木质素基聚氨酯预聚体改性酚醛泡沫的制备及表征（英文）

Preparation and Characterization of Phenolic Foams Modified by Lignin-based Polyurethane Prepolymers

以聚乙二醇(PEG)为液化剂液化木质素,得到液化产物直接合成木质素基聚氨酯预聚体(LLPUPs),并用来改性酚醛泡沫。采用FT-IR对木质素液化产物(LLs)和LLPUPs的结构进行了表征和分析,通过SEM、万能试验机结合热重分析仪研究了LLPUPs对酚醛泡沫的形态,机械性能和热稳定性的影响。结果表明:木质素液化产物的羟值为177~286 mg/g,并随着PEG相对分子质量的增加而下降;添加LLPUPs可以增强酚醛泡沫的压缩强度和比压缩强度,当LLPUP2添加量为9%时,比压缩强度最高,为4.44(Pa·m^3)/g;LLPUP1和LLPUP2添加量为9%时,酚醛泡沫泡孔均匀,当LLPUP1添加量为9%时,比弯曲强度最高,为8.23(Pa·m^3)/g;LLPUPs改性酚醛泡沫与纯酚醛泡沫相比,具有相似的热稳定性。

Lignin was liquefied with polyethylene glycol （PEG） in a solvent-free system and then directly used with suitable PEG as a co-monomer and co-solvent to prepare liquefied lignins （LLs）-based polyurethane prepolymers （LLPUPs）. The structural changes that lignin undergoes after liquefaction were studied by Fourier transform infrared spectroscopy （FT-IR）, the hydroxyl number of LL is 177-286 mg/g and decreases with the increasing of molecular mass of PEG. The structures of LLPUPs were characterized by FT-IR. Then, phenolic foams （PFs） modified with different contents of LLPUPs were prepared. Morphological properties, mechanical properties and thermal stability of PFs were assessed by scanning electron microscopy （SEM）, universal test and thermogravimetric analysis （TGA）. Results show that uniform cells can be prepared by incorporating 9% LLPUP1 and LLPUP2 into the network. The addition of LLPUPs into foam formulations improves the compressive strength and specific compressive strength of PFs, and the highest specific compressive strength is obtained by adding 9% LLPUP2 （4.44（Pa·m^3）/g）. Appropriate levels of LLPUPs could improve the specific flexural strength of PFs, and the highest specific flexural strength is obtained by adding 9% LLPUP1 （8.23（Pa·m^3）/g）. PFs modified with different contents of LLPUPs show similar thermal resistance as pristine foam.