Sánchez-Calderón Ismael, Bernardo Victoria, Santiago-Calvo Mercedes, Naji Haneen, Saiani Alberto, Rodríguez-Pérez Miguel Ángel
Cellular Materials Laboratory (CellMat), Condensed Matter Physics Department, University of Valladolid, Campus Miguel Delibes, Paseo de Belén n°7, 47011 Valladolid, Spain.
CellMat Technologies S.L., Paseo de Belén 9-A, 47011 Valladolid, Spain.
Polymers (Basel). 2021 Sep 10;13(18):3055. doi: 10.3390/polym13183055.
In this work, the effects of thermoplastic polyurethane (TPU) chemistry and concentration on the cellular structure of nanocellular polymers based on poly(methyl-methacrylate) (PMMA) are presented. Three grades of TPU with different fractions of hard segments (HS) (60%, 70%, and 80%) have been synthesized by the prepolymer method. Nanocellular polymers based on PMMA have been produced by gas dissolution foaming using TPU as a nucleating agent in different contents (0.5 wt%, 2 wt%, and 5 wt%). TPU characterization shows that as the content of HS increases, the density, hardness, and molecular weight of the TPU are higher. PMMA/TPU cellular materials show a gradient cell size distribution from the edge of the sample towards the nanocellular core. In the core region, the addition of TPU has a strong nucleating effect in PMMA. Core structure depends on the HS content and the TPU content. As the HS or TPU content increases, the cell nucleation density increases, and the cell size is reduced. Then, the use of TPUs with different characteristics allows controlling the cellular structure. Nanocellular polymers have been obtained with a core relative density between 0.15 and 0.20 and cell sizes between 220 and 640 nm.
在本研究中，展示了热塑性聚氨酯（TPU）的化学性质和浓度对基于聚甲基丙烯酸甲酯（PMMA）的纳米多孔聚合物泡孔结构的影响。通过预聚物法合成了三种不同硬段（HS）含量（60%、70%和80%）的TPU。以TPU为成核剂，通过气体溶解发泡法制备了不同含量（0.5 wt%、2 wt%和5 wt%）的基于PMMA的纳米多孔聚合物。TPU表征表明，随着HS含量的增加，TPU的密度、硬度和分子量更高。PMMA/TPU多孔材料呈现出从样品边缘到纳米多孔核心的梯度泡孔尺寸分布。在核心区域，TPU的添加对PMMA具有很强的成核作用。核心结构取决于HS含量和TPU含量。随着HS或TPU含量的增加，泡孔成核密度增加，泡孔尺寸减小。因此，使用具有不同特性的TPU可以控制泡孔结构。已获得核心相对密度在0.15至0.20之间且泡孔尺寸在220至640 nm之间的纳米多孔聚合物。
