PBT: Polybutylene Terephthalate

General Properties

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PBT

Polybutylene Terephthalate


Polybutylene terephthalate (PBT) is a polyester and has properties similar to that of polyethylene terephthalate (PET, see page 112). It is, however, better suited for injection molding due to its cooling and processing behavior.

Structural Formula


Properties

Glass Transition Temperature40 to 60°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 230°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 Enthalpy142 J/g
Decomposition Temperature400 to 420°C
Young's Modulus2500 to 2800 MPa
Coefficient of Linear Thermal Expansion80 to 100 *10-6/K
Specific Heat Capacity1.3 J/(g*K)
Thermal Conductivity0.25 to 0.29 W/(m*K)
Density1.30 to 1.32 g/cm³
MorphologySemi-crystalline thermoplastic
General propertiesHigh stability and stiffness. Good chemical resistance to many solvents. High dimensional stability. Good friction and wear properties
ProcessingInjection molding, extrusion
ApplicationsElectrical engineering/electronics. Vehicle manufacturing. Household goods

NETZSCH Measurement

InstrumentDSC 204 F1 Phoenix®
Sample Mass12.06 mg
Isothermal Phase3 min/ / 3 min / 5 min
Heating/Colling Rates10 K/min
CrucibleAl, pierced lid
AtmosphereN2 (50 ml/min)

Evaluation

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 (here at 42°C, midpoint) and a clearly structured endothermal melting effect for the α (peak temperature 226°C) and β phase (peak temperature 217°C) in the 2nd heating (red) are characteristic of PBT. In the 1st heating (blue), the glass transition midpoint temperature of 44°C was comparable to that in the 2nd heating, but is overlapped with a RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation peak. Prior to the melting transition, a Post Crystallization (Cold Crystallization)The post crystallization of semi-crystalline plastics occurs primarily at elevated temperatures and increased molecular mobility above the glass transition.post crystallization (small EsotermicoUna transizione o reazione è esotermica se il materiale genera calore exothermal peak at 207°C) occurred in the 1st heating.