Tire components, curing

There are many ways to measure these properties and some of them are proprietary. However, most laboratory tests are standardized by American Standard Testing Methods (ASTM). Many of them are interactive to various degrees. The rate and state of vulcanization is especially important to consider for components of heavier and thicker tires. The heat used to vulcanize the tire in a mold under pressure requires time to penetrate from both sides of the giant tire to the innermost portions. Securing a balanced state of cure, ie, the maximizing of physical properties in all the components, results in the innermost components having a faster rate of cure. The peripheral compounds should have a cure system which holds its physical properties well when overcured. 

The irradiated components can be placed adjacent to sulfur-containing unvulcanized elastomeric compounds and, when necessary, coated with suitable adhesive between the contacting surfaces to ensure good bond after final cure of the tire. ... 

The compounded rubber stock will be further processed for use. The process could be injection or transfer molding into a hot mold where it is cured. Tire curing bladders are made in this fashion. Extrusion of the rubber stock is used to make hose or tire treads and sidewalls. Another common process is calendaring, in which a fabric is passed through rolls where rubber is squeezed into the fabric to make fabric-reinforced rubber sheets for roofing membranes or body plies for tires. The actual construction of the final product can be quite complex. For example, a tire contains many different rubber components some of which are cord or fabric reinforced. All of... 

Bilodeau [4] prepared barriers consisting of radiation cured A -vinyl-2-pyrro-lidone and A -vinylcaprolactam that were impervious to migratory components in autmotive tires. 

A catalyst combination consisting of the barium salt of tri(ethyleneglycol)ethyl ether, Ba(0CH2CH20CH2CH20CH2CH3)2, with tri-n-octyl aluminum and n-butyl lithium has been used to prepare random poly(styrene-co-butadiene) containing a high butadiene transcontent. These polymers were designed to be co-cured with natural rubber and used as components in automotive tires. 

Blends of elastomers are routinely used to improve processability of unvulcanized rubbers and mechanical properties of vulcanizates like automobile tires. Thus, cis-1,4-polybutdiene improves the wear resistance of natural rubber or SBR tire treads. Such blends consist of micron-sized domains. Blending is facilitated if the elastomers have similar solubility parameters and viscosities. If the vulcanizing formulation cures all components at about the same rate the cross-linked networks will be interpenetrated. Many phenolic-based adhesives are blends with other polymers. The phenolic resins grow in molecular weight and cross-link, and may react with the other polymers if these have the appropriate functionalities. As a result, the cured adhesive is likely to contain interpenetrating networks. 

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