Cov khoom siv yas yog dab tsi?
Raws li cov khoom siv tseem ceeb hauv lub neej niaj hnub no, plastics tau siv dav hauv ntau qhov chaw xws li ntim khoom, khoom siv hluav taws xob, tsheb, thiab kev tsim kho. Cov ntaub ntawv dab tsi yog cov yas ua los ntawm? Qhov no tiag tiag koom nrog txoj kev tshawb fawb ntawm polymers hauv kev lag luam tshuaj. Cov yas yog tsim los ntawm ntau yam khoom siv hluavtaws lossis semi-synthetic polymers, thiab cov khoom siv polymer no tau ua tiav los ntawm cov txheej txheem tshwj xeeb rau hauv cov khoom niaj hnub peb paub. Hauv qab no, peb yuav txheeb xyuas cov ntsiab lus ntawm cov yas thiab cov txheej txheem ntawm lawv cov kev npaj.
1. Basic Cheebtsam ntawm yas: polymers
Plastics yog dab tsi? Cov lus teb hauv nruab nrab yog polymers. Ib tug polymer yog ib tug saw ntawm siab molecules ua los ntawm ib tug loj tus naj npawb ntawm rov qab monomers txuas los ntawm ib tug polymerisation cov tshuaj tiv thaiv. Cov polymers muaj xws li polyethylene (PE), polypropylene (PP), polystyrene (PS) thiab polyvinyl chloride (PVC). Cov khoom sib txawv ntawm cov yas muaj cov khoom sib txawv ntawm lub cev thiab tshuaj lom neeg nyob ntawm seb hom monomer siv, txoj kev ntawm polymerization thiab cov qauv molecular.

Polyethylene (PE): polymerised los ntawm ethylene monomer, feem ntau siv rau hauv kev tsim cov hnab yas, ntim zaub mov, thiab lwm yam.
Polypropylene (PP): polymerization ntawm propylene monomer, nrog rau cov cua sov zoo, dav siv hauv lub hau yas, cov khoom siv hauv tsev.
Polystyrene (PS): polymerised los ntawm styrene monomer, pob tshab thiab yooj yim rau daim ntawv, feem ntau siv nyob rau hauv zus tau tej cov tais diav, ntim khoom.

2. Cov khoom siv ntxiv siv rau hauv kev tsim cov yas
Ntxiv rau cov polymers, cov yas muaj ntau yam khoom siv ntxiv uas siv los txhim kho lawv cov khoom lossis txo cov nqi tsim khoom. Cov additives muaj xws li antioxidants, plasticizers, stabilizers, colouring agents, fillers thiab hais txog. Hom thiab tus nqi ntawm cov additives ncaj qha cuam tshuam rau lub cev thiab kev siv cov yas.

Plasticisers: ua kom yooj yim ntawm cov yas thiab ua kom yooj yim rau kev ua thiab pwm. Feem ntau siv nyob rau hauv PVC ntau lawm.
Antioxidants: tiv thaiv cov yas los ntawm kev laus vim oxidation thaum lub sij hawm tsim khoom thiab siv, thiab txhim kho nws cov kav ntev.
Fillers: xws li calcium carbonate, talcum hmoov, siv los ua kom cov tawv tawv thiab ruaj khov ntawm cov yas, thaum txo cov nqi tsim khoom.

3. Yas txheej txheem: polymerization cov tshuaj tiv thaiv thiab molding tshuab
Kev tsim cov yas feem ntau muab faib ua ob theem: cov tshuaj tiv thaiv polymerization thiab molding. Monomers hloov mus rau hauv cov polymers los ntawm cov tshuaj tiv thaiv. Nyob ntawm txoj kev ntawm polymerization, nws tuaj yeem muab faib ua dawb radical polymerization, anionic polymerization, cationic polymerization thiab copolymerisation. Tom ntej no, cov polymer yog ua tiav rau hauv cov khoom ntawm qhov xav tau los ntawm kev txhaj tshuaj molding, extrusion, tshuab moulding thiab lwm yam txheej txheem.

Txhaj tshuaj molding: Cov yas molten kub yog nias rau hauv pwm thiab zoo li tus, feem ntau yog siv los tsim cov khoom siv niaj hnub.
Extrusion: Yas yog rhuab thiab tom qab ntawd tsim los ntawm extrusion, haum rau ua cov khoom txuas ntxiv xws li cov kav dej thiab cov yeeb yaj kiab.
Tshuab moulding: Molten yas yog tshuab moulded thiab siv los ua cov khoom hollow xws li lub raj mis.

4. Txoj kev loj hlob ntawm eco-friendly plastics
Nrog rau kev paub txog ib puag ncig, tib neeg tau muab tso rau ntau qhov kev xav tau ib puag ncig rau kev tsim thiab siv cov yas. Cov plastics degradable, bio-based plastics thiab cov khoom siv rov ua dua tshiab tau dhau los ua cov kev taw qhia tshiab ntawm kev txhim kho.

Cov yas degradable: xws li polylactic acid (PLA), tuaj yeem maj mam degraded rau carbon dioxide thiab dej hauv ib puag ncig ntuj.
Bio-based plastics: polymers ua los ntawm cov khoom siv cog qoob loo, xws li pob kws thiab qab zib, tau los ntawm kev hloov pauv lom neeg.
Recycled plastics: los ntawm kev siv cov khoom qub qub, los ntawm cov txheej txheem ntawm kev ntxuav, crushing thiab remoulding, lawv tau siv dua los tsim cov khoom tshiab.

Xaus
Los ntawm kev soj ntsuam saum toj no, peb tuaj yeem teb cov lus nug ntawm "dab tsi yog cov khoom siv yas ua los ntawm": yas yog tsim los ntawm hluavtaws polymers thiab ntau yam additives, ua tiav los ntawm ntau yam txheej txheem molding. Nrog rau kev nce qib ntawm kev tshawb fawb thiab thev naus laus zis, kev txhim kho ntawm ib puag ncig tus phooj ywg plastics yog maj mam hloov peb txoj kev cia siab rau cov khoom siv niaj hnub, thiab txhawb txoj kev loj hlob ntawm kev lag luam plastics nyob rau hauv ib qho kev coj noj coj ua ntsuab thiab muaj txiaj ntsig zoo dua.