scholarly journals Elastic waves in particulate glass-rubber mixtures

2021 ◽  
Vol 477 (2249) ◽  
Author(s):  
Kianoosh Taghizadeh ◽  
Holger Steeb ◽  
Stefan Luding ◽  
Vanessa Magnanimo
Keyword(s):  
Elastic Waves ◽  
Wave Speed ◽  
Hydrostatic Stress ◽  
Damping Properties ◽  
Rubber Content ◽  
Physical Experiments ◽  
Triaxial Cell ◽  
Rubber Particles ◽  
Granular Packings ◽  
Propagation Of Waves

We investigate the propagation of waves in dense static granular packings made of soft and stiff particles subjected to hydrostatic stress. Physical experiments in a triaxial cell equipped with broadband piezoelectric wave transducers have been performed at ultrasound frequencies. The time of flight is measured in order to study the combined effect of applied stress and rubber content on the elastic properties of the mixtures. The bulk stiffness deduced from the wave speed is nonlinear and non-monotonic with the increasing percentage of rubber with a more prominent effect at higher pressures. Moreover, in the frequency domain, a spectral analysis gives insights on the transition from a glass- to a rubber-dominated regime and the influence of rubber particles on the energy dissipation. Mixtures with rubber content below 30% show enhanced damping properties, associated with slightly higher stiffness and lighter weight.

The State of Polydispersion of Hevea Latex. I

1946 ◽  
Vol 19 (1) ◽  
pp. 176-186
Author(s):  
J. H. E. Hessels
Keyword(s):  
Protein Content ◽  
Hevea Brasiliensis ◽  
The State ◽  
Rubber Content ◽  
Rubber Latex ◽  
Latex Particles ◽  
Rubber Particles ◽  
The Subject ◽  
Points Of View ◽  
Good Agreement

Abstract The rubber particles in the latex of Hevea brasiliensis are present in the form of a polydispersion, and their diameters lie within the range of 0.1 to 3 microns. The rubber hydrocarbon itself is composed of a mixture of macromolecules of different degrees of polymerization. Rubber latex is, therefore, a system which is at the same time both polydispersed and polymolecular. It is well known that the degree of dispersion of a substance governs to a great extent certain properties of the substance. Moreover, astonishing as it may seem, in the great number of investigations which have been made of the composition and properties of latex and crude rubber, almost no attention has been paid to the part which may be played by the dimensions of the latex particles. However, in an investigation concerned with the centrifugation of latex, Loomis and Stump have called attention to this possibility, and in a study of latex obtained by fractionation, and in which the majority of the latex particles were of large dimensions, McGavack came to the conclusion that the protein content is proportional to the surface area of the globules. This limited knowledge of the subject seemed to warrant a more thorough study of the problem, which is of fundamental importance both from the theoretical and practical points of view. The investigation as a whole divided itself into three essential parts: (1) separation of latex into fractions containing particles of different sizes, and measurement of the state of dispersion in these fractions, (2) a study of the relation of these fractions to the composition of the rubber, i.e., the relation between the content of nonrubber components and the size of the latex particles, and (3) a study of the changes in the properties of the rubber hydrocarbon with change in the size of the latex particles. The latex used in this investigation was ordinary latex, containing 38–40 per cent dry-rubber content and preserved with ammonia. For the most important points, a concentrated latex (creamed latex containing 60 per cent dry-rubber content) was also tested. These two latices were about two years old when the investigation was started, and they gave results which were in good agreement with each other. In the present paper, only the data obtained with the first of the two latices are presented.

Laboratory Evaluation of Rubberized Binder and Mix Containing a Low Content of Devulcanized Rubber Modifier

2020 ◽  
Vol 2674 (11) ◽  
pp. 53-63
Author(s):  
Yanlong Liang ◽  
David Jones ◽  
John T. Harvey ◽  
Jeffery Buscheck
Keyword(s):  
Asphalt Binder ◽  
Fatigue Cracking ◽  
Laboratory Evaluation ◽  
Rubber Content ◽  
Area Index ◽  
Lower Phase ◽  
Waste Tires ◽  
Stiffness Reduction ◽  
Rubber Particles ◽  
Devulcanized Rubber

This paper evaluates the mechanical properties of rubberized asphalt binder and mix containing 5% and 10% rubber. This rubberized asphalt binder was manufactured in a field-blend process using devulcanized rubber particles, finer than 250 microns, derived from waste tires. Comparison between the rubberized binder and the base binder test results showed that the rubberized binders had higher complex moduli and lower phase angles at the grade temperature. They also had a higher percentage recovery in the multiple stress creep recovery test, and a significant creep stiffness reduction in the bending beam rheometer test. Given the low rubber content and small rubber particle size, this rubberized binder can be used in dense-graded mixes, whereas asphalt rubber binders, with larger rubber particles and higher rubber content (>15%), must be used in gap- or open-graded mixes. This rubberized dense-graded mix met the volumetric design criteria at the same binder content as the control mix prepared with the unmodified base binder. Laboratory tests on the mix included repeated load triaxial, Hamburg wheel track, flexural dynamic modulus, and beam fatigue. The rubberized mixes had slightly lower stiffnesses than the control mix, but better resistance to moisture damage, rutting, and fatigue cracking. A strong linear correlation was found between the carbonyl area index and the rheological properties of the long-term aged binder and fatigue life of the mixes. Based on these findings, these rubber-modified binders can be considered for use in dense-graded mixes to improve overall performance and make use of waste tires.

scholarly journals Effects of inclusion of granulated rubber tires on the mechanical behaviour of a compressive sand

2020 ◽  
Vol 57 (5) ◽  
pp. 763-769 ◽  
Author(s):  
W. Li ◽  
C.Y. Kwok ◽  
K. Senetakis
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Mechanical Behaviour ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Rubber Content ◽  
Filling Materials ◽  
Rubber Particles ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

Drained triaxial shearing tests were performed on a well-graded compressive sand (completely decomposed granite, CDG) and its mixtures with granulated rubber tires to investigate the effects of rubber size and content on their mechanical behaviour. Three sizes of rubber particles, GR1, GR2, and GR3, were used with size ratios to CDG (D50,rubber : D50,CDG) of 0.9, 3.5, and 7.2, respectively, and the rubber content ranged from 0% to 30%. The results show that for CDG–GR1 mixtures, the strength decreases with increasing rubber content, while for CDG–GR2 and CDG–GR3 mixtures, the strength decreases only at 10% rubber content and then increases markedly with increasing rubber content. The increase of strength is mainly because the inclusion of large rubber particles widens the particle size distributions of the mixtures, resulting in denser packings. The denser packings also lead to a decrease in compressibility. At larger size ratio and higher rubber content, the CDG–rubber mixtures show higher shear strength and lower compressibility than pure CDG, which indicates the CDG–rubber mixtures are very suitable to be used as filling materials.

Rubber-Toughened Long Glass Fiber Reinforced Thermoplastic Composite

2012 ◽  
Vol 2 (4) ◽  
pp. 47-58
Author(s):  
Fabrizio Quadrini ◽  
Claudia Prosperi ◽  
Loredana Santo
Keyword(s):  
Glass Fiber ◽  
Thermoplastic Composite ◽  
Dissipated Energy ◽  
Powder Size ◽  
Damping Properties ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced ◽  
Rubber Toughened ◽  
Long Glass Fiber ◽  
Rubber Particles

A rubber-toughened thermoplastic composite was produced by alternating long glass fiber reinforced polypropylene prepregs and rubber particles. Several composite laminates were obtained by changing the number of plies, the rubber powder size distribution, and the stacking sequence. Quasi-static mechanical tests (tensile and flexure) and time dependent tests (dynamic mechanical analysis and cyclic flexure) were carried out to evaluate strength and damping properties. As expected, 10 wt% rubber-filled laminates showed lower strengths than rubber-free laminates but the effect of the rubber on the composite damping properties was evident. At low rates, the rubber particles can also double the dissipated energy under cyclic loading, even if this effect disappears by increasing the test rate.

Torsional Wave Propagation in a Circular Cylinder with a Periodically Corrugated Outer Surface

1999 ◽  
Vol 121 (4) ◽  
pp. 501-505 ◽  
Author(s):  
J. O. Kim
Keyword(s):  
Circular Cylinder ◽  
Outer Surface ◽  
Elastic Waves ◽  
Wave Speed ◽  
Perturbation Technique ◽  
Phase Speed ◽  
Outer Radius ◽  
Axial Coordinate ◽  
Speed Reduction ◽  
Smooth Cylinder

The paper describes a theoretical study on the speed of torsional elastic waves propagating in a circular cylinder whose outer radius varies periodically as a harmonic function of the axial coordinate. An approximate solution for the phase speed was obtained by using the perturbation technique for sinusoidal modulation of a small amplitude. This shows that the wave speed in the cylinder with a corrugated outer surface is less than that in a smooth cylinder by the square of the amplitude of the surface perturbation. This theoretical prediction reasonably agrees with an experimental observation reported earlier. It is also shown that the wave speed reduction due to the surface corrugation becomes larger for a thinner cylinder and for a bigger density of corrugation.

Microturbidimeter for Determination of Rubber Content of Latex

1931 ◽  
Vol 4 (4) ◽  
pp. 601-611
Author(s):  
S. D. Gehman ◽  
J. S. Ward
Keyword(s):  
Particle Size ◽  
Rubber Content ◽  
Mean Particle Size ◽  
Rubber Particles ◽  
Color Filters

Abstract It is desirable to devise a method for determining the dry rubber content of latex which will be both more rapid than the two trial coagulation methods and more precise than the hydrometric method. The turbidity of latex, depending upon the volumetric number and size of the suspended rubber particles, offers a satisfactory criterion for the determination of the rubber content of latex. A microturbidimeter, herein described, has been adapted to such determinations. It permits more rapid determinations of the rubber content than the two trial coagulation methods. Its precision is less than the lengthy trial coagulation method, involving coagulation, creping, and drying, but is probably greater than that of the shortened trial coagulation method involving only coagulation and creping. Its precision is approximately 1 per cent rubber in 35 per cent latex. The turbidity of latex obeys the turbidity-dilution law for rubber-content values less than 15 per cent. The use of color filters, transmitting the shorter wave lengths of light, minimizes the effects of a difference in the effective mean particle size of different kinds of latex.

scholarly journals An Evaluation of the Resilient Modulus and Permanent Deformation of Unbound Mixtures of Granular Materials and Rubber Particles from Scrap Tyres to Be Used in Subballast Layers

2016 ◽  
Author(s):  
Carlos Hidalgo Sgnes
Keyword(s):  
Granular Materials ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Waste Material ◽  
Triaxial Tests ◽  
Rubber Content ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Vibration Attenuation ◽  
Rubber Particles

Over the last years rubber from scrap tyres has been reused in different civil works such as road embankments and railway platforms due to its resilient properties, low degradation and vibration attenuation. Unfortunately, this issue is still scarce. For instance, in Spain about 175.000 tonnes of scrap tyres were collected in 2014, of which only 0.6% were reused in civil works. Aiming to contribute to the reutilisation of large quantities of this waste material, this paper focuses on the analysis of unbound mixtures of granular materials with different percentages of rubber particles to be used as subballast layers. Mixtures are tested under cyclic triaxial tests so as to obtain their resilient modulus and evaluate their permanent deformations. It is found that as the rubber content increases, the resilient modulus decreases and the permanent deformation increases. Taking into account the usual loads transmitted to the subballast layer, the optimum rubber content that does not compromise the behaviour of the mixture is set in a range between 2.5% and 5% in terms of weight.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4231

scholarly journals The speed, reflection and intensity of waves propagating in flexible tubes with aneurysm and stenosis: Experimental investigation

2019 ◽  
Vol 233 (10) ◽  
pp. 979-988 ◽  
Author(s):  
Wisam S Hacham ◽  
Ashraf W Khir
Keyword(s):  
Reflection Coefficient ◽  
Wave Speed ◽  
Expansion Waves ◽  
Reflected Wave ◽  
Compression And Expansion ◽  
Contracting Heart ◽  
Propagation Of Waves ◽  
Flexible Tubes ◽  
Mother Tube

A localized stenosis or aneurysm is a discontinuity that presents the pulse wave produced by the contracting heart with a reflection site. However, neither wave speed ( c) in these discontinuities nor the size of reflection in relation to the size of the discontinuity has been adequately studied before. Therefore, the aim of this work is to study the propagation of waves traversing flexible tubes in the presence of aneurysm and stenosis in vitro. We manufactured different sized four stenosis and four aneurysm silicone sections, connected one at a time to a flexible ‘mother’ tube, at the inlet of which a single semi-sinusoidal wave was generated. Pressure and velocity were measured simultaneously 25 cm downstream the inlet of the respective mother tube. The wave speed was measured using the PU-loop method in the mother tube and within each discontinuity using the foot-to-foot technique. The stenosis and aneurysm dimensions and c were used to determine the reflection coefficient ( R) at each discontinuity. Wave intensity analysis was used to determine the size of the reflected wave. The reflection coefficient increased with the increase and decrease in the size of the aneurysm and stenosis, respectively. c increased and decreased within stenosis and aneurysms, respectively, compared to that of the mother tube. Stenosis and aneurysm induced backward compression and expansion waves, respectively; the size of which was related to the size of the reflection coefficient at each discontinuity, increases with smaller stenosis and larger aneurysms. Wave speed is inversely proportional to the size of the discontinuity, exponentially increases with smaller stenosis and aneurysms and always higher in the stenosis. The size of the compression and expansion reflected wave depends on the size of R, increases with larger aneurysms and smaller stenosis.

scholarly journals Comparison of Morphological Characteristics and Determination of Different Patterns for Rubber Particles in Dandelion and Different Rubber Grass Varieties

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1561
Author(s):  
Boxuan Yuan ◽  
Guohua Ding ◽  
Junjun Ma ◽  
Lingling Wang ◽  
Li Yu ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Morphological Characteristics ◽  
Leaf Margin ◽  
Rubber Content ◽  
Flower Buds ◽  
Promising Alternative ◽  
Alternative Crop ◽  
Rubber Particles ◽  
Common Dandelion

Russian dandelion Taraxacum kok-saghyz (TKS) is one promising alternative crop for natural rubber production. However, it is easily confused with other dandelions. In this study, we performed a systematical comparison of the morphological characteristics for different TKS varieties and common dandelion Taraxacum officinale (TO). Our results demonstrated that several obvious differences in morphology can be found between TKS and TO. TO leaf is a pinnate shape, its margin is heavily jagged and its base is cuneate, but TKS leaf is more cuneate and its leaf margin is nearly smooth and round. There are obvious differences for the outer bracts of TO and TKS flower buds. TKS bracts are oblanceolate, apex obtuse, margin smooth and sinuate, and its outer layer of flower buds and faceplate involucre sepal is buckled inward to form a certain angle. TKS is self-incompatible, and its seeds are spindle-shaped achene and show upright plumpness. A large amount of laticifer cells and rubber particles can be detected from many TKS tissues, and dry roots of TKS contain high contents of natural rubber. Laticifer cells and rubber particles can only be examined in the vein, stem, and roots of TKS. Our statical results also revealed that the numbers of laticifer cells and rubber particles have a positive relationship with the rubber content in TKS roots. These morphological features can help us to easily distinguish TKS from common dandelion and approximately estimate the rubber content in the roots of different TKS varieties for TKS breeding in future.

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