**14. Future directions**

Thermoplastic elastomer structure, performance and specialty applications are interconnected with block copolymer molecular characteristics. Block continuity, molar mass, molar mass distribution and stereochemistry must be controlled. New polymerisation techniques and initiators are expanding the choice of monomers that can be polymerised under controlled conditions. This allows monomer selection and molecular architecture to provide elastomers with chemical resistance, self-healing, abrasion resistance and unique mechanical performance to be prepared for special applications.

Further thermoplastic elastomers can be prepared by creating blends of an elastic polymer with a dimensional stabilising polymer. Inclusion of ionomers as a physically cross-linking phase can be extended with carboxylates, sulfonates and phosphates with various metal ions. In conjunction with polyfluorocarbon elastomers chemical resistance can potentially be improved.

Nanocomposites are being formed with elastomers where the nanoparticles form selfassembled clusters or bridges to provide physical cross-links. Nano-particles have traditionally been used to modify elastomeric properties. Such modification will be expanded through increasing knowledge of nano-composite preparation and morphologies. Carbon black is a much used nano-fillers that is now being assisted or replaced by carbon nanotubes, graphenes and silicas with a diversity of surface modifications. Carbon blacks are known to form reversible clusters and to binder elastomer molecules within the clusters. Nano-silicas remain in multi-particles aggregates while forming reversible agglomerates that enhance absorption of elastic energy. Now carbon nanotubes and graphenes have been found to create reversible networks at low volume fraction.

## **15. Conclusions**

The characteristics of an elastomer require that there is a mechanism to provide reversible deformation. Only the elastic component of the three-component viscoelastic model must be active. The viscous contribution resulting from molecules sliding past each other, this results in irreversible flow, is eliminated by cross-linking in a thermoset elastomer. Physical crosslinks are present in a thermoplastic elastomer as a second vitrified or crystalline phase. The viscoelastic component can be reduced by minimising chain stiffness and intermolecular interactions in the continuous elastic phase. Thermoplastic elastomers offer

Automotive: windshield seal (SEBS), wire/cable (SEBS, TPU), fibre reinforced soft

Medical devices: syringe (TPV), medical tubing (TPO), medical wrapping and

Household appliance sector: sporting goods (TPU), footwear soles (SBS), toys (SEBS),

The only constraint of TPEs is the physical reversible crosslinks need to be disrupted by heat

Thermoplastic elastomer structure, performance and specialty applications are interconnected with block copolymer molecular characteristics. Block continuity, molar mass, molar mass distribution and stereochemistry must be controlled. New polymerisation techniques and initiators are expanding the choice of monomers that can be polymerised under controlled conditions. This allows monomer selection and molecular architecture to provide elastomers with chemical resistance, self-healing, abrasion resistance and unique

Further thermoplastic elastomers can be prepared by creating blends of an elastic polymer with a dimensional stabilising polymer. Inclusion of ionomers as a physically cross-linking phase can be extended with carboxylates, sulfonates and phosphates with various metal ions. In conjunction with polyfluorocarbon elastomers chemical resistance can potentially be

Nanocomposites are being formed with elastomers where the nanoparticles form selfassembled clusters or bridges to provide physical cross-links. Nano-particles have traditionally been used to modify elastomeric properties. Such modification will be expanded through increasing knowledge of nano-composite preparation and morphologies. Carbon black is a much used nano-fillers that is now being assisted or replaced by carbon nanotubes, graphenes and silicas with a diversity of surface modifications. Carbon blacks are known to form reversible clusters and to binder elastomer molecules within the clusters. Nano-silicas remain in multi-particles aggregates while forming reversible agglomerates that enhance absorption of elastic energy. Now carbon nanotubes and graphenes have been

The characteristics of an elastomer require that there is a mechanism to provide reversible deformation. Only the elastic component of the three-component viscoelastic model must be active. The viscous contribution resulting from molecules sliding past each other, this results in irreversible flow, is eliminated by cross-linking in a thermoset elastomer. Physical crosslinks are present in a thermoplastic elastomer as a second vitrified or crystalline phase. The viscoelastic component can be reduced by minimising chain stiffness and intermolecular interactions in the continuous elastic phase. Thermoplastic elastomers offer

touch surface for interior (TPO), gaskets (TPV) and spoiler (SEBS)

Mobile electronics: wire/cable (SEBS), earplugs (TPV), cell phone (TPV).

packaging (TPU)

adhesives (SIS)

**14. Future directions** 

improved.

**15. Conclusions** 

Construction: gaskets (SEBS)

to mould, but they maybe disrupted during use.

mechanical performance to be prepared for special applications.

found to create reversible networks at low volume fraction.

ease of processing the same as thermoplastics without the need for a separate curing reaction. Waste material can be reprocessed and production rates will be fast consistent with a thermoplastic. Upper application temperature limitations exist dependent upon the glass transition or melting temperature of the hard phase. Stress resistance is limited to the yield stress of the hard phase since permanent deformation will follow distortion or flow of the hard phase. Thermoplastic elastomers are enhanced by fillers, with nano-fillers having particular relevance when small amounts can support the hard phase. In the soft phase fillers will modify the elastic response. Structural diversity is found in thermoplastic elastomers with many chemical structures such as polyurethanes and polyolefins available as both thermoset and thermoplastic elastomers.

#### **16. References**


**9** 

*Łódź Poland* 

**Modification of Thermoplastics** 

Jerzy J. Chruściel\* and Elżbieta Leśniak *Technical University of Łódź, Faculty of Chemistry,* 

 *Institute of Polymer and Dye Technology,* 

 **with Reactive Silanes and Siloxanes** 

In a contemporary world goods made from plastics and other polymeric materials are applied in many areas of our life. Growing practical applications are mainly stimulated by better properties of modified polymers, in a comparison with the polymeric materials used so far. On a world polymer market a biggest production concerns thermoplastics, thus modification of their properties has become one of a most important research challenges in a

Silicones (polysiloxanes) are a large and most important group of various inorganic-organic (hybrid) compounds and materials, composed of silicon and oxygen atoms in their main chains and organic substituents bound to silicon. Silicones play an important role among polymers with special properties, because they possess many unusual features. Even an addition of a very small amount of silicones causes a crucial improvement of properties of modified materials. Most importantly: silicones increase hydrophobicity and improve water resistance and thermal stability of many materials. Silicones exhibit excellent chemical, physical, and electrical properties. Most popular organosilicon polymers are polydimethylsiloxanes (PDMS). Silicones are mainly applied as silicone oils, rubbers, and resins (Noll, 1968; Rościszewski & Zielecka, 2002). Similar positive effects on properties of polymers and other materials can be reached by the addition of reactive silanes, siloxanes, and silicates, which are also used very often in practice for the modification of polymeric and inorganic materials. An important practical meaning have also other organosilicon polymers (polysilanes, polycarbosilanes, polysilazanes, etc.), and many functional silanes with different chemical structures, containing reactive groups, mostly bound to silicon atom, but

We observe a continuously growing interest in applications of reactive silanes and polysiloxanes in many different fields of science (with focus on materials science) and the

field of a polymer chemistry and technology, and materials science as well.

**1. Introduction** 

also quite often attached to carbon.

Corresponding Author

 \*

chemical technology, and this is a subject of our review.

from thermoplastic elastomers. *Nuclear Instruments and Methods in Physics Research B*, Vol. 208, pp. 58-65, ISSN 0168-583X.

