Ezinye izinto ezibalulekileyo zokuthotywa kwe-polyester yokwambathisa

Ukuthotywa kwePolyester kuchatshazelwa yimitha yelanga, i-photocatalytic admixtures, amanzi kunye nokufuma, iikhemikhali, ioksijini, i-ozone, ubushushu, i-abrasion, uxinzelelo lwangaphakathi nangaphandle, kunye ne-pigment fading. Kuzo zonke ezi zinto zilandelayo, zonke zikhoyo kwimozulu yangaphandle, zikho eyona nto ibalulekileyo ukuthotywa komgangatho:

ukufuma, amaqondo obushushu, oxidation, UV radiation.

ukufuma

I-Hydrolysis iyenzeka xa iplastiki ibonakaliswe kumanzi okanye umswakama.Le mpendulo yeekhemikhali ingaba yinto ephambili ekuthotyweni kweepolymers ze-condensation ezifana ne-polyesters, apho iqela le-ester lihlanjululwe ngamanzi.

iqondo lobushushu

Xa i-polymer iphantsi kwamandla okushisa amakhulu kunamandla ebhondi abambe ii-athom kunye, iyacandeka ngokukhawuleza. Ngenxa yoko, ii-macroradicals ezimbini, okanye i-electron-deficient molecules, zenziwa.
Iiplastiki ezininzi ziyimfuzaralivandlakanywe kwiimeko ezintathu zokuvezwa kobushushu obuphakamileyo: ubushushu obuphezulu ngexesha elide, ubushushu obuphakamileyo ngexesha elifutshane, okanye ukuvezwa komjikelo kumaqondo obushushu anyusiweyo naphantsi, anokuthi kwenzeke ngexesha lokuchaswa kwemini nobusuku. ubushushu bunyukile, iziphumo ezitshabalalisayo zongezwa ngakumbi kukuvezwa kwe-UV okongeziweyo.

Ukuxhomekeka

Ngenxa yobukho beoksijini emoyeni, olona hlobo luqhelekileyo lokuthotywa kwemitha, ifotooxidation, lwenzeka kuzo zonke iipolymers eziphilayo. Kwakhona, inkqubo iya kukhawuleziswa yimitha ye-UV kunye namaqondo obushushu aphezulu. Ukusabela kweekhemikhali kunokuchazwa ngokuhlaselwa kwe-oksijeni kwibhondi kwi-polymer chain, enokuthi yenze amaqela e-carbonyl okanye i-crosslink.I-stabilizers ehlukeneyo ingasetyenziselwa ukunciphisa ukuchithwa kwe-polymer: i-antioxidants, i-thermostabilizers, i-photostabilizers, njl.

Imitha ye-UV

Xa kufikwa kwizicelo zangaphandle, eyona nkxalabo iphambili kuphononongo lwezinto eziphathekayo kukuthotywa kokukhanya kwelanga xa iiplastiki zenzelwe ukusetyenziswa ngaphandle. yespectrum kwaye ngokuqhelekileyo iya kwahluka kunye neemeko zemozulu mihla le.
Impembelelo yefotochemical yokukhanya kwelanga kwizinto zeplastiki ixhomekeke kwiipropati zokufunxa ezingaphezulu kunye namandla ebhondi yeekhemikhali zezinto eziphathekayo. Amaza okukhanya achaphazeleka kakhulu kwiiplastiki avela kwi-290 ukuya kwi-400 nm. Ubude bemitha ye-UV ene-photon ene-photon ihambelana namandla athile ebhondi kwi-polymer chain iyakwazi ukuphula iibhondi zeekhemikhali (ngokusebenzisa i-chain scission), ukuguqula iipropati, ngoko ke ukusebenza kwe-polymer.6 I-wavelength eyonakalisayo ye-polyester Kukholelwa ukuba yi-325 nm