1
He mau mea polyurethane kū'ē i nā wela kiʻekiʻe? Ma keʻano laulā, ʻaʻole kūpaʻa ka polyurethane i nā mahana kiʻekiʻe, ʻoiai me kahi ʻōnaehana PPDI maʻamau, hiki i kona palena wela kiʻekiʻe ma kahi o 150 ° wale nō. ʻAʻole hiki i nā ʻano polyester maʻamau a i ʻole polyether ke kū i nā mahana ma luna o 120°. Eia nō naʻe, ʻo ka polyurethane he polymer polar nui, a ke hoʻohālikelike ʻia me nā plastics maʻamau, ʻoi aku ka pale ʻana i ka wela. No laila, he mea koʻikoʻi loa ka wehewehe ʻana i ka pae wela no ke kūpaʻa 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 e hoʻonui i ka crystallinity o ka mea, e like me ka isocyanate PPDI maʻamau i ʻōlelo ʻia ma mua. No ke aha e hoʻonui ai i ka crystallinity o ka polymer i kona kūpaʻa wela? ʻIke ʻia ka pane i kēlā me kēia kanaka, ʻo ia hoʻi, ʻo ka hoʻolālā e hoʻoholo i nā waiwai. I kēia lā, makemake mākou e wehewehe i ke kumu o ka hoʻomaikaʻi ʻana o ka hoʻonohonoho molekala maʻamau e hoʻomaikaʻi i ka paʻa wela, ʻo ka manaʻo kumu mai ka wehewehe a i ʻole ka hoʻohālikelike o ka ikehu manuahi ʻo Gibbs, ʻo ia hoʻi △G=H-ST. ʻO ka ʻaoʻao hema o G ka ikehu manuahi, a ʻo ka ʻaoʻao ʻākau o ka hoohalike H he enthalpy, S he entropy, a ʻo T ka wela.
3
ʻO ka Gibbs free energy he manaʻo ikehu i ka thermodynamics, a ʻo kona nui he waiwai pili pinepine, ʻo ia hoʻi ka ʻokoʻa ma waena o nā waiwai hoʻomaka a me ka hopena, no laila ua hoʻohana ʻia ka hōʻailona △ i mua ona, no ka mea ʻaʻole hiki ke loaʻa pololei a hōʻike ʻia ka waiwai paʻa. Ke emi iho nei ka △G, ʻo ia hoʻi inā ʻino, ʻo ia hoʻi, hiki i ka hopena kemika ke hiki koke mai a maikaʻi paha no kekahi pane i manaʻo ʻia. Hiki ke hoʻohana ʻia kēia no ka hoʻoholo ʻana inā loaʻa ka hopena a i ʻole hiki ke hoʻohuli ʻia i ka thermodynamics. Hiki ke hoʻomaopopo ʻia ke degere a i ʻole ka nui o ka hoʻemi ʻana ma ke ʻano he kinetics o ka pane ponoʻī. ʻO H ka enthalpy maʻamau, hiki ke hoʻomaopopo ʻia ʻo ia ka ikehu kūloko o kahi mole. Hiki ke kuhi ʻia mai ka manaʻo o nā huaʻōlelo Kina, ʻoiai ʻaʻole ahi

4
Hōʻike ka S i ka entropy o ka ʻōnaehana, i ʻike ʻia a maopopo loa ke ʻano maoli. Ua pili a i ʻole i hōʻike ʻia ma ke ʻano o ka wela T, a ʻo kona ʻano kumu ke degere o ka pilikia a i ʻole ke kūʻokoʻa o ka ʻōnaehana liʻiliʻi microscopic. I kēia manawa, ua ʻike paha ka hoa liʻiliʻi i ka ʻike ʻana o ka wela T e pili ana i ke kūpaʻa wela a mākou e kamaʻilio nei i kēia lā. E ʻae mai iaʻu e kamaʻilio iki e pili ana i ka manaʻo entropy. Hiki ke hoʻomaopopo naʻaupō ʻo Entropy ma ke ʻano he kūʻē i ka crystallinity. ʻOi ke kiʻekiʻe o ka waiwai entropy, ʻoi aku ka ʻino a me ka chaotic o ka molecular structure. ʻO ke kiʻekiʻe o ka hana maʻamau o ka molekala, ʻoi aku ka maikaʻi o ka crystallinity o ka mole. I kēia manawa, e ʻoki kākou i kahi ʻāpana liʻiliʻi mai ka ʻōwili pahu polyurethane a nānā i ka huinaha liʻiliʻi ma ke ʻano he ʻōnaehana piha. Hoʻopaʻa ʻia kona nuipaʻa, me ka manaʻo he 100 mau molekele polyurethane (ma ka ʻoiaʻiʻo, aia ka nui o N), no ka mea, ʻaʻole i hoʻololi ʻia kona nuipa a me ka leo, hiki iā mākou ke hoʻohālikelike i ka △G ma ke ʻano he helu helu liʻiliʻi a kokoke loa i ka ʻole, a laila hiki ke hoʻololi ʻia ke ʻano o ka ikehu manuahi ʻo Gibbs i ka entropy, kahi o T, kahi e hoʻololi ai i ka entropy a me T. ʻO ia hoʻi, ʻo ke kūpaʻa wela o ka pāhaʻi liʻiliʻi polyurethane e like me ka enthalpy H a me ka hoʻohālikelike ʻana i ka entropy S. ʻOiaʻiʻo, he ʻano like kēia, a ʻoi aku ka maikaʻi e hoʻohui i △ ma mua o ia (loaʻa ma ka hoʻohālikelike).
5
ʻAʻole paʻakikī ka loaʻa ʻana o ka hoʻomaikaʻi ʻana o ka crystallinity ʻaʻole hiki ke hōʻemi wale i ka waiwai entropy akā hoʻonui pū i ka waiwai enthalpy, ʻo ia hoʻi, ka hoʻonui ʻana i ka mole me ka hoʻemi ʻana i ka denominator (T = H/S), ʻike ʻia no ka piʻi ʻana o ka mahana T, a ʻo ia kekahi o nā ʻano hana maʻamau a maʻamau, ʻaʻole paha ʻo T ka mahana hoʻololi aniani a i ʻole ka wela heheʻe. ʻO ka mea e pono ai ke hoʻololi ʻia ʻo ka maʻamau a me ka crystallinity o ka monomer molecular structure a me ka maʻamau holoʻokoʻa a me ka crystallinity o ka solidification molecular kiʻekiʻe ma hope o ka hōʻuluʻulu ʻana he linear maoli nō ia, hiki ke ʻano like a hoʻomaopopo ʻia ma ke ʻano laina. ʻO ka enthalpy H ka mea nui i hāʻawi ʻia e ka ikehu kūloko o ka mole, a ʻo ka ikehu kūloko o ka mole ka hopena o nā ʻano molekala like ʻole o ka ikehu molecular ʻē aʻe, a ʻo ka ikehu molecular ka hiki ke kemika, ua maʻamau a kauoha ʻia ka molecular structure, ʻo ia hoʻi, ʻoi aku ka kiʻekiʻe o ka ikehu mole, a ʻoi aku ka maʻalahi o ka hana ʻana i ka crystallization condenomena i loko o ka wai. Ma waho aʻe o kēia, ua manaʻo mākou he 100 polyurethane molekala, ʻo ka hui pū ʻana ma waena o kēia mau molekala 100 e hoʻopilikia pū i ke kūpaʻa wela o kēia huila liʻiliʻi, e like me nā paʻa hydrogen kino, ʻoiai ʻaʻole ikaika lākou e like me nā mea paʻa kemika, akā nui ka helu N, ʻo ka ʻike maopopo o ka molekele hydrogen e hiki ke hoʻemi i ke kiʻekiʻe o ka maʻi a i ʻole ka palena o ka neʻe ʻana o ka polyficial mole o kēlā me kēia. kūʻē.