I-Polypropylene iyi-polymer esetshenziswa kabanzi ezinhlotsheni ezahlukene ngenxa yokuhlanganiswa kwayo okuhle kwezakhiwo. Izakhiwo zayo, njengezomzimba, ezemishini kanye nezokukhanya zingathuthukiswa ngokusetshenziswa okufanele kwama-nucleating agents kanye nama-clearing agents. Lezi zithasiselo zisiza ekwenzeni i-PP ikhanye ngesikhathi sokucubungula, ngaleyo ndlela kuthuthukiswe izakhiwo esezivele zitholakale.

Qonda ukuthi ungazisebenzisa kanjani izinto ezibangela ukubola kanye nezinto ezibangela ukubola kanye nokuthola amathiphu okukhetha ukuze wandise ngempumelelo izinga lokukhiqiza, ushintshe isakhiwo kanye nesimo, futhi unciphise umswakama ekwakhekeni kwakho kwe-polypropylene.

I. Indima Yama-Nucleating Clarifying Agents ku-PP

Ubukristalu bama-polymer acwebezelayo yibo obubangela izici eziningi, njengokuqina kobukhulu, ukucaca, kanye nokuqina.

Ngengxenye nenqubo echaziwe, ubukristalu bulawulwa yisakhiwo se-polymer, ukwakheka, kanye nezimo zokucubungula eziholela ebhalansini ethile yokwakheka kokushisa nokupholisa. Ngenxa yalokho, ubukristalu buvame ukungafani, umlando wokushisa uhlukile esikhumbeni kanye nasenkabeni yezingxenye noma izimpahla.

Ama-nucleating agents kanye nama-clarifiers asheshisa futhi alungise i-crystallization evumela ukulungisa izakhiwo zokugcina zama-polymers a-semi-crystalline ukuze zivumelane nezidingo zokusebenza.

·Ezakhiweni ze-polypropylene, ukwengeza ama-nucleating agents (abizwa nangokuthi ama-nucleator) kuphumela ekusebenzeni okuthuthukisiwe kanye nezakhiwo zokucubungula, njenge:

· Ukucaca okuthuthukisiwe kanye nomswakama oncishisiwe

· Amandla nokuqina okuthuthukisiwe

· Izinga Lokushisa Elithuthukisiwe Lokuncishiswa Kokushisa (i-HDT)

· Isikhathi somjikelezo esincishisiwe

· Ukuncishiswa kwe-warpage kanye nokuncipha okufanayo

· Ukuzwela kombala okunciphile maqondana noshintsho lwesakhiwo ngemibala ehlukene

·Ukuthuthukiswa kokucutshungulwa kwezinye izinhlelo zokusebenza

Ngakho-ke, i-nucleation iyindlela enamandla yokuthuthukisa izakhiwo zomzimba, ze-mechanical, kanye nezokubona ze-polypropylene. Ukucaca, ukuzinza kobukhulu, i-warpage, i-shrinkage, i-CLTE, i-HDT, izakhiwo ze-mechanical kanye nomphumela wokuvimbela kungathuthukiswa ngokukhetha ngokucophelela ama-nucleator noma ama-clarifier.

II. I-Polypropylene kanye nokuKhazimula Kwayo

I-Polypropylene iyi-crystalline esetshenziswa kabanzi, i-commodity polymer eyenziwe nge-polymerization ye-propene monomer. Lapho i-polymerization ifakwa, i-PP ingakha izakhiwo ezintathu eziyisisekelo zeketanga (i-atactic, i-isotactic, ne-syndiotactic) kuye ngokuthi amaqembu e-methyl amiphi. Ukuqina kwe-polymer kubonakala kanje:

·Izimo nobukhulu bamakristalu

·Izilinganiso zekristali, futhi ekugcineni

· Ukuqondiswa kwamakristalu

I-Isotactic polypropylene (iPP) iyi-polymer e-semi-crystalline. Ibonakala ngesilinganiso esihle kakhulu sezindleko nokusebenza, okwenza ikhange kakhulu ezinhlotsheni eziningi zezicelo ezifana nezimoto, izinto zikagesi, amapayipi, ukupakisha, njll.

Inkomba ye-Isotacticity ye-iPP ihlobene ngqo nezinga le-crystallinity elinomthelela omkhulu ekusebenzeni kwe-polymer. I-Isotacticity yandisa i-crystallization kinetics, i-flexural modulus, ubulukhuni kanye nokucaca, futhi yehlisa ukumelana nomthelela kanye nokuvuleka.

Ithebula elingezansi liqhathanisa izakhiwo zama-homopolymer amabili e-polypropylene ane-index ehlukile ye-isotacticity.

III. Ukwakheka kwe-Polypropylene ngekristalu
Kuye ngezimo, i-Isotactic Polypropylene ingakhazimula ibe yizigaba ezine ezahlukene ezimele i-α, β, γ kanye ne-mesomorphic smectic. Izigaba ze-α kanye ne-β yizona ezibaluleke kakhulu.

Isigaba se-α

1. Lesi sigaba sizinzile futhi saziwa kakhulu.

2. Lawa makristalu angaphansi kohlelo lwekristalu lwe-monoclinic.

Isigaba se-β

1. Lesi sigaba sizinzile, futhi amakristalu aso angaphansi kohlelo lwekristalu olungama-pseudo-hexagonal.

2. Isigaba se-β sikhona kakhulu ku-block copolymerized polypropylene futhi singadalwa ngokungeza ama-nucleating agents athile.

3. Lolu hlobo lwekristalu lwatholakala nguPadden noKeith ngo-1953; lungathuthukiswa ngokwenziwa kwekristalu phakathi kuka-130°C no-132°C, ukuthambekela kokusika okuphezulu, noma ukungezwa kwama-nucleating agents athile.

4. Ukuba khona kwesigaba se-β kuma-homopolymer e-polypropylene kuvame ukuthuthukisa ukuguquguquka komkhiqizo oqediwe, futhi umphumela ubaluleke kakhulu lapho okuqukethwe kwesigaba se-β kufinyelela ku-65%.

Isigaba se-γ

1. Lesi sigaba siphinde sibe namandla, sinamakristalu e-triclinic.

2. Lolu hlobo lwekristalu aluvamile; luvela kakhulu ku-polypropylene enesisindo esincane sama-molecule futhi lwakhiwa yi-crystallization ngaphansi kwengcindezi ephezulu kakhulu kanye namazinga okupholisa aphansi kakhulu.

Ⅳ. Inqubo ye-Nucleation ku-Polypropylene

Kuyaziwa kahle ukuthi indawo yokuqala yokwenza ama-polymer abe yi-crystallization amagciwane amancane (izinhlayiya ezincane) ezifakwe ngokwemvelo kuma-catalyst residues afana nokuncibilika, ukungcola, uthuli, njll. Ngemuva kwalokho kungenzeka ukuguqula nokulawula i-crystalline morphology ngokungeza amagciwane "okwenziwa" angeniswe ekuncibilikeni kwe-polymer. Lo msebenzi ubizwa ngokuthi i-Nucleation.

Ama-nucleator noma ama-nucleating agents asetshenziswa ahlinzeka ngezindawo zokuqala amakristalu.

Ama-Clarifier ayiqembu elincane lama-nucleator ahlinzeka ngama-crystallite amancane asakaza ukukhanya okuncane, futhi ngenxa yalokho, athuthukisa ukucaca kobukhulu bodonga obufanayo bengxenye.

Indima yalezi zinto ezibangela i-nucleating iwukuthuthukisa izakhiwo zomzimba nezemishini zezingxenye eziqediwe.

Ⅴ. Ama-Nucleator kanye nama-Clarifier: Iphaneli Ecebile Yezithasiselo

Ama-Nucleating Ejenti Ezinhlayiya

Ama-nucleating agent/ama-nucleant e-particulate ngokuvamile amakhemikhali ancibilikayo kakhulu ahlakazeka ekuncibilikeni kwe-polymer ngokuhlanganiswa. Lezi zinhlayiya zisebenza 'njenge-point nuclei' ehlukile lapho ukukhula kwe-polymer crystal kungaqala khona.

Ukuhlushwa okuphezulu kwama-nuclei kuholela ekubunjweni kwama-crystal okusheshayo (izikhathi zomjikelezo ezimfushane), kanye namazinga aphezulu e-crystallinity, okuthuthukisa amandla, ukuqina, kanye ne-HDT ye-PP.

Ubukhulu obuncane bama-crystal aggregates (ama-spherulite) buholela ekunciphiseni ukusabalala kokukhanya kanye nokucaca okuthuthukisiwe.

Ama-nucleating agents asetshenziswa kakhulu ahlanganisa usawoti namaminerali, njenge-talc, i-sodium benzoate, ama-phosphate esters kanye nosawoti we-organic.

I-Talc kanye ne-sodium benzoate kubhekwa njengezinto ezisebenza kahle kakhulu, ezingabizi kakhulu, futhi zinikeza ukuthuthuka okuncane emandleni, ukuqina, i-HDT, kanye nesikhathi sokujikeleza.

Ama-nucleant asebenza kahle kakhulu, abiza kakhulu, njenge-phosphate esters kanye nosawoti we-bicycloheptane anikeza izakhiwo zomzimba ezingcono kanye nokuthuthuka okuthile ekucaceni.

Ama-Nucleating E-Soluble

Ama-nucleating agents ancibilikayo, abizwa nangokuthi 'azwela ukuncibilika', ngokuvamile anamaphuzu aphansi okuncibilika futhi ancibilika ku-PP encibilikisiwe.

Njengoba ukuncibilika kwe-polymer kuphola esikhumbeni, lawa ma-nucleant aqala ngokwakha inethiwekhi esakazeke kahle enobuso obuphakeme kakhulu.

Njengoba izinga lokushisa liqhubeka nokwehla, ama-fibrils aqukethe le nethiwekhi asebenza njenge-nuclei ukuqalisa i-polymer crystallization.

Ukuhlushwa okuphezulu kakhulu kwama-nuclei kuholela kuma-PP crystal aggregates amancane kakhulu, anikeza izinga eliphansi kakhulu lokusabalala kokukhanya kanye nokucaca okungcono kakhulu.

Zonke izihlungi ziyi-nucleants, kodwa akuzona zonke izihlungi eziyi-clarifier ezinhle.

Amanye ama-nucleant avamile, njenge-sodium benzoate ne-talc, awanciphisi usayizi we-spherulite ngenani elanele ukuze anikeze ingxenye ebunjiwe ekhanyayo necacile kakhulu. Ukucaca okuhle kakhulu kuvame ukutholakala lapho kusetshenziswa ama-nucleant ancibilikayo.

Amakhemikhali e-organic ancibilikayo asebenza njengezicwengisi afaka ama-sorbitol, ama-nonotol, nama-trisamides.

Nakuba la ma-nucleant esetshenziswa kakhulu ukuthola ukucaca okuphezulu kanye nomswakama ophansi, athuthukisa nezakhiwo zomzimba futhi anciphise isikhathi sokujikeleza.

Isilinganiso Sokuma Kwezinhlayiyana kanye Nokubukeka

Izinhlayiya ze-Nucleant ezinezimo ezifana nenaliti (njenge-ADK STAB NA-11) zingaholela ekuncipheni okuhlukile emshinini naseziqondisweni eziphambene. Lokhu kuncipheka kwe-anisotropy kungaholela ekuncipheni engxenyeni yokugcina. Izinhlayiya ze-Nucleant ezine-geometry ye-planer zinganikeza ukuncipheka okufanayo kakhulu eziqondisweni ezimbili okuholela ekuncipheni kwe-warpage.

Usayizi Wezinhlayiyana Nokusatshalaliswa Kosayizi Wezinhlayiyana

Ubukhulu bezinhlayiya ezincane buholela ekuthuthukisweni kwe-nucleation, kodwa izinhlayiya ezincane nazo zingaba nzima ukuzihlakaza. Ezinye izinhlayiya ze-nucleant, njenge-sodium benzoate, zivame ukuhlangana kabusha.

Isitsha Sokukhuhla Esine-asidi Esisetshenzisiwe

Ezinye izinto ezisusa i-asidi, njengosawoti we-fatty acid (isb. i-calcium stearate) zingaphikisana nama-nucleants athile, njenge-phosphate esters kanye ne-sodium benzoate. I-Dihydrotalcite kufanele isetshenziswe nala ma-nucleants.

Ungalokothi usebenzise i-calcium stearate ne-sodium benzoate ngoba i-calcium stearate izoqeda ngokuphelele i-nucleation ye-sodium benzoate.

Izinga Lokuhlakazeka Nokuba Khona Kwama-Agglomerate Angahlakazekile

I-sodium benzoate ivame ukwakha ama-agglomerate futhi kunzima ukuhlakazeka kahle.

Izinga Lokushisa Elincibilikayo

Ama-Sorbitol adinga amazinga okushisa aphezulu okuncibilika ukuze anikeze ukucaca okungcono kakhulu, njengoba kumele ancibilike ngokuphelele ekuncibilikeni kwe-polymer.

Ukusebenzisana kanye nokungezwani phakathi kwama-Nucleants nezinye izithako

Izinto ezisusa i-asidi zingaba ezihambisanayo noma eziphikisanayo. Usawoti we-asidi enamafutha uthinta kabi i-modulus ye-PP ene-phosphate ester.

Khetha OkulungileIzinto ze-Nucleantkanye neziClarifier ze-PP

Ngaphambi kokukhetha i-nucleating noma i-clarifying ejenti efanelekile yesicelo sakho se-PP, nquma ukuthi iyiphi i-property expansion oyithandayo kakhulu:

a. Uma umswakama ophansi kanye nokucaca okuphezulu kubalulekile, khetha enye yezici ezincibilikayo.

b. Ngezidingo zokucaca okuphansi,ama-ester e-phosphateingasetshenziswa.

c.Uma i-modulus ephezulu ibaluleke kakhulu, khetha enye yama-phosphate esters.

d.Uma izindleko eziphansi zibaluleke kakhulu, khetha i-sodium benzoate.

e. Uma ukugoba okuphansi kanye nokuzwela okuphansi kombala kubaluleke kakhulu, khetha usawoti we-bicycloheptane.

Kubalulekile futhi ukunquma ukuthi i-nucleant izofakwa kanjani ku-resin ye-PP. Njalo yenza izivivinyo ezifanele ukuqinisekisa ukuthi ukuhlakazeka okuhle kanye ne-nucleation kufeziwe.

Sebenzisa i-DSC ku-resin ye-PP ene-nucleated. Ukuthuthukiswa kwesikhathi somjikelezo ngokuvamile kuhlobene nokwenyuka kwezinga lokushisa le-crystallization (Tc). Hlola izakhiwo zesampula ebunjiwe.

Uma ufuna ukubuza ngemikhiqizo ehlobene nama-nucleating agents, sicela ukhululeke ukuXhumana nathinganoma yisiphi isikhathi.