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Ko polyurethane zvinhu zvinodzivirira kutonhora kwakanyanya? Kazhinji, polyurethane haimirire kune tembiricha yakakwira, kunyangwe neyakajairwa PPDI system, iyo yakanyanya tembiricha muganho inogona kutenderedza 150 °. Mhando dzepolyester dzakajairwa kana dzepolyether dzinogona kusakwanisa kumira tembiricha dziri pamusoro pe120°. Nekudaro, polyurethane i polymer yakanyanya polar, uye kana ichienzaniswa neyakajairwa mapurasitiki, inoshingirira kupisa. Naizvozvo, kutsanangura tembiricha yemhando yepamusoro-yekudzivirira yekupisa kana kusiyanisa kushandiswa kwakasiyana kwakakosha.
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Saka kugadzikana kwekupisa kwe polyurethane zvinhu kunogona kuvandudzwa sei? Mhinduro yakakosha ndeyekuwedzera crystallinity yezvinhu, senge yakajairika PPDI isocyanate yambotaurwa. Sei kuwedzera kupenya kwepolymer kuchivandudza kugadzikana kwayo kwekupisa? Mhinduro yacho inonyanya kuzivikanwa kune wese munhu, ndiko kuti, chimiro chinotarisa zvivakwa. Nhasi, tinoda kuyedza kutsanangura kuti sei kuvandudzwa kwemamorekuru kugadzika kwemaitiro kuchiunza kuvandudzwa kwekudzikama kwekupisa, pfungwa yekutanga inobva patsanangudzo kana fomula yeGibbs simba remahara, kureva △G=H-ST. Rutivi rworuboshwe rweG runomiririra simba rekusununguka, uye rutivi rworudyi rweequation H is enthalpy, S is entropy, uye T ndiyo tembiricha.
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Iyo Gibbs yemahara simba isimba resimba mu thermodynamics, uye ukuru hwayo kazhinji hune huwandu hunokosha, kureva musiyano pakati pekutanga nekuguma kwemaitiro, saka chiratidzo △ chinoshandiswa pamberi payo, sezvo kukosha kwakakwana hakugone kuwanikwa zvakananga kana kumiririrwa. Kana △G yadzikira, kureva kuti kana isina, zvinoreva kuti kemikari inogona kuitika yega kana kuti yakanaka kune imwe inotarisirwa kuita. Izvi zvinogona zvakare kushandiswa kuona kana kuita kuriko kana kudzoserwa mu thermodynamics. Dhigirii kana chiyero chekudzikisa chinogona kunzwisiswa sekinetics yemhinduro pachayo. H inonyanya kunzi enthalpy, iyo inogona kunzwisiswa sesimba remukati remorekuru. Inogona kufungidzirwa kubva pane zvinorehwa nepamusoro pemavara echiChinese, sezvo moto usiri

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S inomiririra entropy yehurongwa, iyo inowanzo zivikanwa uye chirevo chaicho chakajeka. Iyo ine hukama kana kuratidzwa maererano netembiricha T, uye chirevo chayo chikuru chiyero chekusagadzikana kana rusununguko rweiyo microscopic diki system. Panguva ino, shamwari diki inocherekedza inogona kunge yaona kuti tembiricha T ine chekuita nekushomeka kwekupisa kwatiri kukurukura nhasi kwakazoonekwa. Rega ndingo svetuka zvishoma nezve iyo entropy pfungwa. Entropy inogona kunzwisiswa nehupenzi seyakapesana nekristaro. Iyo yakakwira iyo entropy kukosha, iyo inowedzera kusagadzikana uye chaotic iyo molecular chimiro. Kukwirira kwemaitiro emamorekuru, zvinoita kuti crystallinity yemorekuru iri nani. Zvino, ngatichekei diki diki kubva papolyurethane rubber roll toona diki diki sehurongwa hwakakwana. Huremu hwayo hwakamisikidzwa, tichifunga kuti sikweya inoumbwa ne100 polyurethane mamorekuru (chaizvoizvo, kune N akawanda), sezvo huwandu hwayo uye huwandu hwayo husina kuchinjika, tinogona kufungidzira △G sechiverengero chidiki diki kana padhuze ne zero, ipapo iyo Gibbs yemahara simba formula inogona kushandurwa kuita ST=H, tro uye S ndipo pane tembiricha. Iko ndiko, kupikisa kwekushisa kwe polyurethane duku square inofananidzwa ne enthalpy H uye inversely proportional kune entropy S. Zvechokwadi, iyi ndiyo nzira yekufungidzira, uye zvakanakisisa kuwedzera △ pamberi payo (yakawanikwa kuburikidza nekuenzanisa).
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Hazvina kuoma kuwana kuti kuvandudzwa kwekristallinity hakugone chete kuderedza kukosha kweentropy asiwo kuwedzera kukosha kweenthalpy, ndiko kuti, kuwedzera molecule paunenge uchideredza denominator (T = H / S), iyo iri pachena nokuda kwekuwedzera kwekushisa T, uye ndiyo imwe yenzira dzinoshanda uye dzakajairika, pasinei nokuti T ndiyo tembiricha yekuchinja kwegirazi kana kunyunguduka kwekushisa. Chinoda kushandurwa ndechekuti kugara uye crystallinity yemonomer molecular chimiro uye iyo yakazara kurongeka uye crystallinity yeakakwira mamorekuru kusimba mushure mekuunganidzwa ane mutsara, izvo zvinogona kuenzana kana kunzwisiswa nenzira yemutsara. Iyo enthalpy H inonyanya kupihwa nesimba remukati remorekuru, uye simba remukati remorekuru mhedzisiro yeakasiyana mamorekuru emhando dzakasiyana siyana anogona simba, uye simba ringangoita kemikari ndiko kugona kwekemikari, chimiro chemolecular chinogara uye chakarairwa, izvo zvinoreva kuti simba ringaite rakakwirira, uye zviri nyore kugadzira crystallization phenomena, semvura inonyungudika kuita ice. Kunze kwezvo, isu takangofungidzira 100 polyurethane mamorekuru, kupindirana kwemasimba pakati peaya 100 mamorekuru kuchakanganisawo kupisa kwekupisa kweiyi diki roller, senge yemuviri hydrogen zvisungo, kunyangwe iyo isina kusimba semakemikari bond, asi nhamba N yakakura, maitiro ari pachena eiyo yakawanda mamorekuru hydrogen bond inogona kuderedza dhigirii renyonganiso kana kudzora hupamhi hwema hydrogen bond, saka imwe neimwe inobatsira hydrogen bond. kupikisa kupisa.