Polymers

Versatile polymers can generally be divided into three main groups: thermoplastics, elastomers and thermosets. Their thermal properties can be determined with our thermoanalytical measuring systems in the fields of product development, quality assurance, failure analysis and process optimization.

Thermosets, Paints and Adhesives

Surely you must deal with issues such as these on a day-to-day basis:

  • How high is the degree of curing of the paint system?
  • Can the cycle time of the thermosetting moulding still be reduced by a temperature increase?
  • To what extent does the glass-fiber reinforcement of the composite influence the direction-dependent coefficient of thermal expansion?
  • How high is the thermal conductivity of the electronic component?

Elastomers and Rubbers

Surely you must deal with issues such as these on a day-to-day basis:

  • Of which individual components does the rubber seal consist?
  • How does the thermal stability of a rubber mixture change under the influence of different atmospheres?
  • Which gases evolve during the processing of an elastomer?
  • How do the visco-elastic properties of the damping element change under high frequency stress?

Thermoplastics and Thermoplastic Elastomers

Surely you must deal with issues such as these on a day-to-day basis:

  • Is the sample really the specified granulate?
  • Is the thermoplastic sample contaminated with recycling material?
  • How high is the degree of crystallinity of the semi-crystalline thermoplastic moulding?
  • Where does the glass transition of the soft component of the thermoplastic elastomer occur?

Reommended literature:

Reommended literature:

Knowledge Compact – The Handbook DSC on Polymers – Essential for the Analysis of Plastics, Rubber or Resins

The handbook DSC on Polymers provides you quickly and competently with helpful tips to enable you to carry out measurements on thermoplastics, elastomers, thermoplastic elastomers or thermosets and interpret the results. For 64 polymers, we have compiled measuring plots, measurement parameters, interpretation of the results and general material properties. Also chemical structures (if available), processing possibilities and application ranges, all of which are presented in a clearly structured and practice-oriented overview.  

The introductory chapters offer an easy-to-understand introduction to DSC (including special measuring techniques such as temperature-modulated DSC, OIT, specific heat), lists national and international standards important for DSC measurements and describe their recommendations for the evaluation of polymer measurements.   The DSC handbook is available in German and English. Reserve your personal copy today.

Detailed Insight Into the World of Thermal Analysis

Detailed Insight Into the World of Thermal Analysis

The No. 1 thermo-analytical method for polymers is DSC (Differential Scanning Calorimetry), with which thermal effects and derivational magnitudes for such properties as melting, crystallization, crosslinking, glass transition, specific heat, and oxidation can be investigated.

TG (Thermogravimetry) provides information about the composition and thermostability of polymer mixtures and blends. In addition, gas analyses with QMS (Quadrupole Mass Spectrometry) or FTIR (Fourier Transform Infrared-Spectroscopy) can also be performed.

Dilatometry and TMA (Thermomechanical Analysis) yield the coefficient of thermal expansion. DMA (Dynamic Mechanical Analysis) also provides values for the coefficient of elasticity and information regarding the visco-elastic behavior, aging, creep and relaxation.

With DEA (Dielectric Analysis), the curing behavior of reactive resin systems can be measured, even during processing.

Using LFA (Laser/Light Flash Analysis), the thermal diffusivity for thermoplastic melts can also be measured and the thermal conductivity can be determined. The thermal conductivity of polymer isolation foams can be measured with the heat flow meter (HFM).

Overview of Suitable Methods

DSCPressure-DSCPhoto-DSCTG / STADILTMADMADEALFAHFM / GHP
Thermoplasticso---
Thermoplastic Elastomerso---
Elastomers / Rubberso-oo
Thermosetso
Paints / Coatingso-o-
Adhesives-oo-
Foams--o-
Composites---

legend:

• ideal
o possible with some effort
- not possible, not practical

Some Application Examples

Some Application Examples

Thermal Behavior of Thermoplastic Polyurethane
Quality Control of Polymers by means of DSC

This plot shows a measurement on TPU. During the 1st heating, the endothermic step at -42°C (mid-point) reflects the glass transition of the soft segments of the sample. Additionally, the curve exhibits an endothermic double peak between 100°C and 210°C. The reversible part of it, which can be detected again in the 2nd heating (7.40 J/g), is caused by the melting of the hard (thermoplastic) segments. The irreversible part is probably due to evaporation of volatiles or distribution of additives in the polymer matrix. This process explains the fact that the glass transition was detected at a higher temperature (mid-point at -28°C) in the 2nd heating.

Thermal properties of the soft and hard segments in a thermoplastic polyurethane (TPU). Sample mass: 10.47 mg; heating from -100°C to 250°C at 10 K/min, twice; dynamic N2 atmosphere.Thermal properties of the soft and hard segments in a thermoplastic polyurethane (TPU). Sample mass: 10.47 mg; heating from -100°C to 250°C at 10 K/min, twice; dynamic N2 atmosphere.

Dynamic-Mechanical Properties of Glass Fiber Reinforced PBT

A 30% glass fiber-reinforced PBT (parallel and perpendicular to the fiber orientation) was measured in the 3-point bending mode at 1 Hz and 2 K/min. Considerably higher values for the stiffness and the onset of the E'-decrease (43°C) are obtained for the parallel-oriented type (solid line). The tanδ values are accordingly lower. The tanδ peaks are at the same temperature.

The polyester fiber tested in the tension mode shows relaxations in the low-temperature range, which can be evaluated at E' onset, E'' peak or tanδ peak. Glass transition starts at 75°C. The storage modulus decreased from approx. 4,200 MPa to 200 MPa. (measurement with DMA 242 E Artemis)

Thermal Conductivity & Thermal Diffusivity of Fiber-Reinforced Epoxy

More and more polymers, metals or ceramics are being reinforced with fibers to improve their bending strength and to adjust them to special applications. In many cases, the fiber reinforcement results in a high degree of anisotropy to the mechanical and thermal transport properties. By employing special sample holders, the flash technique allows analysis of this anisotropy in the thermal diffusivity and thermal conductivity. The measurement example clearly demonstrates that the values for both the thermal diffusivity and thermal conductivity, perpendicular to the fiber direction are significantly lower than the results of the in-plane test (in the fiber direction). (measurement with LFA 447 NanoFlash®)