Halayen da aka fara hasashe za a iya karkasa su zuwa nau'i biyu: (1) haɗin kai da scission da (2) grafting da waraka.
Crosslinking shine haɓakar haɗin gwiwar intermolecular na sarƙoƙi na polymer.Matsayin crosslinking yayi daidai da adadin radiation.Ba ya buƙatar ƙungiyoyi marasa ƙarfi ko wasu ƙarin ƙungiyoyi masu amsawa.Tare da wasu keɓancewa (kamar a cikin polymers masu ɗauke da aromatics), baya bambanta sosai da tsarin sinadarai.Ba ya bambanta sosai da zafin jiki.Ko da yake ana nazarin tsarin haɗin kai ta hanyar radiation tun lokacin da aka fara gano shi, har yanzu babu wata yarjejeniya da ta yadu dangane da ainihin yanayinta.Tsarin ƙetare gabaɗaya ya bambanta da polymers da abin ya shafa.Tsarin da aka yarda da shi a duk duniya ya haɗa da ɓarkewar haɗin C–H akan sarkar polymer guda ɗaya don samar da zarra na ahydrogen, sannan abstraction na atom na biyu na hydrogen daga sarkar makwabta don samar da hydrogen kwayoyin halitta.Sa'an nan biyu da ke kusa da polymeric radicals sun haɗu don samar da hanyar haɗin gwiwa. Sakamakon gaba ɗaya na crosslinking shine cewa yawan kwayoyin halitta na polymer yana ƙaruwa akai-akai tare da kashi na radiation, wanda zai haifar da sarƙoƙi har sai, a ƙarshe an samar da hanyar sadarwa ta polymer mai girma uku lokacin da aka haɗa kowane sarkar polymer. zuwa wata sarkar.
Sabanin haka, scission shine kishiyar tsarin haɗin kai wanda rupturing C-C bondsoccus.Crosslinking yana ƙara matsakaicin nauyin kwayoyin halitta yayin da na ƙarshe ya rage shi.Idan ƙarfin radiation yana da girma, karya sarkar yana faruwa ta hanyar ɓarkewar haɗin C-C.A cikin matsakaicin matsakaici, duk da haka, hanyar injina na scission yana gudana ta hanyar kai tsaye.Thepolymeric free radicals suna samuwa ta hanyar radicals-free radicals, wanda aka riga an kafa ta hanyar radiation. Bugu da kari na oxygen tare da polymeric free radicals ya samar da nau'in peroxy, wanda a kan lalata-matsayi ya samar da ƙananan kwayoyin halitta.Lalacewar oxidative na polymers ya dogara ne akan warwarewar da ke cikin tsarin.A zahiri, lalacewar polymer yana gasa tare da iskar shaka na sauran ƙarfi.
Grafting wata hanya ce da aka gabatar da monomers a kai tsaye zuwa sarkar polymer inda tabbatarwa shine saurin polymerisation na cakuda monomer na oligomer don samar da sutura, wanda ke da alaƙa da ƙarfi ta zahiri zuwa ƙasa.A cikin mafi sauƙi nau'i, irin waɗannan hanyoyin sun haɗa da tsarin daban-daban, ma'aunin shine fim, fiber ko ma foda, tare da monomer a matsayin ruwa mai narkewa, tururi ko bayani.Akwai dangantaka ta kud-da-kud tsakanin grafting da waraka ko da yake akwai wasu bambance-bambance.A gaskiya, babu ƙayyadaddun lokaci don aiwatar da grafting.Yana iya ɗaukar mintuna, sa'o'i ko ma kwanaki, yayin da warkewa yawanci tsari ne mai saurin gaske wanda ke faruwa a cikin ɗan kashi na biyu.A cikin grafting, covalent C-C shaidu suna samuwa yayin da a cikin curing, bonding yawanci ya ƙunshi weakervan der Waals ko London watsawa sojojin.van der Waals bonding yana aiki a nesa inda babu ƙarami ko babu zoba ko musanya kuma ana danganta shi da ƙananan kuzari.Duk da haka, covalentbonding, yana da tasiri a ƙananan nisa na internuclear kuma yana da alaƙa da zoba na lantarki, musayar, da kuma saboda haka mafi girman kuzari.Wani muhimmin al'amari na waraka halayen shine yuwuwar dasawa tare da waraka na faruwa wanda zai haifar da ingantattun kaddarorin samfurin da aka gama, musamman a mannewa da sassauci.
Grafting yana samuwa ta hanyoyi daban-daban guda uku: (a) pre-irradiation;(b) peroxidation da (c) dabarar irradia-tion juna.A cikin fasahar riga-kafin hasken iska, ƙashin baya na farko na polymer yana haskakawa a cikin injin daɗaɗawa ko gaban iskar da ba ta da iska don samar da radicals kyauta.Sannan ana bi da ɗigon polymer da aka lalata da monomer, wanda ko dai ruwa ne ko tururi ko kuma a matsayin bayani a cikin kaushi mai dacewa.Koyaya, a cikin hanyar grafting theperoxidation, polymer akwati yana fuskantar radiation mai ƙarfi a gaban iska ko iskar oxygen.Sakamakon shine samuwar hydroperoxides ko diperoxides dangane da yanayin kashin baya na polymeric da yanayin iska.Samfuran peroxy, waɗanda suke da ƙarfi, ana bi da su tare da monomer a mafi girman zafin jiki, inda peroxides ke juyar da bazuwar toradicals, wanda sannan ya fara grafting.Amfanin wannan fasaha shine cewa ana iya adana samfuran peroxy na matsakaici na dogon lokaci kafin aiwatar da matakin grafting.A gefe guda, tare da dabarar haskakawa juna da polymer da monomers suna haskakawa lokaci guda don samar da radicals masu 'yanci don haka ƙari yana faruwa.Tun da monomers ba a fallasa su ga radiation a cikin fasahar riga-kafin hasken iska, fa'idar fa'idar wannan hanyar ita ce ta ba da ɗanɗano daga matsalar samuwar homopolymer wanda ke faruwa tare da dabarar lokaci guda.Koyaya, yanke shawarar rashin amfani da fasahar riga-kafin hasken iska shine scission na polymer tushe saboda jagorar sa, wanda ke haifar da samuwar toshe copolymers a maimakon graftcopolymers.
Lokacin aikawa: Mayu-03-2017