Tikanga Tātari Thermogravimetric
Ko te tātaritanga werawera (TGA) he tikanga whakaahua rauemi e ine ana i te huringa o te papatipu tauira hei pānga o te pāmahana me/ranei te wā i roto i te hau e whakahaerehia ana. He whānuitia te whakamahinga o tēnei tikanga i roto i te matū, te hangarau rauemi, te rongoā, ngā pūmua, me te pūngao nā te mea ka taea e ia te whakarato i ngā mōhiohio nui e pā ana ki te pumau o te wera, te hanganga, te ihirangi wai/whakarewa, te pirau, me te tere o te tauhohenga. Mā te pihi TGA me ōna pānga (DTG), ka taea e ngā kairangahau te mārama ki te whanonga o ngā rauemi ina werahia, ina whakamataohia, ina puritia rānei i tētahi pāmahana.
Ngā mātāpono taketake o te TGA
He māmā noa te mātāpono mahi o te TGA: ka paunatia tonutia te tauira mā te whakamahi i tētahi taurite iti kua whakauruhia ki roto i te taputapu, kātahi ka whakamahanatia ki tētahi kaupapa pāmahana motuhake. I te pikinga ake o te pāmahana, ka taea e te tauira te whai i ngā tukanga maha pēnei i te mimiti wai, te whakapūngao whakarewa, te waikura, te maroke, te tango i te polymerization, te hanganga rānei o ngā toenga kore-waro. Ka taea e ēnei tukanga katoa te whakaheke i te papatipu (hei tauira, nā te tukunga o ngā ngota ngota) i ētahi wā rānei, ka piki ake te papatipu (hei tauira, nā te waikura, e whakanui ana i te papatipu nā te here o te hāora).
Ka mahia ēnei inenga i raro i ngā āhuarangi whakahaeretia, pērā i te hauota (N₂) te argon rānei (Ar) mō ngā āhuatanga kore mahi, me te hāora (O₂) te hau rānei mō ngā āhuatanga waikura. He mea nui te whiriwhiri i te āhuarangi mō te tikanga e whai wāhi ana: ka taea e ngā pūmua e mau ana i roto i te hauota te pirau tere i roto i te hau nā te waikura.
Ngā wāhanga matua o te taputapu TGA
Ko ngā taputapu TGA he maha ngā wāhanga nui:
1. Ōumu (ōumu whakamahana): ka whakaputa i te whakamahana kua whakaritea ki ngā pāmahana teitei (he maha ngā wā 800–1000°C, i runga i te taputapu).
2. Taurite iti (taurite iti): ka ine i ngā panoni papatipu me te aro nui (tae atu ki ngā maikirokaramu).
3. Paraharaha/para tauira: he ipu tauira, he mea hanga ki te alumina, te konukawata, te uku rānei—i tīpakohia kia rite ki te tauhohenga me te pāmahana whakahaere.
4. Pūnaha whakahaere hau: e whakahaere ana i te momo hau, te tere rere, me te whakawhiti hau (hei tauira, mai i te N₂ ki te O₂).
5. Pūmana me te pūoko pāmahana: ka whakahaere i te tere whakamahana me te whakarite i te tika o te pāmahana.
6. Pūmanawa kohikohi raraunga: ka tuhia ngā pihi papatipu me ngā pihi pāmahana/wā, ā, he maha ngā wā ka whakaratohia he tātaritanga DTG, he tātaitanga ngaronga papatipu ia taahiraa, me te whakatau tata i te nekenekehanga.
Momo raraunga me te pihi hua
Ko te hua matua o te TGA ko te kōpiko TG (te ōrau papatipu, te ōrau papatipu rānei, me te pāmahana/wā). He maha ngā tawhā nui ka taea te pānui mai i tēnei kōpiko:
– Te pāmahana tīmatanga: te pāmahana tīmatanga e puta ai te ngaronga nui o te papatipu (he tohu wawe o te pirau, o te mimiti rānei).
– Te ngaronga papatipu o te taahiraa: te nui o te ngaronga papatipu i ia taahiraa.
– Toenga/ngā: papatipu toenga i te pāmahana whakamutunga (e pā ana ki te ihirangi kore-waro, te whakakī, te pungarehu, te hanganga rānei o te ngā).
– Te pāmahana pumau: te awhe pāmahana ina pumau tonu te papatipu.
Hei tāpiri, ko te tuatahi o ngā pānga o te pihi TG ka puta he pihi DTG (Derivative Thermogravimetry), arā, te tere o te huringa o te papatipu ki te pāmahana. Ka āwhina te tihi DTG ki te wehewehe i ngā wāhanga e taupatupatu ana, ā, ka āwhina i te tautuhi i te pāmahana e puta ai te tere whakahekenga mōrahi.
I ētahi pūnaha, ka honoa te TGA me ētahi atu tikanga pēnei i te FTIR (TGA-FTIR) MS rānei (TGA-MS) hei tautuhi i ngā hau e tukuna ana i te wā whakamahana, ā, ka kaha ake te whakamāramatanga o te tikanga.
Ngā tikanga whakamātautau: ngā taahiraa whānui
I roto i te mahi, ka whakahaerehia te tātaritanga TGA mā roto i ngā wāhanga e whai ake nei:
1. Te whakarite tauira: ka whakamaroketia te tauira mēnā e tika ana, ka hurihia kia ōrite, kātahi ka paunatia (ko te tikanga he 5–20 mg, kei te rauemi me te taputapu).
2. Te kōwhiringa o te oko whakarewa: hei tauira, te alumina mō te nuinga o ngā tauira; te konukawata mō ngā hiahia motuhake; karohia te tauhohenga i waenga i te tauira me te oko whakarewa.
3. Ngā tautuhinga āhuarangi: kore mahi hei ako i te mura/te pirau me te kore waikura; te hau/hāora hei ako i te tahunga, te pumau waikura rānei.
4. Kaupapa pāmahana: ka taea te whakamahana rārangi (hei tauira, 10°C/min), te whakamahana taahiraa me te pupuri isothermal, te huringa whakamahana-whakamatao rānei.
5. Te ine me te tuhi raraunga: ka tuhia e te pūmanawa te pihi TG/DTG.
6. Tātari i ngā hua: whakatau i te wāhanga o te ngaronga papatipu, tatauhia te ōrau o ngā wāhanga, me te whakamārama i ngā tukanga e puta ana.
He mea nui te whiriwhiri i te tere whakamahana: ka tere ake te whakamātautau i ngā tere teitei engari ka taea te neke i te tīmatanga ki te pāmahana teitei ake, ka kino ake te wehenga wāhanga; ka pai ake te whakataunga i ngā tere iti engari ka roa ake te wā.
Ngā tono matua o TGA
1. Whakatauhia te wai me te ihirangi pūngāwerewere
He maha ngā rauemi kei roto he wai kore utu, he wai here, he toenga whakarewa rānei. I te awhe pāmahana iti (hei tauira, 30–150°C), ko te ngaronga papatipu he mea hono ki te mimiti wai/whakarewa. He mea nui tēnei mō ngā rongoā (te nui o te wai i roto i ngā mea tāpiri), ngā kai, me ngā pūmua.
2. Te ine i te pumau me te pirau o te wera
Ka taea e te TGA te tohu i te pāmahana tīmatanga o te pirau, te wāhanga o te pirau, me te toenga. Hei tauira, i roto i ngā pūmua pēnei i te PVC, ko te wāhanga tuatahi ko te tango i te waikura, ā, muri iho ko te wehenga mekameka me te hanganga waro.
3. Whakatauhia te hanganga o te rauemi whakaranu
He maha ngā wā ka heke haere te papatipu o ngā rauemi hiato, ngā rauemi whakaranu rānei: ka pirau ngā wāhanga rauropi, ko te whakakī kore-rauropi ia ka noho hei toenga. Nō reira, ka taea e te TGA te whakatau tata i te wāhanga papatipu o tētahi wāhanga motuhake (hei tauira, te pango waro, te muka, te kohuke, te pungarehu rānei).
4. Ngā rangahau mō te waikura me te tahunga
I roto i te āhuarangi waikura, ka taea e ngā rauemi waro, polymer rānei te tahu, ka waiho te pungarehu. Ka āwhina te TGA ki te whakatau i te pāmahana tahunga, te tere waikura, me te ine i te nui o te pungarehu.
5. Te tere o te tauhohenga wera
Mā te whakahaere i te TGA i ngā tere whakamahana maha, ka taea e ngā kairangahau te whakatau tata i ngā tawhā nekeneke pēnei i te pūngao whakahohenga mā te whakamahi i ngā huarahi pēnei i a Kissinger, Ozawa–Flynn–Wall, Friedman rānei (ngā tikanga isoconversional). He mea nui tēnei mō te whakatauira i te roanga o te ora o tētahi rauemi i tētahi pāmahana kua whakaritea.
Ngā āhuatanga e pā ana ki ngā hua me te whakamaoritanga
Ehara i te mea ko ngā rauemi anake te take e whakatauhia ai ngā hua o te TGA, engari ko ngā āhuatanga whakamātautau anō hoki. Ko ētahi o ngā mea matua ko:
– Papatipu tauira: ki te nui rawa te tauira, ka pāngia pea e te pikinga pāmahana me te puhoi o te horapa o te hau, ā, ka āhua neke, ka whānui rānei te pihi.
– Te rahi me te ōritetanga o te matūriki: ka taea e ngā matūriki nunui te aukati i te putanga o ngā hau pūngāwerewere.
– Momo oko whakarewa: ka taea e ngā oko whakarewa kua kati/taupokina te pupuri i te hau me te whakarerekē i te ara tauhohenga ki te whakaritea ki ngā oko whakarewa tuwhera.
– Te tere rere o te hau me te momo hau: me nui te rere o te hau kia kore ai e mau tonu ngā hua pūngāwerewere huri noa i te tauira.
– Te tere o te wera: ka pā ki te taumira o te atamira me ngā pāmahana āhuatanga (tīmatanga, te tihi o te DTG).
– Te whakatikatika i te pāmahana me te taurite: ka puta pea ngā whakamaoritanga hē i ngā hapa whakatikatika.
Nō reira, ko te pūrongo TGA pai kei roto ko ngā taipitopito whakamātautau: te papatipu tauira, te tere whakamahana, te tere rere me te hau, te momo paraharaha, me te awhe pāmahana.
Ngā painga me ngā herenga
Ko ngā painga o te TGA ko te iti o ngā tauira e hiahiatia ana, te tere o te tātari, te aro nui ki ngā huringa papatipu, me te kaha ki te ako i ngā tukanga maha-taahiraa. Heoi, ko tōna herenga ko te kore e tautuhi tika a te TGA i te momo matū i ngaro—e tohu noa ana i te huringa o te papatipu. Hei whakatau i "te mea e mimiti ana, e hanga ana rānei," he maha ngā wā ka hiahiatia ngā tikanga pēnei i te FTIR/MS me ētahi atu tātaritanga hanganga.
Hei tāpiritanga, kāore ētahi tukanga wera e whakaputa i ngā huringa papatipu nui (hei tauira, ngā whakawhiti karāhe i roto i ngā pūmua), nō reira kāore e pai mō te tātaritanga mā te TGA anake, ā, he pai ake te whakamahi i te DSC, i te DMA rānei.
Te Katinga
He taputapu nui te tātaritanga wera-rahi i roto i te pūtaiao rauemi me te hangarau, e āhei ana ki te mahere tika i ngā huringa o te papatipu rauemi i roto i te wā me te pāmahana. Mā roto i ngā kōpiko TG me DTG, ka whakaratohia e te TGA he mōhiohio hōhonu mō te ihirangi pūngāwerewere, te pumau wera, ngā wāhanga pirau, ngā toenga kore-waro, me te tere o te tauhohenga wera. Mā ngā āhuatanga hau e tika ana, ngā tere whakamahana, me te whakarite tauira, ka taea e te TGA te whakarato i tētahi turanga pakari mō te whakawhanaketanga hua, te whakahaere kounga, me te mārama ki ngā tikanga pirau rauemi. Mā te whakakotahi i te TGA me ngā tikanga tautuhi hau pēnei i te FTIR, te MS rānei ka whakarei ake i te whakamaoritanga, ka waiho te TGA hei tētahi o ngā tikanga tautuhi wera tino maha i roto i te rangahau hou.
