**6. References**

344 Thermoplastic Elastomers

approximately the same result. The weight loss result indicate the influence of coating on protecting OPEFB fibres from biodegradation, around 50% decrease on weight loss were

Fig. 18. Biodegradation of the fibres inside Silty sand, Organic soil and be in contact with

The thermoplastic was used as a treatment of the OPEFB fibres. The ABS coated fibres had an acceptable effect on the protection of fibre as the same as other treatment techniques. The water absorption of the coated fibre decreased due to protection capacity of the coated layer. The ABS coated fibre was found to be more durable compared to uncoated due to the condition of fibre. Morphological studies revealed that the coating modifies and protects the fibre surface entirely and the covered structure of the ABS over fibres can be seen from the respective scanning electron micrographs, also FTIR studies shown the chemical modifications within the ABS thermoplastic and fibres. From the tensile test it was found the Young's modulus of the coated fibre shown improvement due to ABS coating. However, the

tensile strength of the fibre indicated less increase in comparison to untreated fibre.

The previous studies describe that inclusion of OPEFB fibres can significantly increase the peak shear strength of silty sand soil (Ahmad et al., 2010). The fibre content increment leads to increasing the shear strength and consequently stabilized the reinforced soil. Coated OPEFB fibres increased the shear strength of silty sand compared to uncoated fibres. Coated fibres shown higher interface friction between fibre and soil particles by increasing the

estimated from tests after three months.

fungus after 3 months

**4. Conclusion** 

surface area.


**17** 

Vennemann Norbert

*Germany* 

*University of Applied Sciences Osnabrück* 

**Characterization of Thermoplastic Elastomers** 

Thermoplastic elastomers (TPE) and, in particular thermoplastic vulcanizates (TPV), are a new class of materials, combining the properties of conventional elastomers (rubber) and the processibility of thermoplastics. Compared with conventional rubber elastomers, these materials can be more easily processed and more easily recycled. TPE are often used to replace conventional thermoset rubber, but those are also used for a great variety of new applications and products, particularly in hard/soft combinations with other thermoplastics. Due to the advantages over conventional thermoset rubber, the commercial uses for thermoplas-

Beside many advantages, some disadvantages do exist, also. In comparison to chemically crosslinked elastomers (e.g., EPDM or natural rubber), TPE materials have stronger limitations with respect to upper service temperature, which is caused by softening or melting of the hard phase. Furthermore, TPE exhibit higher creep and stress relaxation, than thermoset rubber, even at ambient temperatures (Holden et al., 2004). Thus, new demands on polymer testing arise from the assessment of thermoplastic elastomers (TPE) with respect to their rubber elastic

Due to the complex molecular structure and phase morphology of TPE, traditional test methods normally used for characterization of elastomers give only limited information about the unique properties of TPE. For this reason, temperature scanning stress relaxation (TSSR) test method has been developed, recently (Vennemann et al., 2001, 2003). In this work, the basic principle of the TSSR test method as well as the theoretical background will be described. Furthermore, an overview of numerous results obtained from selected TPE materials, will be presented to demonstrate the versatility of the TSSR method. In addition, further development of the method will be presented, in particular for rapid determination

Polymers exposed to constant strain exhibit the well known phenomenon of stress relaxation, i.e. a more or less strong decrease of stress as a function of time. The microscopic

use properties and stress relaxation behaviour, particularly at elevated temperatures.

tic elastomers are growing rapidly (Schäfer, 2001; Bittmann, 2004).

**2.1 Stress relaxation and determination of relaxation spectra** 

**1. Introduction** 

of crosslink density of TPV.

**2. Theoretical background** 

**by Means of Temperature Scanning** 

 **Stress Relaxation Measurements** 

