PMMA: Polymethylmethacrylate

General Properties

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PMMA

Polymethylmethacrylate

PMMA is produced from the monomer methyl methacrylate mostly by radical polymerization and is entirely amorphous. The structure of the thermoplastic (e.g., mean chain length or degree of cross-linking) is influenced by the pressure, temperature course and duration of the polymerization process. This, in turn, influences the physical and chemical properties of the material.

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 Temperature	115 (synd.), 105 (atact.), 45 (isotac.)°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 Temperature	-
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 Enthalpy	-
Decomposition reactionA decomposition reaction is a thermally induced reaction of a chemical compound forming solid and/or gaseous products. Decomposition Temperature	360 to 390°C
Young's Modulus	3100 to 3300 MPa
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	90 to 110 *10^-6/K
Specific Heat Capacity	1.45 to 1.47 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	0.16 to 0.25 W/(m*K)
DensityThe mass density is defined as the ratio between mass and volume. Density	1.15 to 1.19 g/cm³
Morphology	Amorphous polymer
General properties	High stiffness, high hardness. Very good translucence and light resistance. Good electrical insulation properties
Processing	Extrusion, injection molding, thermoforming, machining
Applications	Optics (e.g., eyeglasses). Automotive industry. Building industry

NETZSCH Measurement

Instrument	DSC 204 `F1` `Phoenix^®`
Sample Mass	12.33 mg
IsothermalTests at controlled and constant temperature are called isothermal.Isothermal Phase	5 min / 3 min / 5 min
Heating/Colling Rates	10 K/min
Crucible	Al, pierced lid
Atmosphere	N₂ (50 ml/min)

Evaluation

In the above DSC curve − typical for amorphous materials − a 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 can be seen as a step in the endothermal direction with step heights (Δc_p) of 0. 21 J/(g*K) (1^st heating, blue) and 0.32 J/(g*K) (2^nd heating, red) caused by the change in specific heat during transition from a glassy, brittle into a flexible, rubber-like state. 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 midpoint temperature occurs at 110°C in the 1^st heating (blue) and at 109°C in the 2^nd heating.