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Control of Coefficient of Thermal Expansion in Elastomers using Boron Nitride For Industrial Fabrics

IP.com Disclosure Number: IPCOM000144716D
Publication Date: 2007-Jan-05

Publishing Venue

The IP.com Prior Art Database

Abstract

The thermal expansion properties of three commercial elastomers; Pebax®, Estane® and Hytrel®, generically known as polyether block polyamide elastomers, polyester type thermoplastic polyurethane, and polyether block polyester elastomers, respectively, modified with 2.5-10 wt% boron nitride were investigated. The glass transition temperatures of the filled materials were relatively unaffected; however boron nitride did effectively reinforce all the 3 elastomers as seen by dynamic mechanical analysis and tensile tests. The coefficients of thermal expansion of the composite materials do not obey the rule of mixtures and show a large decrease without the loss of ductility typically associated with filled elastomers.

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Control of Coefficient of Thermal Expansion in Elastomers using Boron Nitride For Industrial fabrics

 

Sanjay Patel ,  David A. Schiraldi and Subramanian Iyer

 

Abstract

The thermal expansion properties of three commercial elastomers; Pebax®, Estane® and Hytrel®, generically known as polyether block polyamide elastomers, polyester type  thermoplastic polyurethane, and polyether block polyester elastomers, respectively, modified with 2.5-10 wt% boron nitride were investigated. The glass transition temperatures of the filled materials were relatively unaffected; however boron nitride did effectively reinforce all the 3 elastomers as seen by dynamic mechanical analysis and tensile tests. The coefficients of thermal expansion of the composite materials do not obey the rule of mixtures and show a large decrease without the loss of ductility typically associated with filled elastomers.

 

 

 

Keywords:  elastomers, composites, thermal properties, mechanical properties

 


BACKGROUND OF THE INVENTION

1.   Field of the Invention

Modification of thermoplastic polymers by the addition of different organic and inorganic fillers is an effective method for generating a nearly limitless array of new materials with unique properties.  The fillers used in these systems differ in physical and chemical properties as well as in their size and geometries.  Inorganic fillers constitute a significant group of fillers used for reinforcing and toughening of thermoplastic polymers. 

2.   Discussion of the Background Information

Glass transition of high polymers is virtually unaffected by the incorporation of reinforcing fillers at technologically important loadings.1  In spite of this observation several authors have proposed that fillers significantly impede segmental motion in the rubbery and transition regions of viscoelastic response.2  It is postulated that adsorption of polymer molecules on filler surfaces occurs with considerable loss in segmental mobility, affecting a substantial fraction of the total polymer volume and causing a shift in the relaxation spectrum toward higher temperatures.  It would seem that such a mechanism would result, if not in an actual increase in the experimentally observed glass transition, then at least in the change in the coefficient of thermal expansion, the latter being related to the free volume of the system and hence to the mobility of the polymeric chain segments.  

Fillers generally used for control of coefficient of thermal expansion of elastomers include mica, chalk, kaolin, lampblack, carbon black and glass fibers.  Voevodskaya et al. have shown that the addition of up to 30 volume % chalk to elastomers resulted in a linear decrease in the coefficient of thermal expansion below the glass transition and a negligible change above the glass transition.3 Faehndrich and cow...