PVAL: Polyvinyl Alcohol

General Properties

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PVAL

Polyvinyl Alcohol


Polyvinyl alcohol (PVAL) cannot be produced by means of polymerization, but only by hydrolysis of polyvinyl esters, such as poly- vinyl acetate. The plastic is water-soluble and therefore easily absorbs air humidity. The melting and Temperatura di transizione vetrosaLa transizione vetrosa è una delle più importanti proprietà chimico-fisiche dei materiali amorfi e semi-cristallini, come, ad esempio, vetri, metalli (amorfi), polimeri, ingredienti farmaceutici e alimentari e definisce l’intervallo di temperatura in cui le proprietà meccaniche die materiali variano da duro e fragile a più morbido, malleabile o gommoso.glass transition temperatures depend on various parameters such as the degree of hydrolysis, the molar mass, the distribution of the acetyl groups (statistical or in blocks), and the water content.

Structural Formula


Properties

Glass Transition Temperature70 to 100°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Temperature220 to 260°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Enthalpy156 J/g
Decomposition Temperature260 to 320 / 420 to 450°C
Young's Modulus-
Coefficient of Linear Thermal Expansion-
Specific Heat Capacity1.55 J/(g*K)
Thermal Conductivity-
Density1.21 g/cm³
MorphologySemi-crystalline thermoplastic
General propertiesGood solubility in water, good resistance against organic solvents, good film formation properties, high bonding strength
ProcessingExtrusion
ApplicationsWater-soluble films, adhesives, toys (e.g. component of modelling clay), textiles, textile fibres, medical technology, pharmacy (e.g. tablet coatings).

NETZSCH Measurement

InstrumentDSC 204 F1 Phoenix®
Sample Mass10.26 mg
Isothermal Phases5 min
Heating/Colling Rates10 K/min
CrucibleAl, pierced lid
AtmosphereN2 (50 ml/min)

Evaluation

Water has plasticizing properties. For this reason, the glass transition is considerably lower in the 1st heating (blue) than in the 2nd heating (red) by 34 K. Directly related to this is the broad endothermal effect between approx. 60°C and 170°C (1st heating). It can be attributed to the evaporation of humidity. By using aluminum crucibles with pierced lids, water was eliminated from the sample during the 1st heating. Above 150°C and 170°C, PVAL exhibited melting transition with peak temperatures of 229°C (1st heating, blue) and 226°C (2nd heating, red). The corresponding melting enthalpies were approx. 78 J/g (1st heating) and 75 J/g (2nd heating), respectively.