Polyolefin processing stabilizers

Spivack J D, Pastor S D, Patel A and Steihuebel L D (1985) Bis- and trisphosphites having dioxapho-sphepin and dioxaphosphocin rings as polyolefin processing stabilizers, In Polymer stabilization and degradation, Klemchuk P (Ed), ACS Symp Ser 280 247-257. 

Bis- and Trisphosphites Having Dioxaphosphepin and Dioxaphosphocin Rings as Polyolefin-Processing Stabilizers... 

Poly(hydrosilane)s have been successfully applied as processing stabilizers for organic polymeric materials subject to oxidative degradation. The degradation of polyolefins during processing takes place by a widely accepted... 

Selected Novel Trivalent Organophosphorus Processing Stabilizers for Polyolefins... 

Hindered phenols and dialkylhydroxylamines protect plastics against thermal oxidation. Alkylated benzo[b]furane-2(3H)-ones was introduced very recently as a processing stabilizer for polyolefins. 

Secondary liquid phosphite antioxidant that functions as a peroxide decomposer and as a processing stabilizer in a wide variety of polymers, including polyolefins and styrenics. 

Figure 2 - Processing Stabilizers and Antioxidants used in Polyolefin Testing...

Comparative Effectiveness of Experimental Processing Stabilizers in Polyolefins... 

Ethylidene bis(4,6-di-t-butylphenol), 2,2 -Ethylidenebis(4,6-di-t-butylphenol)i EINECS 252-816-3 Phenol, 2,2 -ethylidenebis(4,6-bis(1,1-dimethyl-ethyl)- Vanox 1290, Antioxidant oxidative inhibitor for polymers process stabilizer for polyolefins stabilizer for PU and PS, Crystals mp 162-164°, Vanderbilt R.T. Co. Inc. 

The latter is confirmed by the fact that the reaction proceeds with no loss of efficiency when performed in the presence of radical traps, or the thermal stabilizers usually used in polyolefin processing operations (38-45). The low grafting yield was obtained, both in terms of the number of bonded polar groups and of conversion levels. However, the experimental evidence reveals higher grafting yields obtained when the process occur in the melt rather than in solution (38,40,45). Scheme 13.2 once particularized for the molten state reaction media (46) drive us to the following. 

The investigation of the compatibilization and crystallization of blends of polyolefins with a semiflexible LCP leads to the following conclusions the compatibilization of polyolefin/LCP blends has been realized successfully by the addition of ad hoc synthesized polyolefin-g-LCP copolymers. The compatibilization results into materials, characterized by a stabilized morphology, improved crystallization kinetics under nonisothermal and isothermal conditions, and enhanced mechanical properties. Moreover, polyolefin processability has been enhanced by the addition of LCP, even in the presence of compatibilizers. New high quality materials with improved processability have been produced by technologies, which are economic, friendly to the environment, and socially acceptable. 

Low-density polyethylene (LDPE) is extensively used for the manufacture of films. During processing, which is carried out at temperatures of approximately 200°C, cross-Unking, and thus formation of gel, can occur through oxidation if the polymer is not stabilized. Such gel particles are visible in the film as agglomerates, known as fish eyes or arrow heads. The processing stabilizers used in LDPE consist of systems commonly used for polypropylene, namely, combinations of a phosphite or phosphonite and a long-term heat stabilizer (hindered phenol) in overall concentrations up to 0.1%. Concentrations seldom exceed 0.1%, since the compatibility of any additive in LDPE is considerably lower than in any other polyolefins. 

Chem. Descrip. Trisnonylphenyl phosphite CAS 26523-78-4 EINECS/ELINCS 247-759-6 Uses Processing stabilizer, heat stabilizer for polyolefins, acrylics, adhesives, elastomers, nylon, PC, PU, PS, PVC, coatings, ABS, and PET, food-contact pkg., m lcal devices, color-critical polyolefins, sfyrene block copolymers... 

Uses Effective processing stabilizer, sec. antioxidant for polymers incl. filled polyolefins, ABS, PS, polybutylene, PBT, PC, thermoplastic polyester, nitrile barrier resins, and fibers peroxide decomposer for plastics mfg. reduces equipment corrosion in flame-retardant applies. antioxidant and color suppressant for powd. coatings antioxidant, stabilizer for food-grade polymers... 

Uses Lt. stabilizer for PP, ABS, PS, nylon, LDPE, LLDPE, HOPE, acrylics, PC, thermoplastic polyester, SAN, thermoplastic elastomers, surf, coatings, suitable for thin films, fibers, or molded parts Features Esp. effective in polyolefins for outstanding heat and processing stability use with UV-Chek AM-340 Properties Lt. amber micro-pastille very sol. in aromatic hydrocarbons, ketones, esters, some alcohols very low sol. in aliphatic hydrocarbons and water misc. with methylene, methylene chloride m.w. > 2400 sp.gr. 1.03 bulk dens. 5.8 Ib/gal soften, pt. 100 C min. 

Uses Lt. stabilizer for plastics, surf, coatings esp. effective in polyolefins for outstanding heat and processing stability Trade Names UV-Chek AM-806... 

Figure 11.1 shows a collection of FTIR spectra through the thickness of a shelf-aged, EtO-sterilized cup where bulk oxidation was evident. Gamma irradiation of the UHMWPE was ruled out by examination of the transvinylene region of the ETIR spectra. The absorption at 1718 cm i is attributed to ketones. In this case, the oxidation was associated with poor consolidation of the UHMWPE, rather than the result of the sterilization process itself. These results suggest that prosthetic UHMWPE needs stabilization, as the totality of commercial polyolefines. Biocompatible stabilizers, such as vitamin E (an a-tocopherol), are easily available on the market and already employed in a number of different applications (Costa et al. 1998b, Costa et al. 2000). 

As it is known, polymers are not used without addional stabilization. As polyolefin s stabilizers particularly for HDPE various phenols with tretbutul substitutes are often used. One of them is lrganox-1010 (Swiss production). In this connection one of purposes of our testing was the comparison of influence character of phosphoroorganic polymer and lrganox-1010 on Mw change with multiple processing of HDPE. 

Blends of primary anti-oxidants and a high-temperature hydrolytically stable organophosphite secondary anti-oxidant have been developed for high-temperature processing of polyolefins, polyamides, and polycarbonates in colour-critical applications. Irganox LM blends of primary anti-oxidants and a new phosphite processing stabilizer offer melting at 90°C and can be applied to polymer reactor products, especially polyolefins, linear polyesters, polycarbonates, polyamides, HIPS, ABS, SAN, and elastomers. 

Description Thioethers (long-term stability of polyolefins) phosphite/phosphonite (superior processing stability) both with phenolic antioxidants ... 

In practical application, it is reasonable to use more than one type of antioxidant in order to meet the requirements of the application, snch as melt-processing stability as well as long-term thermal stability. The most common combination of stabilizers used, particularly in polyolefins, are blends of a phenolic antioxidant and a phosphite melt-processing stabilizer. Another common combination is a blend of a phenolic antioxidant and a thioester, especially for applications that require long-term thermal stability. These common phenol-based blends have been used successfully in many different types of end-nse applications. The combination of phenolic, phosphite, and lactone moieties represents an extremely efficient stabilization system since all three components provide a specific fimction. 

Studies on vitamin E in polymers have demonstrated its high antioxid-ancy in different polymers, especially as a melt-processing stabilizer in polyolefins (119,179-186). Figure 6 shows the superior performance of vitamin E when compared to Irganox 1010 during melt extrusion of PE and PP at all concentrations and, in particular, at very low concentrations. Vitamin E can, therefore, be... 

Drake, W.O. Franz, T Hofmann, P. and Sitek, F. (1991) The Role of Processing Stabilizer in Recycling of Polyolefins, Presentation, Davos Recycle 91, Davos. 

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