U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Kurth, Todditem
                                            SHARMA, BRAJENDRA - PENNSYLVANIA STATE UNIVitem
                                            Doll, Kenneth

                                                         - *Ken*item
                                            Erhan, Sevim
  Submitted to: Chemical Engineering Communications
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 3/1/2007
                                    Publication  Date: 5/2/2007
                                    Citation: Kurth, T.L., Sharma, B.K., Doll, K.M., Erhan, S.Z. 2007. Adsorption behavior of epoxidized fatty esters via boundary lubrication coefficient of friction measurements. Chemical Engineering Communications. 194:1065-1077.Interpretive Summary: Using friction measurements and theoretical modeling, a variety of modified and un-modified bio-based materials have been compared and contrasted.  Specifically epoxy methyl oleate (EMO) and methyl oleate (MO), epoxy methyl linoleate (EMLO) and methyl linoleate (MLO), epoxy methyl linolenate (EMLEN ) and methyl linolenate (MLEN)), epoxidized soybean oil (ESBO) and a commercial epoxidized 2-ethylhexyl transesterified soybean oil (VF), as additives in hexadecane.  A simple model was used to determine the relative interaction energies of each compound with a steel surface.  The order of interaction energies was found to be: ESBO > VF > EMO greater than or equal to EMLO > EMLEN and MLEN greater than or equal to MLO > MO.  This ordering agrees with that obtained via a more complex theoretical treatment.  The relative data obtained allowed several conclusions to be drawn.  The interactions of additive molecules with one another contribute to the measured interaction with a surface.  For the epoxidized materials, the additive-additive interactions increase with epoxidation, but the observed interactions with the steel surface decrease.  For analogous unsaturated esters the opposite trends are observed.  By comparing individual epoxidized materials to the analogous unsaturated methyl esters, it is evident that there is decreasing benefit of epoxidation with increasing degree of unsaturation.  This new information has led to greater understanding of additive-additive and additive-surface interactions at the molecular level.  Such information will be useful in the development of new products and applications for these and similar bio-based materials.
                                Technical Abstract: The frictional behaviors of a variety of fatty alkenyl esters and their corresponding fatty epoxide esters (epoxy methyl oleate (EMO) and methyl oleate (MO), epoxy methyl linoleate (EMLO) and methyl linoleate (MLO), epoxy methyl linolenate (EMLEN ) and methyl linolenate (MLEN)), epoxidized soybean oil (ESBO) and a commercial epoxidized 2-ethylhexyl transesterified soybean oil (VF), as additives in hexadecane have been examined in a boundary lubrication test regime using steel contacts.  Langmuir critical additive concentrations were determined which provide the following order of negative adsorption energies:  ESBO > VF > EMO greater than or equal to EMLO > EMLEN and MLEN greater than or equal to MLO > MO.  Thus, for the similar epoxidized materials the greater degree of epoxidation results in less negative calculated total adsorption energies; this trend is reversed for the olefinic parent systems.  This ordering agrees with that obtained via a more complex unconstrained cooperative interaction adsorption model.  Fits of the steady-state Coefficient of Friction versus concentration data indicate an inverse relation of the obtained interaction parameters with the primary adsorption energies.  These results demonstrate the complexity of the adsorption mechanism that is determined both by the adsorbate-adsorbent and adsorbate-adsorbate interactions.  The relative adsorption parameters suggest that for the epoxide materials studied, the intermolecular interactions increase with increasing epoxidation, and the total adsorption energies become more negative; this is opposite for the olefinic compounds studied.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov