Plasticizer, tseem hu ua plasticizer, yog siv dav siv cov khoom siv polymer ntxiv hauv kev lag luam. Ntxiv cov khoom no rau kev ua cov yas tuaj yeem ua kom cov yas tsis muaj kev cuam tshuam rau cov yam ntxwv tseem ceeb ntawm cov polymer. Nws tuaj yeem txhim kho qhov elongation, yooj, thiab yooj yim ntawm cov yas, tab sis cov hardness, modulus, softening kub thiab embrittlement kub yuav txo. Yog li dab tsi yog vim li cas cuam tshuam rau cov yas yas yas, koj puas paub?
1. Lub luag haujlwm ntawm plasticizers
• Txo cov iav hloov pauv kub ntawm cov polymer.
● Hloov cov qauv ntawm cov polymer kom cov khoom siv yas mos.
● Ua kom lub elongation ntawm cov polymer thiab txo lub zog tensile.
● Ua kom lub zog ntawm cov polymer thiab txhim kho qhov cuam tshuam.
● Txhim kho qhov ua tau zoo ntawm qhov kub thiab txias.
2. Lub ntsiab tseem ceeb cuam tshuam rau plasticization
●Intermolecular rog ntawm polymers
Thaum lub plasticizer ntxiv rau polymer, kev sib cuam tshuam ntawm plasticizer molecules thiab nruab nrab ntawm plasticizer thiab polymer molecules muaj kev cuam tshuam zoo rau plasticization. Qhov kev sib cuam tshuam no feem ntau yog van der Waals quab yuam thiab hydrogen bond force, thiab van der Waals quab yuam suav nrog peb hom dispersion force, inductive force thiab orientation force.
(1) Van der Waals quab yuam
▶ Lub zog dispersion muaj nyob nruab nrab ntawm tag nrho cov polar lossis non-polar molecules, thiab nws yog lub zog nqus tau tsim los ntawm kev cuam tshuam nrog cov me me tam sim no dipoles, uas ua rau cov dipoles nyob ze rau ntawm cov ncej sab nraud uas nyob ib sab, tab sis tsuas yog nyob rau hauv cov tsis- polar xeev. Nyob rau hauv lub system, nws dispersion quab yuam occupies lub ntsiab txoj hauj lwm.
▶ Thaum lub molecule nrog ib tug dipole induces ib tug induced dipole nyob rau hauv ib tug nyob ib sab uas tsis yog-polar molecule, lub molecular attraction ntawm induced dipole thiab lub intrinsic dipole yog hu ua lub inductive quab yuam. Lub zog inductive tshwj xeeb yog muaj zog rau cov tshuaj tsw qab. Cov nyhuv plasticizing ntawm polystyrene nrog qis molecular hnyav esters yog feem ntau inductive.
▶ Thaum cov polar molecules nyob ze rau ib leeg, vim yog lub hauv paus ntawm dipole orientation, lub zog yog tsim los ntawm cov molecules, uas feem ntau hu ua lub zog taw qhia. Kev sib cuam tshuam ntawm ester plasticizers thiab PVC yog ib qho piv txwv sawv cev.
(2) Hydrogen daim ntawv cog lus
Hydrogen bonding yog ib qho kev sib raug zoo sib raug zoo, thiab nws lub neej yuav tiv thaiv kev nkag ntawm plasticizer molecules rau hauv polymer molecules. Lub denser cov hydrogen bonds raug faib raws cov polymer molecular saw, qhov nyuaj dua qhov sib thooj plasticizer molecules yog ntxig, Yog li ntawd, cov yas yuav tsum muaj zog zoo ib yam li cov polymer molecules. Thaum qhov kub thiab txias, cov nyhuv ntawm hydrogen bonds yuav tsis muaj zog vim qhov thermal txav ntawm cov molecules cuam tshuam rau kev taw qhia ntawm cov khoom siv polymer.
● Lub crystallinity ntawm cov polymer
Nws yog qhov nyuaj dua rau plasticizer molecules kom ntxig rau hauv cov cheeb tsam crystalline dua rau hauv thaj tsam amorphous. Vim tias qhov chaw dawb ntawm cov saw hlau polymer hauv thaj tsam crystalline yog me me. Plasticizer yog cov yas tsis muaj kuab tshuaj yog tias nws cov molecules tsuas tuaj yeem ntxig rau hauv cov cheeb tsam amorphous ntawm ib feem crystalline polymer. Yog tias cov molecules ntawm plasticizer tuaj yeem muab tso rau hauv ob qho tib si hauv cheeb tsam amorphous thiab thaj tsam crystalline ntawm cov polymer, cov plasticizer yog cov khoom hnyav-raws li plasticizer, uas yog hu ua thawj plasticizer.
Cov saum toj no yog cov ntsiab lus tseem ceeb txog cov laj thawj uas cuam tshuam rau cov yas ntawm plasticizers. Kuv vam tias nws yuav pab tau tom qab nyeem nws. Nyob rau hauv cov ntsiab lus, lub ntsiab yam tseem ceeb cuam tshuam rau lub plasticization ntawm plasticizers yog intermolecular quab yuam thiab polymerization ntawm polymers. Thaum lub plasticizer ntxiv rau lub polymer, kev sib cuam tshuam ntawm cov plasticizer molecules thiab nruab nrab ntawm plasticizer thiab polymer molecule yuav muaj kev cuam tshuam zoo rau cov nyhuv plasticization.