Zhang Tao, Jang Yunjae, Lee Eunhye, Shin Sooan, Kang Ho-Jong
Department of Polymer Science and Engineering, Dankook University, 152 Jukjeon-ro, Suji-gu, Yongin-si 16890, Gyeonggi-do, Korea.
CJ Cheiljedang Corporation, 55 Gwanggyo-ro, 42 beon-gil, Yeongtong-gu, Suwon-si 16495, Gyeonggi-do, Korea.
Polymers (Basel). 2022 May 15;14(10):2018. doi: 10.3390/polym14102018.
The supercritical carbon dioxide foaming characteristics of the biodegradable polymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB--4HB)) are studied for environmentally friendly packaging materials. The effect of the 4HB composition of the P(3HB--4HB) copolymers on the foaming conditions such as pressure and temperature is studied and the density and the expansion ratio of the resulting P(3HB--4HB) foam are together evaluated. The increase in the 4HB content reduces the crystallinity and tan δ value of P(3HB--4HB) required for the growth of the foam cells. Therefore, the foaming temperature needs to be lower to retain a suitable tan δ value of P(3HB--4HB) for foaming. It was found that P(3HB--4HB) with less crystallinity showed better formability and cell uniformity. However, foaming is not possible regardless of the foaming temperature when the 4HB content of P(3HB--4HB) is over 50%, due to the high tan δ value. A lower foam density and higher expansion ratio can be obtained with crystalline P(3HB--4HB) of low 4HB content, compared with non-crystalline P(3HB--4HB) of high 4HB content. The expansion ratio of P(3HB--4HB) foams can be increased slightly by using a chain extender, due to the lowing of crystallinity and tan δ. This is most effective in the case of P(3HB--4HB), whose 4HB content is 16%.
为了制备环保型包装材料，研究了可生物降解聚合物聚（3-羟基丁酸酯-co-4-羟基丁酸酯）（P(3HB-4HB)）的超临界二氧化碳发泡特性。研究了P(3HB-4HB)共聚物中4HB组成对发泡条件（如压力和温度）的影响，并同时评估了所得P(3HB-4HB)泡沫的密度和膨胀率。4HB含量的增加降低了泡沫细胞生长所需的P(3HB-4HB)的结晶度和损耗角正切值。因此，需要较低的发泡温度以保持P(3HB-4HB)适合发泡的损耗角正切值。发现结晶度较低的P(3HB-4HB)具有更好的成型性和泡孔均匀性。然而，当P(3HB-4HB)的4HB含量超过50%时，无论发泡温度如何都无法发泡，这是由于损耗角正切值较高。与4HB含量高的非结晶P(3HB-4HB)相比，4HB含量低的结晶P(3HB-4HB)可以获得更低的泡沫密度和更高的膨胀率。由于结晶度和损耗角正切值的降低，使用扩链剂可以使P(3HB-4HB)泡沫的膨胀率略有提高。这在4HB含量为16%的P(3HB-4HB)情况下最为有效。
