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Zvinhu zvepolyurethane zvinoramba kupisa kwakanyanya here? Kazhinji, polyurethane hairambi kupisa kwakanyanya, kunyangwe nePPDI system yakajairika, muganho wayo wekupisa mukuru unogona kungosvika 150°. Mhando dzepolyester dzakajairika kana polyether dzingasakwanise kumira kupisa kuri pamusoro pe120°. Zvisinei, polyurethane ipolymer ine polar yakawanda, uye kana ichienzaniswa nepurasitiki yakajairika, inoramba kupisa zvakanyanya. Nokudaro, kutsanangura tembiricha yekuramba kupisa kwakanyanya kana kusiyanisa mashandisirwo akasiyana kwakakosha zvikuru.
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Saka kugadzikana kwekupisa kwezvinhu zve polyurethane kungavandudzwa sei? Mhinduro huru ndeyekuwedzera kusimba kwekristaro kwezvinhu, senge iyo PPDI isocyanate yagara iripo yambotaurwa. Sei kuwedzera kusimba kwepolymer kuchiwedzera kusimba kwayo kwekupisa? Mhinduro yacho inozivikanwa nemunhu wese, ndiko kuti, chimiro chinosarudza hunhu. Nhasi, tinoda kuedza kutsanangura kuti sei kuvandudzwa kwekugara kwenguva dzose kwechimiro chemorekuru kunounza kuvandudzwa kwekusimba kwekupisa, pfungwa huru inobva mutsananguro kana fomura yeGibbs free energy, kureva △G=H-ST. Rutivi rweruboshwe rwaG runomiririra simba rakasununguka, uye rutivi rwerudyi rwe equation H i enthalpy, S i entropy, uye T i temperature.
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Simba reGibbs free ipfungwa yesimba muthermodynamics, uye saizi yaro inowanzova kukosha kwakaenzana, kureva musiyano uripo pakati pekutanga nekuguma, saka chiratidzo △ chinoshandiswa pamberi paro, sezvo kukosha kwakazara kusingawanikwe kana kumirirwa zvakananga. Kana △G yadzikira, kureva kuti kana iri negative, zvinoreva kuti reaction yemakemikari inogona kuitika yoga kana kuva nerubatsiro kune imwe reaction inotarisirwa. Izvi zvinogona zvakare kushandiswa kuona kana reaction iripo kana kuti inodzokororwa muthermodynamics. Dhigirii kana mwero wekudzikira unogona kunzwisiswa se kinetics ye reaction pachayo. H inonyanya kureva enthalpy, iyo inogona kunzwisiswa sesimba remukati remorekuru. Inogona kufungidzirwa kubva pamusoro pechirevo chemavara echiChinese, sezvo moto usingashandiswe.

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S inomiririra entropy yesystem, iyo inozivikanwa kazhinji uye zvinoreva chaizvo zvakajeka. Inoenderana kana kutaurwa maererano netembiricha T, uye zvinoreva zvikuru dhigiri rekusagadzikana kana rusununguko rwe microscopic small system. Panguva ino, shamwari diki inocherechedza ingave yakaona kuti tembiricha T ine chekuita nekupisa kwatinotaura nhasi yakabuda pakupedzisira. Regai ndingotaura zvishoma nezvepfungwa ye entropy. Entropy inogona kunzwisiswa zvisina musoro seyakapesana necrystallinity. Kana entropy yakakwira, chimiro chemamorekuru chinova chisina kurongeka uye chisina kurongeka. Kana chimiro chemamorekuru chakakwira, crystallinity yemorekuru inova nani. Iye zvino, ngaticheke sikweya diki kubva pa polyurethane rabha roll toona sikweya diki sesystem yakazara. Huremu hwayo hwakagadzika, tichifunga kuti sikweya inoumbwa nemamorekuru zana epolyurethane (muchokwadi, kune N akawanda), sezvo huremu hwayo nevhoriyamu zvisina kuchinja, tinogona kuyera △G senhamba diki kana kuti pedyo ne zero, saka fomura yesimba reGibbs free inogona kushandurwa kuita ST=H, uko T iri tembiricha, uye S iri entropy. Kureva kuti, kuramba kupisa kwe polyurethane small square kwakaenzana ne enthalpy H uye kwakaenzana ne entropy S. Ehe, iyi inzira yekufungidzira, uye zvakanakisa kuwedzera △ pamberi payo (inowanikwa kuburikidza nekuenzanisa).
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Hazvina kuoma kuona kuti kuvandudzwa kwekristaro hakungogumiri pakuderedza kukosha kwe entropy asiwo kuwedzera kukosha kwe enthalpy, ndiko kuti, kuwedzera molekyuru uku uchideredza denominator (T = H/S), izvo zviri pachena pakuwedzera kwekushisa T, uye ndeimwe yenzira dzinoshanda uye dzakajairika, zvisinei nekuti T ingave tembiricha yekuchinja kwegirazi kana tembiricha yekunyunguduka. Chinofanira kuchinjwa ndechekuti kurongeka uye kristaro yechimiro chemonomer molecular uye kurongeka uye kristaro yekukwirira kwemamorekuru mushure mekuunganidzwa zviri nyore, izvo zvinogona kuenzana kana kunzwisiswa nenzira yakatsetseka. Enthalpy H inonyanya kupihwa nesimba remukati remorekyuru, uye simba remukati remorekyuru imhedzisiro yemaumbirwo akasiyana emamorekuru esimba rakasiyana remorekyuru, uye simba remorekyuru isimba remakemikari, chimiro chemorekyuru chakarongeka uye chakarongwa, zvinoreva kuti simba remorekyuru rakakwirira, uye zviri nyore kugadzira zviitiko zvekristaro, semvura inodzika kuita chando. Kunze kwezvo, takangofungidzira mamorekuru zana epolyurethane, masimba ekudyidzana ari pakati pemamorekuru aya zana achakanganisawo kuramba kupisa kwemuchina uyu mudiki, senge mabhondi ehydrogen chaiwo, kunyangwe asina kusimba semabhondi emakemikari, asi nhamba N yakakura, maitiro ari pachena ebhondi rehydrogen remamorekuru akawanda anogona kuderedza kusagadzikana kana kudzora kufamba kwemorekuru yega yega yepolyurethane, saka hydrogen bond inobatsira mukuvandudza kuramba kupisa.