Kukhazikika kwa kutentha ndi njira zowongolera ma elastomer a polyurethane

ChotchedwapolyurethaneNdi chidule cha polyurethane, chomwe chimapangidwa ndi momwe polyisocyanates ndi polyols zimachitikira, ndipo chili ndi magulu ambiri a amino ester obwerezabwereza (- NH-CO-O -) pa unyolo wa mamolekyulu. Mu ma resin enieni a polyurethane opangidwa, kuwonjezera pa gulu la amino ester, palinso magulu monga urea ndi biuret. Ma polyol ndi a mamolekyu a unyolo wautali omwe ali ndi magulu a hydroxyl kumapeto, omwe amatchedwa "magawo ofewa a unyolo", pomwe ma polyisocyanates amatchedwa "magawo olimba a unyolo".
Pakati pa ma resin a polyurethane opangidwa ndi zigawo zofewa ndi zolimba, ndi ochepa okha omwe ali ndi ma amino acid esters, kotero sizingakhale zoyenera kuwatcha polyurethane. Mwachidule, polyurethane ndi chowonjezera cha isocyanate.
Mitundu yosiyanasiyana ya isocyanates imagwira ntchito ndi polyhydroxy compounds kuti ipange mapangidwe osiyanasiyana a polyurethane, motero imapanga zinthu za polima zokhala ndi makhalidwe osiyanasiyana, monga mapulasitiki, rabala, zokutira, ulusi, zomatira, ndi zina zotero. Rabala ya polyurethane
Rabala ya polyurethane ndi ya mtundu wapadera wa rabala, womwe umapangidwa ndi polyether kapena polyester yogwirizana ndi isocyanate. Pali mitundu yambiri chifukwa cha mitundu yosiyanasiyana ya zipangizo zopangira, momwe zimachitikira, ndi njira zolumikizirana. Kuchokera pamalingaliro a kapangidwe ka mankhwala, pali mitundu ya polyester ndi polyether, ndipo kuchokera pamalingaliro a njira yopangira, pali mitundu itatu: mtundu wosakaniza, mtundu woponyera, ndi mtundu wa thermoplastic.
Rabala ya polyurethane yopangidwa nthawi zambiri imapangidwa pogwiritsa ntchito polyester yolumikizana kapena polyether yokhala ndi diisocyanate kuti ipange prepolymer yolemera pang'ono, yomwe kenako imayikidwa mu chain extension reaction kuti ipange polima yolemera kwambiri ya molekyulu. Kenako, zinthu zoyenera zolumikizirana zimawonjezedwa ndikutenthedwa kuti zichiritsidwe, zomwe zimapangitsa kuti zikhale rabala ya vulcanized. Njira iyi imatchedwa prepolymerization kapena njira ya magawo awiri.
Ndizothekanso kugwiritsa ntchito njira imodzi - kusakaniza mwachindunji polyester yolunjika kapena polyether ndi diisocyanates, zowonjezera unyolo, ndi zinthu zolumikizirana kuti ziyambe kuchitapo kanthu ndikupanga rabala ya polyurethane.
Gawo la A mu mamolekyu a TPU limapangitsa kuti unyolo wa macromolecular ukhale wosavuta kuzungulira, kupatsa mphira wa polyurethane kusinthasintha bwino, kuchepetsa malo ofewa ndi malo osinthira achiwiri a polima, ndikuchepetsa kuuma kwake ndi mphamvu ya makina. Gawo la B lidzamangirira kuzungulira kwa unyolo wa macromolecular, zomwe zimapangitsa kuti malo ofewa ndi malo osinthira achiwiri a polima achuluke, zomwe zimapangitsa kuti kuuma ndi mphamvu ya makina ziwonjezeke, komanso kuchepa kwa kusinthasintha. Mwa kusintha chiŵerengero cha molar pakati pa A ndi B, ma TPU okhala ndi mawonekedwe osiyanasiyana a makina amatha kupangidwa. Kapangidwe ka TPU kolumikizana sayenera kungoganizira zolumikizira zoyambira zokha, komanso zolumikizira zachiwiri zomwe zimapangidwa ndi ma hydrogen bonds pakati pa mamolekyu. Cholumikizira chachikulu cha polyurethane cholumikizana ndi chosiyana ndi kapangidwe ka vulcanization ka mphira wa hydroxyl. Gulu lake la amino ester, gulu la biuret, gulu la urea formate ndi magulu ena ogwira ntchito amakonzedwa mu gawo lokhazikika komanso lokhazikika la unyolo wolimba, zomwe zimapangitsa kuti pakhale kapangidwe ka netiweki ya rabara, yomwe ili ndi kukana bwino kukalamba ndi mawonekedwe ena abwino kwambiri. Kachiwiri, chifukwa cha kukhalapo kwa magulu ambiri ogwira ntchito mogwirizana monga magulu a urea kapena carbamate mu rabara ya polyurethane, ma hydrogen bonds omwe amapangidwa pakati pa ma molecular chains ali ndi mphamvu zambiri, ndipo ma secondary crosslinking bonds omwe amapangidwa ndi ma hydrogen bonds nawonso amakhudza kwambiri makhalidwe a rabara ya polyurethane. Secondary cross-linking imalola rabara ya polyurethane kukhala ndi makhalidwe a thermosetting elastomers mbali imodzi, ndipo kumbali ina, cross-linking iyi si yogwirizana kwenikweni, zomwe zimapangitsa kuti ikhale cross-linking yeniyeni. Mkhalidwe wa cross-linking umadalira kutentha. Pamene kutentha kukukwera, cross-linking iyi imafooka pang'onopang'ono ndikutha. Polima imakhala ndi fluidity inayake ndipo imatha kukonzedwa ndi thermoplastic. Pamene kutentha kukuchepa, crosslinking iyi imabwereranso pang'onopang'ono ndikupanganso. Kuwonjezera kwa filler pang'ono kumawonjezera mtunda pakati pa mamolekyulu, kumachepetsa mphamvu yopanga ma hydrogen bonds pakati pa mamolekyulu, ndipo kumabweretsa kuchepa kwakukulu kwa mphamvu. Kafukufuku wasonyeza kuti dongosolo la kukhazikika kwa magulu osiyanasiyana ogwira ntchito mu rabara ya polyurethane kuyambira pamwamba mpaka pansi ndi: ester, ether, urea, carbamate, ndi biuret. Pa nthawi yokalamba ya rabara ya polyurethane, gawo loyamba ndi kusweka kwa ma bond olumikizana pakati pa biuret ndi urea, kutsatiridwa ndi kusweka kwa ma bond a carbamate ndi urea, kutanthauza kusweka kwa unyolo waukulu.
01 Kufewetsa
Ma elastomer a polyurethane, monga zinthu zambiri za polima, amafewa kutentha kwambiri ndipo amasamuka kuchoka pa mkhalidwe wotanuka kupita ku mkhalidwe wokhuthala, zomwe zimapangitsa kuti mphamvu ya makina ichepe mofulumira. Kuchokera ku lingaliro la mankhwala, kutentha kofewa kwa kutakasuka kumadalira makamaka zinthu monga kapangidwe ka mankhwala, kulemera kwa mamolekyu, ndi kuchulukana kwa crosslinking.
Kawirikawiri, kuwonjezera kulemera kwa mamolekyulu, kuwonjezera kulimba kwa gawo lolimba (monga kulowetsa mphete ya benzene mu molekyulu) ndi kuchuluka kwa gawo lolimba, ndikuwonjezera kuchuluka kwa ma crosslinking zonse ndi zabwino pakuwonjezera kutentha kofewa. Pa ma elastomer a thermoplastic, kapangidwe ka mamolekyulu makamaka ndi kolunjika, ndipo kutentha kofewa kwa elastomer kumawonjezekanso pamene kulemera kwa mamolekyulu kukuwonjezeka.
Pa ma elastomer a polyurethane olumikizidwa ndi mtanda, kuchulukana kwa ma crosslinking kumakhudza kwambiri kuposa kulemera kwa mamolekyu. Chifukwa chake, popanga ma elastomer, kuwonjezera magwiridwe antchito a isocyanates kapena polyols kumatha kupanga kapangidwe kolumikizana ndi mankhwala ogwirizana ndi kutentha m'mamolekyu ena olumikizana, kapena kugwiritsa ntchito ma isocyanate ratios ochulukirapo kuti apange kapangidwe kolumikizana ndi isocyanate kokhazikika m'thupi lolumikizana ndi mtanda ndi njira yamphamvu yowonjezerera kukana kutentha, kukana zosungunulira, komanso mphamvu yamakina ya elastomer.
Pamene PPDI (p-phenyldiisocyanate) imagwiritsidwa ntchito ngati zopangira, chifukwa cha kulumikizana mwachindunji kwa magulu awiri a isocyanate ndi mphete ya benzene, gawo lolimba lopangidwalo limakhala ndi mphete ya benzene yambiri, zomwe zimapangitsa kuti gawo lolimba likhale lolimba motero limawonjezera kukana kutentha kwa elastomer.
Malinga ndi momwe zinthu zilili, kutentha kwa ma elastomer kumadalira kuchuluka kwa kulekanitsidwa kwa microphase. Malinga ndi malipoti, kutentha kwa ma elastomer omwe sadutsa m'kulekanitsidwa kwa microphase ndi kochepa kwambiri, ndi kutentha kwa processing kwa pafupifupi 70 ℃, pomwe ma elastomer omwe amapita m'kulekanitsidwa kwa microphase amatha kufika 130-150 ℃. Chifukwa chake, kuwonjezera kuchuluka kwa kulekanitsidwa kwa microphase mu ma elastomer ndi njira imodzi yothandiza yowonjezerera kukana kwawo kutentha.
Mlingo wa kulekanitsa kwa microphase ya elastomers ukhoza kukonzedwa mwa kusintha kugawa kwa kulemera kwa mamolekyulu a zigawo za unyolo ndi kuchuluka kwa zigawo zolimba za unyolo, motero kumawonjezera kukana kwawo kutentha. Ofufuza ambiri amakhulupirira kuti chifukwa cha kulekanitsa microphase mu polyurethane ndi kusagwirizana kwa thermodynamic pakati pa zigawo zofewa ndi zolimba. Mtundu wa unyolo wowonjezera, gawo lolimba ndi zomwe zili mkati mwake, mtundu wa gawo lofewa, ndi mgwirizano wa hydrogen zonse zimakhudza kwambiri.
Poyerekeza ndi zowonjezera za unyolo wa diol, zowonjezera za unyolo wa diamine monga MOCA (3,3-dichloro-4,4-diaminodiphenylmethane) ndi DCB (3,3-dichloro-biphenylenediamine) zimapanga magulu ambiri a polar amino ester mu elastomers, ndipo ma hydrogen bond ambiri amatha kupangidwa pakati pa magawo olimba, zomwe zimawonjezera kuyanjana pakati pa magawo olimba ndikukweza mulingo wa kulekanitsidwa kwa microphase mu elastomers; Zowonjezera za aromatic chain monga p, p-dihydroquinone, ndi hydroquinone ndizothandiza pakubwezeretsa ndi kulongedza bwino magawo olimba, motero zimathandizira kulekanitsidwa kwa microphase kwa zinthu.
Magawo a amino ester opangidwa ndi aliphatic isocyanates amagwirizana bwino ndi magawo ofewa, zomwe zimapangitsa kuti magawo olimba ambiri asungunuke m'magawo ofewa, zomwe zimachepetsa kuchuluka kwa kulekanitsidwa kwa microphase. Magawo a amino ester opangidwa ndi aromatic isocyanates sagwirizana bwino ndi magawo ofewa, pomwe kuchuluka kwa kulekanitsidwa kwa microphase ndi kwakukulu. Polyolefin polyurethane ili ndi kapangidwe kosiyana ka microphase chifukwa chakuti gawo lofewa silipanga ma hydrogen bonds ndipo ma hydrogen bonds amatha kuchitika kokha mu gawo lolimba.
Zotsatira za kulumikiza kwa haidrojeni pa malo ofewa a elastomer nazonso n'zofunika kwambiri. Ngakhale kuti ma polyether ndi ma carbonyl omwe ali mu gawo lofewa amatha kupanga ma bond ambiri a haidrojeni ndi NH mu gawo lolimba, zimawonjezeranso kutentha kwa ma elastomer. Zatsimikiziridwa kuti ma bond a haidrojeni akadali ndi 40% pa 200 ℃.
02 Kuwonongeka kwa kutentha
Magulu a Amino ester amawonongeka motere kutentha kwambiri:
- RNHCOOR – RNC0 HO-R
- RNHCOOR – RNH2 CO2 ene
- RNHCOOR – RNHR CO2 ene
Pali mitundu itatu ikuluikulu ya kuwonongeka kwa kutentha kwa zinthu zopangidwa ndi polyurethane:
① Kupanga ma isocyanates ndi ma polyols oyambilira;
② α— Mpweya wa okosijeni womwe uli pa maziko a CH2 umasweka ndipo umasakanikirana ndi mpweya umodzi wa haidrojeni womwe uli pa CH2 yachiwiri kuti upange ma amino acid ndi ma alkenes. Ma amino acid amawola kukhala amine imodzi yoyambirira ndi carbon dioxide:
③ Pangani 1 amine yachiwiri ndi carbon dioxide.
Kuwonongeka kwa kutentha kwa kapangidwe ka carbamate:
Aryl NHCO Aryl,~120 ℃;
N-alkyl-NHCO-aryl,~180 ℃;
Aryl NHCO n-alkyl,~200 ℃;
N-alkyl-NHCO-n-alkyl,~250 ℃.
Kukhazikika kwa kutentha kwa ma amino acid esters kumagwirizana ndi mitundu ya zinthu zoyambira monga isocyanates ndi polyols. Aliphatic isocyanates ndi apamwamba kuposa aromatic isocyanates, pomwe mafuta ochulukirapo ndi apamwamba kuposa aromatic alcohols. Komabe, mabuku amanena kuti kutentha kwa kutentha kwa ma aliphatic amino acid esters kuli pakati pa 160-180 ℃, ndipo kwa aromatic amino acid esters kuli pakati pa 180-200 ℃, zomwe sizikugwirizana ndi zomwe zili pamwambapa. Chifukwa chake chingakhale chogwirizana ndi njira yoyesera.
Ndipotu, aliphatic CHDI (1,4-cyclohexane diisocyanate) ndi HDI (hexamethylene diisocyanate) zimakhala ndi kukana kutentha bwino kuposa aromatic MDI ndi TDI zomwe zimagwiritsidwa ntchito nthawi zambiri. Makamaka trans CHDI yokhala ndi kapangidwe kofanana yadziwika kuti ndi isocyanate yolimba kwambiri kutentha. Ma elastomer a polyurethane opangidwa kuchokera pamenepo ali ndi kuthekera kokonza bwino, kukana hydrolysis bwino, kutentha kofewa kwambiri, kutentha kochepa kwa kusintha kwa galasi, kutentha kochepa kwa kutentha, komanso kukana kwa UV kwambiri.
Kuwonjezera pa gulu la amino ester, ma polyurethane elastomers alinso ndi magulu ena ogwira ntchito monga urea formate, biuret, urea, ndi zina zotero. Maguluwa amatha kuwonongeka ndi kutentha kwambiri:
NHCONCOO – (aliphatic urea formate), 85-105 ℃;
- NHCONCOO – (fungo la urea), pa kutentha kwa 1-120 ℃;
- NHCONCONH – (aliphatic biuret), pa kutentha kuyambira 10 ° C mpaka 110 ° C;
NHCONCONH – (fungo labwino), 115-125 ℃;
NHCONH – (aliphatic urea), 140-180 ℃;
- NHCONH – (fungo la urea), 160-200 ℃;
Mphete ya Isocyanurate> 270 ℃.
Kutentha kwa kutentha kwa biuret ndi urea formate ndi kotsika kwambiri kuposa kwa aminoformate ndi urea, pomwe isocyanurate imakhala ndi kutentha kokhazikika bwino. Pakupanga ma elastomer, ma isocyanate ochulukirapo amatha kuchitapo kanthu ndi aminoformate ndi urea opangidwa kuti apange urea based formate ndi biuret cross-linked structures. Ngakhale amatha kusintha mawonekedwe a elastomer, ndi osakhazikika kwambiri kutentha.
Kuti muchepetse magulu osakhazikika a kutentha monga biuret ndi urea formate mu elastomers, ndikofunikira kuganizira za chiŵerengero chawo cha zinthu zopangira ndi njira zopangira. Ma ratios ochulukirapo a isocyanate ayenera kugwiritsidwa ntchito, ndipo njira zina ziyenera kugwiritsidwa ntchito momwe zingathere kuti mupange mphete za isocyanate zosakwanira mu zinthu zopangira (makamaka isocyanate, polyols, ndi zowonjezera unyolo), kenako ndikuziyika mu elastomer malinga ndi njira zachizolowezi. Iyi yakhala njira yogwiritsidwa ntchito kwambiri popanga ma elastomers a polyurethane osatentha komanso osayaka moto.
03 Hydrolysis ndi kutentha kwa okosijeni
Ma elastomer a polyurethane amatha kuwonongeka ndi kutentha m'magawo awo olimba komanso kusintha kwa mankhwala komwe kumachitika m'magawo awo ofewa kutentha kwambiri. Ma elastomer a polyester ali ndi kukana kofooka kwa madzi ndipo amakonda kwambiri hydrolyze kutentha kwambiri. Nthawi yogwira ntchito ya polyester/TDI/diamine imatha kufika miyezi 4-5 pa 50 ℃, milungu iwiri yokha pa 70 ℃, komanso masiku ochepa okha pamwamba pa 100 ℃. Ma Ester bond amatha kuwola kukhala ma acid ndi ma alcohols ofanana akakumana ndi madzi otentha ndi nthunzi, ndipo magulu a urea ndi amino ester mu ma elastomer amathanso kuchitidwa hydrolysis:
RCOOR H20- → RCOOH HOR
Mowa wa Ester
RNHCONHR imodzi H20- → RXHCOOH H2NR -
Ureamide
RNHCOOR-H20 imodzi- → RNCOOH HOR -
Amino formate ester Amino formate alcohol
Ma elastomer okhala ndi polyether ali ndi kukhazikika koipa kwa kutentha, ndipo ma elastomer okhala ndi ether α- Hydrogen yomwe ili pa atomu ya kaboni imasungunuka mosavuta, ndikupanga hydrogen peroxide. Pambuyo powola ndi kugawanika kwina, imapanga ma oxide radicals ndi ma hydroxyl radicals, omwe pamapeto pake amawola kukhala ma formates kapena aldehydes.
Ma polyester osiyanasiyana sakhudza kwambiri kukana kutentha kwa ma elastomer, pomwe ma polyether osiyanasiyana ali ndi mphamvu inayake. Poyerekeza ndi TDI-MOCA-PTMEG, TDI-MOCA-PTMEG imakhala ndi mphamvu yosungira mphamvu ya 44% ndi 60% motsatana ikasungidwa pa 121 ℃ kwa masiku 7, ndipo yomalizayo imakhala yabwino kwambiri kuposa yoyamba. Chifukwa chake chingakhale chakuti mamolekyu a PPG ali ndi unyolo wolumikizana, womwe sugwirizana ndi dongosolo lokhazikika la mamolekyu osalala ndipo umachepetsa kukana kutentha kwa thupi losalala. Dongosolo lokhazikika la kutentha la ma polyether ndi: PTMEG>PEG>PPG.
Magulu ena ogwira ntchito mu polyurethane elastomers, monga urea ndi carbamate, nawonso amakumana ndi ma oxidation ndi hydrolysis reactions. Komabe, gulu la ether ndilosavuta kuoxidized, pomwe gulu la ester ndilosavuta kuoxidized. Dongosolo la kukana kwawo antioxidant ndi hydrolysis ndi:
Ntchito ya antioxidant: esters>urea>carbamate>ether;
Kukana kwa hydrolysis: ester
Kuti pakhale kukana kwa okosijeni kwa polyether polyurethane ndi kukana kwa hydrolysis kwa polyester polyurethane, zowonjezera zimawonjezedwanso, monga kuwonjezera 1% phenolic antioxidant Irganox1010 ku PTMEG polyether elastomer. Mphamvu yokoka ya elastomer iyi imatha kuwonjezeka ndi nthawi 3-5 poyerekeza ndi yopanda ma antioxidants (zotsatira za mayeso pambuyo pa kukalamba pa 1500C kwa maola 168). Koma si antioxidant iliyonse yomwe imakhudza ma elastomer a polyurethane, phenolic 1rganox 1010 ndi TopanOl051 (phenolic antioxidant, hinderled amine light stabilizer, benzotriazole complex) zokha zomwe zimakhala ndi zotsatirapo zazikulu, ndipo yoyamba ndiyo yabwino kwambiri, mwina chifukwa ma antioxidants a phenolic amagwirizana bwino ndi ma elastomer. Komabe, chifukwa cha ntchito yofunika ya magulu a phenolic hydroxyl mu njira yokhazikika ya ma antioxidants a phenolic, kuti tipewe kuchitapo kanthu ndi "kulephera" kwa gulu la phenolic hydroxyl ili ndi magulu a isocyanate mu dongosolo, chiŵerengero cha isocyanate ndi polyols sichiyenera kukhala chachikulu kwambiri, ndipo ma antioxidants ayenera kuwonjezeredwa ku ma prepolymers ndi ma chain extenders. Ngati awonjezeredwa panthawi yopanga ma prepolymers, adzakhudza kwambiri mphamvu yokhazikika.
Zowonjezera zomwe zimagwiritsidwa ntchito poletsa hydrolysis ya polyester polyurethane elastomers makamaka ndi mankhwala a carbodiimide, omwe amachita ndi carboxylic acids opangidwa ndi ester hydrolysis mu mamolekyu a polyurethane elastomer kuti apange acyl urea derivatives, zomwe zimaletsa hydrolysis yowonjezera. Kuwonjezera kwa carbodiimide pa 2% mpaka 5% kumatha kuwonjezera kukhazikika kwa madzi a polyurethane ndi nthawi 2-4. Kuphatikiza apo, tert butyl catechol, hexamethylenetetramine, azodicarbonamide, ndi zina zotero zimakhala ndi zotsatira zina zotsutsana ndi hydrolysis.
04 Makhalidwe Abwino Ogwira Ntchito
Ma elastomer a polyurethane ndi ma copolymers odziwika bwino a multi block, okhala ndi maunyolo a molekyulu opangidwa ndi magawo osinthasintha okhala ndi kutentha kwa kusintha kwa galasi kotsika kuposa kutentha kwa chipinda ndi magawo olimba okhala ndi kutentha kwa kusintha kwa galasi kokwera kuposa kutentha kwa chipinda. Pakati pawo, ma polyol a oligomeric amapanga magawo osinthasintha, pomwe ma diisocyanates ndi ma molecule ang'onoang'ono owonjezera unyolo amapanga magawo olimba. Kapangidwe kokhazikika ka magawo osinthasintha komanso olimba a unyolo kumatsimikiza magwiridwe antchito awo apadera:
(1) Kuuma kwa rabara wamba nthawi zambiri kumakhala pakati pa Shaoer A20-A90, pomwe kuuma kwa pulasitiki kumakhala pafupifupi Shaoer A95 Shaoer D100. Ma elastomer a polyurethane amatha kufika pa Shaoer A10 ndi Shaoer D85, popanda thandizo la filler;
(2) Mphamvu ndi kusinthasintha kwakukulu kumatha kusungidwabe mkati mwa kuuma kosiyanasiyana;
(3) Kukana kwabwino kwambiri kuwonongeka, kuwirikiza kawiri mpaka khumi kuposa mphira wachilengedwe;
(4) Kukana bwino madzi, mafuta, ndi mankhwala;
(5) Kukana kugwedezeka kwambiri, kukana kutopa, komanso kukana kugwedezeka, koyenera kugwiritsidwa ntchito popindika pafupipafupi;
(6) Kukana kutentha kochepa, ndi kufooka kwa kutentha kochepa pansi pa -30 ℃ kapena -70 ℃;
(7) Ili ndi mphamvu yabwino kwambiri yotetezera kutentha, ndipo chifukwa cha kutentha kochepa, ili ndi mphamvu yabwino yotetezera kutentha poyerekeza ndi rabara ndi pulasitiki;
(8) Kugwirizana bwino kwa thupi ndi mphamvu zoletsa magazi kuundana;
(9) Kuteteza bwino magetsi, kukana nkhungu, komanso kukhazikika kwa UV.
Ma elastomer a polyurethane amatha kupangidwa pogwiritsa ntchito njira zomwezo monga mphira wamba, monga pulasitiki, kusakaniza, ndi vulcanization. Amathanso kupangidwa ngati mphira wamadzimadzi pothira, kupanga centrifugal, kapena kupopera. Amathanso kupangidwa kukhala zinthu zopyapyala ndikupangidwa pogwiritsa ntchito jakisoni, extrusion, rolling, blow molding, ndi njira zina. Mwanjira imeneyi, sikuti imangowonjezera magwiridwe antchito, komanso imawongolera kulondola kwa mawonekedwe ndi mawonekedwe a chinthucho.