Mechanisms of antioxidant action: Mechanochemically bound antioxidants to polyethylene and polypropylene

It is shown that a thiolamide antioxidant, 4-mercaptoacetamido diphenylamine (MADA) can be reacted with both polypropylene and polyethylene in a mechanochemical process. The resulting bound antioxidant concentrates (MADA-B) can be used for the thermal and photostabilisation of the parent polymers. The adduct is very stable to solvent extraction and is also very effective as a high temperature antioxidant for polypropylene subjected to water leaching.The uv stabilising mechanism of MADA-B is believed to be related to the regenerative process involved in the mechanism of stabilisation by hindered nitroxyl radicals.     

Using deep learning to learn physics of conduction heat transfer

Journal of Thermal Analysis and Calorimetry - In the present study, an advanced type of artificial intelligence, a deep neural network, is employed to learn the physic of conduction heat transfer...     

Effects of reprocessing on polymers—V. Effects of antioxidants in polyethylene based blends containing solid phase dipsersants

The effects of commercial antioxidants and u.v. stabilisers are examined for two typical polyethylene based polyblends containing solid phase dispersants. Both were found to be effectively stabilised against the effects of light and heat by nickel dibutyl dithiocarbamate, a u.v. stable catalytic peroxide decomposer.     

Polymer blends—V: The effects of solid phase dispersants on the properties of ternary incompatible blends

The effects of two solid phase dispersants have been examined in a ternary blend of polyethylene, polypropylene and polystyrene. A styrene-butadiene block copolymer (SBS) is particularly effective in improving the balance of mechanical performance of the polyblend but it markedly sensitises the blend to thermal and photo-oxidation. An ethylene-propylene-diene terpolymer (EPDM) is rather less effective but is also not so powerful a photo-activator.     

Mechanisms of antioxidant action: Effects of rubberbound antioxidants in rubber modified polypropylene

The effect of thermal and photo-oxidation on rubber (ethylene-propylenediene terpolymer) modified polypropylene is examined and it is concluded that, although the rate of photo-oxidation increases with the amount of modifier, the rate of loss of impact resistance decreases. Antioxidants and uv stabilisers improve the oxidation resistance of the impact modified polypropylene but conventional stabilisers are removed by solvent leaching. Antioxidants bound to the EPDM through sulphur show a similar stabilising performance to commercial stabilisers before extraction but are much more effective after extraction.     

Effects of reprocessing on polymers—Part III: Photo-oxidation of polyethylene-polypropylene blends

It is shown that blends of low density polyethylene (LDPE) and polypropylene (PP) photo-oxidise more readily than LDPE alone and there was evidence of cross-linking between the two phases. An ethylene-propylene rubber (EPDM) which improved the mechanical performance of LDPE/PP blends caused an increase in the rate of photo-degradation as measured by carbonyl formation and by loss of toughness.     

Effects of reprocessing on polymers—IV: Photo-oxidation of polyethylene-polystyrene blends containing a styrene-butadiene block copolymer as solid phase dispersant

Modification of low density polyethylene-polystyrene blends by means of a solid phase dispersant (SPD: a block copolymer of styrene and butadiene) markedly improves the mechanical behaviour of the blend but also causes rapid degradation of its desirable properties in the presence of u.v. light. It is concluded that the photosensitisation of the rubber interphase is so rapid that increasing the amount of SPD cannot outweigh the effect of photosensitiser concentration.     

Mechanisms of antioxidant action: The mechanochemical attachment of sulphur-containing antioxidants to an ethylene-propylene-diene terpolymer

Sulphur-containing antioxidants are shown to react with an ethylene-propylene-diene terpolymer in a mechanochemical process. At 10% concentration, high yields of adduct are formed in the case of thiols. A sulphide reacts to a lower level.