Kim Hyeon Jeong, Jin Xuanjun, Choi Joon Weon
Graduate School of International Agricultural Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea.
Institute of Green-Bio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea.
Sci Rep. 2024 Jun 12;14(1):13490. doi: 10.1038/s41598-024-64318-8.
In this study, polyurethane (PU) foams were manufactured using kraft lignin and castor oil as bio-based polyols by replacing 5-20 wt% and 10-100 wt% of conventional polyol, respectively. To investigate the effects of unmodified bio-based polyols on PU foam production, reactivity and morphology within PU composites was analyzed as well as mechanical and thermal properties of the resulting foams. Bio-based PU foam production was carried out after characterizing the reagents used in the foaming process (including hydroxyl group content, molecular weight distribution, and viscosity). To compare the resulting bio-based PU foams, control foam were produced without any bio-based polyol under the same experimental conditions. For lignin-incorporated PU foams, two types, LPU and lpu, were manufactured with index ratio of 1.01 and 1.3, respectively. The compressive strength of LPU foams increased with lignin content from 5 wt% (LPU5: 147 kPa) to 20 wt% (LPU20: 207 kPa), although it remained lower than that of the control foam (PU0: 326 kPa). Similarly, the compressive strength of lpu foams was lower than that of the control foam (pu0: 441 kPa), with values of 164 kPa (lpu5), 163 kPa (lpu10), 167 kPa (lpu15), and 147 kPa (lpu20). At 10 wt% lignin content, both foams (LPU10 and lpu10) exhibited the smallest and most homogenous pore sizes and structures. For castor oil-incorporated PU foams with an index of 1.01, denoted as CPU, increasing castor oil content resulted in larger cell sizes and void fractions, transitioning to an open-cell structure and decreasing the compressive strength of the foams from 284 kPa (CPU10) to 23 kPa (CPU100). Fourier transform infrared (FT-IR) results indicated the formation of characteristic urethane linkages in PU foams and confirmed that bio-based polyols were less reactive with isocyanate compared to traditional polyol. Thermogravimetric analysis (TGA) showed that incorporating lignin and castor oil affected the thermal decomposition behavior. The thermal stability of lignin-incorporated PU foams improved as the lignin content increased with char yields increasing from 11.5 wt% (LPU5) to 15.8 wt% (LPU20) and from 12.4 wt% (lpu5) to 17.5 wt% (lpu20). Conversely, the addition of castor oil resulted in decreased thermal stability, with char yields decreasing from 10.6 wt% (CPU10) to 4.2 wt% (CPU100). This research provides a comprehensive understanding of PU foams incorporating unmodified biomass-derived polyols (lignin and castor oil), suggesting their potential for value-added utilization as bio-based products.
在本研究中，使用硫酸盐木质素和蓖麻油作为生物基多元醇来制造聚氨酯（PU）泡沫，分别替代5 - 20 wt%和10 - 100 wt%的传统多元醇。为了研究未改性生物基多元醇对PU泡沫生产的影响，分析了PU复合材料中的反应活性和形态以及所得泡沫的机械性能和热性能。在对发泡过程中使用的试剂（包括羟基含量、分子量分布和粘度）进行表征后，开展了生物基PU泡沫的生产。为了比较所得的生物基PU泡沫，在相同实验条件下制备了不含任何生物基多元醇的对照泡沫。对于含木质素的PU泡沫，制造了两种类型，LPU和lpu，其指数比分别为1.01和1.3。LPU泡沫的抗压强度随着木质素含量从5 wt%（LPU5：147 kPa）增加到20 wt%（LPU20：207 kPa）而提高，尽管其仍低于对照泡沫（PU0：326 kPa）。同样，lpu泡沫的抗压强度低于对照泡沫（pu0：441 kPa），其值分别为164 kPa（lpu5）、163 kPa（lpu10）、167 kPa（lpu15）和147 kPa（lpu20）。在木质素含量为10 wt%时，两种泡沫（LPU10和lpu10）均呈现出最小且最均匀的孔径和结构。对于指数为1.01的含蓖麻油的PU泡沫，记为CPU，蓖麻油含量增加导致泡孔尺寸和孔隙率增大，转变为开孔结构，并使泡沫的抗压强度从284 kPa（CPU10）降至23 kPa（CPU100）。傅里叶变换红外（FT - IR）结果表明PU泡沫中形成了特征性的聚氨酯键，并证实生物基多元醇与异氰酸酯的反应活性低于传统多元醇。热重分析（TGA）表明，加入木质素和蓖麻油会影响热分解行为。含木质素的PU泡沫的热稳定性随着木质素含量的增加而提高，炭产率从11.5 wt%（LPU5）增加到15.8 wt%（LPU20），从12.4 wt%（lpu5）增加到17.5 wt%（lpu20）。相反，加入蓖麻油导致热稳定性降低，炭产率从10.6 wt%（CPU10）降至4.2 wt%（CPU100）。本研究全面了解了包含未改性生物质衍生多元醇（木质素和蓖麻油）的PU泡沫，表明了它们作为生物基产品进行增值利用的潜力。
