Ionic mobility and dielectric relaxation in supercooled liquid KCl-glycerol solutions

Champeney, D. C.; Kaddour, F. Ould

doi:10.1080/00268978400101371

Cited by 33 publications

(12 citation statements)

References 28 publications

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“…16 The following Tg's of the pure components were used in the calculations: Tg = −85°C for glycerol 17 and Tg = −137°C for water. 18 Tg = 90°C for a starch film with 13% moisture [19][20] was taken to calculate the theoretical Tg for a dry starch film through Equation 3.…”

Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Effects of film forming and hydrophobic properties of starches on surface sized packaging paper

2007

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The effect on mechanical and barrier properties upon addition of glycerol to temperature-responsive hydrophobically modified (HM) potato starch was studied on free films. The addition of glycerol lowered the glass transition temperature, the storage modulus, and the water vapor permeability (WVP) for the HM starch films. The HM starch phase separates upon cooling below an upper critical temperature into a solid and a liquid phase. Adding glycerol to the warm starch solution had an inhibiting effect on the particulate precipitation. Substrates surface sized with HM starch with various amounts of glycerol were investigated with respect to barrier properties; WVP, contact angle and Cobb values. Hydroxypropylated starch was used as a reference. Cobb values and WVP results on surface-sized substrates indicated that the film formation properties of the starches were of great importance for the final surface properties. Good film formation properties were essential for the gas barrier and water resistance while they were less important for high contact angles. The WVP decreased as the glycerol content of the sizes increased, but no sufficient water vapor barrier could be obtained. The HM starches investigated in this work provided good oxygen barrier and the contact angles indicated a hydrophobic character of the surface. The role of the precipitate was investigated, and surface sizing with the precipitate gave low WVP and high contact angles despite its poor film-forming properties under the experimental conditions. Cobb 60 values were slightly improved for HM starch with increasing glycerol content over glycerol-free sizing.

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Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Effects of film forming and hydrophobic properties of starches on surface sized packaging paper

2007

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“…The measured values are comparable with the calculated values. The calculation of the theoretical T g is based on a T g of 90°C for starch film, T g of À83°C for glycerol (Champeney and Kaddour 1984), and a T g of À132°C for water (Vellicov et al 2001). Since moisture content decreases with increasing glycerol content, there was no great difference in T g with small amounts of glycerol.…”

Section: Glass Transition Temperaturementioning

confidence: 99%

Barrier and mechanical properties of modified starches

Jansson

Järnström

2005

Cellulose

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The study addressed starch-based coatings on paper and fabrics. Coated materials and free starch films containing different amounts of a well-established plasticizer (glycerol) or potential plasticizer (mainly polyols) were tested with respect to water vapour permeance (WVPe), water vapour permeability (WVP), glass transition temperature (T g ), and mechanical strength (tensile tests). Both normal and high-amylose potato starch were used. These starches were modified by (a) oxidation, (b) oxidation and hydroxypropylation or (c) oxidation and hydrophobically modified by reaction with octenyl-or alkenyl-substituted succinic acid anhydride. Free films of hydroxypropylated high-amylose potato starch showed a lower WVP than did the corresponding starches based on regular potato starch. The WVP of the hydrophobically modified regular potato starches was substantially higher than that of films of the corresponding hydroxypropylated starches. The expected hydrophobic effect of the succinic acid anhydrides in terms of a reduced WVP could not be observed. When glycerol was used as a plasticizer, about 30 parts (by wt.) per hundred parts of starch were needed in order to reduce the T g and to cause observable changes in the mechanical properties of the free films.

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“…We estimated the T g for a dry starch film by taking T g = 907C for a starch film with 13% moisture [4,7] and using T g = -1377C for water [25]. Insertion of these values in Equation (2) led to a theoretical T g for a dry starch film of 1247C, which was used to calculate the theoretical T g 's for the films in our study at the given moisture and secondary plasticizer concentrations using T g = -857C for glycerol [26] and measured values of T g for pure PVOH (737C) and pure PVOH mod (667C). Measured and theoretically calculated T g values appear in Tabs.…”

Section: Glass Transition Temperatures In Starch Filmsmentioning

confidence: 99%

Composition and Film Properties of Temperature Responsive, Hydrophobically Modified Potato Starch

2008

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The film-forming properties of hydrophobically modified potato starch were studied to optimize coating and surface sizing formulations for improvement of barrier properties of paper and paperboard. The spontaneous fractionation of a potato starch hydrophobically modified with a quaternary dodecylammonium chloride resulted in an amylose-rich precipitate with properties differing from those of the original starch. Film formation was investigated in the presence of glycerol and poly(vinyl alcohol) plasticizers. Anti-plasticization was found to occur at low and intermediate plasticizer levels but highly flexible, continuous films were obtained when 30 parts of plasticizer were added to 100 parts of dry starch. The highest transparency and greatest flexibility were obtained with glycerol, while the hydrophobic film properties were maintained with poly(vinyl alcohol). A study of the glass transition temperatures and melting behavior of starch-plasticizer films by differential scanning calorimetry gave useful information about the crystallinity of the films.

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Ionic mobility and dielectric relaxation in supercooled liquid KCl-glycerol solutions

Cited by 33 publications

References 28 publications

Effects of film forming and hydrophobic properties of starches on surface sized packaging paper

Effects of film forming and hydrophobic properties of starches on surface sized packaging paper

Barrier and mechanical properties of modified starches

Composition and Film Properties of Temperature Responsive, Hydrophobically Modified Potato Starch

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