Haitao Cheng

Mechanical properties and prediction for nanocalcium carbonate-treated bamboo fiber/high-density polyethylene composites

AbstractnNanocalcium carbonate (CaCO3) was successfully adhered to the surface of bamboo fiber (BF) via both impregnation and blending modification. The BF-, BMBF (bamboo fiber treated by blending modification)- and IMBF (bamboo fiber treated by impregnation modification)-reinforced high-density polyethylene (HDPE) composites were all manufactured by means of extrusion molding. The flexural and impact properties of the composites (the addition of BF, BMBF and IMBF were all 30 wt%) were analyzed. CaCO3 with a loading of 15 wt% had an effect on the performance of the composites. The flexural strength (FS) of the BMBF and IMBF composites increased by 1.09 and 9.36%, respectively, while the differences of the impact strength were insignificant among these, compared to the BF/HDPE composites. The flexural properties of the IMBF/HDPE composites were investigated with different mass fractions of IMBF (5, 10, 15, 20, 30, 50, 60 and 70 wt%). The results showed that the FS of the IMBF/HDPE composites reached a maximum value (58.99xa0MPa) when the mass fraction of the IMBF was 30 wt% and increased by 50.95% compared to when the mass fraction was 5 wt%. These results were supported by ESEM and fractal dimension analysis in terms of proper distribution of nano-CaCO3 and interfacial adhesion between the IMBF and HDPE matrix. The results revealed that the fractal dimension D of IMBF/HDPE composite with a mass fraction of 30 wt% reached a maximum value (2.2036), which was similar to the FS results. There was a linear correlation between lg (FS) and fractal dimension D, indicating that the fractal dimension was practicable for the IMBF-reinforced HDPE composites. The fractal features could reflect the macro-mechanical properties, and the percentage error of the fitting function was within 10%.n

Dipping Modification with Nano-CaCO3 to Improve Tensile Properties of Individual Bamboo Fiber for Developing Bamboo–Plastic Composite

ABSTRACT Nano-CaCO3 dipping modification was proposed to improve the tensile performance of individual bamboo fiber prepared by sulfate process. Effects of nano-CaCO3, EDTA-2Na concentration, and dipping time on the morphological and mechanical of fiber were characterized. Results show that sulfate isolated fiber surface is smooth and porous, providing potential adsorption site for nano-particle. Under nano-CaCO3 1.00 × 10–2 g/mL, EDTA-2Na 6.25 × 10–4 g/mL, and a dipping time of 25 min, both the number and the size distribution of nano-CaCO3 are relatively uniform while tensile parameters achieve maximums (i.e., tensile strength 1302.47 MPa, modulus of elasticity 61.83 GPa, and elongation at break 3.38%).

Mussel-Inspired Polydopamine as a Green, Efficient, and Stable Platform to Functionalize Bamboo Fiber with Amino-Terminated Alkyl for High Performance Poly(butylene succinate) Composites

A new and eco-friendly mussel-inspired surface modification pathway for bamboo fiber (BF) is presented in this study. The self-assembly polydopamine (PDA) coating can firmly adhere on BF surface, which also serves as a bridge to graft octadecylamine (ODA) for hydrophobic surface preparation. The as-formed PDA/ODA hybrid layer could supply abundant hydrophobic long-chain alkyls groups and generated a marked increase in BF surface roughness and a marked decrease in surface free energy. These changes provided advantages to improve fiber–matrix interfacial adhesion and wettability. Consequently, high performance was achieved by incorporating the hybrid modified BF into the polybutylene succinate (PBS) matrix. The resultant composite exhibited excellent mechanical properties, particularly tensile strength, which markedly increased by 77.2%. Meanwhile, considerable high water resistance with an absorption rate as low as 5.63% was also achieved. The gratifying macro-performance was primarily attributed to the excellent interfacial adhesion attained by hydrogen bonding and physical intertwining between the PDA/ODA coating on the BF and the PBS matrix, which was further determined by fracture morphology observations and dynamic mechanical analysis. Owing to the superior adhesive capacity of PDA, this mussel-inspired surface modification method may result in wide-ranging applications in polymer composites and be adapted to all natural fibers.

An empirical model for predicting the mechanical properties degradation of bamboo bundle laminated veneer lumber (BLVL) by hygrothermal aging treatment

An empirical 3-D model was developed to evaluate the effect of ambient environment on the mechanical properties and degradation behavior of bamboo-bundle laminated veneer lumber (BLVL) fabricated with different levels of PF/PVAc resin. This model can describe the relationship between the modulus of elasticity (MOE), water absorption ratio, and aging temperature. Five levels of PF/PVAc weight ratio (2:1, 4:1, 6:1, 8:1 and 10:1) and three treatment conditions (18, 63, and 100xa0°C) were examined in this experiment. Computed tomography (CT) scanning technology was employed to observe the morphology of damage degree as well as explore the mechanism of degradation behavior of BLVL. The results indicated that the 3-D model used for tracking and monitoring the variance of MOE provided good predictors. The higher the water impregnation temperature the larger the water absorption ratio and the higher the MOE degradation were. The aging temperature had a significant effect on the mechanical properties and degradation behavior of BLVL. A linear relationship between modulus of rupture (MOR) degradation and aging temperature was observed. The degradation rate of MOE and MOR increased as the temperature increased. The aging degree tested by CT along with damage of inner board showed the PF/PVAc ratio had a significant influence on the mechanical degradation of treated BLVL when the PF/PVAc ratio was below 6:1. Localized yielding, micro-cracks developing between interfaces, PVAc resin softening along with delamination, and debonding were the main failure models for the BLVL by hygrothermal aging treatment.

Evaluation of Water Absorption and its Influence on the Physical-Mechanical Properties of Bamboo-Bundle Laminated Veneer Lumber

To investigate the possibility of using bamboo-bundle laminated veneer lumber (BLVL) as a cooling tower packing material, the water absorption rates, thickness swelling rates, and flexural properties of three different composite materials were studied. The BLVL was combined with either 12% or 24% phenol formaldehyde resin (PF), and the moso bamboo strips were exposed to water baths at three different temperatures (45, 65, and 85 °C) for 30 d. After the aging treatments, the 24%-BLVL samples showed lower water absorption rates and better bending properties than the other two composites. The temperature was found to have a significant effect on the modulus of rupture (MOR), modulus of elasticity (MOE), and the thickness swelling rate. As the temperature increased, the swelling rate and the rate of weight gain increased and the MOE and MOR decreased. According to the activation energies for swelling calculated from the Arrhenius-type plots, compared with the 24%-BLVL (22.95 kJ·mol-1) and the moso bamboo strips (12.69 kJ·mol-1), the effect of temperature on the swelling rate was greatest for the 12%-BLVL (24.15 kJ·mol-1). Results showed that the BLVL material is a promising candidate for a novel cooling tower packing material.