1
He kūpaʻa anei nā mea polyurethane i nā mahana kiʻekiʻe? Ma keʻano laulā, ʻaʻole kūpaʻa ka polyurethane i nā mahana kiʻekiʻe, ʻoiai me kahi ʻōnaehana PPDI maʻamau, ʻo kona palena wela kiʻekiʻe loa ma kahi o 150° wale nō. ʻAʻole hiki i nā ʻano polyester maʻamau a polyether paha ke kūpaʻa i nā mahana ma luna o 120°. Eia nō naʻe, he polymer polar kiʻekiʻe ka polyurethane, a i hoʻohālikelike ʻia me nā plastics maʻamau, ʻoi aku ka kūpaʻa i ka wela. No laila, he mea koʻikoʻi loa ka wehewehe ʻana i ka pae mahana no ke kūpaʻa wela kiʻekiʻe a i ʻole ka hoʻokaʻawale ʻana i nā hoʻohana like ʻole.
2
No laila pehea e hoʻomaikaʻi ʻia ai ke kūpaʻa wela o nā mea polyurethane? ʻO ka pane kumu, ʻo ia ka hoʻonui ʻana i ka crystallinity o ka mea, e like me ka isocyanate PPDI maʻamau i ʻōlelo ʻia ma mua. No ke aha e hoʻomaikaʻi ai ka hoʻonui ʻana i ka crystallinity o ka polymer i kona kūpaʻa wela? Ua ʻike nui ʻia ka pane e nā mea āpau, ʻo ia hoʻi, ʻo ke ʻano e hoʻoholo ai i nā waiwai. I kēia lā, makemake mākou e ho'āʻo e wehewehe i ke kumu e lawe mai ai ka hoʻomaikaʻi ʻana o ke ʻano maʻamau o ka molekala i ka hoʻomaikaʻi ʻana i ke kūpaʻa wela, ʻo ka manaʻo kumu mai ka wehewehe a i ʻole ke ʻano o ka ikehu manuahi ʻo Gibbs, ʻo ia hoʻi △G=H-ST. ʻO ka ʻaoʻao hema o G e hōʻike ana i ka ikehu manuahi, a ʻo ka ʻaoʻao ʻākau o ka hoohalike H he enthalpy, ʻo S he entropy, a ʻo T ka mahana.
3
ʻO ka ikehu manuahi ʻo Gibbs kahi manaʻo ikehu i ka thermodynamics, a ʻo kona nui he waiwai pili pinepine ia, ʻo ia hoʻi ka ʻokoʻa ma waena o nā waiwai hoʻomaka a me nā waiwai hopena, no laila ua hoʻohana ʻia ka hōʻailona △ i mua ona, ʻoiai ʻaʻole hiki ke loaʻa pololei a hōʻike ʻia paha ka waiwai paʻa. Ke emi iho ʻo △G, ʻo ia hoʻi ke maikaʻi ʻole, ʻo ia hoʻi hiki i ka hopena kemika ke hana koke a kūpono paha no kahi hopena i manaʻo ʻia. Hiki ke hoʻohana ʻia kēia e hoʻoholo ai inā aia ka hopena a i ʻole he hoʻohuli ʻia i ka thermodynamics. Hiki ke hoʻomaopopo ʻia ke kekelē a i ʻole ka helu o ka hōʻemi ʻana e like me ke kinetics o ka hopena ponoʻī. ʻO H ke kumu o ka enthalpy, hiki ke hoʻomaopopo ʻia e like me ka ikehu kūloko o kahi mole. Hiki ke kuhi maʻamau ʻia mai ka manaʻo o luna o nā huapalapala Kina, ʻoiai ʻaʻole ke ahi.

4
Hōʻike ʻo S i ka entropy o ka ʻōnaehana, ka mea i ʻike nui ʻia a ua maopopo loa ke ʻano maoli. Pili ia a hōʻike ʻia paha ma ke ʻano o ka mahana T, a ʻo kona ʻano kumu ʻo ia ke kekelē o ka haunaele a i ʻole ke kūʻokoʻa o ka ʻōnaehana liʻiliʻi microscopic. I kēia manawa, ua ʻike paha ka hoaaloha liʻiliʻi makaʻala ua puka hope mai ka mahana T e pili ana i ke kūʻē wela a mākou e kūkākūkā nei i kēia lā. E ʻae mai iaʻu e kamaʻilio iki e pili ana i ka manaʻo entropy. Hiki ke hoʻomaopopo naʻaupō ʻia ʻo Entropy ma ke ʻano he kūʻē i ka crystallinity. ʻO ke kiʻekiʻe o ka waiwai entropy, ʻoi aku ka haunaele a me ka chaotic o ke ʻano molekala. ʻO ke kiʻekiʻe o ke ʻano maʻamau o ke ʻano molekala, ʻoi aku ka maikaʻi o ka crystallinity o ka molekala. I kēia manawa, e ʻoki kākou i kahi huinaha liʻiliʻi mai ka ʻōwili polyurethane rubber a manaʻo i ka huinaha liʻiliʻi he ʻōnaehana piha. Ua paʻa kona nuipaʻa, me ka manaʻo ua hana ʻia ka huinahā me 100 mau molekala polyurethane (ʻo ka ʻoiaʻiʻo, he N ka nui), ʻoiai ʻaʻole i loli iki kona nuipaʻa a me ka nui, hiki iā mākou ke hoʻokokoke iā △G ma ke ʻano he waiwai helu liʻiliʻi loa a kokoke loa i ka ʻole, a laila hiki ke hoʻololi ʻia ke ʻano ikehu manuahi ʻo Gibbs i ST=H, kahi ʻo T ka mahana, a ʻo S ka entropy. ʻO ia hoʻi, ʻo ke kū'ē wela o ka huinahā liʻiliʻi polyurethane e pili ana i ka enthalpy H a me ka inversely proportional i ka entropy S. ʻOiaʻiʻo, he ʻano hoʻokokoke kēia, a ʻoi aku ka maikaʻi o ka hoʻohui ʻana i ka △ ma mua o ia (loaʻa ma o ka hoʻohālikelike ʻana).
5
ʻAʻole paʻakikī ke ʻike ʻaʻole hiki i ka hoʻomaikaʻi ʻana o ka crystallinity ke hōʻemi wale i ka waiwai entropy akā hoʻonui pū i ka waiwai enthalpy, ʻo ia hoʻi, ka hoʻonui ʻana i ka molekala me ka hoʻemi ʻana i ka denominator (T = H/S), kahi mea maopopo no ka hoʻonui ʻana o ka mahana T, a ʻo ia kekahi o nā ʻano hana kūpono a maʻamau, me ka nānā ʻole inā ʻo T ka mahana hoʻololi aniani a i ʻole ka mahana hoʻoheheʻe. ʻO ka mea e pono ai ke hoʻololi ʻia, ʻo ke ʻano maʻamau a me ka crystallinity o ke ʻano molekala monomer a me ke ʻano maʻamau a me ka crystallinity o ka solidification molekala kiʻekiʻe ma hope o ka hōʻuluʻulu ʻana he linear ma ke ʻano, hiki ke like like a hoʻomaopopo ʻia paha ma ke ʻano linear. ʻO ka enthalpy H ka mea nui i hāʻawi ʻia e ka ikehu kūloko o ka molekala, a ʻo ka ikehu kūloko o ka molekala ka hopena o nā ʻano molekala like ʻole o ka ikehu hiki ke hoʻohuihui ʻia, a ʻo ka ikehu hiki ke hoʻohuihui ʻia ka hiki kemika, he maʻamau a hoʻonohonoho ʻia ke ʻano molekala, ʻo ia hoʻi ke kiʻekiʻe o ka ikehu hiki ke hoʻohuihui ʻia, a ʻoi aku ka maʻalahi o ka hana ʻana i nā hanana crystallization, e like me ka wai e hoʻopili ana i ka hau. Eia kekahi, ua manaʻo wale mākou he 100 mau molekala polyurethane, e hoʻopilikia pū ka pilina ma waena o kēia mau molekala 100 i ke kūpaʻa wela o kēia wili liʻiliʻi, e like me nā pilina hydrogen kino, ʻoiai ʻaʻole lākou ikaika e like me nā pilina kemika, akā he nui ka helu N, ʻo ke ʻano maopopo o ka pilina hydrogen molekala ʻoi aku ka nui hiki ke hōʻemi i ke kiʻekiʻe o ka haunaele a i ʻole e kaupalena i ka laulā neʻe o kēlā me kēia molekala polyurethane, no laila he mea maikaʻi ka pilina hydrogen no ka hoʻomaikaʻi ʻana i ke kūpaʻa wela.