Medical plastics, additives

Apart from routine quality control actions, additive analysis is often called upon in relation to testing additive effectiveness as well as in connection with food packaging and medical plastics, where the identities and levels of potentially toxic substances must be accurately known and controlled. Food contact plastics are regulated by maximum concentrations allowable in the plastic, which applies to residual monomers and processing aids as well as additives [64-66]. Analytical measurements provide not only a method of quality control but also a means of establishing the loss of stabilisers as a function of material processing and product ageing. 

Also, polymer additives in medical plastics have been analysed by means of GC-MS [293]. 4,4 -Methyl-enebis(2-chloroaniline) (MBOAC), used in the polymer industry to cure urethane elastomers and epoxy resins, has been analysed in body fluids by means of GC-MS [294]. GC-MS has also been used to examine extracted PP/Triclosan (sanitiser) [243]. 

The rapid movement in the global phthalates market away from using plasticisers 2-ethylhexanol (2-EH) and diethylhexyl phthalate (DEHP) in favour of alternative products was underscored recently when BASF revealed plans to close its 2-EH and DEHP plants in Germany. The restructuring in Europe will have no effect on BASF s plasticiser portfolio in Nafta and Asia, however, where the company will continue to offer 2-EH and DEHP. About 70% of the plasticiser maiket volume is phthalates, and plasticisers make up about 60% of the plastic additives maiket. PVC accounts for 80-90% of global plasticiser consumption. In October 2003, California added DEHP to the state s list of more than 750 chemicals known to cause birth defects or reproductive harm. Previous studies had shown that the chemical can leach from plastic bags that contain intravenous fluids, blood, tube feedings or other medical treatment, and thereby enter the bodies of patients. 

Plastics Additives and Compounding 2, No.6, June 2000, p.16-21 COMPOUNDING FOR MEDICAL APPLICATIONS... 

Williams DF. 1981. The toxicology of additives in medical plastics. In Williams DF, ed. Systemic aspects of biocompatibility. Volume II. Boca Raton, FL CRC Press, Inc., 145-157. 

Hydrocarbons contain only hydrogen and carbon. The hydrocarbon functional groups include alkanes, alkenes, alkynes, and arenes (aromatic compounds). Simple hydrocarbons have few medicinal applications, but are the feedstock of the petrochemical industry to produce plastics, dyes, solvents, detergents, and adhesives (to name just a few). Therefore, hydrocarbons are essential to the medical field. Additionally, all hydrocarbons are flammable and, therefore, find application as fuels. For example, gasoline is a mixture of hydrocarbons. 

Markarian J. Slip and antiblock additives surface medication for film and sheet. Plastics Addit Compound [trade journal—Elsevier Ltd.) November/... 

Calcium-zinc stabilisers are rated as relatively nontoxic and are favoured for use in medical plastics, toys and food contact applications. They can be formulated as one-pack systems along with other additives to minimise handling problems. They normally have a self-lubricating role... 

The properties of the piezocomposite material mentioned above offer special benefits when the transducer is coupled to a material of low acoustic impedance. This especially applies to probes having plastic delay lines or wedges and to immersion and medical probes. These probes with piezocomposite elements can be designed to have not only a high sensitivity but also at the same time an excellent resolution and, in addition, the effort required for the probe s mechanical damping can be reduced. 

In the field of plastics, the annual production of polyvinylchloride (PVC) is second only to polyethylene. PVC has long been used in various areas, ranging from agriculture and industry to medical equipment and daily life, due to its well-developed production techniques, easy processing, and low price. However, PVC has its own disadvantages, mainly its low stability toward heat and ultraviolet (UV) light. Also, pure PVC is a very hard material that cannot be easily processed and practically used. Common PVC plastics contain various amounts of plasticizers and other additives, including modifiers, stabilizers, and lubricants. 

The quality control of PVC, plasticizers, and additives must be done according to certain standards. In the case of making the blending material for medical uses, medical grade PVC, which contains <3 ppm vinylchloride monomers, should be used. 

Plastics continue to make inroads regarding medical applications. Certain plastics have been found to exist in the environment of living tissues. In addition to being of direct aid in medicine, they are also important in medical devices and packaging medical items. 

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