Polyolefins degradation during

Ethanox 376 is a stabilizer that provides heat stability by preventing thermo-oxidative degradation during processing and service life. It provides compatibility with resins and extraction resistance. It can be applied in polyolefins, such as polyethylene, polypropylene, polybutene-1 and other polymers such as engineering plastics, styrenes, polyurethanes, saturated and unsaturated elastomers, styrenics, rubber modified styrenics, segmented block copolymers, and PVC. 

The formation of compatibilizer frequently occurs by interfacial reaction of the modified polymers. An example is the use of maleic anhydride grafted to a polyolefin elastomer (EPM/EPM-g-MA) as the interfacial additive for reactive blending with a polyamide, nylon-6 (Van Duin et al., 2001), in a twin-screw extruder. It was found that the consumption of MA occurred rapidly and different blend morphologies were produced. However, it was found that the nylon-6 degraded during processing, due to the reaction of anhydride with the... 

The hypothetical life trajectory of the polyolefin product is depicted in Scheme 12.1. Its characteristic feature is the existence of the so-called induction period of degradation during which the material properties change insigruficantly and are rather similar to those in the point A in Scheme 12.1. The time lag AB (induction period) of this interval depends on the efficiency of the polyolefin stabilization. In point B, the protection effect of polymer stabilizers is ended due to the permanent initiation attack and the product properties start to deteriorate. Point C designates the failure of the product, and its further utilization becomes impossible. 

Transition metal ions by themselves, for example in the form of stearates or acetyl acetonates (I), have also been widely used to catalyse the photooxidation of polyolefins. Whilst they are very effective in this respect, they again cause degradation during processing and storage unless used with a metal restraining agent [32, 33] (see below). 

Phenolic antioxidants that are used to protect polyolefins for degradation during processing, and HA(L)S stabilizers can show synergisms as well as antagonisms [199-201]. The largest synergism was observed for combinations with PAO-1 [2(X),201]. 

ColtelliMB BS, Aglietto M. Poly(ethylene terephthalate) (PET) degradation during the Zn catalysed transesteiification with dibutyl maleate functionalized polyolefins. Polymer 2007 48 1276-1286. 

A WBL can also be formed within the silicone phase but near the surface and caused by insufficiently crosslinked adhesive. This may result from an interference of the cure chemistry by species on the surface of substrate. An example where incompatibility between the substrate and the cure system can exist is the moisture cure condensation system. Acetic acid is released during the cure, and for substrates like concrete, the acid may form water-soluble salts at the interface. These salts create a weak boundary layer that will induce failure on exposure to rain. The CDT of polyolefins illustrates the direct effect of surface pretreatment and subsequent formation of a WBL by degradation of the polymer surface [72,73]. 

---