Generation Mechanism of Oxidation Products during the Air Atmosphere Oxidation of SEBS/PP Blends: Tracked by 2D Correlation Infrared Spectroscopy

Abstract

In this paper, the generation mechanism of oxidation products during the oxidation of the polystyrene‐block‐poly(ethylene‐co‐1‐butene)‐block‐polystyrene copolymer (SEBS)/poly(propylene) (PP) blend in air atmosphere is investigated using temperature‐dependent FTIR combined with 2D correlation infrared spectroscopy. Differential scanning calorimetry, thermogravimetric analysis, and perturbation‐correlation moving‐window 2D correlation FTIR spectroscopy find three processes associated with SEBS/PP oxidative degradation. The 2D correlation analysis is used to study the sequential order of groups' movement of reactants and oxidation products involved in the main oxidation. It is found that the main oxidation starts from the molecular chains of PP and EB blocks of SEBS. It firstly forms COC structure between the molecular chains of PP and the EB blocks, resulting in the cross‐linked structure. Aliphatic ketones are formed via the β‐scission of the main chains of PP or the EB blocks. Then, aliphatic ketones are converted into aliphatic esters. After the above reactions, the S blocks of SEBS begin to oxidize. The S blocks are generated into aromatic ketones through β‐scission. The formation of lactones in the molecular chains of PP and EB blocks is followed via the radical biting back. Finally, aromatic ketones generated from the S blocks are converted into aromatic esters through the reactions of Norrish I, the radical coupling, and so on.

Surface Studies of UV Irradiated Polypropylene Films Modified with Mineral Fillers Designed as Piezoelectric Materials

“…The broad band in the region of stretching hydroxyl/hydroperoxides bonds vibrations indicates the existence of hydrogen bonded OH/OOH groups present in alcohols and carboxylic acids, which are the product of photooxidation of the polymer. [12,14,41,44]. In the carbonyl band, one can distinguish a maximum at about 1718 cm −1 and shoulders at 1770 and 1645 cm −1 .…”

“…The position of the main maximum indicates the presence of ketone groups, the shoulder at higher wavenumbers suggests the existence of peroxyesters, peroxyacids, or lactones [10,12,15,44,45]. The shoulder at 1645 cm −1 indicates the presence of unsaturated polymer chain ends [8,26,41,44,46]. These oxygen-containing products were created during the photooxidation of the polymer, the unsaturated groups could be formed as a result of Norrish type II reactions [8,41,42,44].…”

“…The shoulder at 1645 cm −1 indicates the presence of unsaturated polymer chain ends [8,26,41,44,46]. These oxygen-containing products were created during the photooxidation of the polymer, the unsaturated groups could be formed as a result of Norrish type II reactions [8,41,42,44]. This type of the reaction requires space which is created by increasing the free volume of the polymer after adding the fillers and after orientation.…”

“…The intensity of these bands increased with UV irradiation time, however, a quantitative analysis revealed only slight differences between the samples. The third region attributed to stretching C-O bond vibrations is indicative of the presence of oxidized products, such as alcohols, acids, ethers, esters, and lactones [10,41,44].…”

Influence of extender oil composition on flowing property, thermal stability, and morphology of styrene‐b‐ethylene‐co‐butylene‐b‐styrene copolymer/polypropylene/oil blends

“…There has been a mature system for modification of SEBS, in which polypropylene (PP) is the most used modify resin for SEBS, as the stable cocontinuous interpenetrating polymer network (IPN) structure could be found in SEBS/PP blends with PP weight content range from 10% to 55%, this can be ascribed to the good miscibility of PP with EB phase while immiscibility with PS phase . Typically, the addition of PP improves the modulus and tensile strength, while decreases the tensile strain of SEBS.…”