Extraction resistance

Extraction of metal ions Extraction processes Extraction resistance Extractive distillation... 

Plasticizers. About 2.5% of U.S. adipic acid consumed in 1988 was used in two basic types of adipic ester based plasticizers (195). Simple adipate esters prepared from Cg—alcohols are used especially as PVC plasticizers (qv). Eor special appHcations requiring low volatility or extraction resistance, polyester derivatives of diols or polyols are preferred. 

Chlorinated polyethylene CPEs provide a very wide range of properties from soft/ elastomeric to hard. They have inherent oxygen and ozone resistance, have improved resistance (compared to PEs) to chemical extraction, resist plasticizers, volatility, and weathering. Products do not fog at high temperatures as do PVCs and can be made flame retardant. 

Various additives show considerable extraction resistance, such as impact modifiers (polyacrylates and polyblends PVC/EVA, PVC/ABS, etc.), highpolymeric processing aids (PMMA-based), elastomers as high-MW plasticisers, reactive flame retardants (e.g. tetrabromobisphenol-A, tetrabromophthalic anhydride, tetrabromophthalate diol, dibromostyrene). Direct measurement of additives by UV and IR spectroscopy of moulded films is particularly useful in analysing for additives that are difficult to extract, although in such cases the calibration of standards may present a problem and interferences from other additives are possible. 

Figure 3.24 Extraction resistance for graftable Silanox. , Anox 20 , Anox PP18 , Silanox (as shown in Figure 3.22) O, Silanox graft n/m = 5. After Gray and Lee [144]. Reproduced by permission of Blackwell Science...

High-MW hindered amine thermal stabiliser (HATS) formulations are designed for advanced extraction resistant long-term stabilisation, i.e. for use in extractive environments such as polyolefin pipes, fulfilling the stringent requirement of guaranteeing product lifetime of more than 50 years [565], These systems offer much better gas and hot water resistance than the low-MW phenolic antioxidant systems. Ethanox 330... 

The commercial evolution of hindered amine stabilisers is best illustrated by the sequence of the monomeric Tinuvin 770, oligomeric Tinuvin 622, Chimassorb 944 and Chimassorb 119, and most recently Chimassorb 2020 (Figure 3.25) with increased control on volatility, migration, extractability and co-additive interactions [597]. The hindered amine thermal stabilisers Chimassorb 944 and Chimassorb 119, outperform Cyasorb UV3346 as to extraction resistance [565]. 

The evolution of HALS technology to meet the requirements of emerging polyolefin markets and applications is a story of continuous improvement and structure/property optimisation [19-21], Current trends in the industry are toward low-volatility, extraction-resistant, hindered phenolic AOs, such as oligomeric polysiloxane based, high-MW antioxidants... 

Pigments for plastic articles, e.g. films, that are used for packaging food or cosmetics must be not only migrationfast and extraction-resistant but also physiologically safe. Furthermore, a number of countries have different regulations that contain specific purity requirements. 

Cronin and Hay 1996c Dictyota ciliolata Dictyotales Young (high) Old (low) No Lipophilic extracts Resistance... 

The gel block has been found useful for organized investigations of the type discussed here and for technical service work or works study on fixed formulations chosen for their ultimate properties—for example, low temperature flexibility and extraction resistance. 

The use of trimellitates is expected to regain ground lost due to TMA shortages in the late seventies. Polymeries will continue to be used in those areas where high solvent extraction resistance and migration are major concerns. Phosphates are expected to continue their growth in flame retardant applications. Also, new capacity for dioctyl terephthalate (DOTP) has been announced(25). 

Figure I. Water-extraction resistance test with treated boiling water using 25-mil samples at 125°C.

Some applications require materials which are continuously or intermittently in contact with aqueous systems. Therefore, it is desirable to evaluate resins in a simulated test to determine water-extraction resistance (3). A commonly used test is the so-called seven-day boiling water test. Samples of 25-mil thickness were treated with boiling water for four and seven days (water changed daily) and then exposed in a circulating air oven at 125 °C. The relative stabilities are shown in Figure 1. The data... 

Stain resistance of resilient sheet flooring has been related to the plasticiser, wear layer toughness and thermoplastic nature. The plasticiser structure, level, extraction resistance, volatility and solubility all have an influence (389). 

For applications requiring high temperature and extraction resistance, polymeric esters are used (88). New polymeric plasticisers are in development (87) including adipate based for improved low temperature properties (103). Plastisols based on propyleneglycol adipate have been examined (198) and the thermal degradation has been determined using dynamic and isothermal thermogravimetric analysis (188). 

Stain resistance, or more accurately appearance retention, is a complex phenomenon in resilient sheet flooring applications. The process can be complex involving the plasticiser, the overall toughness (or abrasion resistance) of the wear layer and the thermoplastic nature of plasticised PVC. The plasticiser-related portions of the stain resistance phenomenon are explored. Data are presented to illustrate relationships between stain resistance and plasticiser structure, concentration, extraction resistance, volatility and solubility parameter. 9 refs. 

Used for polyurethane, polypropylene, polyester and polyamide fibers where it provides gas fading resistance at low load levels. In addition, the molecular structure and the relatively high molecular weight results in a high extraction resistance in demanding applications like hot water conducting polypropylene pipes. 

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. 

Simulants used for extraction procedures for foodstuffs include distilled water and aqueous solution of ethyl alcohol, or rectified olive oil. Under the EC global migration proposals, extraction is limited to either 60 ppm or 10 mg/dm2, see EEC 90/ 128 plus amendments. Extraction resistance see ASTM F-34 and USPXXIII. 

A variety of factors, including compounding or processing conditions, end use, and expected performance, should influence the selection of an appropriate antioxidant system. These factors include compatibility with the polymer and other additives or components, antioxidant mobility and volatility, discoloration, resistance to hydrolysis, extraction resistance, radical trapping efficiency, toxicity, and cost-effectiveness. 

HALS-9 -1- UVA-4 see above Cyasorb THT 4611 Long-term protection, efficient, low-color, extraction-resistant... 

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