2019, Vol. 4, No. 1
Display Method:
2019, 4(1): 3-10.
doi: 10.21967/jbb.v4i1.186
Abstract:
The demand for sustainable functional materials with an eco-friendly preparation process is on the rise. Lignocellulosics has been attributed as the most sustainable bioresource on earth which can meet the stringent requirements of functionalization. However, cellulose nanomaterials obtained from lignocellulosics which has reached advanced stages as a sustainable functional material is challenged by its preparation procedures. These procedures can not best be described as sustainable and eco-friendly owning to lots of energy and chemicals spent in the pre-treatment and purification processes. These processes are intended to aid fractionation into the major components in order to remove lignin and hemicellulose for the production of cellulose nanomaterials. This work is thus centred on reviewing the progress achieved in introducing a new cellulose nanomaterial containing lignin. The preparation processes, properties and applications of this new lignin-containing cellulose nanomaterial will be discussed in order to chart a sustainable preparation route for cellulose nanomaterials.
The demand for sustainable functional materials with an eco-friendly preparation process is on the rise. Lignocellulosics has been attributed as the most sustainable bioresource on earth which can meet the stringent requirements of functionalization. However, cellulose nanomaterials obtained from lignocellulosics which has reached advanced stages as a sustainable functional material is challenged by its preparation procedures. These procedures can not best be described as sustainable and eco-friendly owning to lots of energy and chemicals spent in the pre-treatment and purification processes. These processes are intended to aid fractionation into the major components in order to remove lignin and hemicellulose for the production of cellulose nanomaterials. This work is thus centred on reviewing the progress achieved in introducing a new cellulose nanomaterial containing lignin. The preparation processes, properties and applications of this new lignin-containing cellulose nanomaterial will be discussed in order to chart a sustainable preparation route for cellulose nanomaterials.
2019, 4(1): 11-21.
doi: 10.21967/jbb.v4i1.189
Abstract:
Chitosan, derived from chitin, a major constituent (in quantity) of crustaceans, is a unique aminopolysaccharide with emerging commercial potential in agriculture, food, pharmaceuticals and nutraceuticals due to its nontoxic, biodegradable and biocompatable properties. Chitosan coating on fruits and vegetables has been found to be effective for the reduction of a variety of harmful micro-organims and extend the shelf-life of these products. In this review, our focus is on the antimicrobial properties of chitosan and its application as a natural preservative for fresh products. We detailed the key properties that are related to food preservation, the molecular mechanism of the antimicrobial activity of chitosan on fungi, gram-positive and gram-negative bacteria, coating methods for using chitosan and its formulation for preserving fruits and vegetables, as well as the radiation method of producing chitosan from chitin. Understanding the economic and scientific factors of chitosan's production and efficiency as a preservative will open its practical application for fruits and vegetable preservation.
Chitosan, derived from chitin, a major constituent (in quantity) of crustaceans, is a unique aminopolysaccharide with emerging commercial potential in agriculture, food, pharmaceuticals and nutraceuticals due to its nontoxic, biodegradable and biocompatable properties. Chitosan coating on fruits and vegetables has been found to be effective for the reduction of a variety of harmful micro-organims and extend the shelf-life of these products. In this review, our focus is on the antimicrobial properties of chitosan and its application as a natural preservative for fresh products. We detailed the key properties that are related to food preservation, the molecular mechanism of the antimicrobial activity of chitosan on fungi, gram-positive and gram-negative bacteria, coating methods for using chitosan and its formulation for preserving fruits and vegetables, as well as the radiation method of producing chitosan from chitin. Understanding the economic and scientific factors of chitosan's production and efficiency as a preservative will open its practical application for fruits and vegetable preservation.
2019, 4(1): 22-30.
doi: 10.21967/jbb.v4i1.190
Abstract:
As a new type of green low-carbon engineered wood product, cross-laminated timber (CLT) is widely used in various types of wooden buildings in Europe and North America, and the number of high-rise wood construction is also increasing. Based on the introduction of the structural characteristics of the CLT and the development status of the CLT in developed countries, this paper focused on the review of the status of research and development of the CLT in China, with an emphasis on the breakthrough technologies of new bamboo-wood composite CLT developed. Finally, the prospects of the CLT in China were discussed.
As a new type of green low-carbon engineered wood product, cross-laminated timber (CLT) is widely used in various types of wooden buildings in Europe and North America, and the number of high-rise wood construction is also increasing. Based on the introduction of the structural characteristics of the CLT and the development status of the CLT in developed countries, this paper focused on the review of the status of research and development of the CLT in China, with an emphasis on the breakthrough technologies of new bamboo-wood composite CLT developed. Finally, the prospects of the CLT in China were discussed.
2019, 4(1): 31-42.
doi: 10.21967/jbb.v4i1.180
Abstract:
Modified biochar (BC) is reviewed in its preparation, functionality, application in wastewater treatment and regeneration. The nature of precursor materials, preparatory conditions and modification methods are key factors influencing BC properties. Steam activation is unsuitable for improving BC surface functionality compared with chemical modifications. Alkali-treated BC possesses the highest surface functionality. Both alkali modified BC and nanomaterial impregnated BC composites are highly favorable for enhancing the adsorption of different contaminants from wastewater. Acidic treatment provides more oxygenated functional groups on BC surfaces. Future research should focus on industry-scale applications and competitive sorption for contaminant removal due to scarcity of data.
Modified biochar (BC) is reviewed in its preparation, functionality, application in wastewater treatment and regeneration. The nature of precursor materials, preparatory conditions and modification methods are key factors influencing BC properties. Steam activation is unsuitable for improving BC surface functionality compared with chemical modifications. Alkali-treated BC possesses the highest surface functionality. Both alkali modified BC and nanomaterial impregnated BC composites are highly favorable for enhancing the adsorption of different contaminants from wastewater. Acidic treatment provides more oxygenated functional groups on BC surfaces. Future research should focus on industry-scale applications and competitive sorption for contaminant removal due to scarcity of data.
2019, 4(1): 43-50.
doi: 10.21967/jbb.v4i1.185
Abstract:
With the increasing usage of varied electronic devices, the induced electromagnetic interference (EMI) irradiation pollution has become a novel environmental pollution besides of water and air pollutions, drawing a great of interests from the scientists to address EMW radiation problem via designing various electromagnetic wave (EMW) absorbers, which is supposed to be with lightweight, thin thickness, wide effective absorbing bandwidth and strong absorbing capacity. One kind of the most attractive absorbers is magnetic carbon composites. Here, we successfully synthesized porous structural C/Fe composites by in-situ carbonization of pre-prepared Fe3O4/wood fibers at 1000℃. The EMW absorption property of C/Fe composites is excellent with a minimum RL value of -32.67 dB at 9.86 GHz, a matching thickness of 2.2 mm and a wide response bandwidth of 14.5 GHz. This excellent absorption performance is proved to be due to the continuous network of Fe3O4/Fe/ Fe3C hybrids, permitting optimal impedance matching, the strongest dielectric loss and the optimal magnetic loss. Moreover, the interface polarizations of Fe-Fe3C and Fe3O4-Fe interfaces, are positive to improve the microwave absorption performance.
With the increasing usage of varied electronic devices, the induced electromagnetic interference (EMI) irradiation pollution has become a novel environmental pollution besides of water and air pollutions, drawing a great of interests from the scientists to address EMW radiation problem via designing various electromagnetic wave (EMW) absorbers, which is supposed to be with lightweight, thin thickness, wide effective absorbing bandwidth and strong absorbing capacity. One kind of the most attractive absorbers is magnetic carbon composites. Here, we successfully synthesized porous structural C/Fe composites by in-situ carbonization of pre-prepared Fe3O4/wood fibers at 1000℃. The EMW absorption property of C/Fe composites is excellent with a minimum RL value of -32.67 dB at 9.86 GHz, a matching thickness of 2.2 mm and a wide response bandwidth of 14.5 GHz. This excellent absorption performance is proved to be due to the continuous network of Fe3O4/Fe/ Fe3C hybrids, permitting optimal impedance matching, the strongest dielectric loss and the optimal magnetic loss. Moreover, the interface polarizations of Fe-Fe3C and Fe3O4-Fe interfaces, are positive to improve the microwave absorption performance.
2019, 4(1): 51-59.
doi: 10.21967/jbb.v4i1.184
Abstract:
In order to improve the mechanical properties and toughness of phenolic foams, a reinforcement method using two kinds of bamboo fibers was optimized with respect to the fiber contents. The compressive and flexural properties, thermal stability, friability and morphology of the phenolic foam composites were studied. The mechanical properties of the pristine foam and composites were evaluated by measuring the compressive strength. The results showed that the greatest mechanical properties were achieved by incorporating 2.5wt% of the reinforcement, and the compressive and flexural strengths of the two composites increased by 26.21% and 24.35%, respectively, compared with that of the pristine foam. The results of thermogravimetric testing demonstrated that the addition of bamboo fiber imparted better thermal stability to the phenolic foam, which was mainly attributed to the higher initial thermal decomposition temperature of the bamboo fiber. However, the influences of both reinforcements on the thermal stability of the material were negligible. The incorporation of bamboo fiber decreased the friability of the phenolic foam. Furthermore, the reduction in friability of the foam composites with longer lengths were higher than that in foams with shorter bamboo fibers. Moreover, the morphology and cell sizes of the fiber-reinforced phenolic foams were analyzed by scanning electron microscopy, the results indicated strong bonding between the fibers and phenolic matrix, and the incorporation of the bamboo fibers into the foam resulted in increased cell size of the material. Finally, the thermal conductivity and flame resistance of the phenolic foams reinforced by the bamboo fibers were also measured.
In order to improve the mechanical properties and toughness of phenolic foams, a reinforcement method using two kinds of bamboo fibers was optimized with respect to the fiber contents. The compressive and flexural properties, thermal stability, friability and morphology of the phenolic foam composites were studied. The mechanical properties of the pristine foam and composites were evaluated by measuring the compressive strength. The results showed that the greatest mechanical properties were achieved by incorporating 2.5wt% of the reinforcement, and the compressive and flexural strengths of the two composites increased by 26.21% and 24.35%, respectively, compared with that of the pristine foam. The results of thermogravimetric testing demonstrated that the addition of bamboo fiber imparted better thermal stability to the phenolic foam, which was mainly attributed to the higher initial thermal decomposition temperature of the bamboo fiber. However, the influences of both reinforcements on the thermal stability of the material were negligible. The incorporation of bamboo fiber decreased the friability of the phenolic foam. Furthermore, the reduction in friability of the foam composites with longer lengths were higher than that in foams with shorter bamboo fibers. Moreover, the morphology and cell sizes of the fiber-reinforced phenolic foams were analyzed by scanning electron microscopy, the results indicated strong bonding between the fibers and phenolic matrix, and the incorporation of the bamboo fibers into the foam resulted in increased cell size of the material. Finally, the thermal conductivity and flame resistance of the phenolic foams reinforced by the bamboo fibers were also measured.
2019, 4(1): 60-66.
doi: 10.21967/jbb.v4i1.182
Abstract:
Plantation Chinese fir wood was modified by low molecular weight phenol melamine urea formaldehyde (PMUF) resin and boron compounds (BB) through a progressive gradual infiltration process. The results showed that the limiting oxygen index (LOI) values, density, dimensional stability and static flexural properties of the PMUF resin treated wood gradually improved with the increase of resin solid content. When boron compounds were additionally introduced into the PMUF resin, the density and the LOI values of the samples of compound modification increased, whereas the anti-swelling efficiency, the modulus of rupture and impact toughness decreased by more than 17.6%, 10.1% and 42.9%, respectively. It was demonstrated by X-ray diffraction and Fourier transform infrared spectroscopy that boron compounds could improve the crystallinity of resin modified samples and did not have a chemical reaction with resin or wood. Scanning electron microscope analysis indicated boron compounds made the microstructure of the resin polymers loose, influencing the mechanical properties and dimensional stability of resin modified wood.
Plantation Chinese fir wood was modified by low molecular weight phenol melamine urea formaldehyde (PMUF) resin and boron compounds (BB) through a progressive gradual infiltration process. The results showed that the limiting oxygen index (LOI) values, density, dimensional stability and static flexural properties of the PMUF resin treated wood gradually improved with the increase of resin solid content. When boron compounds were additionally introduced into the PMUF resin, the density and the LOI values of the samples of compound modification increased, whereas the anti-swelling efficiency, the modulus of rupture and impact toughness decreased by more than 17.6%, 10.1% and 42.9%, respectively. It was demonstrated by X-ray diffraction and Fourier transform infrared spectroscopy that boron compounds could improve the crystallinity of resin modified samples and did not have a chemical reaction with resin or wood. Scanning electron microscope analysis indicated boron compounds made the microstructure of the resin polymers loose, influencing the mechanical properties and dimensional stability of resin modified wood.
2019, 4(1): 67-72.
doi: 10.21967/jbb.v4i1.183
Abstract:
In order to maintain soil fertility of Neosinocalamus affinis plantations, fertilizers of N, P, and K were applied. The anatomical and physical-mechanical properties of N. affinis bamboo wood from different fertilization treatments were measured. The aim of this study was to elucidate the effect of fertilization practice on the properties of N. affinis bamboo wood. The results revealed that the fertilization of P and K resulted in a slight reduction in fiber length. The application of P, K, and low level (0.3 kg/clump) of N fertilizers had no significant effect on the fiber morphology, while high level (0.9 kg/clump) of N fertilizer contributed to short fibers. The specific gravity was significantly decreased by fertilization, while the volume shrinkage was increased. Since the effect of various fertilization treatments had different influence patterns on the properties of N. affinis, specific evaluations on the quality of the fertilized bamboo wood should be performed prior to its utilization.
In order to maintain soil fertility of Neosinocalamus affinis plantations, fertilizers of N, P, and K were applied. The anatomical and physical-mechanical properties of N. affinis bamboo wood from different fertilization treatments were measured. The aim of this study was to elucidate the effect of fertilization practice on the properties of N. affinis bamboo wood. The results revealed that the fertilization of P and K resulted in a slight reduction in fiber length. The application of P, K, and low level (0.3 kg/clump) of N fertilizers had no significant effect on the fiber morphology, while high level (0.9 kg/clump) of N fertilizer contributed to short fibers. The specific gravity was significantly decreased by fertilization, while the volume shrinkage was increased. Since the effect of various fertilization treatments had different influence patterns on the properties of N. affinis, specific evaluations on the quality of the fertilized bamboo wood should be performed prior to its utilization.
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