The effect of Ca/Zn stabilizers on the thermooxidative degradation poly(vinyl chloride) /chlorinated polyethylene blends

Termooksidacijska razgradnja mješavina poli(vinil-klorida) (PVC) i polimernoga modifikatora kloriranoga polietilena (CPE) istraživana je metodama diferencijalne pretražne kalorimetrije i termogravimetrije u dinamičkim i izotermnim uvjetima. Ustanovljeno je da istraživani sastavi mješavina PVC-a i CPE-a (sadržaja klora 42 %) nisu mješljivi. U temperaturnom području od 50 do 650 ºC termooksidacijska razgradnja mješavina zbiva se kroz dva temeljna razgradna stupnja. U prvome, do 400 ºC, osnovne reakcije su dehidrokloriranje PVC-a i CPE-a, premda se brzine i mehanizam razgradnje polimera znatno razlikuju. Istraživan je utjecaj Ca/Zn karboksilata različitih omjera kalcija i cinka na toplinsku postojanost komponenata mješavine. Ca/Zn karboksilati stabiliziraju PVC mijenjajući mu brzinu i mehanizam razgradnje, ali istodobno utječu i na razgradnju polimernoga modifikatora CPE-a.The thermooxidative degradation of blends of poly(vinyl chloride) (PVC) and polymeric modifier chlorinated polyethylene (CPE) was investigated by means of differential scanning calorimetry (DSC) and thermogravimetry (TG) under dynamic and isothermal conditions. The immiscibility of PVC and CPE (chlorine content 42 %) was established for all the investigated compositions of the blends. The thermooxidative degradation of PVC/CPE blends in temperature range of 50 – 650 ºC occurs in two basic degradation steps. In the first, up to 400 ºC, the main degradation reactions are dehydrochlorination of PVC and CPE, but the rates and mechanisms of the polymer degradation are significantly different. The influence of Ca/Zn carboxylates with different Ca/Zn ratios, on thermooxidative stability of the blends components was also investigated. Ca/Zn carboxylates stabilize PVC by changing its degradation rate and mechanism, but, at the same time, these stabilizers influence the degradation of the polymeric modifier CPE

Suspension grade poly(vinyl chloride) and hazards of its production

Poli(vinil-klorid) (PVC) najstariji je i više od 70 godina jedan od najvažnijih polimera, na kojeg otpada oko 20 % ukupne svjetske proizvodnje polimera. Usprkos svim tehničkim i gospodarskim problemima vezanim za proizvodnju PVC-a, prigovorima zaštitara okoliša i prirode o rizičnosti proizvodnje i uporabe PVC-a te općenito opasnosti klorne kemije za okoliš, procjenjuje se kako će godišnja potrošnja PVC-a u svijetu do 2010. rasti po stopi od 4,5 %.1 PVC se proizvodi polimerizacijom vinil-klorida (VC) slobodno-radikalskim procesima u suspenziji, emulziji ili u masi. Na svjetskoj razini, 80 % PVC-a proizvodi se suspenzijskom polimerizacijom, 12 % emulzijskom, a 8 % polimerizacijom u masi. U suspenzijskom postupku monomer, ukapljeni vinil-klorid, mehanički se dispergira u vodi i polimerizira s pomoću u monomeru topljiva inicijatora, uz dodatak zaštitnog koloida. Proces je diskontinuiran, a provodi se u zatvorenom sustavu. S ekološkoga gledišta, suvremena suspenzijska polimerizacija opterećena je relativno malim brojem problema, od kojih je najveći kancerogenost monomera, vinil-klorida, objavljena 1973. Ubrzo, alarmiranjem svjetske javnosti te angažiranjem tehnologa, liječnika i znanstvenika pronađena su rješenja kojima je uklonjena opasnost od emisije monomera tijekom tehnološkog procesa, izloženost radnika kancerogenom VC-u te opasnost od visoke koncentracije ostatnog monomera u polimerizatu. Definirane su maksimalne dopuštene koncentracije VC-a. Suvremeni postupak proizvodnje, uz otplinjavanje i rekuperaciju neizreagiranog vinil-klorida, demonomerizaciju polimerne suspenzije i obradu otpadnih voda te dobru kontrolu proizvodnog procesa, omogućuje siguran rad postrojenja i uporabu PVC-a u prehrambenoj i farmaceutskoj industriji te za medicinske potrebe.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

Polymers – from the primeval beginning to plastics and elastomers

Polazeći od fi lozofskih misli O. Spenglera i Aristotela, utvrđeno je da su polimeri prastari, jer sežu tamo do postanka osnovnih prirodnih organskih i anorganskih polimera. Istodobno je uočeno da se riječ polimeri učestalo upotrebljava kao zajedničko ime za plastiku i elastomere. Od osnovnih prirodnih organskih polimera: bjelančevina, nukleinskih kiselina i polisaharida dug je povijesni put. Taj se put pokušalo opisati dijagramom toka, tokovnikom. Za navedeni opis potrebne su brojne defi nicije, ali i motivacijska osnova. To je učinjeno u dodatcima A i B. Zaključak je istraživanja: praoblikovanje i prastrukturiranje prirodnih polimera staro je oko 3,5 milijardi godina, a humana obradba razdvajanjem oko 3,4 milijuna godina. Svatko tko se bavi polimerima trebao bi biti obrazovan na odgovarajućoj razini potrebnog znanja s razvijenim tokovnikom.Based on the philosophic ideas of O. Spengler and Aristotle it has been determined that polymers are ancient since they reach back all the way to the origin of the basic natural organic and inorganic polymers. At the same time it has been noted that the word polymers is frequently used as a common name for plastics and elastomers. Since the basic natural organic polymers: proteins, nucleic acids, and polysaccharides there is a long historical path. An attempt was made to present this path by means of a fl ow chart. For the mentioned description numerous defi nitions are required, as well as a motivating basis. This was done in Annexes A and B. The conclusion of the research is that primary shaping and primary structuring of natural polymers is around 3.5 billion years old and human separation with natural tools about 3.4 million years. Anyone involved in polymers should be educated at an adequate level of the necessary knowledge with the developed fl owchart

International Symposium on Environmental Management Towards Sustainable Technologies Conference Proceedings CONFERENCE PROCEEDINGS of SEM2011 Editors: Scientific and Organizing Committee

Abstract The manufacture of portland cement (PC) consumes huge amount of energy and has a significant CO 2 emission. Calcium sulfoaluminate cement (CSAC) is a promising alternative binder to PC due to: a) lower limestone requirement in CSAC; b) about 200 K lower sintering temperature for CSAC than for PC; and c) much easier grinding of the fired CSAC. Each of these arguments considerably reduces energy consumption and CO 2 emission from cement manufacture. In this paper, the potential benefits offered by CSAC production from industrial wastes or byproducts already present in Republic of Croatia had been addressed. A variety of industrial wastes, namely phosphogypsum (PG), coal bottom ash (BA) and electric arc furnace slag (EAFS), were used as raw materials to provide additional environmental advantages in production of CSAC. Mass fraction of Klein's compound (the principal hydraulic mineral) in the prepared CSAC was determined by quantitative X-ray powder diffraction. In conclusion, CSAC production offers an alternative and feasible way of industrial waste minimization