Pregledni rad
Suspension grade poly(vinyl chloride) and hazards of its production
Tonka KOVAČIĆ
; Kemijsko-tehnološki fakultet, Sveučilište u Splitu
Branka ANDRIČIĆ
orcid.org/0000-0001-6080-7840
; Kemijsko-tehnološki fakultet, Sveučilište u Splitu
Sažetak
Poly(vinyl chloride) (PVC) has, for more than 70 years been one of the most important polymers, with a worldwide capacity of about 20 % of the total plastic production. Despite all technical and economic problems on the production of PVC and public debates about the ecology and environmental hazards of PVC production and use, and chlorine chemistry, in general, PVC production worldwide grows at the rate of more than 9 % per year.1 PVC is obtained by free-radical polymerizations of vinyl chloride (VC) in suspension, emulsion or in bulk. Worldwide, 80 % of total PVC production is obtained by suspension polymerization, 20 % by emulsion polymerization and 8 % by bulk polymerization. In suspension polymerization the monomer, liquid VC, is mechanically dispersed in water and polymerized by monomer-soluble initiator in the presence of protective colloid. The process is carried out in a batch reactor, in a closed system. From the environmental viewpoint, modern suspension polymerization is strained with a relatively small number of problems. Among them, the most important is monomer cancerogenity, as published in 1973. Very soon, the technologists, physicians and scientists were engaged and new technological solutions were found, which eliminated monomer emission during the technological process, exposure of workers to VC, as well as the danger of high residual monomer concentration in the polymer. The maximum allowed concentrations of VC were also defined. Modern technology, using degassing and recovery of excess vinyl chloride, demonomerization of polymer suspension, waste water treatment and good process control, enable safe plant operation and use of PVC in food and pharmaceutical industry and medicine.
Ključne riječi
environmental hazards; poly(vinyl chloride); residual monomer; suspension polymerization
Hrčak ID:
1521
URI
Datum izdavanja:
20.2.2006.
Posjeta: 4.037 *