The
generation of gas hydrates in gas and multiphase flowlines
can cause blockages, leading to downtime, economic losses, and even
potential accidents. Injecting kinetic hydrate inhibitors (KHIs) is
an effective way to prevent gas hydrate formation. Most KHI formulations
are built around water-soluble polymers containing amide groups. On
the basis of past work on N-alkyl-N-vinylamide polymers from our group, we have now been able to become
much closer to designing the optimum KHI for this class of polymers.
In this study, we have synthesized four N-alkyl-N-vinylamide monomers, where the alkyl group is n-propyl, isopropyl, n-butyl, and isobutyl.
These have been copolymerized successfully with N-methyl-N-vinylacetamide and N-vinylformamide
to form a series of copolymers with low molecular weights. We have
investigated their KHI performance using a slow constant cooling method
with a synthetic natural gas mixture in high-pressure rocker cells
at 76 bar. All of the new N-vinylamide copolymers
show good KHI performance. The average onset temperature of the best
copolymer, N-vinylformamide:N-isobutyl-N-vinylformamide copolymer, at 2500 ppm concentration in
deionized water was 8.2 °C. This decreased considerably to 4.7
°C (ca. 15.3 °C subcooling) when 10 000 ppm of n-butyl glycol ether solvent was added, demonstrating good
synergy between the polymer and solvent. Two of the best copolymers
were further investigated at varying concentrations in the range of
1000–7500 ppm and showed increased performance as the dosage
increased.
Thermosensitive poly(N-vinylamide) derivatives bearing an oligo ethylene glycol (OEG) chain at the N-position were designed for development of a kinetic hydrate inhibitor (KHI). Novel N-vinylamide monomers bearing an OEG chain at the N-position were synthesized and copolymerized with N-vinylformamide (NVF) or methyl Nvinylacetamide (MNVA) by free radical polymerization. Then, thermosensitive behaviors, such as lower critical solution temperature (LCST), of the synthesized poly(Nvinylamide) derivatives were investigated by light transmittance and DSC measurement. The LCST values were observed over a wide temperature range from 45 to 90 °C due to the ethoxy OEG chain at the N-position. Their phase transition properties were investigated under dilute condition by light scattering measurement. Furthermore, KHI values of the synthesized polymers were evaluated by the THF hydrate crystal growth method. On the basis of these results, it is expected that the polymers of synthesized poly(N-vinylamide) derivatives will gain a prominent position in the oil industry.
Poly(trimethylene carbonate) (PTMC) derivatives have been extensively researched for use as low‐toxicity biomaterials. Better biocompatibility and lower toxicity have been achieved by eliminating acid generation from the ester group at the side chains. In this study, thermosensitive PTMC derivatives bearing oligo(ethylene glycol) units are synthesized by ring‐opening polymerization for the development of low‐toxicity and thermosensitive soft materials. The viscoelastic properties of the obtained polymers are then investigated by rheometry to clarify the thermosensitive and molecular weight effects. Furthermore, thermosensitive behaviors and dynamics of these polymers are observed by UV–vis transmittance, DSC, and 1H NMR spectra analysis. These data suggest a mechanism for the thermosensitive behavior where it is surmised that some kind of dehydration phenomenon induces aggregation behavior in aqueous media above lower critical solution temperature. These thermosensitive behaviors provide an important road map for the development of thermosensitive soft materials using ester‐free PTMC derivatives by controlling the thermosensitive behaviors and bulk properties.
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