Kevlar yog dab tsi?
Yug hauv xyoo 1960s, Kevlar yog hom tshiab ntawm cov khoom siv hluav taws xob siab. Nws yog dav siv nyob rau hauv lub tshav pob ntawm cov khoom siv mos mos thiab yog ib qho zoo tagnrho cov ntaub ntawv mos mos. Yog li dab tsi ntawm cov khoom siv yog Kevlar, thiab vim li cas nws thiaj li muaj cov mos txwv zoo li no? Cov ntawv thov li cas yog dab tsi? Cia peb pib nrog Kevlar cov qauv molecular thiab lub hauv paus ntsiab lus ntawm mos mos.
1. Molecular qauv ntawm Kevlar
Kevlar yog Ameslikas ib yam khoom siv fiber ntau aramid tsim los ntawm DuPont (DuPont) hauv Tebchaws Meskas. Nws lub npe tshuaj yog polyparaphenylene terephthalamide, uas yog polymerized los ntawm p-phenylene diamine thiab terephthaloyl chloride. rau hauv siab molecular hnyav polymers. Cov mis mos molecular yog (C14H10O2N2)n, uas txhais tau hais tias nws yog tsim los ntawm rov qab units txuas rau ib leeg los tsim ib tug saw qauv, thiab cov saw hlau txuas nrog hydrogen bonds los tsim ib lub network.
Cov qauv molecular ntawm Kevlar txiav txim siab tias nws muaj zog tiv thaiv tshav kub thiab nplaim taws retardancy. Zoo heev tensile zog.
Feem ntau cov txheej txheem tsim ntawm Kevlar fiber ntau muab faib ua ob theem:
1) Polycondensation ntawm p-diphenylamine thiab terephthaloyl chloride rau hauv p-phenylene terephthalamide (PPTA).
2) Cov polymer yog yaj nyob rau hauv ib qho hnyav thiab ces spun los tsim cov khoom siv fiber ntau.
1. Cov mos txwv mechanism ntawm Kevlar
Raws li tau hais ua ntej, tsis zoo li cov ntaub ntawv tsis zoo xws li ceramics thiab hlau, Kevlar muaj lub zog ultra-siab, zoo toughness thiab tensile zog vim yog kev sib xyaw ua ke ntawm cov tshuaj lom neeg hauv cov khoom siv. Lub Vla fiber yuav tsim elastic deformation vim stretching thiab shearing ntawm projectile. Thaum lub sij hawm tus txheej txheem no, lub zog ntawm cov mos txwv yog yuam kom diffuse mus rau qhov chaw uas tsis yog qhov cuam tshuam qhov taw tes. Kev poob ntawm lub zog kinetic yuav txo tau qhov ceev ntawm cov mos txwv, thiab nws thiaj li yuav cuam tshuam los ntawm fiber ntau. Daim ntawv thov Kevlar nyob rau hauv lub tshav pob ntawm cov mos txwv tau zoo heev txhim kho kev tiv thaiv kev ua tau zoo ntawm ntau yam mos txwv cov khoom, thiab nyob rau tib lub sij hawm txo tus luj ntawm cov mos txwv cov khoom, uas yog ib tug zoo kev vam meej nyob rau hauv lub tshav pob ntawm cov mos txwv.
2. Daim ntawv thov Kevlar
Nrog rau kev ua kom sov zoo, lub zog tensile thiab lub zog siab, Kevlar tau siv dav hauv kev tsim khoom ntawm ntau yam khoom siv lub neej txhua hnub thiab cov khoom siv mos mos. Piv txwv li, dej haus straws thiab hnab looj tes kev nyab xeeb uas feem ntau siv hauv peb lub neej txhua hnub; parachute ropes rau aerospace, cables rau nkoj; sib tw suits, cov neeg tua hluav taws kub-insulating tiv thaiv khaub ncaws; cov tub rog lub cev armor, daim hlau tsis muaj phom, cov kaus mom hlau tiv thaiv, thiab lwm yam. Tos. Daim ntawv thov Kevlar pab txhawb peb lub neej thiab txhawb kev nce qib ntawm kev tsim khoom lag luam.
Tab sis aramid kuj muaj ob qhov tsis txaus ntseeg:
1) Nws yuav degrade thaum raug ultraviolet rays;
2) Yooj yim rau hydrolyze, txawm tias nws khaws cia hauv qhov chaw qhuav, nws yuav nqus dej noo hauv huab cua thiab maj mam hydrolyze.
Yog li ntawd, qee cov khoom aramid tsis haum rau kev siv mus sij hawm ntev hauv qhov chaw muaj zog ultraviolet thiab ntub dej, uas yuav txo tau lawv lub neej kev pab cuam.
Cov lus saum toj no yog kev qhia txog Kevlar, yog tias koj muaj lus nug, thov tuaj nrog peb tham.
