Chidziwitso cha Packaging Material - Nchiyani Chimachititsa Kusintha kwa Mtundu wa Zapulasitiki?

• Kuwonongeka kwa okosijeni kwa zinthu zopangira kungayambitse kusinthika pamene akuumba pa kutentha kwakukulu;
• Kusintha kwa utoto pa kutentha kwakukulu kumapangitsa kuti zinthu zapulasitiki zisinthe;
• Zomwe zimachitika pakati pa utoto ndi zopangira kapena zowonjezera zitha kuyambitsa kusinthika;
• Zomwe zimachitika pakati pa zowonjezera ndi makutidwe ndi okosijeni odziwikiratu azowonjezera zidzapangitsa kusintha kwamitundu;
• Tautomerization ya utoto wa utoto pansi pa kuwala ndi kutentha kumapangitsa kusintha kwamitundu yazinthu;
• Zowononga mpweya zimatha kusintha zinthu zapulasitiki.

1. Zimayambitsidwa ndi Pulasitiki Kumangira

1) Kuwonongeka kwa okosijeni kwa zinthu zopangira kungayambitse kusinthika pakumangirira kutentha kwambiri

Pamene mphete yotenthetsera kapena mbale yotenthetsera ya pulasitiki yopangira makina opangira pulasitiki nthawi zonse imakhala yotentha chifukwa chosalamulirika, zimakhala zosavuta kuchititsa kuti kutentha kwa m'deralo kukhale kokwera kwambiri, zomwe zimapangitsa kuti zopangira oxidize ndikuwola pa kutentha kwakukulu. Kwa mapulasitiki omwe samva kutentha, monga PVC, zimakhala zosavuta kuti pamene chodabwitsa ichi chikachitika, chikakhala chachikulu, chidzayaka ndi kutembenukira chikasu, kapena ngakhale chakuda, limodzi ndi kuchuluka kwa maselo otsika omwe akusefukira.

Kuwonongeka uku kumaphatikizapo machitidwe mongadepolymerization, scission chain scission, kuchotsedwa kwamagulu am'mbali ndi zinthu zochepa zolemera mamolekyulu.

• Depolymerization

The cleavage reaction imachitika pa ulalo wa unyolo wa terminal, zomwe zimapangitsa kuti ulalo wa unyolo ugwe m'modzim'modzi, ndipo monomer yopangidwa imasinthidwa mwachangu. Panthawi imeneyi, kulemera kwa maselo kumasintha pang'onopang'ono, monga momwe zimasinthira unyolo polymerization. Monga matenthedwe a depolymerization a methyl methacrylate.

• Random Chain Scission (Kuwonongeka)

Amatchedwanso kuthyoka mwachisawawa kapena maunyolo osweka mwachisawawa. Pansi pa mphamvu yamakina, ma radiation apamwamba kwambiri, mafunde akupanga kapena ma reagents amankhwala, unyolo wa polima umasweka popanda nsonga yokhazikika kuti apange polima yotsika kwambiri. Ndi imodzi mwa njira zowonongera polima. Pamene unyolo wa polima umawonongeka mwachisawawa, kulemera kwa maselo kumatsika mofulumira, ndipo kulemera kwa polima kumakhala kochepa kwambiri. Mwachitsanzo, njira zowonongeka za polyethylene, polyene ndi polystyrene ndizowonongeka mwachisawawa.

Pamene ma polima monga PE amapangidwa pa kutentha kwakukulu, malo aliwonse a unyolo waukulu akhoza kusweka, ndipo kulemera kwa maselo kumatsika mofulumira, koma zokolola za monomer ndizochepa kwambiri. Zochita zamtunduwu zimatchedwa random chain scission, zomwe nthawi zina zimatchedwa kuwonongeka, polyethylene Ma radicals aulere omwe amapangidwa pambuyo pa chain scission amagwira ntchito kwambiri, atazunguliridwa ndi haidrojeni yachiwiri, yomwe imakonda kusuntha unyolo, ndipo pafupifupi palibe ma monomers omwe amapangidwa.

• Kuchotsa zolowa m'malo

PVC, PVAc, ndi zina zotero zimatha kuchotsedwa m'malo mwa kutentha, kotero kuti malo otsetsereka nthawi zambiri amawonekera pamapindikira a thermogravimetric. Pamene polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, polyvinyl fluoride, ndi zina zotero zitenthedwa, zolowa m'malo zidzachotsedwa. Potengera polyvinyl kolorayidi (PVC) monga chitsanzo, PVC ndi kukonzedwa pa kutentha pansi 180 ~ 200 ° C, koma pa kutentha otsika (monga 100 ~ 120 ° C), imayamba dehydrogenate (HCl), ndipo amataya HCl kwambiri. kutentha pafupifupi 200 ° C. Choncho, pokonza (180-200 ° C), polima imakhala yakuda komanso yotsika mphamvu.

HCl yaulere imakhala ndi chothandizira pa dehydrochlorination, ndipo ma chloride achitsulo, monga ferric chloride opangidwa ndi zochita za hydrogen chloride ndi zida zopangira, amalimbikitsa catalysis.

Maperesenti ochepa a zotsekemera za asidi, monga barium stearate, organotin, mankhwala otsogolera, ndi zina zotero, ziyenera kuwonjezeredwa ku PVC panthawi yopangira kutentha kuti ikhale yokhazikika.

Chingwe choyankhulirana chikagwiritsidwa ntchito kupaka utoto wa chingwe cholumikizirana, ngati wosanjikiza wa polyolefin pa waya wamkuwa sakhazikika, carboxylate yamkuwa yobiriwira idzapangidwa pa mawonekedwe a polima-mkuwa. Zochita izi zimalimbikitsa kufalikira kwa mkuwa mu polima, ndikufulumizitsa makutidwe ndi okosijeni amkuwa.

Choncho, pofuna kuchepetsa kuwonongeka kwa okosijeni wa ma polyolefins, phenolic kapena amine antioxidants (AH) nthawi zambiri amawonjezedwa kuti athetse zomwe zili pamwambazi ndikupanga ma free radicals osagwira A·: ROO·+AH-→ROOH+A·

• Kuwonongeka kwa Oxidative

Zopangidwa ndi polima zomwe zimawululidwa mumlengalenga zimayamwa mpweya ndikulowa ndi okosijeni kupanga ma hydroperoxides, kuwolanso kuti apange malo omwe akugwira ntchito, kupanga ma free radicals, kenako amakumana ndi ma free radical chain reactions (mwachitsanzo, auto-oxidation process). Ma polima amakumana ndi okosijeni mumlengalenga panthawi yokonza ndikugwiritsa ntchito, ndipo akatenthedwa, kuwonongeka kwa okosijeni kumachulukitsidwa.

Thermal oxidation ya polyolefins ndi ya free radical chain reaction mechanism, yomwe imakhala ndi machitidwe a autocatalytic ndipo imatha kugawidwa m'magawo atatu: kuyambitsa, kukula ndi kutha.

Kuthamanga kwa unyolo komwe kumayambitsidwa ndi gulu la hydroperoxide kumabweretsa kuchepa kwa kulemera kwa maselo, ndipo zinthu zazikulu za scission ndi ma alcohols, aldehydes, ndi ma ketoni, omwe pamapeto pake amakhala oxidized kukhala carboxylic acid. Ma Carboxylic acid amatenga gawo lalikulu pakupanga makutidwe ndi okosijeni azitsulo. Kuwonongeka kwa okosijeni ndiye chifukwa chachikulu cha kuwonongeka kwa thupi ndi makina azinthu za polima. Kuwonongeka kwa okosijeni kumasiyanasiyana ndi kapangidwe ka maselo a polima. Kukhalapo kwa okosijeni kumatha kukulitsa kuwonongeka kwa kuwala, kutentha, ma radiation ndi mphamvu yamakina pa ma polima, zomwe zimapangitsa kuti pakhale zovuta zowononga. Ma antioxidants amawonjezeredwa ku ma polima kuti achepetse kuwonongeka kwa okosijeni.

2) Pulasitiki ikakonzedwa ndikuwumbidwa, utotowo umatha, umatha komanso umasintha mtundu chifukwa cholephera kupirira kutentha kwambiri.

Mitundu kapena utoto womwe umagwiritsidwa ntchito popaka utoto wa pulasitiki uli ndi malire a kutentha. Pamene kutentha kwa malireku kukufika, inki kapena utoto umasinthidwa ndi mankhwala kuti upangitse mitundu yosiyanasiyana yolemera ya maselo, ndipo momwe amachitira ndi zovuta; mitundu yosiyanasiyana imakhala ndi machitidwe osiyanasiyana. Ndipo zogulitsa, kukana kutentha kwamitundu yosiyanasiyana kumatha kuyesedwa ndi njira zowunikira monga kuchepa thupi.

2. Ma Colourants Amachita ndi Zida Zopangira

Zomwe zimachitika pakati pa mitundu yamitundu ndi zopangira zimawonekera makamaka pakukonza mitundu ina yamitundu kapena utoto ndi zinthu zina. Zochita zamakemikolo izi zimabweretsa kusintha kwa mtundu ndi kuwonongeka kwa ma polima, potero kusintha zinthu zapulasitiki.

• Kuchepetsa Kuchita

Ma polima ena apamwamba, monga nayiloni ndi ma aminoplasts, ndi amphamvu ochepetsera asidi mumkhalidwe wosungunuka, omwe amatha kuchepetsa ndi kuzimiririka utoto kapena utoto womwe umakhala wokhazikika pakutentha.

• Kusinthana kwa Alkaline

Zitsulo zamchere zamchere mu PVC emulsion ma polima kapena ma polypropylenes okhazikika amatha "kusinthana" ndi zitsulo zamchere zamchere mumitundu yosinthira mtundu kuchokera ku buluu-wofiira kupita ku lalanje.

PVC emulsion polima ndi njira imene VC ndi polymerized ndi kusonkhezera mu emulsifier (monga sodium dodecylsulfonate C12H25SO3Na) amadzimadzi njira. Zomwe zili ndi Na+; kuti apititse patsogolo kutentha ndi mpweya kukana kwa PP, 1010, DLTDP, ndi zina zambiri. Oxygen, antioxidant 1010 ndi transesterification reaction catalyzed by 3,5-di-tert-butyl-4-hydroxypropionate methyl ester ndi sodium pentaerythritol, ndipo DLTDP imakonzedwa pochita Na2S amadzimadzi njira ndi acrylonitrile Propionitrile ndi hydrolyodized ndi asidi kupanga, zopezeka ndi esterification ndi lauryl mowa. Zomwe zimachitika zilinso ndi Na+.

Panthawi yokonza ndi kukonza zinthu zapulasitiki, Na+ yotsalira muzopangira idzachitapo kanthu ndi nyanja ya pigment yomwe ili ndi ayoni achitsulo monga CIPigment Red48:2 (BBC kapena 2BP): XCa2++2Na+→XNa2+ +Ca2+

• Kuchita Pakati pa Pigment ndi Hydrogen Halides (HX)

Kutentha kumakwera kufika ku 170 ° C kapena pansi pa kuwala, PVC imachotsa HCI kuti ipange mgwirizano wawiri wogwirizanitsa.

Polyolefin yokhala ndi halogen-retardant flame-retardant polyolefin kapena mapulasitiki amitundu osagwira ntchito ndi malawi amapangidwanso ndi dehydrohalogenated HX akapangidwa pa kutentha kwambiri.

1) Ultramarine ndi HX reaction

Ultramarine blue pigment yomwe imagwiritsidwa ntchito kwambiri mu utoto wa pulasitiki kapena kuchotsa kuwala kwachikasu, ndi sulfure pawiri.

2) Copper golide ufa pigment Imathandizira kuwonongeka kwa okosijeni kwa PVC zopangira

Nkhumba zamkuwa zimatha kukhala oxidized ku Cu + ndi Cu2 + pa kutentha kwakukulu, zomwe zidzafulumizitsa kuwonongeka kwa PVC.

3) Kuwonongeka kwa ayoni zitsulo pa ma polima

Mitundu ina imakhala ndi zotsatira zowononga pa ma polima. Mwachitsanzo, pigment ya nyanja ya manganese CIPigmentRed48:4 siyoyenera kupanga zinthu zapulasitiki za PP. Chifukwa chake ndi chakuti mtengo wosinthika wa ayoni wazitsulo wa manganese umathandizira hydroperoxide kudzera mukusamutsa ma elekitironi mu matenthedwe oxidation kapena photooxidation ya PP. Kuwonongeka kwa PP kumabweretsa kukalamba kofulumira kwa PP; chomangira cha ester mu polycarbonate ndi chosavuta kukhetsedwa ndi kusungunuka mukatenthedwa, ndipo pakakhala ma ion achitsulo mu pigment, zimakhala zosavuta kulimbikitsa kuwonongeka; ayoni zitsulo adzalimbikitsanso thermo-oxygen kuwonongeka kwa PVC ndi zipangizo zina, ndi kuchititsa kusintha mtundu.

Mwachidule, popanga zinthu zapulasitiki, ndiyo njira yotheka komanso yothandiza kwambiri yopewera kugwiritsa ntchito utoto wamtundu womwe umakhudzidwa ndi zida.

3. Zomwe zimachitika pakati pa ma colorants ndi zowonjezera

1) Zomwe zimachitika pakati pa ma pigment okhala ndi sulfure ndi zowonjezera

Mitundu yokhala ndi sulfure, monga cadmium yellow (solid solution ya CdS ndi CdSe), sizoyenera ku PVC chifukwa cha kusamva bwino kwa asidi, ndipo sayenera kugwiritsidwa ntchito ndi zowonjezera zokhala ndi lead.

2) Kuchita kwa mankhwala okhala ndi lead okhala ndi ma stabilizer okhala ndi sulfure

Zomwe zili patsogolo mu chrome yellow pigment kapena molybdenum red zimakumana ndi ma antioxidants monga thiodistearate DSTDP.

3) Zomwe zimachitika pakati pa pigment ndi antioxidant

Kwa zida zopangira ma antioxidants, monga PP, ma pigment ena amathanso kuchitapo kanthu ndi antioxidants, motero kufooketsa ntchito ya antioxidants ndikupangitsa kukhazikika kwa okosijeni wamafuta kuipiraipira. Mwachitsanzo, phenolic antioxidants amatengeka mosavuta ndi mpweya wakuda kapena amachita nawo kuti ataya ntchito yawo; phenolic antioxidants ndi ma ion titaniyamu muzinthu zapulasitiki zoyera kapena zopepuka zimapanga ma phenolic onunkhira a hydrocarbon complexes kuti apangitse zinthu kukhala zachikasu. Sankhani mankhwala oletsa antioxidant kapena onjezani zowonjezera zowonjezera, monga anti-acid zinki mchere (zinc stearate) kapena P2 mtundu wa phosphite kuti muteteze kusinthika kwa pigment yoyera (TiO2).

4) Zomwe zimachitika pakati pa pigment ndi kuwala kokhazikika

Zotsatira za inki ndi kuwala stabilizers, kupatula zimene sulfure munali inki ndi faifi tambala munali kuwala stabilizers monga tafotokozera pamwambapa, zambiri amachepetsa mphamvu ya stabilizers kuwala, makamaka zotsatira za amalepheretsa amine kuwala stabilizers ndi azo yellow ndi wofiira inki. Zotsatira za kuchepa kokhazikika ndizoonekeratu, ndipo sizikhala zokhazikika ngati zosasinthika. Palibe kufotokoza kotsimikizika kwa chochitika ichi.

4. Zomwe Zimachitika Pakati pa Zowonjezera

Ngati zowonjezera zambiri zikugwiritsidwa ntchito molakwika, zochitika zosayembekezereka zimatha kuchitika ndipo mankhwalawo amatha kusintha mtundu. Mwachitsanzo, flame retardant Sb2O3 imakumana ndi sulfure yokhala ndi anti-oxidant kuti ipange Sb2S3: Sb2O3+–S–→Sb2S3+–O–

Choncho, kusamala kuyenera kutengedwa posankha zowonjezera poganizira za kupanga.

5. Zothandizira Auto-oxidation Zimayambitsa

The automatic oxidation of phenolic stabilizers ndi chinthu chofunikira kulimbikitsa kusinthika kwa zinthu zoyera kapena zowala. Kusintha uku kumatchedwa "Pinking" m'mayiko akunja.

Zimaphatikizidwa ndi zinthu zotulutsa okosijeni monga BHT antioxidants (2-6-di-tert-butyl-4-methylphenol), ndipo zimapangidwira ngati 3,3',5,5'-stilbene quinone kuwala kofiyira mankhwala, Kusinthika uku kumachitika. kokha pamaso pa mpweya ndi madzi komanso popanda kuwala. Ikayatsidwa ndi kuwala kwa ultraviolet, kuwala kofiira kwa stilbene quinone kumawola mwachangu kukhala chinthu chachikasu cha mphete imodzi.

6. Tautomerization of Colored Pigments Under The Action of Light and Heat

Mitundu ina yamitundu yosiyanasiyana imakhala ndi tautomerization ya kasinthidwe ka maselo pansi pa kuwala ndi kutentha, monga kugwiritsa ntchito inki ya CIPig.R2 (BBC) kuti isinthe kuchoka ku mtundu wa azo kupita ku mtundu wa quinone, womwe umasintha mawonekedwe oyambilira a conjugation ndikupangitsa kupanga ma conjugated bond. . kuchepa, zomwe zimapangitsa kuti mtundu usinthe kuchoka pamtundu wakuda wabuluu wonyezimira mpaka wofiyira walalanje.

Panthawi imodzimodziyo, pansi pa catalysis ya kuwala, amawola ndi madzi, kusintha madzi a kristalo ndikupangitsa kuzimiririka.

7. Zimayambitsidwa ndi Zowononga Mpweya

Zinthu zapulasitiki zikasungidwa kapena kugwiritsidwa ntchito, zinthu zina zotha mphamvu, kaya zopangira, zowonjezera, kapena utoto wamitundu, zimachita ndi chinyezi chamlengalenga kapena zowononga mankhwala monga ma acid ndi alkalis pansi pa kuwala ndi kutentha. Mitundu yosiyanasiyana yamankhwala imayamba, yomwe imayambitsa kuzimiririka kapena kusinthika pakapita nthawi.

Izi zitha kupewedwa kapena kuchepetsedwa powonjezera zoyezera mpweya wabwino wamafuta, zowongolera zowunikira, kapena kusankha zowonjezera zolimbana ndi nyengo komanso utoto wapamwamba kwambiri.