Polypropylene yog ib qho polymer siv dav dav uas siv rau ntau yam kev siv vim nws muaj cov yam ntxwv zoo sib xws. Nws cov yam ntxwv, xws li lub cev, lub tshuab thiab qhov muag tuaj yeem txhim kho ntxiv nrog kev siv cov neeg sawv cev nucleating thiab cov neeg sawv cev clarifying. Cov additives no pab txhawb rau kev crystallization ntawm PP thaum lub sijhawm ua, yog li txhim kho cov yam ntxwv uas twb tau txais lawm.

To taub yuav siv cov nucleating agents thiab clarifying agents li cas thiab tau txais cov lus qhia xaiv kom ua tau zoo dua qub, hloov kho cov qauv thiab morphology, thiab txo cov pa phem hauv koj cov polypropylene formulations.

I. Lub Luag Haujlwm ntawm Cov Neeg Sawv Cev Ua Kom Pom Tseeb hauv PP

Crystallinity ntawm semi-crystalline polymers yog lub luag haujlwm rau ntau yam ntxwv, xws li kev ruaj khov ntawm qhov ntev, kev meej, thiab kev tawv.

Rau ib feem thiab cov txheej txheem uas tau teev tseg, qhov crystallinity yog tswj los ntawm cov qauv polymer, cov qauv, thiab cov xwm txheej ua haujlwm uas ua rau muaj qhov sib npaug ntawm cov cua sov tsim thiab txias. Yog li ntawd, crystallinity feem ntau yog heterogeneous, keeb kwm cua sov txawv rau daim tawv nqaij thiab lub plawv ntawm cov khoom lossis cov khoom.

Cov neeg sawv cev nucleating thiab clarifiers ua kom nrawm thiab kho qhov crystallization uas tso cai rau kho cov khoom kawg ntawm cov semi-crystalline polymers kom haum rau cov kev xav tau ua haujlwm.

Hauv cov qauv polypropylene, ntxiv cov neeg sawv cev nucleating (tseem hu ua nucleators) ua rau muaj kev ua tau zoo dua & cov khoom ua tiav, xws li:

· Zoo dua qhov pom tseeb thiab txo qhov tsaus ntuj

· Lub zog thiab kev nruj zoo dua

· Kev Txhim Kho Kub Deflection Kub (HDT)

· Lub sijhawm luv dua

· Txo qhov warping thiab ntau dua shrinkage

· Txo cov xim rhiab heev txog kev hloov pauv ntawm cov khoom nrog cov xim sib txawv

· Kev ua haujlwm tau zoo dua hauv qee daim ntawv thov

Yog li, nucleation yog ib txoj hauv kev muaj zog los txhim kho cov khoom siv lub cev, khoom siv kho tshuab, thiab khoom siv kho qhov muag ntawm polypropylene. Kev meej, kev ruaj khov ntawm qhov ntev, kev sib txhuam, kev ntsws, CLTE, HDT, khoom siv kho tshuab thiab cov teebmeem thaiv kev cuam tshuam tuaj yeem txhim kho los ntawm kev xaiv cov nucleators lossis clarifiers.

II. Polypropylene thiab Nws Cov Crystallinity

Polypropylene yog ib qho siv dav dav crystalline, khoom lag luam polymer ua los ntawm polymerization ntawm propene monomer. Thaum polymerization, PP tuaj yeem tsim peb cov qauv saw hlau yooj yim (atactic, isotactic, syndiotactic) nyob ntawm qhov chaw ntawm cov pab pawg methyl. Lub crystallinity ntawm polymer yog tus yam ntxwv los ntawm:

Cov duab thiab qhov loj ntawm cov crystallites

· Cov piv ntawm crystallinity, thiab thaum kawg

· Kev taw qhia ntawm cov crystallites

Isotactic polypropylene (iPP) yog ib hom polymer semi-crystalline. Nws muaj tus nqi zoo heev rau kev ua tau zoo, ua rau nws zoo nkauj heev rau ntau yam kev siv xws li tsheb, khoom siv hauv tsev, kav dej, ntim khoom, thiab lwm yam.

Qhov ntsuas Isotacticity ntawm iPP yog txuas ncaj qha rau qib ntawm crystallinity uas muaj feem cuam tshuam loj rau kev ua tau zoo ntawm polymer. Isotacticity ua rau crystallization kinetics, flexural modulus, hardness & transparency, thiab txo qhov cuam tshuam tsis kam & permeability.

Cov lus hauv qab no piv cov khoom ntawm ob lub polypropylene homopolymers uas muaj cov isotacticity index sib txawv.

III. Kev Ua Crystallization ntawm Polypropylene
Nyob ntawm seb muaj tej yam mob dab tsi, Isotactic Polypropylene tuaj yeem crystallize ua plaub theem sib txawv uas hu ua α, β, γ thiab mesomorphic smectic. Cov theem α thiab β yog cov tseem ceeb tshaj plaws.

α Theem

1. Theem no ruaj khov dua thiab paub zoo dua.

2. Cov siv lead ua no yog cov siv lead ua monoclinic.

β Theem

1. Theem no yog metastable, thiab nws cov siv lead ua koom nrog pseudo-hexagonal crystal system.

2. Cov theem β feem ntau muaj nyob rau hauv cov polypropylene copolymerized thaiv thiab tuaj yeem tsim los ntawm kev ntxiv cov neeg sawv cev nucleating tshwj xeeb.

3. Daim ntawv siv lead no tau tshawb pom los ntawm Padden thiab Keith hauv xyoo 1953; nws tuaj yeem txhawb nqa los ntawm kev siv lead ntawm 130 ° C thiab 132 ° C, kev taw qhia siab, lossis ntxiv cov neeg sawv cev nucleating tshwj xeeb.

4. Qhov muaj cov theem β hauv polypropylene homopolymers feem ntau txhim kho qhov ductility ntawm cov khoom tiav, thiab qhov cuam tshuam yog qhov tseem ceeb tshaj plaws thaum cov ntsiab lus theem β ncav cuag 65%.

γ Theem

1. Theem no kuj tseem metastable, nrog rau triclinic crystals.

2. Cov qauv siv lead ua no tsis tshua muaj; nws feem ntau tshwm sim hauv polypropylene uas tsis muaj molecular thiab yog tsim los ntawm crystallization nyob rau hauv qhov siab heev thiab cov nqi txias qis heev.

Ⅳ. Cov txheej txheem nucleation hauv Polypropylene

Nws yog qhov paub zoo tias qhov pib ntawm kev siv lead ua ke ntawm cov polymers yog cov kab mob me me (cov khoom me me) uas muaj nyob rau hauv cov khoom seem zoo li catalyst yaj, cov khoom tsis huv, hmoov av, thiab lwm yam. Tom qab ntawd nws muaj peev xwm hloov kho thiab tswj cov qauv crystalline los ntawm kev ntxiv cov kab mob "dag" uas tau qhia rau hauv cov polymer yaj. Qhov kev ua haujlwm no hu ua Nucleation.

Cov nucleators lossis nucleating agents raug siv uas muab qhov chaw rau kev pib ntawm cov siv lead ua.

Cov khoom ua kom pom tseeb yog cov khoom me me ntawm cov nucleators uas muab cov crystallites me me uas tawg tsawg dua lub teeb thiab, vim li ntawd, txhim kho qhov pom tseeb rau tib lub phab ntsa tuab ntawm ib feem.

Lub luag haujlwm ntawm cov neeg sawv cev nucleating no yog los txhim kho cov khoom siv lub cev thiab cov khoom siv kho tshuab ntawm cov khoom tiav lawm.

Ⅴ. Cov Nucleators thiab Clarifiers: Ib Pawg Neeg Nplua Nuj ntawm Cov Khoom Ntxiv

Cov Neeg Sawv Cev Ua Rau Cov Khoom Me Me

Cov khoom siv ua nucleating particulate/nucleants feem ntau yog cov tshuaj uas yaj sai heev uas tau tawg ua tej daim me me hauv cov polymer yaj los ntawm kev sib xyaw ua ke. Cov khoom me me no ua haujlwm ua cov 'point nuclei' sib txawv uas cov polymer crystal loj hlob tuaj yeem pib.

Qhov kev sib sau ua ke ntawm cov nuclei ua rau muaj kev sib xyaw ua ke sai dua (lub sijhawm luv dua), thiab cov qib crystallinity siab dua, uas ua rau lub zog, kev tawv, thiab HDT ntawm PP zoo dua.

Qhov me me ntawm cov pob zeb siv lead ua ke (spherulites) ua rau lub teeb tawg tsawg dua thiab ua kom pom tseeb dua.

Cov neeg sawv cev nucleating particulate feem ntau suav nrog cov ntsev thiab cov zaub mov, xws li talc, sodium benzoate, phosphate esters thiab lwm yam ntsev organic.

Talc thiab sodium benzoate raug suav hais tias yog cov nucleants uas tsis muaj zog, pheej yig, thiab muab kev txhim kho me ntsis hauv lub zog, kev tawv, HDT, thiab lub sijhawm voj voog.

Cov nucleants ua haujlwm tau zoo, kim heev, xws li cov phosphate esters thiab cov ntsev bicycloheptane muab cov khoom zoo dua qub thiab qee qhov kev txhim kho hauv kev meej.

Cov Neeg Sawv Cev Uas Yaj Tau

Cov neeg sawv cev nucleating uas yaj tau, uas kuj hu ua 'melt-sensitive', feem ntau muaj cov ntsiab lus melting qis thiab yaj hauv cov PP uas yaj.

Thaum cov polymer yaj txias hauv pwm, cov nucleants no crystallize tawm ua ntej tsim ib lub network faib ua feem me me nrog thaj chaw loj heev.

Thaum qhov kub tseem poob qis, cov fibrils uas muaj cov network no ua haujlwm ua nuclei los pib cov polymer crystallization.

Qhov kev sib sau ua ke ntawm cov nuclei siab heev ua rau muaj cov khoom siv PP me me, uas muab qib qis tshaj plaws ntawm kev tawg ntawm lub teeb thiab qhov meej tshaj plaws.

Txhua cov clarifiers yog nucleants, tab sis tsis yog txhua nucleants yog cov clarifiers zoo.

Qee cov nucleants uas siv ntau, xws li sodium benzoate thiab talc, tsis txo qhov loj ntawm spherulite kom txaus kom muaj qhov tsis pom kev zoo thiab qhov meej meej ntawm cov khoom pwm. Feem ntau qhov meej meej tshaj plaws yog ua tiav thaum siv cov nucleants uas yaj tau.

Cov organic sib xyaw uas ua haujlwm ua cov tshuaj ua kom pom tseeb suav nrog sorbitols, nonotols, thiab trisamides.

Txawm hais tias cov nucleants no feem ntau yog siv los ua kom pom tseeb thiab tsis muaj pos huab, lawv kuj txhim kho cov khoom siv lub cev thiab txo lub sijhawm voj voog.

Cov Duab Particle thiab Qhov Sib Piv

Cov khoom me me Nucleant uas muaj cov duab zoo li koob (xws li ADK STAB NA-11) tuaj yeem ua rau muaj qhov sib txawv ntawm qhov shrinkage hauv lub tshuab thiab cov lus qhia transverse. Qhov shrinkage anisotropy no tuaj yeem ua rau warpage hauv qhov kawg. Cov khoom me me Nucleant nrog lub planer geometry tuaj yeem ua rau muaj qhov shrinkage sib xws ntau dua hauv ob qho kev qhia ua rau warpage tsawg dua.

Qhov Loj ntawm Cov Khoom Me Me & Kev Faib Tawm Qhov Loj ntawm Cov Khoom Me Me

Qhov me me ntawm cov khoom me me ua rau muaj kev txhim kho nucleation, tab sis cov khoom me me kuj tuaj yeem nyuaj rau disperse. Qee cov khoom me me, xws li sodium benzoate, feem ntau rov sib sau ua ke.

Cov Khoom Siv Acid Scavenger

Qee cov tshuaj tua cov kua qaub, xws li cov ntsev fatty acid (piv txwv li calcium stearate) tuaj yeem tawm tsam qee cov nucleants, xws li cov phosphate esters thiab sodium benzoate. Dihydrotalcite yuav tsum tau siv nrog cov nucleants no.

Tsis txhob siv calcium stearate nrog sodium benzoate vim tias calcium stearate yuav ua rau lub nucleation ntawm sodium benzoate ploj mus.

Qib ntawm Kev Sib Tshuam & Kev Muaj Cov Agglomerates Tsis Tau Sib Nraus

Sodium benzoate feem ntau tsim cov agglomerates thiab nyuaj rau disperse kom zoo.

Kub yaj

Sorbitols xav tau qhov kub siab dua kom muab qhov meej tshaj plaws, vim lawv yuav tsum yaj tag nrho hauv cov polymer yaj.

Kev Sib Koom Tes thiab Kev Sib Ntaus Sib Tua Ntawm Nucleants thiab Lwm Cov Khoom Ntxiv

Cov tshuaj tua cov kua qaub tuaj yeem ua ke lossis ua ke. Cov ntsev ntawm cov kua qaub fatty cuam tshuam tsis zoo rau modulus ntawm phosphate ester nucleated PP.

Xaiv Sab XisCov Nucleantsthiab Clarifiers rau PP

Ua ntej xaiv tus neeg sawv cev nucleating lossis clarifying uas haum rau koj daim ntawv thov PP, txiav txim siab seb koj xav tau kev txhim kho vaj tse twg tshaj plaws:

a. Yog tias qhov tseem ceeb yog qhov tsis muaj pos huab thiab qhov meej meej siab, ces xaiv ib qho ntawm cov tshuaj ua kom meej meej uas yaj tau.

b. Rau qhov yuav tsum tau ua kom pom tseeb dua, qhovcov phosphate esterssiv tau.

c. Yog tias qhov modulus siab yog qhov tseem ceeb tshaj plaws, ces xaiv ib qho ntawm cov phosphate esters.

d. Yog tias tus nqi qis yog qhov tseem ceeb tshaj plaws, ces xaiv sodium benzoate.

e. Yog tias qhov tseem ceeb tshaj plaws yog qhov tsis tshua muaj kev sib txhuam thiab tsis tshua muaj xim tsis zoo, ces xaiv cov ntsev bicycloheptane.

Nws tseem ceeb heev rau kev txiav txim siab seb cov nucleant yuav raug muab tso rau hauv PP resin li cas. Ib txwm khiav cov kev ntsuam xyuas kom tsim nyog kom ntseeg tau tias muaj kev sib kis zoo thiab nucleation tau ua tiav.

Khiav DSC ntawm cov PP resin nucleated. Kev txhim kho hauv lub sijhawm voj voog feem ntau cuam tshuam nrog kev nce ntxiv ntawm qhov kub ntawm crystallization (Tc). Cov khoom sim ntawm cov qauv pwm.

Yog tias koj xav nug txog cov khoom lag luam ntsig txog cov neeg sawv cev nucleating, thov koj xav tiv tauj peb.tiv tauj pebtxhua lub sijhawm.