Compared to extrusion and injection, hot-press molding can produce natural fiber plastic composites with many advantages. In this study, large cotton stalk bundles and HDPE composites were fabricated using hot-press molding. The effects of fiber size and drying temperature on the mechanical properties and thickness swelling of these composites were investigated. Cotton stalk bundles of three different sizes were oven-dried at 100 C 120 C, 140 C, and 170 C for 24 h. MAPE (5%) and phenol formaldehyde resin (5%) were added to enhance the interfacial bonding between the bundles and HDPE. Results showed that the mechanical properties of composites increased with the size of the cotton stalk bundles. The best mechanical properties were created at drying temperatures of 100 C and 140 C, with an obvious drop at drying temperatures of 120 C and 170 C. Thickness swelling of the composites was greatly improved and below 5%. The composites showed the lowest thickness swelling at a drying temperature of 170 C, and the highest at 120 C. Good bonding was found between cotton stalk fibers and HDPE, due to the addition of MAPE.

Mode-I interlaminar fracture behavior of laminated bamboo composites was characterized by mechanical testing in a bonded double cantilever beam configuration. No obvious fiber bridging was observed during the test. At the front of crack tip, nonlinear response was relatively small and negligible. The failure mode of laminated bamboo composites was mainly governed by brittle fracture. Mode-I interlaminar fracture toughness ([Formula: see text]) calculated using the modified beam theory was 501.08 J/m2. Besides, numerical simulation combined with cohesive elements was used to simulate the mode-I interlaminar fracture behavior. A direct method for the determination of cohesive parameters without recourse to iterative fitting was presented in detail. The applicability and effectiveness of this method for interpretation of the fracture behavior of laminated bamboo composites were verified by comparing numerical predictions with experimental results.

No abstract

In the present research, the accelerated test using the stepped isothermal method (SIM) was applied to characterize the long-term compressive behavior of laminated bamboo. Generating a creep master curve using the SIM data is somewhat empirical. In particular, the selection of the end and beginning segments in the rescaling process is not standardized, which will affect the determination of virtual time. The variability of the virtual time influences the construction of master curves, thus leading to errors in predicting long-term behavior. The difference in selecting the end and beginning segments was

Summary This study sets out to assess the temperature effect on the physical and mechanical properties of parallel strand bamboo (PSB). Seventeen temperature levels, in the range of 20°C to 290°C, were considered. Results indicated that a high temperature led to a reduction in compressive strength and modulus. The reduction is associated with the glass transition and thermal decomposition of the chemical compositions in bamboo. Due to the higher crystallinity of cellulose at high temperatures between 150°C and 190°C, a rising in the compressive modulus parallel‐to‐grain was observed. The temperature effect on the mechanical properties of PSB was further supported by scanning electron microscopy (SEM) images. Statistical regression‐based models were developed for predicting the reduction of compressive strength and modulus of PSB with exposure temperature. The models provided a good fit to the experimental data. Comparison with that of bamboo scrimber and timber structures in literature was also presented in this study.