Polypropylene ndi polima yomwe imagwiritsidwa ntchito kwambiri m'njira zosiyanasiyana chifukwa cha kuphatikiza kwake kwabwino kwa zinthu. Zinthu zake, monga zakuthupi, zamakaniko ndi zowunikira, zimatha kuwonjezeredwa pogwiritsa ntchito zinthu zopangira nucleating ndi zinthu zowunikira. Zowonjezera izi zimathandiza kuti PP ipangike bwino panthawi yokonza, motero zimawonjezera zinthu zomwe zapezedwa kale.

Mvetsetsani momwe mungagwiritsire ntchito zinthu zopangira nucleating ndi zinthu zowunikira komanso kupeza malangizo osankha kuti muwonjezere bwino kupanga, kusintha kapangidwe kake ndi mawonekedwe ake, komanso kuchepetsa utsi mu mapangidwe anu a polypropylene.

I. Udindo wa Nucleating Clarifying Agents mu PP

Kuchuluka kwa ma polima a semi-crystalline kumayambitsa makhalidwe ambiri, monga kukhazikika kwa mawonekedwe, kumveka bwino, ndi kulimba.

Pa gawo ndi njira yodziwika bwino, kristalo imayendetsedwa ndi kapangidwe ka polima, kapangidwe kake, ndi momwe zinthu zimagwirira ntchito zomwe zimapangitsa kuti kutentha kukhale kofanana komanso kuziziritsa. Chifukwa chake, kristalo nthawi zambiri imakhala yosiyana, mbiri ya kutentha imakhala yosiyana pakhungu ndi pakati pa ziwalo kapena katundu.

Ma nucleating agents ndi clarifiers amafulumizitsa ndikusintha ma crystallization zomwe zimathandiza kusintha mawonekedwe a ma polima a semi-crystalline kuti agwirizane ndi zofunikira za ntchito.

·Mu ma polypropylene formulations, kuwonjezera ma nucleating agents (omwe amatchedwanso ma nucleator) kumapangitsa kuti magwiridwe antchito ndi magwiridwe antchito azikhala bwino, monga:

· Kumveka bwino komanso mdima wochepa

· Mphamvu ndi kuuma bwino

· Kutentha Kochepa Kwambiri (HDT)

· Nthawi yochepa yozungulira

· Kuchepa kwa tsamba lozungulira komanso kufupika kofanana

· Kuchepa kwa mphamvu ya utoto pokhudzana ndi kusintha kwa mawonekedwe ndi mitundu yosiyanasiyana

·Kukonza bwino ntchito zina

Motero, nucleation ndi njira yamphamvu yowongolera mawonekedwe a polypropylene, makina, ndi kuwala. Kumveka bwino, kukhazikika kwa dimensional, warpage, shrinkage, CLTE, HDT, mawonekedwe a makina ndi zotsatira zotchinga zitha kukonzedwa mwa kusankha mosamala ma nucleator kapena clarifiers.

II. Polypropylene ndi Kukongola Kwake

Polypropylene ndi polymer yopangidwa ndi kristalo, yopangidwa ndi zinthu zambiri yopangidwa kuchokera ku polymerization ya propene monomer. Pambuyo pa polymerization, PP imatha kupanga mapangidwe atatu oyambira a unyolo (atactic, isotactic, syndiotactic) kutengera malo a magulu a methyl. Kuchuluka kwa kristalo kwa polima kumadziwika ndi:

· Maonekedwe ndi kukula kwa ma crystallites

· Ma crystallinity ratios, ndipo pamapeto pake

· Kuyang'ana kwa makristalo

Isotactic polypropylene (iPP) ndi polima ya semi-crystalline. Imadziwika ndi chiŵerengero chabwino kwambiri cha mtengo ndi magwiridwe antchito, zomwe zimapangitsa kuti ikhale yokongola kwambiri m'njira zosiyanasiyana monga magalimoto, zida zamagetsi, mapaipi, ma CD, ndi zina zotero.

Chizindikiro cha isotacticity cha iPP chimagwirizana mwachindunji ndi kuchuluka kwa crystallinity komwe kumakhudza kwambiri magwiridwe antchito a polima. Isotacticity imawonjezera kinetics ya crystallization, flexural modulus, hardness & transparency, komanso imachepetsa kukana ndi kulowererapo kwa impact.

Gome ili pansipa likuyerekeza makhalidwe a ma homopolymer awiri a polypropylene omwe ali ndi index yosiyana ya isotacticity.

III. Kupangidwa kwa Polypropylene kukhala kristalo
Kutengera ndi momwe zinthu zilili, Isotactic Polypropylene imatha kupanga ma crystalline m'magawo anayi osiyanasiyana omwe amaimira α, β, γ ndi mesomorphic smectic. Magawo a α ndi β ndi ofunikira kwambiri.

Gawo la α

1. Gawoli ndi lokhazikika komanso lodziwika bwino.

2. Makristalo awa ndi a dongosolo la makristalo la monoclinic.

Gawo la β

1. Gawoli ndi lokhazikika, ndipo makhiristo ake ndi a dongosolo la makhiristo la pseudo-hexagonal.

2. Gawo la β limapezeka makamaka mu polypropylene yopangidwa ndi block ndipo lingapangidwe powonjezera zinthu zinazake zoyambitsa nucleating.

3. Mtundu wa kristalo uwu unapezeka ndi Padden ndi Keith mu 1953; ukhoza kukulitsidwa ndi crystallization pakati pa 130°C ndi 132°C, kupendekeka kwapamwamba, kapena kuwonjezera zinthu zinazake za nucleating.

4. Kupezeka kwa gawo la β mu polypropylene homopolymers nthawi zambiri kumawonjezera kusinthasintha kwa chinthu chomalizidwa, ndipo zotsatira zake zimakhala zofunika kwambiri pamene kuchuluka kwa gawo la β kufika pa 65%.

Gawo la γ

1. Gawoli limakhalanso lokhazikika, ndi makristalo a triclinic.

2. Mtundu uwu wa kristalo ndi wachilendo; umapezeka makamaka mu polypropylene yolemera pang'ono ndipo umapangidwa ndi crystallization pansi pa kupanikizika kwakukulu komanso kuzizira kochepa kwambiri.

Ⅳ. Njira Yopangira Zinthu Zamkati mu Polypropylene

Ndizodziwika bwino kuti malo oyambira kupanga ma crystallization a ma polima ndi majeremusi ang'onoang'ono (tinthu tating'onoting'ono) tomwe timaphatikizidwa mwachilengedwe mu zotsalira za catalyst zonga kusungunuka, zinyalala, fumbi, ndi zina zotero. Kenako n'zotheka kusintha ndikuwongolera mawonekedwe a kristalo powonjezera majeremusi "opangidwa" omwe amalowetsedwa mu kusungunuka kwa polima. Ntchitoyi imatchedwa Nucleation.

Ma nucleator kapena ma nucleating agents amagwiritsidwa ntchito kuti apange malo oyambira makhiristo.

Ma Clarifiers ndi gulu laling'ono la ma nucleator omwe amapereka ma crystallites ang'onoang'ono omwe amafalitsa kuwala kochepa ndipo, motero, amawonjezera kumveka bwino kwa makulidwe ofanana a khoma la gawo.

Ntchito ya zinthu zomangira ma nucleating ndi kukonza mphamvu zakuthupi ndi zamakaniko za zinthu zomalizidwa.

Ⅴ. Ma Nucleator ndi Owunikira: Gulu Lolemera la Zowonjezera

Tinthu Tomwe Timagwiritsa Ntchito Nucleating

Tinthu tating'onoting'ono/tinthu tating'onoting'ono nthawi zambiri timakhala tinthu tating'onoting'ono tomwe timasungunuka kwambiri ndipo timafalikira mu polymer melt kudzera mu compounding. Tinthu tating'onoting'ono timeneti timagwira ntchito ngati 'point nuclei' yapadera yomwe kukula kwa polymer crystal kungayambire.

Kuchuluka kwa ma nuclei kumapangitsa kuti ma crystallization achuluke (nthawi yochepa yozungulira), komanso kuchuluka kwa ma crystallinity, zomwe zimapangitsa kuti PP ikhale ndi mphamvu, kuuma, komanso HDT.

Kukula kochepa kwa ma crystal aggregates (spherulites) kumapangitsa kuti kuwala kusamafalikire bwino komanso kuti kuwalako kuwoneke bwino.

Zinthu zomwe zimagwiritsidwa ntchito kwambiri ndi tinthu tating'onoting'ono timeneti ndi monga mchere ndi mchere, monga talc, sodium benzoate, phosphate esters ndi mchere wina wachilengedwe.

Talc ndi sodium benzoate zimaonedwa kuti ndi zinthu zotsika mtengo, zopanda mphamvu zambiri, ndipo zimapangitsa kuti mphamvu, kuuma, HDT, komanso nthawi yozungulira ziwonjezeke.

Ma nucleants ogwira ntchito bwino komanso okwera mtengo, monga ma phosphate esters ndi mchere wa bicycloheptane amapereka mawonekedwe abwino komanso kumveka bwino.

Zothandizira Kusungunuka kwa Nucleating

Zinthu zosungunula, zomwe zimatchedwanso kuti 'zosasungunuka', nthawi zambiri zimakhala ndi malo otsika osungunuka ndipo zimasungunuka mu PP yosungunuka.

Pamene kusungunuka kwa polima kukuzizira mu chikombole, ma nucleants awa amayamba kupanga maukonde ofalikira bwino okhala ndi malo okwera kwambiri.

Pamene kutentha kukupitirira kutsika, ma fibrils omwe ali ndi netiweki iyi amagwira ntchito ngati ma nuclei kuti ayambitse polymer crystallization.

Kuchuluka kwambiri kwa ma nuclei kumabweretsa ma crystal aggregates ang'onoang'ono a PP, omwe amapereka kuwala kochepa kwambiri komanso kumveka bwino kwambiri.

Zowunikira zonse ndi ma nucleants, koma si ma nucleants onse omwe ndi owunikira bwino.

Ma nucleti ena odziwika bwino, monga sodium benzoate ndi talc, sachepetsa kukula kwa spherulite mokwanira kuti apereke chifunga chochepa komanso gawo lopangidwa bwino kwambiri. Kumveka bwino kwambiri kumachitika nthawi zambiri ma nucleti osungunuka akagwiritsidwa ntchito.

Mankhwala osungunuka achilengedwe omwe amagwira ntchito ngati owunikira ndi monga sorbitols, nonotols, ndi trisamides.

Ngakhale kuti ma nucleants amenewa amagwiritsidwa ntchito kwambiri kuti apeze kuwala kwakukulu komanso chifunga chochepa, amathandizanso kuti zinthu zakuthupi zizikhala bwino komanso amachepetsa nthawi yozungulira.

Chiŵerengero cha Tinthu ndi Mawonekedwe a Tinthu

Tinthu ta Nucleant tokhala ndi mawonekedwe ofanana ndi singano (monga ADK STAB NA-11) tingayambitse kusiyana kwa ma shrinkage mu makina ndi njira zopingasa. Kuchepa kumeneku kungayambitse kugwedezeka mu gawo lomaliza. Tinthu ta Nucleant tokhala ndi mawonekedwe ozungulira tingapangitse kugwedezeka kofanana mbali ziwiri zomwe zimapangitsa kuti kugwedezeka kuchepe.

Kukula kwa Tinthu ndi Kugawa kwa Tinthu

Kukula kwa tinthu tating'onoting'ono kumabweretsa kuwonjezeka kwa nucleation, koma tinthu tating'onoting'ono tingakhalenso kovuta kufalitsa. Tinthu tina ta nucleant, monga sodium benzoate, timakonda kusonkhananso.

Chotsukira Asidi Chogwiritsidwa Ntchito

Zinthu zina zochotsa asidi m'thupi, monga mchere wamafuta acid (monga calcium stearate) zimatha kutsutsana ndi ma nucleants ena, monga ma phosphate esters ndi sodium benzoate. Dihydrotalcite iyenera kugwiritsidwa ntchito ndi ma nucleants awa.

Musagwiritse ntchito calcium stearate ndi sodium benzoate chifukwa calcium stearate idzachotsa kwathunthu nucleation ya sodium benzoate.

Mlingo wa Kufalikira & Kupezeka kwa Ma Agglomerate Osasakanizika

Sodium benzoate nthawi zambiri imapanga ma agglomerate ndipo zimakhala zovuta kufalitsa bwino.

Kutentha kwa Sungunulani

Ma sorbitol amafunika kutentha kwambiri kuti azitha kusungunuka bwino, chifukwa ayenera kusungunuka kwathunthu mu polymer melt.

Mgwirizano ndi Zotsutsana Pakati pa Nucleants ndi Zowonjezera Zina

Zinthu zochotsa asidi zimatha kukhala zogwirizana kapena zotsutsana. Mchere wa mafuta acid umakhudza kwambiri modulus ya phosphate ester nucleated PP.

Sankhani KumanjaNucleantsndi Zowunikira za PP

Musanasankhe chothandizira chowunikira kapena chowunikira choyenera kugwiritsa ntchito pa PP yanu, sankhani chomwe mukufuna kwambiri pakukonza malo:

Ngati chifunga chochepa komanso kuyera bwino ndikofunikira, sankhani chimodzi mwa zowunikira zosungunuka.

b. Pazofunikira zochepa zowunikira,ma ester a phosphateingagwiritsidwe ntchito.

c. Ngati kuchuluka kwa phosphate esters ndikofunikira kwambiri, sankhani imodzi mwa ma phosphate esters.

d.Ngati mtengo wotsika ndi wofunika kwambiri, sankhani sodium benzoate.

Ngati kupotoka kochepa komanso kusakhala ndi mtundu wokwanira ndikofunikira kwambiri, sankhani mchere wa bicycloheptane.

Ndikofunikiranso kusankha momwe nucleant idzaphatikizidwire mu utomoni wa PP. Nthawi zonse chitani mayeso oyenera kuti muwonetsetse kuti mwafalikira bwino komanso kuti nucleation yachitika.

Yendetsani DSC pa utomoni wa PP wokhala ndi nucleated. Kusintha kwa nthawi yozungulira nthawi zambiri kumagwirizana ndi kuwonjezeka kwa kutentha kwa crystallization (Tc). Yesani mawonekedwe a chitsanzo chopangidwa.

Ngati mukufuna kufunsa za zinthu zokhudzana ndi zinthu zopangira nucleating, chonde musazengereze kuteroLumikizanani nafenthawi iliyonse.