PE-LD: Polyethylene Low Density

General Properties

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PE-LD

Polyethylene Low Density


Polyethylene low density (PE-LD) consists of extensively branched polymer chains and therefore has a low density. It is produced from ethylene under high pressure and belongs to the groups of polyolefins. Based on the volume produced, PE-LD is the most important plastic of all.

Structural Formula


Properties

Glass Transition Temperature-130 to - 100/-30 to -10°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 Temperature100 to 115°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 Enthalpy-
Decomposition Temperature487 to 498°C
Young's Modulus200 to 400 MPa
Coefficient of Linear Thermal Expansion400 *10-6/K
Specific Heat Capacity1.8 to 3.4 J/(g*K)
Thermal Conductivity0.3 to 0.34 W/(m*K)
Density0.91 to 0.93 g/cm³
MorphologySemi-crystalline thermoplastic
General propertiesTough and elastic, good electric insulation, minimal moisture absorption, approved for food contact.
ProcessingExtrusion (films, profiles), injection moulding, blow moulding, extrusion-coating.
ApplicationsFilms(for a variety of applications), packaging (e.g. containers, plastic bags).

NETZSCH Measurement

InstrumentDSC 204 F1 Phoenix®
Sample Mass12.11 mg
Isothermal Phases20 min/2 min/20 min
Heating/Colling Rates10 K/min
CrucibleAl, pierced lid
AtmosphereN2 (40 ml/min)

Evaluation

A characteristic feature of this polymer is that the melting transition – as in the present case – can start very early (here at approx. 40°C). The peak temperatures of the endothermal melting effects are at 112/113°C (1st heating, blue and 2nd heating, red) and are therefore relatively high for PE-LD. The shoulder in the melting eff ect in the 1st heating (blue) is absent in the 2nd heating (red). It can be concluded from this observation that stresses in the material (thermomechanical history) were eliminated during the 1st heating. The 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 of polyethylene is generally small (small Δcp, i.e., changes in the specific heat level prior to and after the effect) and therefore sometimes hard to detect by DSC.