Stabilisers in plastics

Before MPW is fed into the process, a basic separation of the non-plastic fraction and size reduction is needed. This prepared feedstock is then introduced in the heated fluidised bed reactor which forms the core of the process. The reactor operates at approximately 500 °C in the absence of air. At this temperature, thermal cracking of the plastics occurs. The resulting hydrocarbons vapourise and leave the bed with the fluidising gas. Solid particles, mainly impurities formed from, e.g., stabilisers in plastics, as well as some coke formed in the process mainly accumulate in the bed. Another fraction is blown out with the hot gas and captured in a cyclone. 

Organotin compounds are used as stabilisers in plastics, especially PVC, and the organotin TBT is used as a treatment against mould in some floor coverings. 

Tin is widely distributed in nature at low concentrations in plants, both marine and land, and animals. It has extensive uses in industry, where organotin compounds are used as heat stabilisers in plastics, salts in glazes in porcelain and oxide coatings used to reduce abrasion of glass containers. The main source of tin in the diet is from tin-plated steel used in the manufacture of cans for foods and beverages. 

Pospisil, J. Horak, Z. Pilar, J. Nespiirek, S. Billingham, N.C. Habicher, W.D. Effect of testing conditions on performance and durability of stabilisers in plastics. Polym. Polym. Compos. 2003, 11, 81-89. 

E Gugumus and H. Zweifel (Ed.), Light Stabilisers in Plastic Additives Handbook, 5th edition, Hanser Publisher, Munich, 2001, pp. 141 125. 

Chalcones are important intermediates in the synthesis of flavanoids and are used industrially in bactericides, antibiotic drugs and UV-stabilisers in plastics. Other base catalysts such as magnesium /-butoxide and barium hydroxides have been used to perform the synthesis.31 However, the Cs+-exchanged zeolites offer a more environmentally friendly alternative route. 

The EU initiated studies to control and stop completely the use of lead stabilisers in plastics by the year 2015. 

Details A powdery solid, used as an antioxidant and stabiliser in plastics packaging materials and in rubber. 

The EU put forward following key milestones as regards to control and diminishing the use of lead stabilisers in plastics by the year 2004, completion of initial risk assessment on lead stabilisers will be accomplished by 2005 15% (to reach 100 Kt), and by 2010 50% rednction target of their use (reaching 60 Kt), and by 2015, it will be 100% off for use of lead stabilisers [33]. 

Simpson and Currell [32] use TEC in the determination of additives such as antioxidants (also UV absorbers and organotin stabilisers) in plastic formulations. Comparatively small samples of the plastics materials are required, and, by means of the techniques described, it is... 

TLC has been used extensively for the determination of phenolic and amine antioxidants and UV stabilisers in plastics and rubber [17, 32, 36-58]. 

Gugumus F.. In Zweifel H, editor. Light stabilisers in plastic additives handbook. 5th ed. Munich Hanser Publisher 2001. p. 141 25. 

Freitag and John [96] studied rapid separation of stabilisers from plastics. Fairly quantitative extraction (>90% of the expected content) of stabilisers from a powdered polymer was achieved by MAE within 3 to 6 min, as compared to 16 h of Soxhlet extraction for the same recovery. MAE and Soxhlet extraction have also been compared in the analysis of cyclic trimer in PET [113]. On the other hand, Ganzler et al. [128] compared the extraction yields for various types of compounds from nonpolymeric matrices for microwave irradiation with those obtained by the traditional Soxhlet or shake-flask extraction methods. Microwave extraction was more effective than the conventional methods, in particular in the case of polar compounds. As expected, the efficiency of the former is high especially when the extraction solvents contain water. With the high dipole moment of water, microwave heating is more... 

Applications Conventional TLC was the most successful separation technique in the 1960s and early 1970s for identification of components in plastics. Amos [409] has published a comprehensive review on the use of TLC for various additive types (antioxidants, stabilisers, plasticisers, curing agents, antistatic agents, peroxides) in polymers and rubber vulcanisates (1973 status). More recently, Freitag [429] has reviewed TLC applications in additive analysis. TLC has been extensively applied to the determination of additives in polymer extracts [444,445]. 

NMR spectroscopy is most effective in qualitative analysis when the samples examinated are substantially pure compounds and has been used to confirm the theoretically predicted low-energy conformations of the Af-acylated hindered amine light stabiliser Tinuvin 440 [210]. Trace amounts of PDMS (quantification limit 0.1 ppm) in plastic additives, dyes and pigments were determined by 111 NMR after Soxhlet extraction [211]. ll NMR was also used for the detection of octadecanol, an impurity in Irganox PS 802 (3,3 -dioctadecyl thiodipropionate). NMR has identified the nature of a supposedly UV stabiliser of empirical formula C17H18N3CIO [44] (Scheme 5.2). 

For samples that meet the solubility requirements of the SEC approach, analyses were also reported for additives in polymers such as PVC and PS [28,29]. Direct SEC analysis of PVC additives such as plasticisers and thermal stabilisers in dissolution mode has been described [28,30,31 ]. In the analysis of a dissolved PS sample using a SEC column of narrow pore size, the group of additives was separated on a normal-phase column after elution of the polymer peak [21]. Column-loading capacity of HPSEC for the analysis of additives, their degradation products and any other low-MW compounds present in plastics has been evaluated for PS/HMBT, PVC/TNPP and PVC/TETO (glyceryl tri[l-14C] epoxyoleate) [31]. It was shown that HPSEC can be used to separate low-MW compounds from relatively large amounts of polymers without serious loss of resolution of the additives the technique has also been used for the group analysis of chlorohydrin transformation products of the TETO model compound [32]. 

Large quantities are used as a raw material in the chemical process industry, especially for urea across C02 reaction with NH3 and later dehydration of the formed carbamate. Urea is the product most used as agricultural fertiliser. It is used in feed for ruminants, as carbon cellulose explosives stabiliser in the manufacture of resins and also for thermosetting plastic products, among others. 

Three Ciba HALS stabilisers are currently approved for use in plastic food-contact materials in Europe (Directive 2002/72/EC, Plastic materials and articles used in contact with food.) These are Chimassorb 944, Tinuvin 622 and Chimassorb 2020. Their chemical structures are given in Figures 31-33, respectively. 

Organo-tin compounds have been used as catalysts, stabilisers for plastics and biocides. Tributyltin (TBT) species are very effective biocides, and have been incorporated as active agents in antifouling compounds for marine applications. However, TBT has seriously affected other marine organisms such as oysters, crabs and fish even at parts per billion and lower concentrations in water. Consequendy, the determinations of low levels of TBT and dibutyl tin (DBT), its less toxic primary degradation product in water and in biological materials, are very important. 

Here we report the use of a readily prepared polymer immobilised TEMPO as a catalyst for alcohol oxidations.15 It was derived from a commercially available oligomeric, sterically hindered amine, poly[[6-[(l,l,3,3-tetramethylbutyl)amino]-l,3,5-triazine-2,4-diyl] [2,2,6,6-teramethyl-4-piperidinyl)-imino]-1,6-hexane-diyl[(2,2,6,6-tetramethyl-4-piperidinylimino]], better known as Chimassorb 944 (MW 3000 see figure 3 for structure). This compound is used as an antioxidant and a light stabiliser for plastics. It contributes significantly to the long-term heat stability of polyolefins and has broad approval for use in polyolefin food packaging.16... 

Cellulose nitrate in combination (gelation) with nitrate esters of polyols (plus - Stabilisers and plasticizers), e.g. NC/NGL (-> Nitroglycerine) or NC/EDDN (- Ethylenediamine dinitrate). 

Tests conducted for the Drinking Water Inspectorate show that some PVC pipes cause breaches of a new standard for lead due to be introduced in 2003. The failures are due to the use of lead salts to stabilise the plastic, and the DWI has warned pipe manufacturers that they must reformulate their products. 

Adhesives Organic and inorganic bases Coolants Cleaners colorants (pigments and dyes) Fragrances Inks Paints Plasticisers (e.g., in plastics) Polymers (rubbers and plastics) Sealants Solvents Stabilisers Synthetic fibres Varnishes Biocides Detergents Fertilisers Fuels Foodstuff additives and flavourings to foodstuffs Medicinal products (for humans and animals) Plant protection products Radioactive substances... 

Table 4.3 Random selection of metal salts used as organometallic stabilisers, UV absorbers, catalyst, colorants, etc., in plastics...

Plastic composition consists mainly of a combination of polymer, stabiliser(s), plasticisers, colorants and fillers. Metals in plastics usually occur in such substances as... 

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