PP (isotactic): Polypropylene

General Properties

Short Name:

Name: 

Chemical Formula:

PP (isotactic)

Polypropylene

(C3H6)n


Polyproyplene (PP) belongs to the polyolefin group. It has an approx. 20% share in plastic production worldwide and is therefore the second most important polymer after PE. Its tacticity (isotactic, syndiotactic and atactic) is dependent on the polymerization conditions employed. 
Polypropylene is nonpolar and cannot be bonded or painted without pre-treatment (activation). A lot of derivatives of the classical PP homopolymer exist. The majority of PP types available are copolymerized with PE in order to reduce their 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 and to improve their impact strength in the low-temperature range. PP is processed with additives, fi llers or other polymers to a variety of PP compounds, which cover a broad range of properties.

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-20 to 20°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 Temperature160 to 165°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 Enthalpy207 to 209 J/g
Decomposition reactionA decomposition reaction is a thermally induced reaction of a chemical compound forming solid and/or gaseous products. Decomposition Temperature450 to 470°C
Young's Modulus1300 to 1800 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 Expansion130 to 180 *10-6/K
Specific Heat Capacity1.8 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 Conductivity0.17 to 0.25 W/(m*K)
DensityThe mass density is defined as the ratio between mass and volume. Density0.90 to 0.91 g/cm³
MorphologySemi-crystalline thermoplastic
IdentificationWhite granule
General propertiesEasy to process, Good combination of stiffness and toughness, Good chemical resistance, High StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress corrosion resistance, High electrical resistance, Better stability, hardness and stiffness than PE
ProcessingInjection molding, extrusion, deep drawing
ApplicationsFood containers, packaging, Automotive engineering, Sports equipment, textiles, toys, Building industry
ModificationsCo-Po with PE, Compounds with rubber, minerals, reinforcement, colored
ManufacturerLyondellbaseel, Borealis, DOW, Exxon, Sabic

NETZSCH Measurement

InstrumentDSC 204 F1 Phoenix®
Sample Mass5.67 mg
IsothermalTests at controlled and constant temperature are called isothermal.Isothermal Phases10 min/3 min/10 min
Heating/Colling Rates10 K/min
CrucibleAl, pierced lid
AtmosphereN2 (40 ml/min)

Evaluation

For commercial semi-crystalline PP types, a 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 (represented by the peak temperature) of approx. 160°C to 165°C is typical. This correlates well with the present case, in which peak temperatures of 168°C and164°C were observed in the 1st heating (blue) and the 2nd heating (red), respectively, with corresponding melting enthalpies of 94 J/g (1st heating) and 112 J/g (2nd heating). The lower 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 in the 2nd heating can be attributed to better contact between the sample and crucible bottom after the first melting (in the 1st heating). The difference in the heat of fusion results from the different cooling conditions used during production or processing of the polymer and during the measurement (cooling rate: 10 K/min). 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 step for PP can usually be found between -20°C and +20°C. In the present example, it was at -8°C (2nd heating). In the 1st heating, 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 was barely detected.