3-D phase diagram of HPC/H2O/H3PO4 tertiary system

International audienceHerein, a novel polymeric porous membrane was developed, without the use of any organic solvent in the initial dope solution and using a biobased polymer derived from cellulose: Hydroxypropylcellulose (HPC). HPC was dissolved in water (20 wt%) and the phase separation was induced by increasing the temperature above the Lower Critical Solution Temperature (LCST) of the polymer solution, around 40 °C in the concentration range concerned in this study. To fix the membrane morphology and to prevent any resolubilization in water during filtration tests, a chemical crosslinking was performed using Glutaraldehyde. The phase diagram of HPC/water system was first studied and not only the cloud point but also the spinodal curves were determined using optical transmission techniques. It was exhibited that HPC phase diagram is very weakly dependent on concentration up to large concentrations and that the metastable region is very small, i.e. the cloud point and the spinodal curves are very close in a large range of concentration. The membrane stability was tested in water and some organic solvents, thus demonstrating the efficiency of the chemical crosslinking during membrane formation. The swelling and mechanical properties of HPC membranes were also investigated depending on the operating condition during membrane formation, showing that the temperature ramp during the membrane formation, from initial to final temperature, have a significant effect on the crosslinking efficiency and hence on the swelling properties. Finally, adding a porogen (PEG200) into the collodion, filtration tests were performed and exhibited that the membrane filtration properties depend on the temperature ramp as well, showing higher water flux for the highest temperature ramp tested

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“…Fossati [26]. The spinodal temperature is, to our knowledge, reported here for the first time [30][31][32].…”

Section: 244mechanical Propertiessupporting

confidence: 52%

Fabrication of novel porous membrane from biobased water-soluble polymer (hydroxypropylcellulose)

Hanafia

Faur

Deratani

et al. 2017

Journal of Membrane Science

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“…The polynitrate ester of the natural polysaccharide, cellulose, and for a polymer averaging 2.3 nitrate groups for each glucose unit has the structure is called cellulose nitrate [129].…”

Section: Cellulose Nitrate Resinsmentioning

confidence: 99%

Consolidation of Fragile Archaeological Bone Artifacts: A review

Abdel-Maksoud

Kira²,

Mohamed³

2022

Egypt. J. Chem.

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Archaeological bone artifacts suffer from fragility and weakness, which are due to the effect of various factors either in the burial environment (such as moisture content, temperature, pH value, pressure, microorganisms, insects, and salts) or after extraction and exposure to surrounding environmental condition in museums, storage and excavation areas to different factors such as air pollutants, light, high temperature, relative humidity and etc. The study focuses on the most critical factors that affected bone artifacts before and after extraction from the excavation areas. It also aims to survey the common polymers used in the consolidation of bone artifacts to produce conservators in Egypt a list of polymers used with mention their advantages and disadvantages in order to choose the best ones. Various polymeric materials (natural and synthetic) were used in the field of archaeological bones in order to enhance the bone's mechanical properties and morphological structure. Archaeology scientists utilize polymeric materials in bone conservation for giving structural support to overcome the fragility and weakness of archaeological bones. Analysis and investigation become vital in the conservation field. They are used to identify the best materials used as bone consolidants, determine the types of materials used successfully in the past for treatment, and point out differences in the approaches of conservation and archaeology towards the preservation of archaeological materials. Polymer application for bone treatment should be carefully considered, according to understanding the physical and chemical interactions between the bone surface and polymer matrix. Some synthetic polymers are used by conservators for the consolidation of archaeological bone artifacts since they gave good results compared to natural consolidants, which gave many disadvantages.

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“…Subsequent cooling of the cloudy solution below the LCST results in the reverse phase transition to restore the original clarity of the solution. Despite thorough experimental investigation of HPC’s reversible demixing behavior, ,− the underlying molecular mechanismparticularly the nature of the driving forceshas remained unclear. ,,,, …”

Section: Introductionmentioning

confidence: 99%

Hydration and Dispersion Forces in Hydroxypropylcellulose Phase Behavior

Dayhoff

Rogers

2019

J. Phys. Chem. B

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Many-body polarization and hydration forces can strongly affect the equilibrium structure and energetics of mixed phases. Accurately reproducing both forces presents a challenge to force field models because it requires balancing hydrogen bonding at short range with many-body orientational order and dispersive attraction at long range. This work reports the first comparison of experimental measurements of the pressure−area isotherm for hydroxypropylcellulose (HPC) against molecular dynamics results with four different force field modelsunited-atom, all-atom (OPLS and CHARMM), and Drude oscillator models. All force fields exhibit the experimentally determined, exponentially shaped repulsive force at short range. Above a critical temperature of about 40 °C and a lattice spacing of around 14 Å, HPC experiments show a reversible, heat-induced polymer aggregation into an ordered phase driven by loss of water. The nonpolarizable force fields do not display the critical point and instead show biphasic behavior at all temperatures tested. This indicates net attractive forces at intermediate lattice spacings. In contrast, the Drude polarizable force field shows positive osmotic pressure and a single, homogeneous phase over all temperatures and spacings tested. Analysis of structural data from our simulations provides several clues to help interpret these findings. Although all force fields show similar water−water hydrogen bond numbers in the mixed phase, the polarizable model predicts that water−HPC hydrogen bonds are much more favorable than HPC−HPC hydrogen bonds when polymers are dispersed. At high density, water is driven out and replaced by HPC−HPC hydrogen bonds. The polarizable force field shows that both effects have a stronger dependence on polymer density than any of the nonpolarizable models. Our observations support the conclusion that hydration forces are coupled to the polymer coordination number by local, structural waters and that long-range dispersive attraction is overestimated by pairwise additive models.

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3-D phase diagram of HPC/H2O/H3PO4 tertiary system

Cited by 8 publications

References 32 publications

Fabrication of novel porous membrane from biobased water-soluble polymer (hydroxypropylcellulose)

Fabrication of novel porous membrane from biobased water-soluble polymer (hydroxypropylcellulose)

Consolidation of Fragile Archaeological Bone Artifacts: A review

Hydration and Dispersion Forces in Hydroxypropylcellulose Phase Behavior

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