Dareen-celinta shucaaca bilaabay ayaa si gaar ah loo kala saari karaa laba nooc: (1) isku-tallaabta iyo maqaska iyo (2) tallaalid iyo daaweyn.
Crosslinking waa isku xidhka intermolecular ee silsiladaha polymer.Heerka isku-tallaabta ayaa u dhiganta qiyaasta shucaaca.Uma baahna kooxaysi aan qancin ama kuwo kale oo firfircoon.Marka laga reebo qaar ka mid ah (sida polymers-ka ay ku jiraan aromatics), si weyn ugama duwana qaab dhismeedka kiimikada.Aad uguma kala duwana heerkulka.Inkasta oo habka isku xidhka shucaaca la darsay tan iyo markii la helay, weli ma jiro heshiis baahsan oo ku saabsan dabeecadda saxda ah.Habka isku xirka guud ahaan wuu ku kala duwan yahay polymers-ka ay khuseyso.Farsamaynta guud ee la aqbalay waxay ku lug leedahay kala-goynta curaarta C-H ee hal silsilad polymer si loo sameeyo atamka ahydrogen, oo ay ku xigto soo saarista atamka hydrogen ee labaad ee silsiladda deriska ah si ay u soo saarto hydrogen molecular.Kadibna labada radical polymeric ee ku xiga waxay isku daraan si ay u sameeyaan isku-xirid. Saamaynta guud ee iskutallaabtu waa in tirada molecular ee polymer-ka ay si joogto ah u kordhiso qiyaasta shucaaca, taasoo keenta silsilado laamo ah ilaa, ugu dambeyntii shabakad polymeric ah oo saddex geesood ah ayaa la sameeyay marka silsilad kasta oo polymer ah lagu xiro. silsilad kale.
Taas bedelkeeda, maqasku waa habka ka soo horjeeda ee isku xidhka kaas oo dillaaca C-C bondsoccus.Crosslinking waxay kordhisaa celceliska miisaanka kelli halka habka dambe uu yareeyo.Haddii tamarta shucaaca uu sarreeyo, jebinta silsiladdu waxay dhacdaa iyada oo la gooyo curaarta C-C.Dhexdhexaadinta xalinta hawada, si kastaba ha ahaatee, habka makaaniga ah ee maqasku wuxuu ku socdaa si dadban.Thepolymeric free radicals waxaa soo saara radicals-free radicals, kuwaas oo horeba u sameeyey by shucaaca.Ku darida ee oxygen la polymeric radicals lacag la'aan ah waxay sameeyaan noocyada peroxy, taas oo on booska-meel-ka-soo-sameeya molecules yar yar.Burburinta ogsaydhiyaha ee polymers-yada waxay ku xiran tahay dareeraha nidaamka.Dhab ahaantii, xaalufka polymerku wuxuu la tartamayaa oksaydhka dareeraha.
Grafting waa hab ay monomer-yada gadaal ka soo galaan silsiladda polymer halkaas oo hubinta ay tahay polymerisation-ka degdega ah ee isku dhafka monomer oligomer si loo sameeyo dahaar, kaas oo asal ahaan ku xidhan xoogagga jireed ee substrate-ka.Habka ugu fudud, hababka noocan oo kale ah waxay ku lug leeyihiin hababka kala duwan, substrate-ku waa filim, fiber ama xitaa budo, oo leh monomer sida dareere aan la karin, uumi ama xal.Waxaa jira xiriir dhow oo ka dhexeeya tallaalka iyo daawaynta inkastoo ay jiraan kala duwanaansho gaar ah.Dhab ahaantii, ma jiro waqti xaddidan habka tallaalka.Waxay qaadan kartaa daqiiqado, saacado ama xitaa maalmo, halka daawaynta ay caadiyan tahay hawl aad u degdeg badan oo ku dhacda jajab ilbiriqsi.Marka la tallaalayo, curaarta C-C ee isku xidhan ayaa la sameeyaa halka daawaynta, isku xidhiddu ay inta badan ku lug leedahay daciifnimada der Waals ama xoogagga kala firdhisan ee London.Van der Waals bonding waxay ka shaqeysaa masaafo aad u yar ama aysan jirin wax isdhaafsi ama is dhaafsi waxaana guud ahaan lala xiriiriyaa tamar yar.Si kastaba ha ahaatee, covalentbonding, waxay wax ku ool u tahay masaafo yar oo nukliyeer ah waxayna la xiriirtaa isku dhafka elektarooniga ah, isweydaarsiga, iyo sidaas awgeed tamar sare.Arrin kale oo muhiim ah oo ka mid ah falcelinta daawaynta ayaa ah suurtagalnimada in tallaalka is dabajooga ah ee daawaynta ay dhacdo taasoo horseedaysa in la hagaajiyo sifooyinka alaabta la dhammeeyey, gaar ahaan ku dheggan iyo dabacsanaanta.
Ku-tallaaliddu waxay ku socotaa saddex siyaabood oo kala duwan: (a) ka-hortagga hawada;(b) Peroxidation iyo (c) Farsamada irradia-tion ee labada dhinac.Farsamada ka-hortagga shucaaca, laf-dhabarta polymer-ka ugu horreeya waxaa lagu shubaa faaruq ama joogitaanka gaas aan shaqaynayn si loo sameeyo xag-jiryo xor ah.Substrate-ka polymer-ka la shiiday ayaa markaa lagu daaweeyaa monomer-ka, kaas oo ah dareere ama uumi ama sida xal dareere ku habboon.Si kastaba ha noqotee, habka tallaalka theperoxidation, polymer-ka jirridda waxaa lagu sammeeyaa shucaac tamar sare leh iyadoo ay jirto hawo ama oksijiin.Natiijadu waa samaynta hydroperoxides ama diperoxides taas oo ku xidhan dabeecadda laf dhabarta polymeric iyo xaaladaha shucaaca.Alaabooyinka peroxy-ka, kuwaas oo xasiloon, ayaa lagu daaweeyaa monomer heerkul sare ah, halkaas oo peroxides ay maraan qalabyada kala-goynta, ka dibna bilaabaya tallaalka.Faa'iidada farsamadan ayaa ah in peroxyproducts dhexdhexaad ah lagu kaydin karo muddo dheer ka hor inta aan la samayn tallaabada tallaalka.Dhanka kale, iyada oo la adeegsanayo farsamada shucaaca-dhexdhexaadka ah ee polymer-ka iyo monomer-yada ayaa si isku mid ah loo shidaa si ay u sameeyaan xagjirrada xorta ah sidaas awgeedna isku-darka ayaa dhacaya.Maadaama monomers-yadu aanay u soo gaadhin shucaaca farsamada hore ee shucaaca, faa'iidada muuqata ee habkaas ayaa ah in ay xor ka tahay dhibaatada samaynta homopolymer ee ku dhacda farsamada isku mar.Si kastaba ha ahaatee, khasaaraha go'aansan ee farsamada ka hor-iradiation waa maqas ee polymer-ka salka ay sabab u tahay hagitaankeeda, kaas oo inta badan soo saara samaynta copolymers block halkii graftcopolymers.
Waqtiga post: May-03-2017