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The crystallization behaviors of acetylated bamboo fiber (BF)/polypropylene (PP) composites were assessed using differential scanning calorimetry (DSC) through isothermal crystallization. The transcrystalline (TC) morphologies of composites were observed through polarized optical microscopy (POM), and their surface free energies were calculated based on Hoffman‒Lauritzen theory. Isothermal DSC thermograms demonstrated that acetylated BF with higher weight percentage gains (WPGs, ~ 19%) exhibited a decreased crystallization rate of the PP matrix. POM images indicated that BF as a nucleation agent induced the TC layer on fiber–PP matrix interfaces. However, when WPG reached 19%, the TC layer was not observed on the BF surface and crystal growth was principally observed in the PP matrix bulk. Based on Hoffman‒Lauritzen theory, the folding-surface free energy (σe) and the work of chain folding (q) for acetylated BF/PP composites were estimated to be higher than those for PP composites with unmodified BF. These results indicate that BFs with different WPGs could affect the crystallization behavior of the PP matrix by inducing or hindering TC on BF–PP matrix interfaces. [ABSTRACT FROM AUTHOR]

In this study, makino bamboo (Phyllostachys makinoi) fibers were acetylated with different solution ratios of acetic anhydride/dimethylformamide using a liquid phase reaction. This reaction resulted in the production of acetylated bamboo fibers (BFs) with the following weight percent gains (WPGs): 2, 6, 9, 13, and 19%. The effects of the acetylation level on the thermal decomposition kinetics of bamboo fibers were evaluated by thermogravimetric analysis. The results revealed that as the acetylation level increased, both the onset and maximum decomposition temperatures increased. In addition, four model-free iso-conversional methods, the Friedman method, Flynn–Wall–Ozawa method, the Starink method, and the modified Coats–Redfern method, were used to determine the thermal decomposition kinetics. Accordingly, the activation energies of thermal decomposition with conversion rates ranging between 10% and 70% were 191–196, 190–191, 192–194, 182–186, 186–191, and 189–201 kJ/mol for unmodified BFs and acetylated BFs with WPGs of 2, 6, 9, 13, and 19%, respectively. There were no significant dependencies among them. Furthermore, the Avrami method was used to determine the reaction order of unmodified BFs (0.47), which was lower than those of acetylated BFs (0.55–0.74). [ABSTRACT FROM AUTHOR]

Bamboo fiber (BF)-reinforced polypropylene (PP) composites (BPCs) have been investigated and it was shown by differential scanning calorimetry (DSC) that BF is a nucleation agent and accelerates the crystallization rate of the PP matrix. Numerical analyses according to Avrami, Avrami-Ozawa, and Friedman described well the nucleation mechanism, the crystallization rate and the activation energy for the non-isothermal crystallization behavior of BPCs, respectively. The Avrami approach indicated that BF as a reinforcement significantly changed the crystal growth mechanism of PP matrix during the cooling process. Based on the Avrami-Ozawa method, a lower cooling rate can achieve a certain relative crystallinity degree within a time period. According to the Friedman method, the activation energies of BPCs were lower than that of neat PP below a relative crystallinity of 35%, when the BF content was more than 60%. [ABSTRACT FROM AUTHOR]

Extrusion and injection moldings are standard processes for fabricating natural fiber-reinforced plastic composites, but both processes are generally not suitable for production of large-size pieces and products with high loadings of lignocelluloses. In this study, a medium-density bamboo plastic composite (BPC) was completely and successfully manufactured from bamboo fibers and polylactic acid (PLA) in the ratio of 1:1 by the flat-platen pressing process. The effects of pressing and cooling parameters on the thermomechanical properties of the BPCPLA have been investigated. The BPCPLA prepared at temperatures >180°C and cooling rates >10°C min-1 exhibited superior mechanical properties and matrix crystallinity. Under these conditions, a stronger interaction between the filler and the polymer matrix occurs and the mobility of the molecular chains at the interface decreases, which leads to a higher stiffness of the composite. [ABSTRACT FROM AUTHOR]

Abstract: The objectives of this study were to search for appropriate low-toxicity preservatives to be used as green colour protectors for makino bamboo (Phyllostachys makinoi) culms, and to find appropriate conditions and process, especially an alkali-pretreatment-free and a solvent-free process, for treating makino bamboo to achieve green colour protection. The influence of various green colour protection reagents and treatment conditions on the colour of bamboo culms was examined using a colour difference meter. Two water-borne copper-based preservatives, namely ammoniacal copper quaternary compound-type B (ACQ-B) and copper azole (CuAz), were tested as protectors. In addition to heating in a water bath, the ultrasonic heating method was also employed. Results revealed that, without alkali-pretreatment, an excellent green colour protection (a * =−11.0) was obtained when the makino bamboo culms were treated with 2% aqueous ACQ-B solution in a 60°C water bath for 1h, and that CuAz has no effect on green colour protection (a * =3.9) under the same conditions. Compared with conventional heating in a water bath, improvement on the green colour protection can be achieved with a shorter treatment time by using ultrasonic heating. The a * value of bamboo culms after the treatment with 2% ACQ-B at a 60°C ultrasonic bath for 15min was −10.0. [Copyright &y& Elsevier]

In the past, a complicated two-step process including alkali pretreatment was necessary for the protection of green bamboo surface colour. However, that process not only diminished the protection effectiveness for bamboo culms against attack by organisms, but also increased the time and cost required. Also, to date, no suitable reagents and treatment processes have been found to achieve the green colour protection of makino bamboo culms. Thus, the objectives of this study were to find an appropriate method and process, especially an alkali-pretreatment-free process, for treating makino bamboo with alcohol-borne copper based reagents. This study investigates influences of various green colour protection treatments and treatment conditions on the colour of bamboo culms. In addition to heating in a water bath, the ultrasonic heating method was examined. The results reveal that, without alkali-pretreatment, an excellent green colour protection was obtained when the makino bamboo culms were treated with 2% methanol-borne copper chloride (CuCl2) in a 60 °C water bath for 2 h. However, compared with conventional heating in a water bath, improvement on the green colour protection cannot be achieved by using ultrasonic heating. [Copyright &y& Elsevier]

The objectives of this study were to find an appropriate method and process for treating ma bamboo ( Dendrocalamus latiflorus ) with a chromium-free copper-phosphorous salt (CuP). The effects of the constituent ratios and concentrations of CuP as well as treatment conditions on the green colour protection were investigated. In addition, accelerated UV light fastness tests, indoor exposure tests, and outdoor weathering tests were also carried out to evaluate the colour fastness and durability of bamboo culms. The results demonstrated that an attractive green colour was obtained by treating ma bamboo with 1% CuP at 60 °C for 3 h, using a 60:40 ratio of CuSO 4 to H 3 PO 4 in an aqueous solution. Compared with untreated bamboo culms, the CuP-treated samples had the brighter greenish skin and also provided better green colour fastness. After 180 days of indoor exposure, the a * value was slightly increased from −5.8 to −5.4. [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of using bamboo to prepare biomorphic porous silicon carbide (bio-SiC) ceramics through a combination of sol–gel impregnation and carbothermal reduction. The effects of sintering temperature, sintering duration, and sol–gel impregnation cycles on the crystalline phases and microstructure of bio-SiC were investigated. X-ray diffraction patterns revealed that when bamboo charcoal–SiO2 composites (BcSiCs) were sintered at 1700 °C for more than 2 h, the resulting bio-SiC ceramics exhibited significant β-SiC diffraction peaks. In addition, when the composites were sintered at 1700 °C for 2 h, scanning electron microscopy micrographs of the resulting bio-SiC ceramic prepared using a single impregnation cycle showed the presence of SiC crystalline particles and nanowires in the cell wall and cell lumen of the carbon template, respectively. However, bio-SiC prepared using three and five repeated cycles of sol–gel impregnation exhibited a foam-like microstructure compared with that prepared using a single impregnation cycle. Moreover, high-resolution transmission electron microscopy and selected area electron diffraction revealed that the atomic plane of the nanowire of bio-SiC prepared from BcSiCs had a planar distance of 0.25 nm and was perpendicular to the (111) growth direction. Similar results were observed for the bio-SiC ceramics prepared from bamboo–SiO2 composites (BSiCs). Accordingly, bio-SiC ceramics can be directly and successfully prepared from BSiCs, simplifying the manufacturing process of SiC ceramics. [ABSTRACT FROM AUTHOR]

The crystallization behavior of bamboo fiber (BF) reinforced polypropylene (PP) composites (BPCs) was investigated using a differential scanning calorimeter (DSC). The results showed that unmodified BF as a nucleation agent accelerated the crystallization rate of the PP matrix during cooling whereas there is no significant effect on the improved crystallization rate in BPCs with acetylated BFs. Based on the Avrami method, Avrami–Ozawa method, and Friedman method, the corresponding crystallization kinetics of PP reinforced with different acetylation levels of BFs were further analyzed. The results demonstrated that the crystal growth mechanism of the PP matrix for BPCs with unmodified and various acetylated BFs exhibited tabular crystal growth with heterogeneous nucleation. A higher cooling rate is required to achieve a certain relative crystallinity degree at the unit crystallization time for BPCs with a higher weight percent gain (WPG) of acetylated BFs (WPG >13%). Furthermore, based on the Friedman method, the lowest crystallization activation energy was observed for the BPCs with 19% WPG of acetylated BFs. [ABSTRACT FROM AUTHOR]

Abstract: The hydrophilic properties of lignocellulosic materials pose problems when they are used as reinforcement in plastics. The hydrophilicity of lignocelluloses influences its durability and also the interfacial adhesion between lignocellulose and polymers. Chemical modification, especially acetylation, has been used successfully to decrease the hydrophilicity and increase the weathering resistance of lignocellulose. Therefore, the purpose of this study is to investigate the natural weathering properties of bamboo plastic composites (BPCs) reinforced with bamboo fibers acetylated to different weight gains (WGs). The results showed that the retention ratios of mechanical properties of acetylated BPCs, especially those containing fibers with a high WG, were significantly improved as compared to the unmodified composite during natural weathering. In addition, the crystallinity of the high-density polyethylene (HDPE) in all BPCs increased after natural weathering for 120–240 days and then leveled off. This result indicates that the chain scission of HDPE mainly occurred during this period, producing shorter and more mobile chains and enabling them to undergo secondary crystallization. Furthermore, the mildew resistance of the acetylated BPCs was higher than that of unmodified composite. These results indicate that the durability and decay resistance of BPCs can be enhanced through acetylation of the bamboo reinforcement. [Copyright &y& Elsevier]

The present study investigates mechanical properties and creep resistance of bamboo fiber reinforced recycled PLA composites (BFRPCs). The results revealed that the modulus of rupture and modulus of elasticity of BFRPCs increased with increasing bamboo fiber loading up to 60 wt% and then declined sharply as the fiber increased further. Short-term accelerated creep tests on BFRPCs were conducted at a series of elevated temperatures by time–temperature superposition principle. As a result, the BFRPC with 60 wt% fiber exhibited the best creep resistance among all the BFRPCs, and then decreased when the fiber loading was more than 70 wt%. [ABSTRACT FROM AUTHOR]