Polymer polyvinyl chloride , contact

While not mandatory from regulatory guidehnes, much research has been carried out to investigate the extractability of plastic additives in contact with a variety of pharmaceutical formulations, mainly those for parenteral use. The research concentrates on the extractability of plasticizer phthalates, mainly di-2-ethylhexylphthalate (DEHP) from polyvinyl chloride (PVC) into the blood, blood components, and infusion solutions. The purpose for these studies lies in its, up to now, controversial hazardous effects on humans. The amount of additive necessary to turn rigid PVC into a flexible material (40% m/m) and the absence of chemical bonds between the polymer and the plasticizer make it a potentially extractable species. 

Vinyl chloride can be polymerised to form polyvinyl chloride (PVC) which is fairly brittle and unsuitable for food contact applications, so it is mixed with plasticisers to soften the polymer and impart flexibility. Plasticised PVC may contain about 30% of plasticisers and is used to make stretch films and flexible PVC. Flexible PVC used for tubing and gaskets may contain di(2-ethylhexyl)phthalate, and stretch films will probably contain di(2-ethylhexyl)adipate and a polymeric adipate plasticiser. Rigid PVC may... 

A different type of experiment was performed by Laurence et al. with a pair of compatible polymers A + B (where A is polyvinyl chloride and B is polycaprolactone). To their surprise, they found D N rather than D N. In fact, their results are quite normal (de Gennes, 1982) the mixture /1 + B is not ideal (in contrast with the experiments discussed previously). A molecule of type A prefers to be in contact with molecules of type B. Thus, a region which is rich in A can be more readily reached by B molecules than in an ideal mixture. When we include these thermodynamic effects, we get exactly D N. Similar changes are possible when studying the adhesion of two polymers A and B (de Gennes, 1982). 

An alkyl-aryl phosphite which is used as a color and processing stabilizer in polycarbonate, polyurethanes, ABS polymers, and coatings where regulatory approval for food contact is not required. It is also used as a secondary stabilizer in polyvinyl chloride. 

The effect of UV radiation in air on the wettability of thin films of polyvinyl chloride (Fig. 10.106) poly(methyl methacrylate), poly(n-butyl methacrylate), poly(ethylene terephthalate) and polystyrene (Fig. 10.107) show that the changes in contact angle for various liquids with irradiation time are a function of the nature of the polymer [667]. 

X-ray fluorescence (XRF) sorting is especially usefirl for sorting polyethene terephthalate (PET) from polyvinyl chloride (PVC). This is essential if the PET is to ultimately be used for food contact applications, and desirable in most other applications, since under the conditions used for PET recycling the PVC would partially degrade and be seen as black specks in the final product. When bombarded with X-rays, polymers containing heavy atoms such as chlorine emit a readily detectable X-ray signal. This signal can be used to control an air jet separation system similar to the one described above. 

---