Cov yas extrusion siv lead ua yog dab tsi? 4 txoj hauv kev los qhia koj kom yooj yim tswj qhov crystallinity thiab crystallization zoo ntawm cov yas!

Cov khoom sib xyaw ua ke ntawm cov yas yog cov khoom sib sau ua ke ntawm ntau cov kab sib xyaw ua ke, ntev. Qib ntawm crystallisation (crystallinity) yog ntsuas los ntawm qib ntawm kev teeb tsa tsis tu ncua ntawm cov molecules, thiab qib ntawm crystallisation tuaj yeem ntsuas los ntawm kev cuam tshuam ntawm x-rays. Cov qauv ntawm cov organic sib xyaw ua ke yog qhov nyuaj, thiab cov qauv ntawm cov yas yog qhov nyuaj dua, thiab cov qauv ntawm cov saw hlau molecular (linear, bulbous, folded, spiral, thiab lwm yam) sib txawv ntau, yog li lawv cov qauv kuj sib txawv heev nyob ntawm cov xwm txheej tsim.

Ib hom yas uas muaj crystallinity siab yog ib hom yas crystalline thiab lub zog gravitational ntawm cov molecule sib cuam tshuam yooj yim, ua rau nws yog ib hom yas muaj zog. Yuav kom crystallize thiab sib dhos zoo, qhov ntim yuav me dua thiab qhov shrinkage thiab thermal expansion ntawm pwm yuav loj dua. Yog li ntawd, qhov crystallinity siab dua, qhov pob tshab tsawg dua, tab sis nws muaj zog dua.

Cov yas siv lead ua muaj qhov chaw yaj (Tm) sib txawv, thiab thaum khov lawm cov molecule yuav raug teeb tsa tas li, muaj zog dua thiab muaj zog dua hauv kev nruj. Thaum yaj, qhov ntim hloov pauv ntau heev, thiab tom qab kho, nws yooj yim dua rau kev ntsws, kev ntxhov siab sab hauv tsis yooj yim tso tawm, cov khoom tiav tsis pob tshab, kev tso cua sov hauv kev tsim khoom qeeb, qhov ntsws tom qab tsim cov pwm txias loj dua, thiab qhov ntsws tom qab tsim cov pwm kub me dua.
Tsis zoo li cov yas crystalline, muaj lwm hom yas uas tsis yog crystalline, uas tsis muaj qhov chaw yaj pom tseeb, cov molecule raug teeb tsa tsis sib xws thaum khov, qhov ntim tshwj xeeb tsis hloov pauv ntau thaum yaj, nws tsis yooj yim rau ntsws tom qab kho, cov khoom tiav lawm yog pob tshab, qhov kub ntawm cov khoom siab dua nws daj ntau dua, thiab cua sov tau yaj sai sai thaum lub sijhawm molding.

Cov yam ntxwv ntawm cov yas crystalline yog raws li nram no:


1. Txoj kev tswj kub
a. qhov kub yaj qis dua, qhov kub yaj qis dua, qhov zoo dua rau kev tsim cov nucleation nucleus, ua rau qhov kev loj hlob ntawm cov siv lead ua kom nce ntxiv, uas tuaj yeem txhim kho qhov crystallinity, tab sis kuj tuaj yeem ua rau qhov loj me ntawm cov siv lead ua kom tsawg dua. Yog li ntawd, hauv cov txheej txheem ua haujlwm tshwj xeeb kom ntseeg tau tias qhov kev ua kom yas, qhov kub yaj qis dua me ntsis, uas yog qhov zoo rau crystallisation.
b. Qhov kub txias, qhov kub txias ntawm qhov degree crystallization thiab crystallization zoo muaj qhov cuam tshuam loj tshaj plaws, yog tus neeg zoo tshaj plaws los tswj crystallization qeeb txias, tuaj yeem ua rau cov yas hauv thaj chaw crystallization nyob ntev dua, yog li ntawd qhov degree crystallization siab dua, tab sis qeeb txias tab sis yooj yim los tsim cov pob zeb siv lead ua, qhov toughness tsis zoo rau rigidity thiab hardness. Kev txias sai, ntawm ib sab tes, tso cai rau cov yas hla dhau thaj chaw crystallisation sai, yog li txo qhov degree ntawm crystallisation; ntawm qhov tod tes, vim yog lub sijhawm luv luv ntawm crystallization, nws kuj ua rau qhov loj me crystallisation zoo dua, uas zoo rau kev txhim kho ntawm kev pom tseeb thiab kev tawv. Hauv kev xyaum, seb qhov txias qeeb lossis ceev ceev puas siv tau nyob ntawm qhov xav tau kev ua haujlwm ntawm cov khoom. Yog tias qhov pom tseeb ntawm cov khoom siab, nws yuav tsum tau txias sai; yog tias qhov rigidity thiab hardness ntawm cov khoom siab, nws yuav tsum tau txias qeeb.

2. Txoj kev tswj cov neeg sawv cev nucleating
Tus neeg sawv cev nucleating feem ntau yog ntxiv rau kev txhawb nqa heterogeneous nucleation, ua rau kom muaj qhov loj hlob ntawm cov siv lead ua, ua rau crystallinity nce ntxiv, thiab ua rau cov khoom siv lead ua me dua, yog li txhim kho lub zog cuam tshuam, lub zog tawm los thiab ci ntsa iab.
Muaj peb hom nucleating agents: inorganic, organic thiab polymeric:
a. cov neeg sawv cev inorganic nucleating rau talc, suav nrog: CaCO3, mica, inorganic pigments, thiab lwm yam. Cov neeg sawv cev nucleating no muaj feem cuam tshuam rau qhov pom tseeb ntawm cov yas, thiab yog li ntawd yuav tsum txwv cov khoom pob tshab.
b. cov neeg sawv cev nucleating organic yog: sodium, magnesium, aluminium, titanium thiab lwm yam hlau aromatic carboxylates, organic phosphates, sorbic acid enzymes, thiab lwm yam.
c. Cov neeg sawv cev nucleating organic polymer rau qee qhov chaw melting siab ntawm cov polymer, xws li vinyl cycloalkanes tsuas yog nyob rau hauv PP, thiab lwm yam.
Nws yog ib qho tsim nyog sau tseg tias tsis ntev los no nws tau pom tias cov neeg sawv cev nucleating tsis yog tsuas yog ua rau qhov loj me ntawm cov siv lead ua tau zoo xwb, tab sis kuj txiav txim siab hom siv lead ua tshwj xeeb.

3. Txoj kev tswj kev ncab
Kev ncab ntawmzaj duab xis yasthiab cov khoom ntawv uas tau crystallized tuaj yeem ua rau cov crystals tawg thiab tsim cov crystals me dua, thiab tsim cov crystals raws li kev ncab, uas tuaj yeem txhim kho qhov tawv ntawm cov khoom thiab ua rau muaj zog tensile, gloss, hardness, barrier peev xwm thiab lwm yam khoom. Txoj kev ncab uas tuaj yeem hloov pauv qhov zoo ntawm cov yas crystalline, kuj tuaj yeem txhim kho nws cov crystallinity.

4. Txoj kev tswj kev kho cua sov
Kev kho cua sov ntawm ib sab tes tuaj yeem txhawb nqa qhov crystallization thiab ua rau crystallinity nce ntxiv; ntawm qhov tod tes tuaj yeem txhim kho qhov zoo ntawm crystallization, yog li cov teeb meem crystallization uas tshuav los ntawm kev maj nrawm crystallization tuaj yeem kho tau tag nrho.
Kev kho cua sov kuj tseem tuaj yeem ua rau cov crystallization ntawm ntau hom kev hloov pauv sib koom ua ke. Xws li cov khoom PP uas muaj β crystalline, kev kho cua sov saum toj no qhov melting point yuav yaj tag nrho, recrystallization, yuav raug hloov mus rau hauv α crystalline, thaum cov lus pom zoo hexagonal crystalline hauv 70 C saum toj no kev kho cua sov uas tuaj yeem hloov mus rau α crystalline.

Piv txwv li, tom qab kev kho cua sov ntawm nws cov khoom, nws cov khoom sib txawv hloov pauv raws li hauv qab no:
a. lub zog tensile hauv qhov kub kho cua sov ntawm 120'180 ℃ thiab tuav lub sijhawm ntawm 10'120min, lub zog tensile nrog kev nce hauv qhov kub kho thiab tuav lub sijhawm thiab kev ncua ntawm kev nce, qhov kev hloov pauv siab tshaj plaws tuaj yeem ncav cuag li 10%.
b. Lub zog cuam tshuam hauv lub sijhawm tuav ntawm 4 teev, qhov kub kho los ntawm 120 ℃ txog 140 ℃, lub zog cuam tshuam txo qis ze li ntawm 60%. Txawm li cas los xij, tom qab qhov kub tshaj 140 ° C, qhov kev poob qis tau du. Ntawm qhov kub ntawm 180, thaum lub sijhawm tuav tau ntev los ntawm 10 feeb txog 30 feeb, lub zog cuam tshuam kuj txo qis 60%. Tom qab lub sijhawm tuav tshaj 30 feeb, qhov kev poob qis yog tiaj tus.
c. qhov nyuaj nyob rau hauv ib qho ntau yam, nrog rau qhov kub thiab txias ntawm kev kho cua sov thiab lub sijhawm ntev ntawm kev tuav, qhov nyuaj tau maj mam nce, qhov nce siab tshaj plaws ntawm kwv yees li 10%.
d. Kev kho cua sov crystallinity tuaj yeem txhawb kev crystallization theem ob, thiab yog li tuaj yeem txhim kho crystallinity. Hauv qhov chaw rwb thaiv tsev 4 teev nrog qhov kub kho cua sov nce, crystallinity nce; pib sai dua me ntsis, ntau dua 140 ℃, me ntsis qeeb dua. Hauv qhov kub kho cua sov ntawm 180 ℃, nrog lub sijhawm rwb thaiv tsev ntev dua, crystallinity pib zoo ib yam; tab sis thaum rwb thaiv tsev ntau dua 120 feeb, crystallinity nce sai.

Yuav ua li cas txiav txim siab qhov crystallinity hauv plastics?
Muaj peb txoj kev siv ntau: txoj kev ntom ntom, txoj kev diffraction XRD thiab txoj kev DSC.
Txoj kev DSC feem ntau siv thiab raug dua, ua raws li txoj kev XRD, uas, ntxiv rau kev ntsuas crystallinity, kuj tseem tuaj yeem txiav txim siab cov ntsiab lus ntawm txhua hom crystal raws li spectrum; txoj kev ceev muaj qhov yuam kev loj tshaj plaws thiab feem ntau tsuas yog siv los sib piv cov crystallinity ntawm tib yam khoom.
Ntxiv rau peb txoj kev no, kuj tseem muaj txoj kev ntsuas infrared spectroscopy, uas yog raws li kev xam yooj yim los ntawm software spectrogram thiab tsis tshua siv.