Rubber oxidative degradation

Ethylene—Propylene (Diene) Rubber. The age-resistant elastomers are based on polymer chains having a very low unsaturation, sufficient for sulfur vulcanization but low enough to reduce oxidative degradation. EPDM can be depicted by the following chain stmcture ... 

There are some aspects in the raw dry NR grades for adhesive manufacturing to be considered. NR tends to suffer oxidative degradation catalyzed by metals (mainly copper). The susceptibility of NR to oxidation can be measured using the plasticity retention index. The better grades of rubber have the higher plasticity retention index. 

With rubber base adhesives, it is necessary to prevent their properties from changing during service life. Oxidative changes induced by thermal, ozone exposure and UV light can dramatically affect service life of rubber base adhesives. More precisely, the rubber and the resin are quite susceptible to oxidative degradation. Environmental and physical factors exert detrimental effects on rubber base adhesive performance. These effects can be mitigated by the incorporation of low levels of stabilizers during the fabrication process of the adhesive. 

Rubber gloves Autoclave Gamma-radiation Ethylene oxide Sterilization Gamma-radiation If autoclave used, care with drying at end of process. Little oxidative degradation when high-vacuum autoclave used... 

Imaging chemiluminescence technique. Chemiluminescence analysis is suitable for studying the early stages of the thermal oxidation of rubbers. A weak emission of light formed by chemical reactions appears during the oxidative degradation of hydrocarbons. This technique can be used to depth profile the oxidation of rubbers. MR... 

The action of certain metals (e.g., copper) on unsaturated rubbers, primarily natural rubber, is to catalyse the oxidative degradation of the polymer. The metal must be in an ionic form, i.e., straightforward contact with the metal such as a seal with a copper pipe will not promote such degradation. 

The unsaturated structure of the diene hydrocarbon rubbers makes them susceptible to attack by both oxygen and ozone. Oxidative degradation of all rubbers, irrespective of their structures, is inevitable as the energy associated with incident natural light is approximately three times that of a typical carbon-carbon or carbon-hydrogen bond. 

Marking crayons and inks/paints are some of the oldest methods of applying identification to slabs of rubber whilst being stored prior to incorporation into products or during factory operations. Care must be taken to ensure that the materials used for such identification are compatible with the rubbers on which they are being used. Coloured markers can also contain pigments which may contain active metal ions which could conceivably cause activation of oxidative degradation of the rubber if used extensively. 

Mattson B (1993) Thermo-oxidative degradation and stabilization of rubber materials. PhD Thesis, Royal Inst of Technology, Stockholm... 

Amines as Antioxidants or Antiozonants for Rubber (13). Oxidative degradation of vulcanized rubber is evaluated from the depression in the tensile properties during aging in the Geer oven. 

The amine derivatives used are listed in Table II together with their oxidation half-wave potentials. The ratio of the tensile strength of aged (TS) to unaged (TS)0 rubber is used as a measure of the degree of oxidative degradation (see Figures 5-8). 

The most thoroughly investigated oxidative degradation is that of natural rubber. In 1943 Farmer and Sundralingham found that in the photochemical oxidation of this polymer a hydroperoxide is formed, the number of double bonds in the chain remaining constant. The oxygen was found to act on an activated methylene group, not on a double bond, as had previously been assumed. 

Oxidative degradation can also occur in other polymers including natural rubber, polystyrene, polypropylene, nylons, polyurethanes, and most natural and naturally derived polymers. With the exception of fluo-ropolymers, most polymers are susceptible to oxidation, particularly at elevated temperature or during exposure to ultraviolet hght. Oxidation usually leads to increasing brittleness and deterioration in strength. 

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