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 Temperature115 (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 Temperature360 to 390°C
Young's Modulus3100 to 3300 MPa
Coefficient of Linear Thermal Expansion90 to 110 *10-6/K
Specific Heat Capacity1.45 to 1.47 J/(g*K)
Thermal Conductivity0.16 to 0.25 W/(m*K)
Density1.15 to 1.19 g/cm³
MorphologyAmorphous polymer
General propertiesHigh stiffness, high hardness. Very good translucence and light resistance. Good electrical insulation properties
ProcessingExtrusion, injection molding, thermoforming, machining
ApplicationsOptics (e.g., eyeglasses). Automotive industry. Building industry

NETZSCH Measurement

InstrumentDSC 204 F1 Phoenix®
Sample Mass12.33 mg
Isothermal Phase5 min / 3 min / 5 min
Heating/Colling Rates10 K/min
CrucibleAl, pierced lid
AtmosphereN2 (50 ml/min)

Evaluation

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