Inkqubela yoPhando kwiPolyurethanes ezingezizo iSocyanate
Ukususela oko zaqaliswa ngo-1937, izixhobo ze-polyurethane (PU) zifunyenwe zisetyenziswa kakhulu kumacandelo ahlukeneyo kuquka ezothutho, ulwakhiwo, iikhemikhali zepetroli, amalaphu, ubunjineli boomatshini nombane, i-aerospace, ukhathalelo lwempilo, kunye nezolimo. Ezi zinto zisetyenziswa kwiindlela ezifana neeplastiki zefoam, iifayibha, ii-elastomers, ii-agents zokuthintela amanzi, ulusu oluyilwe, ii-coating, izincamathelisi, izinto zokuhombisa kunye nezixhobo zonyango. I-PU yendabuko yenziwe ngokuyintloko kwii-isocyanates ezimbini okanye ngaphezulu kunye nee-polyols ze-macromolecular kunye nee-extenders ezincinci ze-molecular chain. Nangona kunjalo, ubuthi obuvela kwi-isocyanates bubeka umngcipheko omkhulu kwimpilo yabantu nakwindalo esingqongileyo; ngaphezu koko zihlala zivela kwi-phosgene—i-precursor enobuthi kakhulu—kunye nezinto eziluhlaza ze-amine ezifanayo.
Ngenxa yokufuna kwamashishini eekhemikhali anamhlanje iindlela zophuhliso oluluhlaza noluzinzileyo, abaphandi bagxila kakhulu ekutshintsheni ii-isocyanates ngezixhobo ezinobuhlobo nokusingqongileyo ngelixa behlola iindlela ezintsha zokwenziwa kwee-polyurethanes ezingezizo i-isocyanate (NIPU). Eli phepha lazisa iindlela zokulungiselela i-NIPU ngelixa liphonononga ukuqhubela phambili kwiintlobo ezahlukeneyo ze-NIPU kwaye lixoxa ngamathuba azo exesha elizayo ukuze linike isalathiso sophando olongezelelekileyo.
1 Ukwenziwa kweePolyurethanes ezingezizo i-Isocyanate
Ukwenziwa kokuqala kwee-carbamate compounds eziphantsi kobunzima beemolekyuli kusetyenziswa ii-monocyclic carbonates ezidityaniswe nee-aliphatic diamines kwenzeka kwamanye amazwe ngeminyaka yoo-1950—okubonisa ixesha elibalulekileyo ekuhlanganisweni kwe-polyurethane engeyiyo isocyanate. Okwangoku kukho iindlela ezimbini eziphambili zokuvelisa i-NIPU: Eyokuqala ibandakanya ukwenziwa kwee-reactions ezithatha inyathelo phakathi kwee-binary cyclic carbonates kunye nee-binary amines; eyesibini ibandakanya ii-polycondensation reactions ezibandakanya ii-diurethane intermediates kunye nee-diols ezenza kube lula ukutshintshana kwesakhiwo ngaphakathi kwee-carbamates. Ii-Diamarboxylate intermediates zinokufunyanwa ngeendlela ze-cyclic carbonate okanye ze-dimethyl carbonate (DMC); ngokusisiseko zonke iindlela zisabela ngamaqela e-carbonic acid avelisa imisebenzi ye-carbamate.
Amacandelo alandelayo achaza iindlela ezintathu ezahlukeneyo zokwenza i-polyurethane ngaphandle kokusebenzisa i-isocyanate.
1.1 Indlela yeBinary Cyclic Carbonate
I-NIPU inokwenziwa ngokwezongezo ezithatha inyathelo ngenyathelo ezibandakanya i-binary cyclic carbonate edityaniswe ne-binary amine njengoko kubonisiwe kuMfanekiso 1.
Ngenxa yamaqela amaninzi e-hydroxyl akhoyo kwiiyunithi eziphindaphindayo kwisakhiwo sayo esiphambili sekhonkco, le ndlela ivelisa oko kubizwa ngokuba yi-polyβ-hydroxyl polyurethane (PHU). ULeitsch et al., baphuhlise uthotho lwee-PHU ze-polyether ezisebenzisa ii-polyethers ezipheliswe yi-cyclic carbonate kunye nee-amines ze-binary kunye nee-molecules ezincinci ezivela kwi-binary cyclic carbonates—bethelekisa ezi neendlela zemveli ezisetyenziselwa ukulungiselela ii-PU ze-polyether. Iziphumo zabo zibonise ukuba amaqela e-hydroxyl ngaphakathi kwee-PHU enza ngokulula ii-hydrogen bonds kunye nee-athomu ze-nitrogen/oxygen ezikwi-soft/hard segments; umahluko phakathi kwe-soft segments ukwachaphazela nokuziphatha kwe-hydrogen bonding kunye ne-microphase separation degrees ezichaphazela kamva iimpawu zokusebenza ngokubanzi.
Ngokwesiqhelo le ndlela ayivelisi mveliso ingaphantsi kwamaqondo obushushu angaphezulu kwe-100 °C, oku kwenza ukuba ingabi namvakalelo kumswakama ngelixa ivelisa iimveliso ezizinzileyo ngaphandle kweengxaki zokuguquguquka, kodwa kufuneka izinyibilikisi eziphilayo ezibonakaliswa yi-polarity enamandla njenge-dimethyl sulfoxide (DMSO), i-N, i-N-dimethylformamide (DMF), njl.njl. Ukongeza, amaxesha okuphendula ande ukusuka naphi na phakathi kosuku olunye ukuya kwiintsuku ezintlanu avelisa ubunzima obuphantsi beemolekyuli, rhoqo ziwela phantsi kwemida ejikeleze i-30k g/mol, nto leyo ebangela ukuba imveliso enkulu ibe nzima ngenxa yokuba iindleko eziphezulu ezidibene nayo zidibene namandla angonelanga abonakaliswa zii-PHU eziphumayo nangona izicelo ezithembisayo zigubungela umswakama, izakhiwo zememori yesakhiwo, iifomyula zokuncamathelisa, izisombululo zokugquma, amagwebu, njl.njl.
1.2 Indlela yeMonocylic Carbonate
I-monocylic carbonate isabela ngokuthe ngqo kwi-diamine ephumela kwi-dicarbamate enamaqela e-hydroxyl end-groups ethi emva koko idlule kwiindlela ezikhethekileyo zokusebenzisana kwe-transesterification/polycondensation kunye nee-diols ekugqibeleni zivelisa i-NIPU efana neyamasiko eboniswe ngokubonakalayo kwiFigure 2.
Iindidi ze-monocylic ezisetyenziswa rhoqo ziquka ii-ethylene kunye ne-propylene carbonated substrates apho iqela likaZhao Jingbo kwiYunivesithi yaseBeijing yeChemical Technology lisebenzise ii-diamines ezahlukeneyo eziziphendula ngokuchasene nezo zinto zijikelezayo zaqala zafumana ii-structural dicarbamate intermediaries ezahlukeneyo ngaphambi kokuba ziqhubekele kwizigaba zokuxinana zisebenzisa i-polytetrahydrofuranediol/polyether-diols ezifikelela kwimveliso ephumelelayo ebonisa iipropati ezinomtsalane zobushushu/zoomatshini ezifikelela phezulu kwiindawo zokunyibilika ezijikeleza umgama ofikelela malunga ne-125 ~ 161°C amandla okuxinana afikelela kwi-24MPa ende esondela kwi-1476%. UWang nabanye, ngokufanayo iindibaniselwano ezisebenzisa i-DMC ezidityaniswe ngokulandelelanayo kunye nee-precursors ze-hexamethylenediamine/cyclocarbonated synthesizing hydroxy-terminated derivatives kamva zafumana ii-dibasic acids ezisekelwe kwi-bio ezifana ne-oxalic/sebacic/acids i-adipic-acid-terephtalics iphumelela kwiziphumo zokugqibela ezibonisa uluhlu oluquka amandla okuxinana kwe-13k~28k g/mol atshintshatshintshayo9~17 MPa elongations ehluka35%~235%.
Ii-esters ze-cyclocarbonic zisebenza ngempumelelo ngaphandle kokufuna ii-catalysts phantsi kweemeko eziqhelekileyo, zigcina ubushushu bufikelela kwi-80° ukuya kwi-120°C, ii-transesterifications ezilandelayo zihlala zisebenzisa iinkqubo ze-catalytic ezisekwe kwi-organotin ukuqinisekisa ukuba ukucutshungulwa okulungileyo akudluli kwi-200°. Ngaphaya nje kwemizamo yokudibanisa okujolise kwi-diolic inputs ezikwaziyo ukuzilungisa/i-deglycolysis phenomena ezenza kube lula ukuvelisa iziphumo ezifunwayo, zenza indlela yokusebenza ibe nobuhlobo nokusingqongileyo, ikakhulu ivelisa i-methanol/small-molecule-diolic residues, ngaloo ndlela iveza ezinye iindlela zoshishino ezisebenzayo.
Indlela ye-1.3Dimethyl Carbonate
I-DMC imele enye indlela ephilileyo/engenabungozi ngokwendalo enezinto ezininzi ezisebenzayo ezibandakanya ulungelelwaniso lwe-methyl/methoxy/carbonyl oluphucula iiprofayili ze-reactivity ezivumela kakhulu ukubandakanyeka kokuqala apho i-DMC isebenzisana ngokuthe ngqo ne-diamines ezenza ii-intermediaries ezincinci eziphelisiweyo ze-methyl-carbamate emva koko kulandele izenzo zokunyibilikisa i-melt ezibandakanya ezinye izakhi ze-small-chain-extender-diolics/larger-polyol ezikhokelela ekuveleni kwezakhiwo ze-polymer ezifunwayo eziboniswe ngokufanelekileyo nge-Figure3.
UDeepa nabanye basebenzise amandla akhankanyiweyo apha ngasentla besebenzisa i-sodium methoxide catalysis eququzelela iifomyula ezahlukeneyo eziphakathi emva koko bebandakanya ulwandiso olujoliswe kuzo olufikelela kubunzima beemolekyuli obumalunga ne(3 ~20)x10^3g/mol glass transition temperatures spanking(-30 ~120°C). I-Pan Dongdong ikhethe ii-strategic pairings eziquka i-DMC hexamethylene-diaminopolycarbonate-polyalcohols ezifumanisa iziphumo eziphawulekayo ezibonisa i-tensile-strength metrics oscillating10-15MPa elongation ratios closing1000%-1400%. Izinto eziphandwayo ezijikeleze iimpembelelo ezahlukeneyo zokwandisa ityathanga zityhile ukhetho oluhambelana kakuhle nokukhethwa kwe-butanediol/hexanediol xa ukulingana kwenani le-athomu kugcine ukulingana okukhuthaza ukuphuculwa kwekristali okucwangcisiweyo okubonwe kuzo zonke iityathanga. Iqela likaSarazin lilungiselele ii-composites ezidibanisa i-lignin/DMC kunye ne-hexahydroxyamine ezibonisa iimpawu zoomatshini ezanelisayo emva kokucutshungulwa kwi-230℃. Uphando olongezelelweyo olujolise ekufumaneni ii-non-isocyante-polyureas ezisebenzisa ukubandakanyeka kwe-diazomonomer okulindelweyo usetyenziso lwepeyinti olunokubakho oluvela kwiingenelo zokuthelekisa kune-vinyl-carbonaceous counterparts ezibonisa ukusebenza kakuhle kweendleko/iindlela zokufumana ezibanzi ezikhoyo. Uphando oluchanekileyo malunga neendlela ezenziwe ngobuninzi zihlala zifuna iindawo zobushushu obuphezulu/i-vacuum ezithintela iimfuno zesinyibilikisi ngaloo ndlela kunciphisa imijelo yenkunkuma ikakhulu ithintela kuphela ukungcola kwe-methanol/molecule encinci-diolic okuseka iiparadigms zokwenziwa okuluhlaza ngokubanzi.
Iinxalenye ezi-2 ezithambileyo ezahlukeneyo ze-polyurethane engeyiyo isocyanate
2.1 I-polyether polyurethane
I-polyether polyurethane (PEU) isetyenziswa kakhulu ngenxa yamandla ayo aphantsi okuhlangana kweebhondi ze-ether kwiiyunithi eziphindaphindayo ze-soft segment, ukujikeleza okulula, ukuguquguquka okuhle kakhulu kobushushu obuphantsi kunye nokumelana ne-hydrolysis.
UKebir nabanye basebenzise i-polyether polyurethane ene-DMC, i-polyethylene glycol kunye ne-butanediol njengezinto eziluhlaza, kodwa ubunzima be-molecular babuphantsi (7 500 ~ 14 800g/mol), i-Tg yayingaphantsi kwe-0℃, kwaye inqanaba lokunyibilika nalo laliphantsi (38 ~ 48℃), kwaye amandla kunye nezinye izalathisi kwakunzima ukuhlangabezana neemfuno zokusetyenziswa. Iqela lophando likaZhao Jingbo lisebenzise i-ethylene carbonate, i-1, i-6-hexanediamine kunye ne-polyethylene glycol ukwenza i-PEU, enobunzima be-molecular obuyi-31 000g/mol, amandla okutsalwa angama-5 ~ 24MPa, kunye nokwandiswa xa ikhefu liyi-0.9% ~ 1 388%. Ubunzima bemolekyuli yoluhlu oluhlanganisiweyo lwe-aromatic polyurethanes yi-17 300 ~ 21 000g/mol, i-Tg yi--19 ~ 10℃, iqondo lokunyibilika yi-102 ~ 110℃, amandla okutsalwa yi-12 ~ 38MPa, kwaye izinga lokubuyisela i-elastic le-200% constant elongation yi-69% ~ 89%.
Iqela lophando likaZheng Liuchun noLi Chuncheng lilungiselele i-intermediate 1, 6-hexamethylenediamine (BHC) ene-dimethyl carbonate kunye ne-1, 6-hexamethylenediamine, kunye ne-polycondensation ene-molecules ezincinci ezahlukeneyo, ii-diols ze-straight chain kunye ne-polytetrahydrofuranediols (Mn=2 000). Uthotho lwee-polyether polyurethanes (NIPEU) ezine-non-isocyanate route zalungiswa, kwaye ingxaki yokudibanisa ii-intermediates ngexesha lokusabela yasonjululwa. Ulwakhiwo kunye neempawu ze-polyether polyurethane (HDIPU) yendabuko elungiselelwe yi-NIPEU kunye ne-1, 6-hexamethylene diisocyanate zathelekiswa, njengoko kubonisiwe kwiTheyibhile 1.
| Isampulu | Inxalenye yobunzima becandelo eliqinileyo/% | Ubunzima beMolekyuli/(g)·mol^(-1)) | Isalathisi sokusasazwa kobunzima beMolekyuli | Amandla okuxinana/i-MPa | Ukwandiswa ngexesha lokuphumla/% |
| NIPEU30 | 30 | 74000 | 1.9 | 12.5 | 1250 |
| I-NIPEU40 | 40 | 66000 | 2.2 | 8.0 | 550 |
| I-HDIPU30 | 30 | 46000 | 1.9 | 31.3 | 1440 |
| I-HDIPU40 | 40 | 54000 | 2.0 | 25.8 | 1360 |
Itheyibhile 1
Iziphumo ezikwiTheyibhile 1 zibonisa ukuba umahluko wolwakhiwo phakathi kwe-NIPEU kunye ne-HDIPU ubangelwa ikakhulu yi-hard segment. Iqela le-urea eliveliswa yi-side reaction ye-NIPEU lifakwa ngokungacwangciswanga kwi-hard segment molecular chain, liqhekeza i-hard segment ukuze lenze ii-hydrogen bonds ezicwangcisiweyo, nto leyo ebangela ii-hydrogen bonds ezibuthathaka phakathi kwee-molecule chains ze-hard segment kunye ne-crystallinity ephantsi ye-hard segment, nto leyo ebangela ukwahlukana kwe-NIPEU ngesigaba esiphantsi. Ngenxa yoko, iipropati zayo zoomatshini zimbi kakhulu kune-HDIPU.
2.2 I-Polyester Polyurethane
I-polyester polyurethane (PETU) ene-polyester diols njengeenxalenye ezithambileyo inezinto ezilungileyo zokubola, ukuhambelana kwezinto eziphilayo kunye neempawu zoomatshini, kwaye ingasetyenziselwa ukulungiselela ii-scaffolds zobunjineli bezicubu, ezizizinto ze-biomedical ezinamathuba amahle okusetyenziswa. Ii-polyester diols ezisetyenziswa kakhulu kwiinxalenye ezithambileyo yi-polybutylene adipate diol, i-polyglycol adipate diol kunye ne-polycaprolactone diol.
Ngaphambili, uRokicki nabanye baphendule i-ethylene carbonate nge-diamine kunye nee-diols ezahlukeneyo (1, 6-hexanediol,1, 10-n-dodecanol) ukuze bafumane i-NIPU eyahlukileyo, kodwa i-NIPU eyenziweyo yayinobunzima obuphantsi beemolekyuli kunye ne-Tg ephantsi. UFarhadian nabanye balungiselele i-polycyclic carbonate besebenzisa ioyile yembewu yelanga njengezinto eziluhlaza, emva koko baxuba ne-polyamines ezisekelwe kwi-bio, bagquma kwipleyiti, baze banyangwa kwi-90 ℃ iiyure ezingama-24 ukuze bafumane ifilimu ye-polyester polyurethane eguquguqukayo, eyabonisa uzinzo oluhle lobushushu. Iqela lophando likaZhang Liqun waseSouth China University of Technology lenze uthotho lwee-diamines kunye ne-cyclic carbonates, baze baxuba ne-biobased dibasic acid ukuze bafumane i-polyester polyurethane esekwe kwi-bio. Iqela lophando likaZhu Jin kwi-Ningbo Institute of Materials Research, i-Chinese Academy of Sciences lilungiselele i-diaminodiol hard segment besebenzisa i-hexadiamine kunye ne-vinyl carbonate, baze balungiselela i-polycondensation nge-bio-based unsaturated dibasic acid ukuze bafumane uthotho lwe-polyester polyurethane, enokusetyenziswa njengepeyinti emva kokulungiswa kwe-ultraviolet [23]. Iqela lophando likaZheng Liuchun noLi Chuncheng lisebenzise i-adipic acid kunye nee-aliphatic diols ezine (i-butanediol, i-hexadiol, i-octanediol kunye ne-decanediol) ezinamanani ahlukeneyo e-carbon atomic ukulungiselela ii-polyester diols ezifanelekileyo njengeenxalenye ezithambileyo; Iqela le-non-isocyanate polyester polyurethane (PETU), ebizwa ngegama lee-athomu ze-carbon ze-aliphatic diols, lafunyanwa ngokunyibilikisa i-polycondensation nge-hydroxy-sealed hard segment prepolymer elungiselelwe yi-BHC kunye nee-diols. Iimpawu ze-mechanical ze-PETU ziboniswe kwiTheyibhile 2.
| Isampulu | Amandla okuxinana/i-MPa | Imodulus ethambileyo/MPa | Ukwandiswa ngexesha lokuphumla/% |
| I-PETU4 | 6.9±1.0 | 36±8 | 673±35 |
| I-PETU6 | 10.1±1.0 | 55±4 | 568±32 |
| I-PETU8 | 9.0±0.8 | 47±4 | 551±25 |
| I-PETU10 | 8.8±0.1 | 52±5 | 137±23 |
Itheyibhile 2
Iziphumo zibonisa ukuba icandelo elithambileyo lePETU4 linobuninzi bekhabhoni, ikhonkco lehydrogen elinamandla kakhulu necandelo eliqinileyo, kunye nenqanaba eliphantsi lokwahlulwa kwesigaba. Ukuqiniswa kwe-crystallization yecandelo elithambileyo neliqinileyo kulinganiselwe, kubonisa indawo ephantsi yokunyibilika kunye namandla okutsalwa, kodwa inqanaba eliphezulu lobude xa kuqhekeka.
2.3 I-polycarbonate polyurethane
I-Polycarbonate polyurethane (PCU), ingakumbi i-aliphatic PCU, inokumelana okuhle kakhulu ne-hydrolysis, ukumelana ne-oxidation, uzinzo oluhle lwebhayoloji kunye nokuhambelana kwezinto eziphilayo, kwaye inamathuba amahle okusetyenziswa kwicandelo le-biomedicine. Okwangoku, uninzi lwe-NIPU elungisiweyo isebenzisa ii-polyether polyols kunye nee-polyester polyols njengeenxalenye ezithambileyo, kwaye zimbalwa iingxelo zophando malunga ne-polycarbonate polyurethane.
I-polyurethane ye-polycarbonate engeyiyo isocyanate elungiselelwe liqela lophando likaTian Hengshui kwiYunivesithi yeTekhnoloji yaseMzantsi China inobunzima be-molecular obungaphezulu kwe-50 000 g/mol. Impembelelo yeemeko zokusabela kubunzima be-molecular ye-polymer iye yafundwa, kodwa iimpawu zayo zoomatshini azikabikwa. Iqela lophando likaZheng Liuchun noLi Chuncheng balungiselele i-PCU besebenzisa i-DMC, i-hexanediamine, i-hexadiol kunye ne-polycarbonate diols, kwaye babiza i-PCU ngokwenxalenye yobunzima beyunithi ephindaphindayo ye-hard segment. Iimpawu zoomatshini ziboniswe kwiTheyibhile 3.
| Isampulu | Amandla okuxinana/i-MPa | Imodulus ethambileyo/MPa | Ukwandiswa ngexesha lokuphumla/% |
| I-PCU18 | 17±1 | 36±8 | 665±24 |
| I-PCU33 | 19±1 | 107±9 | 656±33 |
| I-PCU46 | 21±1 | 150±16 | 407±23 |
| I-PCU57 | 22±2 | 210±17 | 262±27 |
| I-PCU67 | 27±2 | 400±13 | 63±5 |
| I-PCU82 | 29±1 | 518±34 | 26±5 |
Itheyibhile 3
Iziphumo zibonisa ukuba i-PCU inobunzima obuphezulu beemolekyuli, ukuya kuthi ga kwi-6 × 104 ~ 9 × 104g/mol, indawo yokunyibilika ukuya kuthi ga kwi-137 ℃, kunye namandla okutsalwa ukuya kuthi ga kwi-29 MPa. Olu hlobo lwe-PCU lungasetyenziswa njengeplastiki eqinileyo okanye njenge-elastomer, enethuba elihle lokusetyenziswa kwicandelo le-biomedical (ezifana nee-scaffolds zobunjineli bezicubu zomntu okanye izinto zokufakelwa kwentliziyo).
2.4 I-polyurethane exutyiweyo engeyiyo isocyanate
I-hybrid non-isocyanate polyurethane (i-hybrid NIPU) kukungeniswa kwe-epoxy resin, i-acrylate, i-silica okanye amaqela e-siloxane kwisakhelo semolekyuli ye-polyurethane ukwenza inethiwekhi edibanisayo, ukuphucula ukusebenza kwe-polyurethane okanye ukunika i-polyurethane imisebenzi eyahlukileyo.
UFeng Yuelan nabanye baphendule ioyile yesoya ye-epoxy esekelwe kwi-bio kunye ne-CO2 ukuze kuhlanganiswe i-pentamonic cyclic carbonate (CSBO), baza bazisa i-bisphenol A diglycidyl ether (epoxy resin E51) eneziqendu zetyathanga eziqinileyo ukuphucula ngakumbi i-NIPU eyenziwe yi-CSBO eqiniswe yi-amine. Ityathanga le-molecular liqulathe icandelo elide letyathanga eliguquguqukayo le-oleic acid/linoleic acid. Likwaqulathe neziqendu zetyathanga eziqinileyo, ukuze libe namandla aphezulu oomatshini kunye nokuqina okuphezulu. Abanye abaphandi baphinde baqulunqa iintlobo ezintathu ze-prepolymers ze-NIPU ezinamaqela esiphelo se-furan ngokusebenzisa i-reaction yokuvula isantya se-diethylene glycol bicyclic carbonate kunye ne-diamine, baze baphendule nge-polyester engagcwaliyo ukulungiselela i-polyurethane ethambileyo enomsebenzi wokuziphilisa, kwaye baphumelela ekufezekiseni ukusebenza okuphezulu kokuziphilisa kwe-NIPU ethambileyo. I-Hybrid NIPU ayinazo nje kuphela iimpawu ze-NIPU ngokubanzi, kodwa inokuba nokunamathela okungcono, ukumelana nokugqwala kwe-asidi kunye ne-alkali, ukumelana nokunyibilika kunye namandla oomatshini.
3 Imbonakalo
I-NIPU ilungiswa ngaphandle kokusebenzisa i-isocyanate enobuthi, kwaye okwangoku ifundwa ngohlobo lwe-foam, i-coating, i-adhesive, i-elastomer kunye nezinye iimveliso, kwaye ineendlela ezininzi zokusetyenziswa. Nangona kunjalo, uninzi lwazo lusakhawulelwe kuphando lwelabhoratri, kwaye akukho mveliso inkulu. Ukongeza, ngokuphuculwa kwemigangatho yokuphila yabantu kunye nokukhula okuqhubekayo kwemfuno, i-NIPU enomsebenzi omnye okanye imisebenzi emininzi iye yaba yindlela ebalulekileyo yophando, efana nokulwa neentsholongwane, ukuzilungisa, inkumbulo yesimo, ukuthintela ilangatye, ukumelana nobushushu obuphezulu njalo njalo. Ke ngoko, uphando lwexesha elizayo kufuneka luqonde indlela yokugqobhoza iingxaki eziphambili zophuhliso lwemizi-mveliso kwaye luqhubeke nokuhlola indlela yokulungiselela i-NIPU esebenzayo.
Ixesha lokuthumela: Agasti-29-2024