Organic Stabilisers

There has been a big effort to develop different approaches to stabilisation that make more use of organic substances and completely avoid heavy metals. Many of these products were originally aimed at the pipe industry. The recent changes in Emopean legislation relating to the permissible levels of lead in water have focused attention on PVC potable water pipes. Crompton Vinyl Additives GmbH markets heavy metal-free (organic based stabilisers) 

Crompton s latest range of OBS products, known as OBS N, is aimed at flexible PVC rather than rigid, and some are intended for use in injection moulded fittings. 

Reagens SpA offers an organic-based stabiliser called Reapak TU-1626 XO, while Chemson s Naftosafe one-pack organic stabilisers for PVC pipe incorporate an organic stabiliser, a costabiliser, an acid scavenger, and internal and external lubricants. Lamberti SpA has produced organic heat stabilisers based on amino uracils. 

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M. M. Gajdarov and M. A. Tankibaev. Non-clayey drilling solution - contains organic stabiliser, caustic soda, water and mineral additive in form of zinc oxide, to improve its thermal stability. Patent RU 2051946-C, 1996. 

EXTRUSION MANUFACTURE OF PVC-O AND PVC-M PIPES WITH ORGANIC STABILISERS -THE PACIFIC PERSPECTIVE... 

Organic stabilisers are often commercially blended products which may or may... 

In summary, although the MF of coUoids is generally well understood, the literature is somewhat limited in the areas of filtration of colloids much smaller than the membrane pore size, and in systems where aggregation occurs. Systems are, in this regard, often poorly characterised, especially in the presence of humic substances. As shown in Chapter 2 organics stabilise inorganic colloids at sizes much smaller than pores, and their behaviour in MF or surface waters is largely unknown. 

Figure 5. UV irradiation on bilayers of thiol-protected gold nanoparticles formed by Langmuir-Schaeffer deposition induces oxidation of the organic stabiliser in the irradiated regions and particles aggregation, a) Micrometer-scale patterns obtained by irradiation trough a mask, image size 100 x 100 pm2, b) Nanometer-scale patterns obtained by SNP, image size 3.6 x 3.6 pm2.

The move away from lead has inspired intensive development work to produce new heavy metal-free organic stabilisers and improve the existing alternatives, notably calcium-zinc. A stabilised PVC formulation must withstand being heated and subjected to mechanical shear at the same time, because heat-induced decomposition can induce some crosslinking, increasing... 

Thus, Frye and co-workers [47] were able to provide evidence by infrared (IR) spectroscopy [46] and radiochemistry [48] of the insertion of ester groupings from barium, cadmium or zinc-carboxylates into PVC after heat treatment. Tin contents and organic residues of organotin stabilisers in heat-treated PVC are indicated by the same authors [47, 49]. Schlimper [50] and Schroder and co-workers [51] proved the direct reaction between PVC and nitrogen-containing organic stabilisers by elemental analytical examinations and infrared and UV spectrometry. Phenolic antioxidants or their decomposition products in part were re-found in PP after oxidative degradation. With rubber vulcanisates hydrochloric acid-resistant amine-rubber compounds have been reported after thermal oxidation in the presence of aromatic amines [52]. 

Organic stabilisers Kieselgel G Ethanol-free chloroform [12]... 

U.S. EPA, Silicate Technology Corporation s Solidification Stabilisation Technology for Organic and Inorganic Contaminants in S oils Applications Analysis Report, EPA/540/AR-92/010, Washington, D.C., 1992. 

Properties. Hydroxypropylcellulose [9004-64-2] (HPC) is a thermoplastic, nonionic cellulose ether that is soluble in water and in many organic solvents. HPC combines organic solvent solubiUty, thermoplasticity, and surface activity with the aqueous thickening and stabilising properties characteristic of other water-soluble ceUulosic polymers described herein. Like the methylceUuloses, HPC exhibits a low critical solution temperature in water. 

This highly conjugated molecule was stabilised with nitroxyl biradical side chains. The resulting material had sufficient ferromagnetism that a usable compass needle could be made from it. Despite the success of this demonstration, organic ferromagnetism remains a curiosity. Such polymers are not likely to replace conventional ferromagnetic metals in any application within the foreseeable future. 

A60. J. P. Candlin, K. A. Taylor, and D. T. Thompson, "Reactions of Transition-Metal Complexes. Elsevier, Amsterdam, 1968. A review of types of reactions of metal complexes (e.g., substitution, combination, redox) reactions with various reagents (e.g., hydrocarbons, halides, carbon monoxide, and isonitrile) and preparation of new stabilised organic systems (e.g., metallocenes, carbenes). Intended for research workers, consequently written at a fairly high level, with emphasis on organometallics. A61. H. J. Keller, NMR-Untersuchungen an Komplexverbindungen. Springer, Berlin, 1970. Expansion of review article 37.1. 

It is a well-known fact that specific plastic materials like flexible PVC, Polyurethane or Silicone may be easily attacked by microorganisms leading to discoloration or mechanical failures.14 This susceptibility to microbial attack is mainly attributed to the plasticiser content of the material as well as other ingredients such as stabiliser or antioxidants.5,6 The predominant organisms on the surface of those plastics are fungi and actinomycetes and it is said that by the action of their extracellular enzymes other organisms such as bacteria may be able to grow on the material.7... 

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