Toxicity polymer stabilizers

The potentially beneficial properties of antioxidants have been a common subject in the popular press. Such compounds have the ability to eliminate toxic free radical species in living systems. Antioxidants are claimed to have cytoprotective properties in the inhibition of cancer, heart disease, and various skin disorders, and are often simply labeled as antiaging. There is a host of benzofuran examples in the recent literature that find application in all of these areas as potential pharmaceuticals, cosmetics, and polymer stabilizers. 

Toxic and physiological impacts of polymer stabilizers have been carefully elucidated. Pharmaco-kinetic models for determining the chemical dose delivery to die target tissue were examined and doses responsible for allergies, acute and chronic toxicities were defined [306], Information on potential irritant effects, dermatitis, mutagenicity or carcinogenicity due to amines is of prime importance. It has been estimated that about 75-80% of all human cancers are environmentally induced (30-40% of them by contaminated diet [308]). 

The main requirement imposed on all polymer biomaterials applied in medicine is a combination of their desired physicochemical and physicomechanical characteristics with biocompatibility. Depending on particular applications, the biocompatibility of polymers can include various requirements, which can sometimes be contradictory to each other. Thns, in the case of artificial vessels, drainages, intraocular lenses, biosensors, or catheters, the interaction of the polymer with a biological medium should be minimized for the rehable operation of the corresponding device after implantation. In contrast, in the majority of orthopedic applications, the active interaction and fusion of an implant with a tissne is required. General requirements imposed on all medical polymers consist in non-toxicity and stability. 

Toxicology LD50 (oral, rat) 3580 mg/kg, (skin, rabbit) > 7940 mg/kg mod. toxic by ing. low toxicity by skin contact TSCA listed Hazardous Decomp. Prods. Heated to decomp., emits toxic vapors of NOx Uses Staining antioxidant/antiozonant for rubber polymer stabilizer Manuf./Distrib. Akrochem http //www.akrochem.com] Atofina http //WWW. atofinachemicais. com] Bayer/Fi ber, Addits., Rubber http //www.bayerus.com] Crompton/Uniroyal... 

Organotin compounds are widely used as biocides, catalysts and polymer stabilizers. Very sensitive (subpart per billion detection) analytical methods are required to assess their effect on the environment. In addition, speciation information is necessary, since the toxicity of organotin compounds is strongly dependent on the number and nature of the organic substituents. 

The toxicity of commonly used polymer stabilizers and additives are classified in the following table. 

Sesamex [51-14-9] (Sesoxane) (30) is a synergist oflow toxicity, acute oral LD q (rat) = 2000 2270 mg/kg, for pyrethrins and allethrin. 6,7-Dihydroxy 4-methylcoumarin has been offered as an antioxidant for phenoHcs and polymers, and as an anthelmintic. 2,4,5-Trihydroxybutyrophenone has been available as an antioxidant and light stabilizer for polyolefins, waxes, and foods. Isoflavones, eg (31), have been patented as components of antioxidant compositions for foods and cosmetics (qv) (97). 

Articles made from polypropylene have good electrical and chemical resistance and low water absorption. Its other useful characteristics are its light weight (lowest thermoplastic polymer density), high abrasion resistance, dimensional stability, high impact strength, and no toxicity. Table 12-3 shows the properties of polypropylene. 

Another concern, is the potential reactivity of 10 as a transfer agent under polymerization conditions (see 3.3.1.1.4).103 Tetramethylsuccinonitrile (9) appears to be essentially inert under polymerization conditions. However, the compound is reported to be toxic and may be a problem in polymers used in food contact applications.1" 30 Methacrylonitrile (MAN) formed by disproportionation readily copolymerizes.7"34 The copolymerized MAN may affect the thermal stability of polymers. A suggestion103 that copolymerized MAN may be a "weak link" in PS initiated with AIBN has been disputed.14... 

Biodegradable poly(phosphoester-urethanes) containing bisglycophosphite as the chain extender were synthesized. Methylene bis-4-phenyl isocyanate (MDI) and toluene diisocyanate (TDI) were initially used as diisocyanates. Since there was a concern that the degradation products could be toxic, the ethyl 2,6-diisocyanatohexanoate (LDI) was synthesized and replaced the MDI (or TDI). The hydrolytic stability and solubility of these polymers were tested. Preliminary release studies of 5-fluorouracil from MDI based poly(phosphoester-urethane) and methotrexate from LDI based poly(phosphoester-urethane) are also reported. 

The search for synergistic mixtures of stabilizers is an on-going area of research with an emphasis on providing non-toxic additives that are nature-friendly and which are well compatible with a given polymer. 

Stabilization in water (surface tension 72 mN/m) can be achieved through the use of surfactants [77] such as SDBS [78] or sodium cholate [79], or long chain polymers such as polyvinyl alcohol. While this allows a non-toxic and easily removed solvent to be used, the presence of the surfactant or polymer molecules can be detrimental to the subsequent applications [80]. 

Shaw selected a combination of polyolefin resins as the base polymer of choice for its substitute, EcoWorx . Due to the low toxicity of its feedstocks, superior adhesion properties, dimensional stability, and its ability to be recycled, EcoWorx meets all of the design criteria necessary to satisfy the needs of the marketplace from a performance, health, and environmental standpoint. Research also indicated that the post-consumer carpet tile had a positive economic value at the end of its useful life. The cost of collection, transportation, elutriation, and return to manufacturing processes is less than the cost of using virgin raw materials. This is a truly recyclable (or Cradle to Cradle) product and is a good example of how substitution through innovation can make economic as well as environmental sense. ... 

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