Comprehensive multiphase NMR spectroscopy: A new analytical method to study the effect of biodiesel blends on the structure of commercial rubbers

Abstract

h i g h l i g h t sWe evaluate the effect of biodiesel on commercial rubber at molecular level. The new CMP-NMR probe was successful to study the phases in the fuel-rubber system. We observed that the biodiesel penetrates at EPDM despite the opposite report. It is observed the increasing on rubbers softening after biodiesel immersion. a b s t r a c t Biodiesel has been incorporated into the energy matrix in several countries, but its compatibility with some materials used in automotive engines is of growing concern. In the present study, comprehensive multiphase (CMP) NMR is applied to understand the different phases in fuel-rubber systems. CMP NMR is a novel technology that integrates all the hardware from solution-, gel-and solid-state into a single NMR probe, permitting all phases to be studied in samples in their natural unaltered state. Transverse relaxation experiments in combination with inverse diffusion editing permit the increasing mobility of the rubbers chains with biodiesel exposure to be monitored. Conversely diffusion editing and RADE experiments highlight the more rigid domains. In summary NR and NBR showed the absence of highly rigid domains after exposure to biodiesel whereas SBR and EPDM especially better retained their structural integrity. 13 C editing protocols and 13 C-1 H HSQC confirmed the increasing gel-like properties of NR, NBR and SBR with exposure to biodiesel. However, variable contact time experiments showed that biodiesel penetrates even the most resilient EPDM pores causing relaxation of the polymer chains and demonstrates that NMR is sensitive enough to highlight even the very slight swelling of the EPDM. Through these results it is possible to observe that the elastomer that exhibits the lowest susceptibility to biodiesel in molecular terms was EPDM, followed by SBR, NR, and NBR. It was also observed that biodiesel molecules were present in the EPDM structure despite the literature reporting its general resilience to biodiesel.

In vivo comprehensive multiphase NMR

“…As such, it allows for the study of all components (liquids, gels, and solids) in complex multiphase samples. When combined with spectral editing approaches (discussed later), various phases can be studied and differentiated in situ allowing complex processes such as the transport of molecules across phases or swelling between phases to be monitored …”

“…In many ways, CMP NMR can be thought of as changing NMR technology to match natural samples, rather than changing the sample to match a specific NMR technique. CMP NMR has permitted the study of structural interactions and processes in unaltered heterogeneous samples, including soil, swelling of rubber by biofuels, intact plants, and to follow biological processes (seed growth) …”

Ex vivo Comprehensive Multiphase NMR of whole organisms: A complementary tool to in vivo NMR

“…CMP-NMR is still a relatively new technique that provides an overview of organic components in all phases in complex heterogeneous samples. Studies thus far have mainly focused on either non-living materials such as rubber [ 68 ], soil [ 8 , 9 , 69 ] or on living systems [ 10 , 11 ]. However, no studies have applied CMP-NMR to non-living ( ex vivo ) organisms.…”

Ultrasonication Assisted Catalytic Transesterification of Ceiba Pentandra (Kapok) Oil Derived Biodiesel Using Immobilized Iron Nanoparticles

“…The GC-MS analysis has been carried out for the kapok biodiesel as per the standard procedure [47]. The original kapok oil extracted demonstrated the presence of major fatty acids between C11:0 and C24:0 as undecylic acid, tridecyclic acid, pentadecyclic acid, ginkgolic acid, myristic acid, oleic acid, margaric acid, gondoic acid, arachidic acid, behenic acid, tricosanic acid and lignoceric acid [47,48]. Among the resulting fatty acids, short-chain hydrocarbons between C11:0 and C15:0 hold the major mass fraction composition, and transesterification leads to a reduction in the content of the FFA value.…”

“…ginkgolic acid, myristic acid, oleic acid, margaric acid, gondoic acid, arachidic acid, behenic acid, tricosanic acid and lignoceric acid [47,48]. Among the resulting fatty acids, short-chain hydrocarbons between C11:0 and C15:0 hold the major mass fraction composition, and transesterification leads to a reduction in the content of the FFA value.…”