An official website of the United States government
Reinforcing fillers are necessary in rubber compounding to aid in enhancing the mechanical properties of the compound for various applications. Carbon black (CB) is currently the most common reinforcing filler used in tire compounding. Lignin, an amorphous polyphenolic material derived from plants and a by-product of the pulp and paper industry, is also an attractive material that can serve as a dispersant and as a reinforcing filler. This paper evaluates the interactions between styrene-butadiene rubber and reinforcing fillers with an electron-rich π- system, such as lignin and CB, in the presence of a graft copolymer (PB-g-PPFS) of PB and electron-deficient 2,3,4,5,6-pentafluorostyrene (PFS). The interactions are attributed to areneperfluoroarene interactions between the electron-deficient π-system of the polyperfluoroarene grafts and the electron-rich π-system of lignin and/or CB particles. The effects of improved fillerrubber interactions on mechanical properties and dynamic mechanical properties are analyzed. This paper will demonstrate the use of PB-g-PPFS as a coupling agent in rubber compounds to enhance the interaction between the filler, lignin and lignin-carbon black hybrid filler, and the rubber matrix to achieve a reduction in the hysteresis loss and enhanced filler dispersion.
more »
« less
Use of fly ash as eco-friendly filler in synthetic rubber for tire applications
A byproduct of the power generation industries, fly ash can be used as a potential filler in many commercial products including rubber-based products. Reusing the fly ash in this manner is an efficient way to help prevent air pollution which occurs if such particles are released freely to the atmosphere. The reinforcement efficiency of fly ash for partial replacement of carbon black and silica fillers in styrenebutadiene rubber compounds was investigated in this work. The total content of fillers was held constant at 50 phr (weight ratio of filler to rubber was 0.5) when not using silica fillers at all, and 54 phr when using 4 phr carbon black only with silica fillers, while the content of fly ash increased from 0 to 10 phr. In the evaluation of the rubber compounds, the focus was the mechanical properties and adhesion of steel reinforcement cords to the styrene-butadiene rubber compounds. Adhesion between the compounds and steel wire reinforcement was measured for assessing efficacy of adding fly ash to the rubber compounds in tire applications. Ball mill treatment was used to reduce the size of the fly ash particles while also modifying their surface topography. The comparisons of untreated and ball mill treated fly ash filled rubber compounds and rubber compounds containing different fillers were accomplished subsequently. The results revealed that the partial addition of up to 10 phr fly ash to rubber compounds resulted in increases in elongation at break, adhesion to reinforcement steel cord, wet-grip, as well as lower rolling resistance
more »
« less
- Award ID(s):
- 1650460
- PAR ID:
- 10079055
- Date Published:
- Journal Name:
- Journal of cleaner production
- Volume:
- 206
- ISSN:
- 0959-6526
- Page Range / eLocation ID:
- 374 - 382
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
A coarse-grained model has been built to study the effect of the interfacial interaction between spherical filler particles and polymer on the mechanical properties of polymer nanocomposites. The polymer is modeled as bead-spring chains, and nano-fillers grafted with coupling agent are embedded into the polymer matrix. The potential parameters for polymer and filler are optimized to maximally match styrene-butadiene rubber reinforced with silica particles. The results indicated that, to play a noticeable role in mechanical reinforcement, a critical value exists for the grafting density of the filler–polymer coupling agent. After reaching the critical value, the increase of grafting density can substantially enhance mechanical properties. It is also observed that the increase of grafting density does not necessarily increase the amount of independent polymer chains connected to fillers. Instead, a significant amount of increased grafting sites serve to further strengthen already connected polymer and filler, indicating that mechanical reinforcement can occur through the locally strengthened confinement at the filler–polymer interface. These understandings based on microstructure visualization shed light on the development of new filler polymer interfaces with better mechanical properties.more » « less
-
Additives such as nano-silica and fly ash are widely used in cement and concrete materials to improve the rheology of fresh cement and concrete and the performance of hardened materials and increase the sustainability of the cement and concrete industry by reducing the usage of Portland cement. Therefore, it is important to study the effect of these additives on the rheological behavior of fresh cement. In this paper, we study the pulsating Poiseuille flow of fresh cement in a horizontal pipe by considering two different additives and when they are combined (nano-silica, fly ash, combined nano-silica, and fly ash). To model the fresh cement suspension, we used a modified form of the power-law model to demonstrate the dependency of the cement viscosity on the shear rate and volume fraction of cement and the additive particles. The convection–diffusion equation was used to solve for the volume fraction. After solving the equations in the dimensionless forms, we conducted a parametric study to analyze the effects of nano-silica, fly ash, and combined nano-silica and fly ash additives on the velocity and volume fraction profiles of the cement suspension. According to the parametric study presented here, larger nano-silica content results in lower centerline velocity of the cement suspension and larger non-uniformity of the volume fraction. Compared to nano-silica, fly ash exhibits an opposite effect on the velocity. Larger fly ash content results in higher centerline velocity, while the effect of the fly ash on the volume fraction is not obvious. For cement suspension containing combined nano-silica and fly ash additives, nano-silica plays a dominant role in the flow behavior of the suspension. The findings of the study can help the design and operation of the pulsating flow of fresh cement mortars and concrete in the 3D printing industry.more » « less
-
Coupling agents are intended to promote filler dispersion by providing a bridge between the filler and the rubber phase. This study investigated the ability of a novel physical coupling agent, poly(butadienegraft-pentafluorostyrene) in a mixture with polypentafluorostyrene, to improve rubber-filler interactions and suppress filler-filler networking in carbon-black-reinforced styrene-butadiene rubber (SBR), and thereby decrease hysteresis. The electron-rich aromatic rings of carbon black are involved in areneperfluoroarene interactions with the electron-poor pentafluorostyrene aromatic rings of the coupling agent. The SBR chains in the rubber compound have an affinity for the polybutadiene backbone of the coupling agent. The interactions between carbon black and the coupling agent were analyzed using Raman spectroscopy, transmission electron microscopy, zeta potential measurements, surface area measurements, and scanning electron microscopy. Filler flocculation analysis showed that the coupling agent improves the dispersion and lowers the energy of dissipation. The hysteresis loss, quantified in terms of loss tangent values at 60 C, was reduced by up to 12% due to the coupling agent's promotion of better filler-rubber interactions. The influence of the PPFS graft length was also studied.more » « less
-
Fly ash consists of mainly silt-size spherules that form during high-temperature coal combustion, such as in steam locomotives and coal-burning power plants. In the eastern USA, fly ash was distributed across the landscape atmospherically beginning in the late 19th century, peaking in the mid-20th century, and decreasing sharply with implementation of late 20th century particulate pollution controls. Although atmospheric deposition is limited today, fly ash particles continue to be resedimented into alluvial and lacustrine deposits from upland soil erosion and failure of fly ash storage ponds. Magnetic fly ash is easily extracted and identified microscopically, allowing for a simple and reproducible method for identifying post-1850 CE (Common Era) alluvium and lacustrine sediment. In the North Carolina Piedmont, magnetic fly ash was identified within the upper 50 cm at each of eight alluvial sites and one former milldam site. Extracted fly ash spherules have a magnetite or maghemite composition, with substitutions of Al, Si, Ca, and Ti, and range from 3–125 µm in diameter (mainly 10–45 µm). Based on the presence of fly ash, post-1850 alluvial deposits are 15–45 cm thick in central North Carolina river valleys (<0.5 km wide), ~60% thinner than in central Illinois valleys of similar width. Slower sedimentation rates in North Carolina watersheds are likely a result of a less agricultural land and less erodible (more clayey) soils. Artificial reservoirs (Lake Decatur, IL) and milldams (Betty’s Mill, NC), provide chronological tests for the fly ash method and high-resolution records of anthropogenic change. In cores of Lake Decatur sediments, changes in fly ash content appear related to decadal-scale variations in annual rainfall (and runoff), calcite precipitation, land-use changes, and/or lake history, superimposed on longer-term trends in particulate pollution.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- The DOI is not currently available.
