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 Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.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 TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.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 (CLTE/CTE)The coefficient of linear thermal expansion (CLTE) describes the length change of a material as a function of the temperature.Coefficient of Linear Thermal Expansion-
Specific Heat Capacity1.55 J/(g*K)
Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.Thermal Conductivity-
DensityThe mass density is defined as the ratio between mass and volume. 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
IsothermalTests at controlled and constant temperature are called isothermal.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 TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.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.