization, crystallization, amorphous phase separation), molecular and structure orientation, and various forms of self-organization. Some of these time effects are considered to be thixotropic phenomena. Thixotropy of multi-component matters leads to absence of an upper Newtonian plateau, time (rate)-dependence of yield stress and the layered flow in the range of high shear rates. The flow of such matters can lead to the formation of spatially divided structures with different properties and displacement of structures at the macroscopic level that excludes traditional measures of their rheological properties. In addition, the flow of multi-component systems is accompanied by the appearance of anisotropy of their properties. It is emphasized that the stressdriven evolution of rheological properties are not taken into account in the existing widely used constitutive equations.► Cite this publication as follows:
Malkin AY, Kulichikhin V: Spatial-temporal phenomena in the flows of multi-component materials, Appl. Rheol. 25 (2015) 35358.
Monika Dobrzynska Mizera, Tomasz Sterzynski
Congress on Rheology Poznan 2013
Appl. Rheol. 24:1 (2014) 48-49 ►
► Cite this publication as follows:
DobrzynskaMizera M, Sterzynski T: Congress on Rheology Poznan 2013, Appl. Rheol. 24 (2014) 48.
Sergey Ilyin, Valery KuLi.Hikhin, Alexander Malkin
Characterization of material viscoelasticity at large deformations
Appl. Rheol. 24:1 (2014) 13653 (10 pages) ►
Mechanical properties of various technological materials at large deformations are proposed to characterize by means of some generalized parameters obtained at large oscillation strains but not related to any definite rheological equations. The base for the analysis is the Lissajous- Bowditch figures in two coordinate systems - "stress - deformation" and "stress derivative with respect to the phase angle - deformation". An area of the first of these figures provides the well known integral estimation of dissipative losses in the deformation cycle while the second one presents the new integral measure of the matter's elasticity. The correlation between the proposed integral estimations of the "averaged" dynamic modulus and the values found in using Fourier and Chebyshev series was demonstrated. This integral method was applied for three suspensions of various types. The obtained results allowed for viewing the type of non-linearity: pseudo-plasticity or dilatancy, stiffening or softening, as functions of deformation.► Cite this publication as follows:
Ilyin S, Kulichikhin V, Malkin A: Characterization of material viscoelasticity at large deformations, Appl. Rheol. 24 (2014) 13653.
Alexander Malkin, Alexander Semakov, Valery KuLi.Hikhin
Macroscopic modeling of a single entanglement at high deformation rates of polymer melts
Appl. Rheol. 22:3 (2012) 32575 (9 pages) ►
We constructed a macroscopic model illustrating behavior of a single entanglement knot of macromolecules in a melt and examined its behavior at different deformation rates. A model consists of flexible elastic strips, which are tied in a granny knot (modeling not a real geometrical form of entanglements but their behavior at relatively easy sliding). This scheme models the situation when elastic energy exceeds the energy of the Brownian motion. The behavior of a knot chosen for modeling is different at low and high deformation rates. In the previous case knots disentangle as predicted by the .tube. model, elastic strips slip out a knot and this is an illustration of flow. In the latter case, knots tighten up, further extension of strips leads to the increase in stresses up to breakup of a strip. This effect imitates the transition from the flow to the rubbery-like behavior of polymer melts, when flow becomes impossible due to the formation of quasi-permanent entanglements. The general dimensionless correlation for the process under discussion has been proposed.► Cite this publication as follows:
Malkin A, Semakov A, Kulichikhin V: Macroscopic modeling of a single entanglement at high deformation rates of polymer melts, Appl. Rheol. 22 (2012) 32575.
Deepak Arora, Souvik Nandi, H. Henning Winter
A new generation of Li.Ht scattering device with real time data analysis for rheo-optical measurements
Appl. Rheol. 21:4 (2011) 42633 (8 pages) ►
An apparatus for small angle Li.Ht scattering (SALS) and Li.Ht transmission measurements under shear was built and tested at the University of Massachusetts Amherst. As a new development, the polarization direction can be rotated by a liquid crystal polarization rotator (LCPR) with a short response time of about 20 ms.The experiments were controlled and analyzed with a LabVIEWTM based code (LabVIEW-TM 7.1) in real time. Quiescent and flow-induced crystallization experiments on isotactic poly-1-butene (iPB) were conducted to demonstrate the instrument and software capabilities. Software was designed with a modular approach, so that further modules can be added to investigate other systems such as polymer blends, colloidal suspensions, solutions with droplets etc. A replica of the SALS apparatus was custom built for ExxonMobil Research in Clinton NJ.► Cite this publication as follows:
Arora D, Nandi S, Winter HH: A new generation of light scattering device with real time data analysis for rheo-optical measurements, Appl. Rheol. 21 (2011) 42633.
L. Senff, D. Hotza, J.A. Labrincha
Effect of Li.Htweight aggregates addition on the rheological properties and the hardened state of mortars
Appl. Rheol. 21:1 (2011) 13668 (8 pages) ►
This paper evaluates the use of Li.Htweight aggregates (LWA), namely perlite (PER) and vermiculite (VER) in cement mortars. The workability of mortars was defined in rheometer and flow table tests. Three distinct LWA levels were added (0 - 3, 4.5 - 7, and 9 - 10.5 wt%) requiring the use of distinct water/solids (W/S) ratios (0.18, 0.265 and 0.35, respectively). In order to evaluate the performance of such formulations in the hardened state, the flexural and compressive strength after 28 days curing was also measured. In general, LWA caused a high variation on the yield stress and spread on table, being the yield stress the best rheological parameter to be related with the flow table. PER exerts a strong impact on initial yield stress, while the effect of VER is stronger for longer rheology testing periods. The compressive strength ranged from 12.3 MPa (0 % LWA) to 2.77 MPa (PER) and 2.39 MPa (VER).► Cite this publication as follows:
Senff L, Hotza D, Labrincha JA: Effect of lightweight aggregates addition on the rheological properties and the hardened state of mortars, Appl. Rheol. 21 (2011) 13668.
J.K.G. Dhont, G. Gompper, D. Richter
JuLi.H Soft Matter Days 2008
Appl. Rheol. 19:3 (2009) 176-178 ►
► Cite this publication as follows:
Dhont JKG, Gompper G, Richter D: Julich Soft Matter Days 2008, Appl. Rheol. 19 (2009) 176.
VeLi.Hko Hristov, John Vlachopoulos
A Study of Entrance Pressure Loss in Filled Polymer Melts
Appl. Rheol. 17:5 (2007) 57191 (9 pages) ►
The influence of the molecular structure of the polymer matrix and filler loading on the entrance pressure loss of polyethylene/ wood flour composites has been investigated in this research by means of a capillary rheometer equipped with an orifice die. The entry flow of talc- and glass-filled polyethylene composites has been investigated as well. It was found that the entrance pressure loss of wood filled polyethylene composites greatly increased with increasing the wood flour loading. Talc and solid glass spheres also increase the entrance pressure loss, however not as much as wood flour. It was also observed that composites based on narrow molecular weight distribution (MWD) resins exhibited larger entrance pressure loss than the broad MWD and branched polyethylene based ones. It was concluded that measurements of the entrance pressure loss reveal some interesting features of the polymer-filler interactions and could provide significant insights in the processing of highly filled polymer melts.► Cite this publication as follows:
Hristov V, Vlachopoulos J: A Study of Entrance Pressure Loss in Filled Polymer Melts , Appl. Rheol. 17 (2007) 57191.
Vadim E. Dreval', Gleb Vasil'ev, Elena Borisenkova, Alexander Semakov, Valery KuLi.Hikhin
Influence of Molecular Weight of SAN on Rheological and Mechanical Properties of ABS-plastics
Appl. Rheol. 17:4 (2007) 44745 (11 pages) ►
Rheological and mechanical properties of acrylonitrile-butadiene-styrene polymers (ABS) prepared via bulk polymerization depending on the molecular weight (Mw) of styrene-acrylonitrile copolymer (SAN) have been investigated.The tendencies of attaining the yield stress at steady-state shear flow and approaching to the .plateau. region of storage modulus at low frequencies in oscillatory tests were observed. Both these phenomena are induced by formation of the structural skeleton consisting of polybutadiene (PB) particles arranged in the SAN-matrix. Growth of Mw of SAN leads both to increase of the .plateau. value of storage modulus at low frequencies and the yield stress.This fact can be explained by the influence of Mw of SAN chains grafted onto PB particles on structure formation in ABS melts because of a redistribution of the ratio particleparticle / particle-matrix interactions. The elongational viscosity of ABS melts is a power function of Mw of SAN matrix. The power index of this function increases with the polymer straining that reflects orientation of SAN chains with their length increase. The strain-hardening index of ABS melts increases considerably with increase of SAN matrix Mw. However, it does not depend on presence of PB particles in the material. It means that the value of this index is governed by orientation effect in the SAN matrix.The impact strength of the investigated ABS samples is interrelated with rheological characteristics of ABS melts as well as Mw of SAN. The dependence of impact strength on Mw can be explained by increasing role of orientation effects of SAN chains with Mw increase in the copolymer fibrils connecting the walls of crazes formed at impact action.► Cite this publication as follows:
Dreval VE, Vasilev G, Borisenkova E, Semakov A, Kulichikhin VG: Influence of Molecular Weight of SAN on Rheological and Mechanical Properties of ABS-plastics, Appl. Rheol. 17 (2007) 44745.
Publication Specific Impact of Articles PubLi.Hed by Rheological Journals
Appl. Rheol. 15:6 (2005) 406-409 ►
The Impact Factor of a journal is a quantitative way of assessing its worth and relevance to the academic community it serves. Many librarians see the ratio between Impact Factor and price as a suitable yardstick by which to measure the value of their collections. In addition, the research assessment exercises which, in many countries, are now being carried out on a more formal basis mean that authors submitting original research must pubLi.H it in a journal with the highest perceived worth possible in order to secure future funding, job promotions and peer recognition. It has been suspected [T. Opthof, Cardiovasc. Res. 33 (1997) 1; J. Stegmann, Nature 390 (1990) 550], however, that a particular author's impact is not much related to the journals in which her/he pubLi.Hes. As will be demonstrated in this letter, the impact of articles pubLi.Hed in rheological journals is largely influenced by criteria such as length of article, number of authors, number of cited references.► Cite this publication as follows:
Kroger M: Publication Specific Impact of Articles Published by Rheological Journals, Appl. Rheol. 15 (2005) 406.
Gholamhossein Sodeifian, ALi.Haghtalab
Discrete Relaxation Spectrum and K-BKZ Constitutive Equation for PVC, NBR and Their Blends
Appl. Rheol. 14:4 (2004) 180-189 ►
Frequency sweep experiments were performed on poly(vinyl chloride) (PVC) and acrylonitrile butadiene rubber (NBR) as well as their miscible blends PVC/NBR (70/30), PVC/NBR (50/50), and PVC/NBR (30/70) in oscillatory shear. The samples were prepared by mechanical blending at 160.C. In order to investigate the validity of time temperature superposition (TTS) principle the loss angle d versus the logarithm of the absolute value of the complex modulus, G*, were plotted. It was shown that the TTS principle is not valid for the above-mentioned polymer materials and therefore they are not thermorheologically simple. Master curves of PVC, NBR, and PVC/NBR (50/50) blend were therefore obtained approximately. Using a nonlinear regression method, discrete relaxation spectra were determined for PVC, NBR, and PVC/NBR (50/50). To study non-linear viscoelasticity behavior, the experiments of steady shear, start up steady shear, and step strain were carried out. The damping function was determined by the step strain experiments. Using K-BKZ constitutive equation, the shear viscosity and the shear stress growth function were calculated from the discrete relaxation spectra and the damping function and then compared to experimental data. The K-BKZ constitutive equation provides very good prediction over the entire range of experimental results.► Cite this publication as follows:
Sodeifian G, Haghtalab A: Discrete Relaxation Spectrum and K-BKZ Constitutive Equation for PVC, NBR and Their Blends, Appl. Rheol. 14 (2004) 180.
S. V. Kotomin, S. V. Antonov, V. E. Dreval, M. L. Kerber, V. G. KuLi.Hikhin
Impregnation of Fibrous Materials with LC Polyesters and Blends on their Base
Appl. Rheol. 10:2 (2000) 62-72 ►
► Cite this publication as follows:
Kotomin SV, Antonov SV, Dreval VE, Kerber ML, Kulichikhin VG: Impregnation of Fibrous Materials with LC Polyesters and Blends on their Base, Appl. Rheol. 10 (2000) 62.
J WunderLi.H, T Lohmann
Inertial Effects in Oscillatory Experiments with a Coaxial Cylinder Rheometer
Appl. Rheol. 5:3 (1995) 134 ►
► Cite this publication as follows:
Wunderlich J, Lohmann T: Inertial Effects in Oscillatory Experiments with a Coaxial Cylinder Rheometer, Appl. Rheol. 5 (1995) 134.
Laser Diffraction and Dynamic Li.Ht Scattering: Particle Analyser Compared
Appl. Rheol. 2:4 (1992) 264-269 ►
► Cite this publication as follows:
Osterhold M: Laser Diffraction and Dynamic Light Scattering: Particle Analyser Compared, Appl. Rheol. 2 (1992) 264.
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