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Dispersions of Cellulose Esters in Elastomers

IP.com Disclosure Number: IPCOM000197244D
Publication Date: 2010-Jun-29
Document File: 6 page(s) / 547K

Publishing Venue

The IP.com Prior Art Database

Related People

Eastman Chemical Company: OWNER [+4]

Abstract

Dispersions of Cellulose Esters in Elastomers Abstract Application of cellulose esters as a potential functional filler in cured elastomers was evaluated by adding cellulose esters into a formulated tire tread composition. It was found that cellulose esters of suitable molecular weight, glass transition temperature and molecular structure/composition melt disperse as small particles to impart several improvements to the properties. Cellulose esters within a suitable glass transition range that melt and flow at the tire processing temperature act as a processing aid, and thereby reduce the energy required for compounding and dispersing the silica. The same cellulose esters solidify upon cooling and perform as functional fillers at tire operating temperatures.

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Dispersions of Cellulose Esters in Elastomers

Abstract

Application of cellulose esters as a potential functional filler in cured elastomers was evaluated by adding cellulose esters into a formulated tire tread composition. It was found that cellulose esters of suitable molecular weight, glass transition temperature and molecular structure/composition melt disperse as small particles to impart several improvements to the properties. Cellulose esters within a suitable glass transition range that melt and flow at the tire processing temperature act as a processing aid, and thereby reduce the energy required for compounding and dispersing the silica. The same cellulose esters solidify upon cooling and perform as functional fillers at tire operating temperatures.

Detailed Description

Fillers are used in cured elastomers to improve thermophysical properties such as modulus, strength, and expansion coefficient in finished products. The finished products find various applications including auto parts, tires, belts, gaskets, hoses, and industrial components. Recently bio-derived, high Tg polymers such as starch, microcrystalline cellulose, alpha-cellulose and cellulose microfibers have been used for the above purpose. These organic polymeric fillers often have an advantage over their inorganic counterparts in terms of processibility, lower density, bio-renewability and compatibility.

Cellulose esters (CE) are high glass transition temperature (Tg) thermoplastic biopolymers that are made using up to 60% bio-renewable raw materials. These high Tg powders (200-300 micron particle size) could be dispersed in elastomers as solids, but the large particle size does not provide optimal properties. Melt mixing CEs into elastomers under shear has the potential of creating small particles. Most CEs have high Tg and therefore do not melt and flow at typical melt processing temperature of elastomers. This difficulty was overcome by first by selecting CEs with Tg's significantly lower than the elastomer processing temperature and second by choosing proper processing conditions such as temperature, residence time, processing equipment and

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shear profile. Since tires represent a significant portion of the cured elastomer market, a silica-filled tire tread formulation was chosen to demonstrate this concept.

Application of CEs as a potential functional filler in cured elastomers was evaluated by adding CEs into a formulated tire tread composition. It was found that CEs of suitable molecular weight, glass transition temperature and molecular structure/composition melt disperse as small particles to impart several improvements to the properties. CEs within a suitable glass transition range that melt and flow at the tire processing temperature act as a processing aid, and thereby reduce the energy required for compounding and dispersing the silica. The same CEs solidify upon cooling and perform as functional fillers at tire operating temperatures.

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