Utjecaj ultraljubičastih stabilizatora na smanjenje prirodnog starenja polistirena visoke žilavosti. (Croatian)

The influence of ultraviolet stabilizers on high-impact polystyrene natural ageing. (English)

Natural ageing of plastics is caused by all weathering factors in the course of time, the most significant ones being UV-radiation, temperature and humidity. Polystyrene is a widely used thermoplastics material that ages rapidly when exposed to ultraviolet radiation, particularly in direct, outdoor exposure. The main criteria for estimating ageing of high-impact polystyrene are changes in colour and mechanical properties. Polystyrene ageing is different under indoor and outdoor exposure conditions. By the addition of antioxidants and light stabilizers, polystyrene stability is increased, i.e. thermal and photooxidative degradation are slowed down or stopped. In this paper, natural ageing of unstabilised and stabilised PS-HI 485 and flame retardant polystyrene PSVM 40902 AF-N, to which two different masterbatches of light stabilizers were added, is investigated. Unstabilised PS-HI 485 yellowed significantly under indoor and outdoor conditions. UV-stabilized PS-HI 485 did not yellow under indoor conditions in the period of 13 months, but it yellowed slightly and changed its mechanical properties under outdoor conditions in the same period of exposure. Flame retardant polystyrene PSVM 40902 AF-N is prepared by adding 26.6% halogen additive free of decabromo-diphenyl-ether in polystyrene based masterbatch. Non-stabilized PSVM 40902 AF-N yellowed under indoor and outdoor test conditions. Under indoor conditions, UV-stabilized PSVM 40902 AF-N yellowed very lightly but under outdoor conditions in direct exposure to weathering factors, it yellowed significantly and changed its mechanical properties. [ABSTRACT FROM AUTHOR]

Prirodno starenje plastike obuhvaća sve atmosferske čimbenike u vremenu, a najvažniji su ultraljubičasto (UV) zračenje, temperatura i vlaga. Polistiren se ubraja u široko primjenjive plastomere koji izlaganjem UV zračenju, posebice izravnom izlaganju u vanjskom okolišu, ubrzano stari. Najvažniji kriteriji za procjenu starenja polistirena visoke žilavosti jesu promjena boje i promjena mehaničkih svojstava. Polistiren različito stari u unutarnjim i vanjskim uvjetima izlaganja. Dodatkom antioksidansa i svjetlosnih stabilizatora poboljšava se njegova postojanost, tj. usporava ili zaustavlja toplinska i fotooksidacijska razgradnja. U ovom radu istraživano je prirodno starenje nestabiliziranoga i stabiliziranog polistirena visoke žilavosti (PS-HI 485) te polistirena smanjene gorivosti (PSVM 40902 AF-N), u koji su dodane dvije različite matične smjese svjetlosnih stabilizatora. Nestabilizirani PS-HI 485 u unutarnjim i vanjskim uvjetima starenja znatno požućuje. UV stabilizirani PS-HI 485 u unutarnjim uvjetima starenja tijekom 13 mjeseci nije požutio, dok je izložen vanjskim utjecajima u istom razdoblju slabo požutio i promijenio mehanička svojstva. Polistiren smanjene gorivosti PSVM 40902 AF-N dobiven je umješavanjem s halogenim dodatkom koji ne sadržava dekabrom- difenil-eter. Matična smjesa halogenog dodatka je na polistirenskoj osnovi. Nestabilizirani PSVM 40902 AF-N požućuje u unutarnjim i vanjskim uvjetima testiranja. UV stabilizirani PSVM 40902 AF-N u unutarnjim uvjetima vrlo slabo požućuje, ali u vanjskim uvjetima, izravno izložen atmosferilijama, izrazito požućuje i mijenja mehanička svojstva. [ABSTRACT FROM AUTHOR]

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