Polyurethane/polyhydroxyurethane (PU/PHU) hybrid materials are potential alternatives to PU materials in adhesive use, when the user needs to be protected from free di-isocyanates. PU/PHU materials have promising mechanical and adhesive properties, but they are susceptible to a higher water uptake than corresponding PU materials. In adhesive use, water and temperature are typically responsible for environmental ageing, which can cause unexpected bond failure. Therefore, the effect of water uptake on mechanical and adhesive strength is crucial. In this study, the water uptake of PU/PHU at various temperatures was studied and the contribution of absorbed water to material properties was investigated. The highly crosslinked amorphous PU/PHU was synthesized from a multifunctional polyethyleneimine (PEI) and a cyclic carbonate terminated prepolymer made from a hexamethylene di-isocyanate (HDI) based isocyanate prepolymer. High water uptake of PU/PHU originated from the hydrophilic amine used as well as the pendant hydroxyl groups in the hydroxy urethane. After the high initial water absorption, a quasi-equilibrium was reached at room temperature. Water immersion at elevated temperature introduced a second water absorption step which eventually caused PU/PHU to become a water-soluble gel. Considering the potential applications of PU/PHU, the cohesive strength had increased after water immersion cycles, but the adhesive strength was irreversibly reduced resulting in total bond failure after five water immersion cycles. In contrast, longer storage at dry elevated temperature improved the cohesive and adhesive strength. Thus, a careful design of the application is required for PU/PHU adhesives to fully utilize the advantage of the high lap shear strength in dry condition.

当用户需要免受游离二异氰酸酯的影响时，聚氨酯/聚羟基聚氨酯 (PU/PHU) 混合材料是粘合剂使用中 PU 材料的潜在替代品。PU/PHU 材料具有良好的机械和粘合性能，但与相应的 PU 材料相比，它们容易吸收更高的水。在粘合剂使用中，水和温度通常是导致环境老化的原因，这可能导致意外的粘合失败。因此，吸水量对机械强度和粘合强度的影响至关重要。在这项研究中，研究了 PU/PHU 在不同温度下的吸水率，并研究了吸水率对材料性能的贡献。高度交联的无定形 PU/PHU 由多功能聚乙烯亚胺 (PEI) 和由六亚甲基二异氰酸酯 (HDI) 基异氰酸酯预聚物制成的环状碳酸酯封端的预聚物合成。PU/PHU 的高吸水率源于所使用的亲水性胺以及羟基氨基甲酸酯中的侧羟基。在高初始吸水率之后，在室温下达到准平衡。在高温下浸水会引入第二个吸水步骤，最终导致 PU/PHU 变成水溶性凝胶。考虑到 PU/PHU 的潜在应用，水浸循环后内聚强度增加，但粘合强度不可逆地降低，导致在五个水浸循环后完全粘合失效。相比之下，在干燥高温下更长时间的储存提高了内聚力和粘合强度。因此，PU/PHU 粘合剂需要仔细设计应用，以充分利用干燥条件下高搭接剪切强度的优势。