Wednesday 15-06-2022

NIKK Knowledge Base: T

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To temper a plastic means to anneal it at elevated temperature for a defined period.
The tempering or annealing parameters depend strongly on the type of polymer and the wall thickness. The parameters have to be chosen very carefully to avoid deformations.

Tensile testing
Tensile testing is a method to measure the mechanical properties of a sample:
- Tensile strength: maximum stress or force during testing
- Fracture strength: strength at break
- E-Modulus: stiffness of a material. Ratio of stress and rel. strain according to the law from Hooke
- Failure strain: strain at break

Thermo-analytical examinations
DSC is the abbreviation of Differential Scanning Calorimetry. DSC is used for the thermal analysis of polymers:
- melting temperature
- degradation temperature
- measuring of the phase transitions
- thermal stability
TGA is the abbreviation of Thermal Gravimetric Analysis. Plastics often consist of various solid additives having different thermal properties easily be analyses be means of TGA.
MFR is the abbreviation of Melt Flow Ratio. By means of MFR the flow characteristic of polymers at higher temperature could be examined. It is a simple method to characterize a thermoplastic material and to detect changes in production.

Rheological examinations: This method is different for every polymer – thermosets, thermoplastics, rubber materials. Thermoplastic materials are examined by means of oscillating rotation where the dynamic E-Modulus, the attenuation and the stability of the material is measured as a function of temperature and frequency.
Thermosets are characterized with regard to the viscosity at different shear forces. Additionally the curing behaviour could also be measured.
Rubber is characterized mainly regarding the curing behaviour as a function of temperature.

TOC is the abbreviation of Total Organic Carbon. It is the total amount of carbon solved in water.

Thermosets are polymers with a three dimensional cross linking and not smelting contrary to thermoplastic materials. Due to the chemical structure of cross linking the bonds are very stable and could not be destroyed by means of physical processes. At temperatures higher than 500° C thermosets will destroy and burn as oxygen is present. Thermosets were often reinforced with glass or carbon fibres because of their brittleness. Caused to the reinforcing products could be fabricated with outstanding mechanical properties (CRP and GRP).
Examples of thermosets are:
- Acrylic resins
- Phenol formaldehyde (PF)
- Melamine formaldehyde (MF)
- Polyester resins (UP)
- Polyurethane resin (PU)
- Vinylester resin (PHA)

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