Experimental investigations and model validation of compression rheological behavior in bamboo scrimber during the hot-pressing process

The current study investigated the rheological behavior of a heat-treated and phenolic resin-impregnated bamboo bundle slab during the hot-pressing process. These findings have significant implications for advancing hot-pressing technology, conserving energy, and reducing emissions in the bamboo scrimber industry. The results revealed that stress relaxation played a dominant role in the hot-pressing process after reaching the target thickness of the slab, which was influenced by compression deformation stress, hygrothermal stress, and phenolic resin polycondensation. Higher hot-pressing temperature and initial moisture content (IMC) led to increased hygrothermal stress, causing delayed stress relaxation. Increasing target thickness or reducing target density could alleviate hygrothermal stress while phenolic resin curing facilitated stress relaxation by constraining compression deformation. Both the three-element generalized Maxwell model (average R2 = 0.95) and the five-element generalized Maxwell model (average R2 = 0.98) effectively described the slab stress relaxation; however high IMC caused excessive vapor pressure, leading to unsatisfactory fitting of the stage.