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Dissertation Tony Ren 11 22 2019.pdf (4.09 MB)

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Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber

Ren, Xianjie, ren
http://rave.ohiolink.edu/etdc/view?acc_num=osu1574440536318129

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Food, Agricultural and Biological Engineering.
Natural rubber (NR) is essential and its demand increases with the development of human society. Its excellent properties make NR irreplaceable, although synthetic rubber has been well developed. The only commercial source of NR is Hevea brasiliensis, which is grown as clones and has very little genetic heterogeneity. Hevea natural rubber (HNR) production is limited and will not be able to satisfy the increasing NR demand. Thus, alternative sources of NR are needed to increase NR supplies. Guayule is a rubber producing shrub native to the Chihuahuan desert of Texas and Mexico, and is a leading alternative rubber source to the HNR tree. Developing domestic guayule cultivation and guayule natural rubber (GNR) production may satisfy the increasing NR demand and even replace some HNR. GNR characterization is necessary, because the properties of GNR are not yet fully understood. Rubber without reinforcement cannot be directly used in many products, and reinforcing fillers are added to improve mechanical performance and durability. Carbon black (CB) and bifunctionally silanized silica (BSS) are widely used reinforcing fillers in rubber products. However, both CB and BSS are expensive, have high carbon footprints and are not renewable. CB and processing aids such as naphthenic oil in current rubber products are petroleum-derived. Fossil resource derived synthetic rubbers, such as styrene butadiene rubber (SBR), do possess some properties which NR lacks, such as oil resistance, high stiffness and compatibility with polar fillers. Thus, chemically modified GNR may confer such properties and lead to a reduction in synthetic rubber, further increasing the sustainability of the rubber industry. GNR based rubber composites with improved sustainability and reduced carbon footprint form the core of this thesis. GNR composites were made with eggshell (ES), a new, low cost, sustainable filler made from food processing waste, in partial replacement of BSS. The reinforced mechanical properties, dyability, energy consumption, durability and filler dispersion of GNR composites were determined. Eggshell filled GNR composites had higher mechanical performance and lower energy consumption during compounding than BSS filled ones, due to strong rubber-eggshell interactions and improved dispersion. ES-BSS GNR composites, also exhibited comparable aging, cyclic loading and ozone resistance to composites solely filled with BSS. Processability of rubber compounds is another key aspect of sustainable rubber production. Fillers like CB and BSS increase the viscosity of rubber and so increase the mixing temperature and energy consumption of compound mixing. Processing oils reduce viscosity, but most commercial processing oils are petroleum-based diluents, so again are neither sustainable nor renewable. In this research, low molecular weight liquid guayule natural rubber (LGNR) made by thermodegradation, was used as an alternative to naphthenic oil in natural and synthetic rubber CB filled composites. Since both epoxidized and unsaturated groups exist on the backbone of LGNR, LGNR can increase the interaction between rubber and fillers and allow the rubber “oil” to become an integral part of the product thorough chemical cross-links instead of merely a diluent. LGNR acted as a plasticizer reducing energy consumption during compounding, but the resultant natural and synthetic rubber composites had higher mechanical properties and durability than the ones made with naphthenic oil, and were similar to the composites made without processing aids (which require a lot more energy to mix). LGNR is expected to open new markets for renewable processing aids. Although GNR has exceptional resilience and physical properties, modification is needed before it can be used to replace synthetic rubber in applications which require high oil resistance, high stiffness and better dynamic mechanical properties than NR. GNR was epoxidized to convert unsaturated chemical bonds to epoxide rings along the polymer backbone, to increase chemical resistance, polar filler compatibility and stiffness. Composites made with blends of GNR and epoxidized guayule natural rubber (EGNR) had improved stiffness and oil resistance, while maintaining similar energy consumption during compounding, which may allow EGNR to replace synthetic rubbers with similar properties.
Katrina Cornish (Advisor)
Alfred B O Soboyejo (Committee Member)
Kurt William Koelling (Committee Member)
Yael Vodovotz (Committee Member)
Rebecca B. Dupaix (Committee Member)
261 p.
Materials Science; Polymer Chemistry; Polymers

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Citations

  • Ren, ren, X. (2019). Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574440536318129

    APA Style (7th edition)

  • Ren, ren, Xianjie. Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber. 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1574440536318129.

    MLA Style (8th edition)

  • Ren, ren, Xianjie. "Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574440536318129

    Chicago Manual of Style (17th edition)

osu1574440536318129
635
© 2019, some rights reserved.Creative Commons License Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber by Xianjie Ren ren is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.