Polyolefin heat ageing

Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of SOx and NOx Uses UV stabilizer, antioxidant, antiozonant, accelerator, peptizing agent for synthetic rubbers, polyolefins heat-aging inhibitor for neoprene/chlorosulfonated polyethylene Manuf./Distrib. ChemService http //www. chemservice. com Trade Name Synonyms Akrochem Antiozonant NiBud [Akrochem http //www.akrochem.com], Ekaland NDBC [Sovereign http //www.sovereignchemical.com], Naugard NBC [Crompton/Uniroyal http //www.cromptoncorp.com], NDBC... 

The effect of heat ageing on a polyolefin, as on modified polystyrene, is considerably influenced by particular pigment lakes. Heavy metal ions, especially copper,... 

Another extrusion-grade polyamide blend is a reactively compatibihzed PA6/polyolefin (PP or LDPE) alloy with some additional olefinic elastomer present for lowering the modulus (Jacquemet et al. 2000). Such low-modulus PA blends (Orgalloy LT series, Arkema) have been qualified for use in automotive under-the-hood air-intake systems such as clean air tubes and ducts. Low density, high chemical resistance to oil and greases, heat-age resistance, fatigue, and vibration resistance have been the main criteria for the selection of this blend in automotive air-intake duct applications. 

Great Lakes has introduced antioxidants with improved hydrolysis resistance for use in polyolefins, styrenics, PVC and the polyesters. One of the key components of the blends is Alkanox P-24, a solid organophosphite. A new phenolic antioxidant called Anox 330 is intended for long-term protection against heat ageing. It is recommended as an extraction-resistant additive for use in water pipes. 

A high molecular weight, multifunctional phenolic antioxidant for improving processing stability and long term heat aging in a variety of polyaers. Specific applications include styrenics, polyolefins, PVC, urethanes, acrylics, adhesives and elastMters. 

It is noteworthy that the products thus prepared possess remarkable physico-chemieal properties (glass transition point mechanical, electrical, and optical characteristics), as evidenced by exeellent transpareney, good moldability, and high resistance to heat, aging, solvents, and weathering. Furthermore, they are eompatible with many polymers, ineluding polyesters, polyearbonates, polyamides, and polyolefins, and find broad application in the manufactme of optical devices, photo disks, circuit boards for crystalline liquids, printed circuit boards, special electrical and electronic devices, and so on. 

Procedures that may be used to mimie heat ageing during eomposting and outdoor weathering inelude eonventional forced-air ovens and xenon arc weatherometers. Polyolefins treated in this way have been found to generate CO2 to over 60% of theoretical carbon dioxide formation in 18 months to two years in the presence of mature compost." Similarly, inoeulation with soil gives a similar result after two years (see section 12.6.3). 

In the past few decades, piperidine-based sterically hindered amine stabilizers (HA(L)S) gained attention as heat stabilizers for polyolefins at low and moderate temperatures below about 120 °C. It was ascertained that the degradation behavior of polymers, particularly of polyolefins stabilized with HA(L)S, differs significantly from that of phenol-stabilized polyolefins at aging temperatures ranging from T = 100 to 150 °C. 

Polyolefin is used for an insulating material in the electric cable which is used in nuclear power plants. The electric cable is exposed to radiation and heat simnltane-ously during the service condition. Dose was estimated to be 500 kGy over 40 years service time [3, 4]. IEEE standards 323-1974 [3] and 323-1978 [4] have provided guides for class IE equipment and electrical type testing. The standards recommend the sequential addition of radiation and heat instead of simultaneons addition, because the sequential method is practically convenient as a test method. In this article, the effect of pre-irradiation of polyolefin on its thermal aging was also studied. 

When the polyolefin was exposed to heat after irradiation, the heat-resistant properties are affected by the iiradiation. Figure 8.18 shows the effect of pre-irradiation on weight change of LLDPE by thermal aging at 150 °C. Dose of pre-irradiation was 320 kGy. 

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