Mechanism of oxidation in natural rubber compounds at lower (ambient) temperatures

The oxidation mechanism of natural rubber was studied using several techniques. In a prior article, it was found that the crosslink distribution (sulfur types including polysulfidic, disulfidic and monosulfidic) in a belt coat (conventional cured natural rubber compound) had a different crosslink distribution, depending on the aging temperature (ref. 1). The belt coat compound extracted from an oven aged (65°C) tire was compared to the belt coat compound extracted from a normal service tire (23°C, the average annual temperature in Phoenix, AZ)

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Homegrown bioelastomers: A sustainable opportunity

It has been estimated that there are 2,500 plants that can produce a natural latex: a bioelastomer. Of course, not all of them can produce a polymeric latex with a high molecular weight, readily processable and commercially viable. To date, three species account for the majority of interest associated and centered
around the discussion of natural latex: Hevea rubber trees (Hevea brasiliensis), guayule (“why-yule-ee,” Parthenium argentatum) and rubber dandelion (Taraxacum kok-saghyz). The rubber tree, typically found in tropical Southeast Asia, produces nearly 90% of the world’s natural latex. Guayule (a desert shrub) and rubber dandelion are plants found in more temperate regions in the U.S., and figure to be potential domestic sources of natural rubber and latex.

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Staying relevant in a changing industry

In previous Rubber World columns, I have discussed the reintroduction of the manufacture of latex gloves back into the U.S. after a 25 year absence. During those years, in Southeast Asia, there have been significant, evolutionary improvements to the equipment, processing, formulations, and the latex itself. The challenge we face is to develop a competitive, sustainable manufacturing capability in the U.S., utilizing some of the personnel who were involved in glove manufacturing years ago, and merging their experience with new ways of thinking and problem solving.

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CO2-switchable materials for the rubber industry

Recent developments in stimuli-responsive or “smart” materials offer the opportunity for major advances in material design that could impact markets for latexes. One of the lesser known, but simpler technologies includes polymers and latexes whose properties can be dramatically, and reversibly, switched simply by adding or removing CO2. The processes used offer advantages in sustainability without requiring expensive materials or catalysts, and are based on currently used materials and production methods. This article will give a general overview of three examples relevant to latexes and coatings

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Almond Production Residues As Natural Rubber Fillers

Carbon black is commonly used as a filler in rubber and plastic compounds. It is composed of over 90% carbon, with low oxygen and hydrogen content, mainly forming surface functional groups which may participate in polymer reinforcement. Raw almond shells are composed of cellulose, hemicellulose and lignin, representing less than 50% carbon, over 40% oxygen, and at times significant amounts of moisture. The relatively polar nature of almond shells, and their tendency to degrade at processing temperatures, presents a less than ideal alternative when considering fillers for hydrocarbon polymers.

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