Polyisobutenylsuccinic anhydride (PIBSA) has been analyzed using negative ion electrospray ionization mass spectrometry (ESI-MS). This mild technique gives the molecular ion distribution for the PIBSA mono-succinic acid polymer as the major product. Unexpectedly, small amounts of the PIBSA bis-succinic acid polymer were also observed. This can form a basis for a method to determine the succinic ratio of samples of PIBSA. Commercially available samples of PIBSA made from BF 3-catalyzed poly-(isobutylene) and AlCl3-catalyzed poly(isobutylene) were compared. While the PIBSA made from BF3catalyzed poly(isobutylene) consisted of polymers separated by 56 Da, the PIBSA made from AlCl3catalyzed poly(isobutylene) consisted of polymers separated by 14 Da. We attribute this to different molecular weight distributions of the starting poly(isobutylene). Poly(isobutylene) from AlCl3 catalysis is postulated to form via a mechanism that consists of carbenium ion rearrangements and β scission reactions at the active site.
In this work, the adsorption of waxes on different carbonaceous materials is studied to help in the understanding of the wax−asphaltene association that can lead to the possible deposition of these crude oil components. Adsorption isotherms of long n-alkanes and waxes from heptane on carbonaceous materials (graphite, graphene, and asphaltenes) were determined using two different analytical methods. Results indicate that the long nalkanes adsorbed in graphite and graphene by cooperative adsorption. In the adsorption study of commercial waxes, analysis of distributions suggests that the presence of long n-alkanes leads to more significant adsorption. Analysis of n-triacontane adsorption into asphaltenes indicates that long n-alkanes can penetrate the structure of the solid asphaltenes. This is probably helped by the swelling of the asphaltenes in the presence of n-heptane. These results also indicate that the interactions between asphaltenes and long-chain n-alkanes can lead to the formation of composite particles. Molecular simulation studies support the strong interactions between asphaltene aggregates and long-chain n-alkanes.
Methylenedianiline (MDA) is a common industrial chemical with health and product safety concerns. Common analysis methods require many steps including extraction and derivatization ending in GC/MS or HPLC analysis, which minimize its use as an on-line or at-line technique. The procedure can take hours, prohibiting its use as a real-time decision-making tool as well as using valuable resources and laboratory space. The new method presented here has been validated for MDA quantification in industrial grease samples over the concentration range of 1-40 ppm 4,4'-MDA. We present comparative results to the currently accepted method with excellent fidelity. This analytical method using surface-enhanced Raman spectroscopy reduces sample preparation and analysis time by more than an hour while preserving method accuracy, specificity, and dynamic range.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.