scholarly journals THERMAL, MECHANICAL AND WATER SORPTION PROPERTIES OF XANTHAN-BASED COMPOSITE CRYOGELS

2020 ◽  
Vol 54 (9-10) ◽  
pp. 915-924
Author(s):  
IRINA ELENA RASCHIP ◽  
MARIA VALENTINA DINU ◽  
NICUSOR FIFERE ◽  
RALUCA DARIE-NITA ◽  
DANIELA PAMFIL ◽  
...  
Keyword(s):  
Vinyl Alcohol ◽  
Water Sorption ◽  
Surface Characteristics ◽  
Grape Pomace ◽  
Poly Vinyl Alcohol ◽  
Polyphenol Content ◽  
Natural Polyphenol ◽  
Red Grape ◽  
Water Sorption Capacity ◽  
Thermal Stability Of

The thermal, mechanical, rheological, and surface characteristics of some xanthan/poly(vinyl alcohol)/red grape pomace composite cryogels prepared by the freeze/thawing approach were investigated. The results were discussed in comparison with those obtained for individual xanthan or poly(vinyl alcohol) cryogel networks synthesized under the same conditions. The mechanical strength of the cryogels was enhanced by increasing the number of freeze/thawing cycles, and by the addition of a natural polyphenol (i.e. red grape pomace). The thermal stability of the poly(vinyl alcohol) in the blend significantly decreased upon the addition of 50% xanthan, while the presence of a single neat melting profile indicated good component miscibility for the chosen ratios. The water sorption capacity depended on the amount of polyphenol incorporated, thus the hydrophilicity of the cryogel films decreased with the increase of polyphenol content.

scholarly journals Modification of Surface Properties of Colloidal Suspensions of NixOy-SiO2 Mixed Oxides with Different Ni Contents by the Adsorption Layers of Poly(Vinyl Alcohol)

2020 ◽  
Author(s):  
M. Wiśniewska ◽  
S. Chibowski ◽  
T. Urban ◽  
G. Fijałkowska ◽  
M. Medykowska ◽  
...  
Keyword(s):  
Nickel Oxide ◽  
Mixed Oxide ◽  
Vinyl Alcohol ◽  
Mixed Oxides ◽  
Colloidal Suspensions ◽  
Surface Characteristics ◽  
Limited Range ◽  
Poly Vinyl Alcohol ◽  
Solution Interface ◽  
Adsorption Affinity

Abstract The adsorption and electrokinetic properties of hybrid silica materials composed of nickel and silicon oxides (NixOy-SiO2), characterized by different contents of nickel oxide (from 0.5 to 3 mmol/g SiO2), were examined. These solids were also modified by poly(vinyl alcohol) to change their surface characteristics. The polymer is non-toxic and very well soluble in water. Due to incomplete hydrolysis of the polymer acetate groups, its macromolecules become negatively charged. The limited range of studied pH (6–10) resulted from high solubility of nickel oxide at more acidic pH values. The spectrophotometric, surface charge and electrophoretic measurements indicated that PVA exhibits higher adsorption affinity for the surfaces of mixed oxide with a larger content of nickel in its structure. Moreover, the presence of polymeric layers on the solid surface influences considerably the structure of electrical double layer formed at the mixed oxide-aqueous solution interface.

scholarly journals Kinetic models of swelling and thermal stability of silver/poly(vinyl alcohol)/chitosan/graphene hydrogels

2019 ◽  
Vol 77 ◽  
pp. 83-96 ◽  
Author(s):  
Katarina Nešović ◽  
Ana Janković ◽  
Aleksandra Perić-Grujić ◽  
Maja Vukašinović-Sekulić ◽  
Tamara Radetić ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Kinetic Models ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Thermal Stability Of

The properties of sericin/poly(vinyl alcohol) films modified by boric acid

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Qun Wang ◽  
Lu Qi
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Boric Acid ◽  
Vinyl Alcohol ◽  
Water Resistance ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
Blend Ratio ◽  
Percutaneous Drug Delivery ◽  
Thermal Stability Of

AbstractA group of films mainly composed of sericin and poly(vinyl alcohol) (PVA), using boric acid (BA) as a modifier, were prepared by a technique of solution casting. In this work, the effect of BA and sericin on the mechanical properties and water resistance of the films was analyzed, the interior morphology of the films were described by a scanning electron microscopy (SEM), the thermal stability of the films was characterized by differential scanning calorimetry (DSC), and the reaction mechanism was proposed according to the previous literature and the test of Fourier transform infrared spectrum (FTIR). Results indicated that, the properties of the membrane were the functions of the blend ratio of sercin to PVA and the content of BA. The use of BA increased the tensile strength, improved the water resistance and the thermal stability, and varied the interior morphology of the films. The content of sericin greatly influenced the combination of properties of the films, especially the mechanical properties, interior morphology, thermal stability, and water resistance reducing with the increasing of sericin content. The films have potential to be used in materials, such as skin-care coatings for beauty, percutaneous drug delivery systems for exterior intact skin, due to the characteristics of the components and the good mechanical properties of the films.

Effects of SiO2 and In Situ Crosslinking on the Swelling and Thermal Properties of Poly(vinyl Alcohol)/SiO2 Hybrid Films

2011 ◽  
Vol 266 ◽  
pp. 180-183 ◽  
Author(s):  
Jie Liu ◽  
Ke Yong Tang
Keyword(s):  
Vinyl Alcohol ◽  
Sio2 Film ◽  
Poly Vinyl Alcohol ◽  
Swelling Ratio ◽  
Hybrid Films ◽  
Initial Stage ◽  
In Situ Crosslinking ◽  
Hydrolysis Of ◽  
Thermal Stability Of

Poly(vinyl alcohol) (PVA)/SiO2 hybrid films were prepared through hydrolysis of tetraethoxysilane (TEOS) in the presence of PVA solution, followed by the in-situ crosslinking with formaldehyde (HCHO) in acidic circumstance. The swelling and thermal gravimetric (TG) analysis was employed to evaluate the influence of SiO2 and crosslinking on the properties of the hybrid films. The results indicate that SiO2 affects effectively the swelling property and thermal stability of the hybrid films because of both the filling and crosslinking effects of SiO2. With increasing the crosslinking time, the swelling ratio at equilibrium of the hybrid films decreases. The swelling ratio at equilibrium of the hybrid films is sensitive to the SiO2 content, which is similar to the swelling ratio at equilibrium (65~75%) for PVA and PVA/SiO2 hybrid films with enough crosslinking time (12h). Compared to the film without in-situ crosslinking, the crosslinked PVA/SiO2 film showed a lower swelling ratio at equilibrium and an increased diffusion coefficient at the initial stage of swelling.

scholarly journals Impact of poly(vinyl alcohol) adsorption on the surface characteristics of mixed oxide Mn x O y –SiO2

Adsorption ◽  
2015 ◽  
Vol 22 (4-6) ◽  
pp. 417-423 ◽  
Author(s):  
M. Wiśniewska ◽  
V. Bogatyrov ◽  
I. Ostolska ◽  
K. Szewczuk-Karpisz ◽  
K. Terpiłowski ◽  
...  
Keyword(s):  
Mixed Oxide ◽  
Vinyl Alcohol ◽  
Surface Characteristics ◽  
Poly Vinyl Alcohol ◽  
Alcohol Adsorption
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