- Award ID(s):
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- Tire science & technology
- Sponsoring Org:
- National Science Foundation
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Poly(butadiene-graft-pentafluorostyrene) as a Coupling Agent in Rubber Compounding Presented at the 12th Annual Student Colloquium & Poster Session at the Fall 188th Technical Meeting of the Rubber Division, ACS Cleveland, Ohio U.S.A.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.
In standard molecular junctions, a molecular structure is placed between and connected to metal leads. Understanding how mechanical tuning in such molecular junctions can change heat conductance has interesting applications in nanoscale energy transport. In this work, we use nonequilibrium molecular dynamics simulations to address the effect of stretching on the phononic contribution to the heat conduction of molecular junctions consisting of single long-chain alkanes and various metal leads, such as Ag, Au, Cu, Ni, and Pt. The thermal conductance of such junctions is found to be much smaller than the intrinsic thermal conductance of the polymer and significantly depends on the nature of metal leads as expressed by the metal–molecule coupling and metal vibrational density of states. This behavior is expected and reflects the mismatch of phonon spectra at the metal molecule interfaces. As a function of stretching, we find a behavior similar to what was observed earlier [M. Dinpajooh and A. Nitzan, J. Chem. Phys. 153, 164903 (2020)] for pure polymeric structures. At relatively short electrode distances, where the polyethylene chains are compressed, it is found that the thermal conductances of the molecular junctions remain almost constant as one stretches the polymer chains. At critical electrode distances, themore »
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 millmore »
Combining Hyperbranched and Linear Structures in Solid Polymer Electrolytes to Enhance Mechanical Properties and Room-Temperature Ion TransportPolyethylene oxide (PEO)-based polymers are commonly studied for use as a solid polymer electrolyte for rechargeable Li-ion batteries; however, simultaneously achieving sufficient mechanical integrity and ionic conductivity has been a challenge. To address this problem, a customized polymer architecture is demonstrated wherein PEO bottle-brush arms are hyperbranched into a star architecture and then functionalized with end-grafted, linear PEO chains. The hierarchical architecture is designed to minimize crystallinity and therefore enhance ion transport via hyperbranching, while simultaneously addressing the need for mechanical integrity via the grafting of long, PEO chains ( M n = 10,000). The polymers are doped with lithium bis(trifluoromethane) sulfonimide (LiTFSI), creating hierarchically hyperbranched (HB) solid polymer electrolytes. Compared to electrolytes prepared with linear PEO of equivalent molecular weight, the HB PEO electrolytes increase the room temperature ionic conductivity from ∼2.5 × 10 –6 to 2.5 × 10 −5 S/cm. The conductivity increases by an additional 50% by increasing the block length of the linear PEO in the bottle brush arms from M n = 1,000 to 2,000. The mechanical properties are improved by end-grafting linear PEO ( M n = 10,000) onto the terminal groups of the HB PEO bottle-brush. Specifically, the Young’s modulus increases by twomore »
High permittivity polymer-ceramic nanocomposite dielectric films take advantage of the ease of flexibility in processing of polymers and the functionality of electroactive ceramic fillers. Hence, films like these may be applied to embedded energy storage devices for printed circuit electrical boards. However, the incompatibility of the hydrophilic ceramic filler and hydrophobic epoxy limit the filler concentration and therefore, dielectric permittivity of these materials. Traditionally, surfactants and core-shell processing of ceramic fillers are used to achieve electrostatic and steric stabilization for adequate ceramic particle distribution but, questions regarding these processes still remain. The purpose of this work is to understand the role of surfactant concentration ceramic particle surface morphology, and composite dielectric permittivity and conductivity. A comprehensive study of barium titanate-based epoxy nanocomposites was performed. Ethanol and 3-glycidyloxypropyltrimethoxysilan surface treatments were performed, where the best reduction in particle agglomeration, highest value of permittivity and the lowest value of loss were observed. The results demonstrate that optimization of coupling agent may lead to superior permittivity values and diminished losses that are ~2–3 times that of composites with non-optimized and traditional surfactant treatments.