Silicone

I- silicone noma i- polysiloxane iyi- polymer eyenziwe nge- siloxane (2R ₂ Si − O − SiR ₂ -, lapho R = iqembu lezinto eziphilayo).Ngokuvamile akunambala, uwoyela noma izinto ezifana nenjoloba.Ama-silicone asetshenziswa kuma-sealants, ama-adhesives, izinto zokuthambisa, imithi, izitsha zokupheka, nokufakwa okushisayo nokugesi.Amanye amafomu ajwayelekile afaka uwoyela we-silicone, i- silicone grease, iraba le- silicone, i-resin ye-silicone, ne-silicone caulk.

I-caulk yesilicone ingasetshenziswa njenge-sealant eyisisekelo emele ukungena kwamanzi nomoya

I-Chemistry

Ukwakhiwa kwamakhemikhali kwe-silicone polydimethylsiloxane (PDMS)

Okuningi ngokunembile ngokuthi polymerized siloxanes noma polysiloxanes, silicones aqukethe i wezinto Silicon--mpilo backbone uchungechunge (⋯ -Si-O-Si-O-Si-O- ⋯) nemacembu lamabili organic enamathiselwe ngamunye isikhungo silicon.Imvamisa, amaqembu aphilayo yi-methyl.Izinto zokwakha zingaba yi-cyclic noma i-polymeric.Ngokushintshashintsha ubude beketanga le-iSi − O−, amaqembu asemaceleni, nokuxhumeka kwe-crosslinking, ama-silicone angahlanganiswa nezinto eziningi ezahlukahlukene nokwakhiwa.Zingahluka ngokungaguquguquki kusuka kuketshezi kuya ku-gel kuye kuraba kuye kupulasitiki onzima.I-siloxane ejwayelekile kakhulu i-linear polydimethylsiloxane (PDMS), uwoyela we-silicone.Iqembu lesibili ngobukhulu lezinto zokwenziwa ze-silicone lincike ezinhlakeni ze-silicone, ezakhiwa ngama-oligosiloxanes anamagatsha kanye nezinyosi.

Ukuhlanganiswa

Okuvame kakhulu izinto ezisuselwa ku- polydimethylsiloxane, etholakala nge-hydrolysis ye- dimethyldichlorosilane.Le dichloride iphendula ngamanzi ngale ndlela elandelayo:

n Si (CH ₃ ) ₂ Cl ₂ + n H ₂ O → [Si (CH ₃ ) ₂ O] _n + 2 n I-HCl

I-polymerization ivame ukukhiqiza amaketanga aqondile ahlanganiswe namaqembu e-Si-Cl noma ama-Si-OH ( silanol ).Ngaphansi kwezimo ezihlukile, i-polymer iyindilinga, hhayi iketanga.

Ezinsizeni zabathengi ezifana ne-caulks silyl acetates zisetshenziswa esikhundleni sama-silyl chloride.I-hydrolysis yama-acetate ikhiqiza i- acetic acid engeyona ingozi (i-asidi etholakala kuviniga ) njengomkhiqizo wokuphendula wenqubo yokwelapha ehamba kancane.Le chemistry isetshenziswa ezinhlelweni eziningi zabathengi, njenge-silicone caulk kanye nama- adhesives .

n Si (CH ₃ ) ₂ (CH ₃ COO) ₂ + n H ₂ O → [Si (CH ₃ ) ₂ O] _n + 2 n CH ₃ COOH

Amagatsha noma ama-crosslinks kuketanga le-polymer angeniswa ngokusebenzisa i-organosilicone precursors enamaqembu ama-alkyl ambalwa, njenge-methyl trichlorosilane ne- methyltrimethoxysilane .Ngokufanelekile, i-molecule ngayinye yenkomfa enjalo iba iphuzu legatsha.Le nqubo ingasetshenziselwa ukukhiqiza izinhlaka ze-silicone ezinzima.Ngokufanayo, abangaphambi kwamaqembu amathathu e-methyl bangasetshenziswa ukunciphisa isisindo samangqamuzana, ngoba i-molecule ngayinye enjalo inesiza esisodwa kuphela esisebenzayo ngakho-ke yakha ukuphela kochungechunge lwe-siloxane.

Izici

Le chesi yebhodi elenziwe ngentambo yenjoloba emelana nokuqunjelwa nokushwabana

Ama-silicone akhombisa izici eziningi eziwusizo, kufaka phakathi:

• Ukuqhuba okuphansi kokushisa
• Ukusebenza kabusha kwamakhemikhali okuphansi
• Ubuthi obuphansi
• Ukuqina kwe-Thermal (ukungaguquguquki kwezakhiwo ebangeni lokushisa elibanzi le- −100 to 250 °C )
• Ikhono lokuxosha amanzi nokwakha izimvu zamanzi ezingangeni manzi.
• Ayinamatheli kuma-substrate amaningi, kepha inamathela kahle kwabanye, isib. Ingilazi
• Ayisekeli ukukhula kwamagciwane
• Ukumelana nomoya-mpilo, i-ozone, ne- ultraviolet (UV) light . Le mpahla iholele ekusetshenzisweni kabanzi kwama-silicone embonini yezokwakha (isb. Ukumbozwa, ukuvikelwa komlilo, izimpawu zohlobo lwe-glazing) kanye nemboni yezimoto (ama-gaskets angaphandle, i-trim yangaphandle).
• Izici zokufakwa kukagesi . Ngoba abicah bungakhelwa ukuthi buvikeleke ngogesi noma buqhube, kufanelekile ezinhlotsheni eziningi zezicelo zikagesi.
• Ukungena kwegesi ephezulu: ekamelweni lokushisa (25 ° C), ukungena kwenjoloba abicah emagesi anjenge-oksijini kucishe kube izikhathi ezingama-400 kuleyo yenjoloba ye-butyl, okwenza i-silicone ilusizo kuzicelo zezokwelapha lapho kudingeka khona i-aeration eyengeziwe. Ngakolunye uhlangothi, ama-rubbers abicah awanakusetshenziswa lapho kudingeka khona izivalo eziqinisa igesi njengezimpawu zamandla okuphefumula okuphezulu noma i-vacuum ephezulu.

Abicah angakhiwa amashidi wenjoloba, lapho enezinye izinto, njengokuhambisana ne-FDA.Lokhu kunweba ukusetshenziswa kwamashidi abicah ezimbonini ezifuna inhlanzeko, isibonelo, ukudla neziphuzo kanye nemithi.