Polypropylene (PP) muaj ntau- qhov kev faib tawm qhov ntev vim qhov sib txawv ntawm cov qauv molecular thiab txheej txheem polymerization. Cov pawg sib txawv muaj cov yam ntxwv tshwj xeeb hauv kev ua haujlwm thiab kev siv, ua lub hauv paus rau nws qhov kev hloov pauv dav dav.
Raws li txoj kev polymerization, PP feem ntau muab faib ua ob pawg: homopolymer polypropylene thiab copolymer polypropylene. Homopolymer polypropylene yog polymerized los ntawm ntshiab propylene monomers, nrog siab molecular saw tsis tu ncua thiab crystallinity tshaj 60%. Yog li ntawd, nws pom zoo rigidity, hardness, thiab kub tsis kam, nrog ib tug melting point ntawm kwv yees li 165 degree. Nws yog qhov tsim nyog rau kev tsim cov khoom lag luam uas xav tau lub zog siab, xws li cov thawv ntim khoom, cov ntim khoom nruj, thiab cov khoom siv hluav taws xob. Copolymer polypropylene, ntawm qhov tod tes, qhia me me ntawm ethylene monomers thaum lub sij hawm txheej txheem polymerization. Raws li kev faib tawm ethylene, nws muab faib ua thaiv copolymer thiab random copolymer. Block copolymer polypropylene tsim cov qauv thaiv los ntawm segmental polymerization ntawm propylene thiab ethylene. Cov kev taw qhia ntawm ethylene ntu cuam tshuam qhov kev sib tsoo ntawm cov saw hlau molecular, txo cov crystallinity tab sis txhim kho cov khoom cuam tshuam cov tawv nqaij. Nws qhov kub thiab txias tuaj yeem txo qis rau qis dua -20 degree, ua rau nws siv dav hauv kev cuam tshuam -cov ntawv siv tiv thaiv xws li tsheb bumpers thiab cov thawv ntim khoom lag luam. Nyob rau hauv random copolymer polypropylene, cov ethylene monomers random faib nyob rau hauv lub propylene saw, ntxiv txo molecular saw tsis tu ncua thiab ua rau qis crystallinity (feem ntau qis dua 30%). Qhov no pab txhim kho cov khoom pob tshab thiab muab qhov zoo qis - qhov kub thiab txias, ua rau nws feem ntau siv hauv cov khoom ntim pob tshab, cov koob txhaj tshuaj, thiab cov khoom siv hauv tsev.
Raws li stereoregularity, PP tuaj yeem muab faib ua isotactic polypropylene, syndiotactic polypropylene, thiab atactic polypropylene. Isotactic polypropylene muaj methyl sab pawg txheej txheem tsis tu ncua thiab nyob rau hauv tib txoj kev raws lub ntsiab saw, yooj yim tsim ib tug heev crystalline qauv, ua rau nws cov mainstream industrial cov khoom thiab tuav lub feem ntau ntawm kev ua lag luam qhia. Syndiotactic polypropylene muaj alternating methyl pawg, nrog me ntsis qis crystallinity thiab rigidity tshaj isotactic polypropylene, tab sis superior transparency thiab gloss, ua rau nws feem ntau siv nyob rau hauv siab - kawg films thiab nplooj ntawv. Atactic polypropylene, vim yog qhov tsis sib haum xeeb ntawm pawg methyl, nws nyuaj rau crystallize thiab nthuav tawm viscoelasticity ntawm chav tsev kub, feem ntau yog siv los ua tus neeg sawv cev tawv lossis sib xyaw nrog lwm cov polymers.
Tsis tas li ntawd, raws li cov ntawv thov, polypropylene tuaj yeem muab faib ua cov khoom siv tshwj xeeb xws li qib fiber ntau, qib txhaj tshuaj molding, qib zaj duab xis, qib fiber ntau, thiab qib extrusion. Lawv qhov hnyav molecular, molecular hnyav tis, thiab additive formulations yog optimized rau txawv molding txheej txheem kom tau raws li qhov sib txawv cov kev xav tau ntawm niche ciaj uas muag xws li woven hnab, automotive qhov chaw, cam khwb cia films, thiab polypropylene fibers.
Qhov ntau- theem kev faib tawm ntawm polypropylene no qhia txog kev tswj cov peev txheej ntawm cov ntaub ntawv tshawb fawb thiab muab cov kev lag luam hauv qab nrog cov kev daws teeb meem uas ua tau raws li qhov yuav tsum tau ua, tsis tu ncua nws txoj kev nkag mus rau hauv ntim, tsheb, thiab kev kho mob.