I-Polypropylene yi-polymer esetyenziswa kakhulu kwiindawo ezahlukeneyo ngenxa yokudibanisa kwayo iipropati ezintle. Iipropati zayo, ezifana nezomzimba, ezomatshini kunye nezokukhanya zinokuphuculwa ngakumbi ngokusebenzisa ngokufanelekileyo ii-nucleating agents kunye nee-clearing agents. Ezi zongezo zinceda ekukhanyeni kwe-PP ngexesha lokucubungula, ngaloo ndlela ziphucula iipropati esele zifunyenwe.

Qonda indlela yokusebenzisa ii-nucleating agents kunye nee-clearing agents kunye nokufumana iingcebiso zokukhetha ukuze wonyuse ngempumelelo izinga lemveliso, utshintshe isakhiwo kunye nemo, kunye nokunciphisa umhlwa kwi-polypropylene formulations yakho.

I. Indima yee-Nucleating Clarifying Agents kwi-PP

Ubukrelekrele beepolymers ezi-semi-crystalline bubangela iimpawu ezininzi, ezinje ngokuzinza kobukhulu, ukucaca, kunye nokuqina.

Kwinxalenye ethile kunye nenkqubo ethile, ubukristali bulawulwa yisakhiwo sepolymer, indlela esenziwa ngayo, kunye neemeko zokucubungula ezikhokelela kwibhalansi ethile yokwakheka kobushushu kunye nokupholisa. Ngenxa yoko, ubukristali buhlala bungalingani, imbali yobushushu yahlukile kulusu kunye nombindi weendawo okanye iimpahla.

Ii-nucleating agents kunye nee-clarifiers ziyakhawulezisa kwaye zilungelelanise i-crystallization ezivumela ukuba kulungiswe iipropati zokugqibela zee-polymers ze-semi-crystalline ngokweemfuno zokusebenza.

·Kwiifomyula ze-polypropylene, ukongeza ii-nucleating agents (ezikwabizwa ngokuba zii-nucleators) kubangela ukuphuculwa kokusebenza kunye neepropati zokucubungula, ezinje:

· Ukucaca okuphuculweyo kunye nokuncipha kombala womkhenkce

· Amandla aphuculweyo kunye nokuqina

· Ubushushu obuphuculweyo bokuPhambuka koBushushu (HDT)

· Ixesha lokujikeleza elincitshisiweyo

· Ukuncitshiswa kwe-warpage kunye nokuncipha okufanayo

· Ukuncipha kobuntununtunu bemibala malunga notshintsho lweempawu ngemibala eyahlukeneyo

·Ukuphuculwa kokuqhubekeka kweenkqubo kwezinye izicelo

Ngoko ke, i-nucleation yindlela enamandla yokuphucula iimpawu zomzimba, zoomatshini, kunye nezokukhanya ze-polypropylene. Ukucaca, uzinzo olunemilinganiselo, i-warpage, i-shrinkage, i-CLTE, i-HDT, iimpawu zoomatshini kunye nesiphumo somqobo zinokuphuculwa ngokukhetha ngononophelo ii-nucleators okanye ii-clarifiers.

II. I-Polypropylene kunye ne-Crystallinity yayo

I-Polypropylene yi-crystalline esetyenziswa kakhulu, i-commodity polymer eyenziwe nge-polymerization ye-propene monomer. Emva kwe-polymerization, i-PP inokwenza izakhiwo ezintathu ze-chain ezisisiseko (i-atactic, i-isotactic, i-syndiotactic) kuxhomekeke kwindawo yamaqela e-methyl. I-crystallinity ye-polymer ibonakaliswa yi:

·Iimilo kunye nobukhulu beekristale

·Ii-crystallinity ratios, kwaye ekugqibeleni

·Indlela iikristale ezibekwe ngayo

I-Isotactic polypropylene (iPP) yi-semi-crystalline polymer. Iphawulwa ngomlinganiselo ogqwesileyo weendleko zokusebenza, nto leyo eyenza ukuba ibe nomtsalane kakhulu kwiintlobo ngeentlobo zezicelo ezifana neemoto, izixhobo, imibhobho, ukupakisha, njl.

Isalathisi se-Isotacticity se-iPP sinxulumene ngokuthe ngqo nomgangatho we-crystallinity onempembelelo enkulu ekusebenzeni kwe-polymer. I-Isotacticity yonyusa i-crystallization kinetics, i-flexural modulus, ubulukhuni kunye nokucaca, kwaye inciphisa ukumelana nempembelelo kunye nokuvuleka.

Itheyibhile engezantsi ithelekisa iipropati zee-homopolymers ezimbini ze-polypropylene ezine-index eyahlukileyo ye-isotacticity.

III. Ukwenziwa kwekristale yePolypropylene
Ngokuxhomekeke kwiimeko, i-Isotactic Polypropylene inokwakheka ibe zizigaba ezine ezahlukeneyo ezimele i-α, β, γ kunye ne-mesomorphic smectic. Izigaba ze-α kunye ne-β zezona zibalulekileyo.

Isigaba se-α

1. Eli nqanaba lizinzile kwaye liyaziwa kakhulu.

2. Ezi kristali zezenkqubo yekristali ye-monoclinic.

Isigaba se-β

1. Eli nqanaba liyakwazi ukuguquguquka, kwaye iikristale zalo zezenkqubo yekristale engalinganiyo nehexagonal.

2. Isigaba se-β sifumaneka ikakhulu kwi-polypropylene e-copolymerized block kwaye sinokuveliswa ngokongeza ii-nucleating agents ezithile.

3. Olu hlobo lwekristale lwafunyanwa nguPadden noKeith ngo-1953; lunokukhuthazwa ngokukristaleka phakathi kwe-130°C kunye ne-132°C, ukucheba okuphezulu, okanye ukongezwa kwee-nucleating agents ezithile.

4. Ubukho besigaba se-β kwii-homopolymers ze-polypropylene buhlala buphucula ukuguquguquka kwemveliso egqityiweyo, kwaye isiphumo sibaluleke kakhulu xa umxholo wesigaba se-β ufikelela kwi-65%.

Isigaba se-γ

1. Eli nqanaba liyakwazi ukuguquguquka, lineekristale ze-triclinic.

2. Olu hlobo lwekristale aluqhelekanga; luvela ikakhulu kwi-polypropylene ene-molecular-weight ephantsi kwaye lwenziwa yi-crystallization phantsi koxinzelelo oluphezulu kakhulu kunye namazinga okuphola aphantsi kakhulu.

Ⅳ. Inkqubo yeNucleation kwiPolypropylene

Kuyaziwa kakuhle ukuba indawo yokuqala yokwenza ii-polymers zibe yi-germs ezincinci (ii-small particles) ezifakwe ngokwendalo kwi-melt-like catalyst residues, ukungcola, uthuli, njl.njl. Emva koko kunokwenzeka ukutshintsha nokulawula i-crystalline morphology ngokongeza ii-germs "zokwenziwa" ezifakwe kwi-polymer melt. Olu sebenzi lubizwa ngokuba yi-Nucleation.

Iinucleators okanye ii-nucleating agents zisetyenziswa ezibonelela ngeendawo zokuqalisa iikristale.

IiClarifiers ziyinxalenye encinci yeenucleators ezibonelela ngeekristali ezincinci ezisasaza ukukhanya okuncinci, kwaye ngenxa yoko, ziphucula ukucaca kobukhulu bodonga obufanayo benxalenye.

Indima yezi zixhobo zokukhupha ii-nucleating kukuphucula iimpawu zomzimba nezoomatshini zeendawo ezigqityiweyo.

Ⅴ. IiNucleators kunye neeClarifiers: Iphaneli etyebileyo yezongezo

Ii-Nucleating Agents ze-Particles

Ii-nucleating agents/ii-nucleants ze-particle zidla ngokuba zii-compounds ezinyibilikayo kakhulu ezisasazwa kwi-polymer melt ngokusebenzisa i-compounding. Ezi particles zisebenza njenge-'point nuclei' eyahlukileyo apho ukukhula kwe-polymer crystal kunokuqala khona.

Uxinzelelo oluphezulu lweenuclei lukhokelela ekukhanyeni ngokukhawuleza (amaxesha omjikelo amafutshane), kunye namanqanaba aphezulu e-crystallinity, nto leyo ephucula amandla, ukuqina, kunye ne-HDT ye-PP.

Ubukhulu obuncinci bee-crystal aggregates (ii-spherulites) zikhokelela ekuncipheni kokusasazeka kokukhanya kunye nokucaca okuphuculweyo.

Ii-particulate nucleating agents ezisetyenziswa kakhulu ziquka iityuwa kunye neeminerali, ezifana ne-talc, i-sodium benzoate, ii-phosphate esters kunye nezinye iityuwa ze-organic.

I-Talc kunye ne-sodium benzoate zithathwa njengezona zinto zisebenza kancinci, zingabizi kakhulu, kwaye zibonelela ngophuculo oluncinci kumandla, ukuqina, i-HDT, kunye nexesha lokujikeleza.

Ii-nucleants ezisebenza kakuhle nezibiza kakhulu, ezifana nee-phosphate esters kunye neetyuwa ze-bicycloheptane zinika iipropati zomzimba ezingcono kunye nokuphuculwa kokucaca okuthile.

Iiarhente zeNucleating ezinyibilikayo

Ii-nucleating agents ezinyibilikayo, ezikwabizwa ngokuba 'zii-melt-sensitive', zihlala zineendawo zokunyibilika eziphantsi kwaye zinyibilika kwi-PP enyibilikisiweyo.

Njengoko i-polymer melt iphola kwi-mold, ezi nucleants ziqala ngokudibanisa i-crystalline zenze inethiwekhi esasazeke kakuhle enommandla ophezulu kakhulu.

Njengoko ubushushu buqhubeka buhla, ii-fibrils eziquka olu nxibelelwano zisebenza njengee-nuclei ukuqalisa i-polymer crystallization.

Uxinzelelo oluphezulu kakhulu lweenuclei lukhokelela kwii-PP crystal aggregates ezincinci kakhulu, ezinika inqanaba eliphantsi lokusasazeka kokukhanya kunye nokucaca okungcono.

Zonke ii-clarifiers zii-nucleants, kodwa ayizizo zonke ii-nucleants ezi-clarifiers ezilungileyo.

Ezinye iinucleants eziqhelekileyo, ezifana ne-sodium benzoate kunye ne-talc, azinciphisi ubungakanani be-spherulite ngobuninzi obaneleyo ukuze zinike indawo ebunjiweyo enomkhenkce ophantsi kunye necacileyo eliphezulu. Ukucaca okungcono kakhulu kudla ngokufumaneka xa kusetyenziswa iinucleants ezinyibilikayo.

Iikhompawundi ze-organic ezinyibilikayo ezisebenza njenge-clarifiers ziquka ii-sorbitols, ii-nonotols, ii-trisamides.

Nangona ezi nucleants zisetyenziswa kakhulu ukufikelela ekukhanyeni okuphezulu kunye nokukhanya okuphantsi, zikwaphucula iipropati zomzimba kwaye zinciphisa ixesha lokujikeleza.

Umlinganiselo woBume kunye noBume beParticle

Iinxalenye zeNucleant ezineemilo ezifana neenaliti (ezifana ne-ADK STAB NA-11) zinokukhokelela kwiixabiso ezahlukeneyo zokuncipha kumatshini nakwizikhokelo ezinqamlezileyo. Olu hlobo lokuncipha lunokukhokelela kwi-warpage kwinxalenye yokugqibela. Iinxalenye zeNucleant ezine-planer geometry zinokunika ukuncipha okufanayo kwiindlela ezimbini ezikhokelela kwi-warpage encinci.

Ubungakanani beeParticle kunye noSasazo lweeParticle

Ubungakanani obuncinci bee-particle bukhokelela ekuphuculeni i-nucleation, kodwa ii-particles ezincinci nazo zinokuba nzima ukuzisasaza. Ezinye ii-particles ze-nucleant, ezifana ne-sodium benzoate, zihlala zihlangana kwakhona.

Isixhobo sokusika iasidi esisetyenzisiweyo

Ezinye izinto ezisusa i-asidi, ezifana neetyuwa ze-fatty acid (umz. i-calcium stearate) zinokuchasana nee-nucleants ezithile, ezifana nee-phosphate esters kunye ne-sodium benzoate. I-Dihydrotalcite kufuneka isetyenziswe kunye nezi nucleants.

Ungaze usebenzise i-calcium stearate kunye ne-sodium benzoate kuba i-calcium stearate iya kuyicima ngokupheleleyo i-nucleation ye-sodium benzoate.

Umlinganiselo wokusasazeka kunye nobukho bee-Agglomerate ezingasasazekanga

I-sodium benzoate idla ngokwenza ii-agglomerates kwaye kunzima ukuzisasaza kakuhle.

Ubushushu obunyibilikayo

IiSorbitol zifuna amaqondo obushushu aphezulu okunyibilika ukuze zinike ukucaca okungcono, kuba kufuneka zinyibilike ngokupheleleyo kwi-polymer melt.

Ukusebenzisana kunye nokuchasana phakathi kweeNucleants kunye nezinye izongezo

Izinto ezisusa i-asidi zinokuba zezonxibelelwano okanye ezichaseneyo. Iityuwa ze-asidi enamafutha ziyichaphazela kakubi i-modulus ye-phosphate ester nucleated PP.

Khetha EkuneneIinucleantskunye neeClarifiers zePP

Ngaphambi kokuba ukhethe i-nucleating okanye i-clarifying agent efanelekileyo kwisicelo sakho se-PP, misela ukuba loluphi uphuculo lwepropathi onomdla kulo:

a. Ukuba i-inkungu ephantsi kunye nokucaca okuphezulu kubalulekile, khetha enye yezicacisi ezinyibilikayo.

b. Ngeemfuno zokucaca okuncinci,ii-ester ze-phosphateingasetyenziswa.

c.Ukuba i-modulus ephezulu ibaluleke kakhulu, khetha enye yee-phosphate esters.

d.Ukuba ixabiso eliphantsi lelona libaluleke kakhulu, khetha i-sodium benzoate.

e. Ukuba i-warpage ephantsi kunye nobuthathaka obuphantsi bepigment yeyona nto ibalulekileyo, khetha ityuwa ye-bicycloheptane.

Kwakhona kubalulekile ukugqiba indlela i-nucleant eza kufakwa ngayo kwi-PP resin. Soloko uqhuba uvavanyo olufanelekileyo ukuqinisekisa ukuba ukusasazeka kakuhle kunye ne-nucleation kufezekisiwe.

Sebenzisa i-DSC kwi-resin ye-PP ene-nucleated. Uphuculo kwixesha lomjikelo luqhele ukuhambelana nokunyuka kobushushu be-crystallization (Tc). Vavanya iipropati zesampuli ebunjiweyo.

Ukuba ufuna ukubuza malunga neemveliso ezinxulumene nee-nucleating agents, nceda uzive ukhululekileQhagamshelana nathinangaliphi ixesha.