2016, Vol. 1, No. 3
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2016, 1(3): 106-113.
doi: 10.21967/jbb.v1i3.49
Abstract:
Synthetic polymers are the most widely used materials for packaging because of their ease of processing, low cost, and low density. However, many of these materials are not easily recyclable and are difficult to degrade completely in nature, creating environmental problems. Thus, there is a tendency to substitute such polymers with natural polymers and copolymers that are easily bio-degraded and less likely to cause environmental pollution. There has been a greater interest in poly-lactic acid (PLA), poly-hydroxyalkanoates (PHAs), cellulose and starch based polymers and copolymers as the emerging biodegradable material candidates for the future. This paper reviews the present state-of-the-art biodegradable polymers made from renewable resources and discusses the main features of their properties and design.
Synthetic polymers are the most widely used materials for packaging because of their ease of processing, low cost, and low density. However, many of these materials are not easily recyclable and are difficult to degrade completely in nature, creating environmental problems. Thus, there is a tendency to substitute such polymers with natural polymers and copolymers that are easily bio-degraded and less likely to cause environmental pollution. There has been a greater interest in poly-lactic acid (PLA), poly-hydroxyalkanoates (PHAs), cellulose and starch based polymers and copolymers as the emerging biodegradable material candidates for the future. This paper reviews the present state-of-the-art biodegradable polymers made from renewable resources and discusses the main features of their properties and design.
2016, 1(3): 114-119.
doi: 10.21967/jbb.v1i3.6
Abstract:
Cellulose nano-crystals (CNC) can be tailored for various value-added applications. However, its use in aqueous systems is hampered by its limited dispersability, especially at a high CNC concentration. In this study, the improvement of CNC colloidal stability by surface chemical grafting with polyacrylic acid (PAA) was investigated, and the zeta potential and the charge density of the chemically modified CNC were analyzed. The results showed that an acrylic dosage of 1% (based on the dry weight of CNC) was sufficient to significantly enhance the colloidal stability. CNC, after chemical grafting with PAA, showed better stability against the increase in storage time or solid content of the aqueous medium, compared with the un-modified CNC.
Cellulose nano-crystals (CNC) can be tailored for various value-added applications. However, its use in aqueous systems is hampered by its limited dispersability, especially at a high CNC concentration. In this study, the improvement of CNC colloidal stability by surface chemical grafting with polyacrylic acid (PAA) was investigated, and the zeta potential and the charge density of the chemically modified CNC were analyzed. The results showed that an acrylic dosage of 1% (based on the dry weight of CNC) was sufficient to significantly enhance the colloidal stability. CNC, after chemical grafting with PAA, showed better stability against the increase in storage time or solid content of the aqueous medium, compared with the un-modified CNC.
2016, 1(3): 120-126.
doi: 10.21967/jbb.v1i3.23
Abstract:
Centrifugal cleaners are commonly used in the pulp and paper industry to separate contaminates from pulp fibers. To reveal the separation mechanism of cellulose fibers and impurities in a centrifugal cleaner, three-dimensional computational fluid dynamics (CFD) models were established based on experimental analyses with the inlet flow rate and outlet diameter as the variables. The incompressible three-dimensional Navier-Stokes equations were applied to describe the fluid motion. Numerical simulation results showed that an increased inlet flow rate could improve the efficiency by enhance of the centrifugal force on particles. Secondary swirling patterns were predominant for centrifugal cleaners with smaller lower outlets. The crowding effect played an important role in the separation of heavy contaminants, and the separating efficiency was proportional to the inlet flow rate and inverse proportional to the lower outlet diameter.
Centrifugal cleaners are commonly used in the pulp and paper industry to separate contaminates from pulp fibers. To reveal the separation mechanism of cellulose fibers and impurities in a centrifugal cleaner, three-dimensional computational fluid dynamics (CFD) models were established based on experimental analyses with the inlet flow rate and outlet diameter as the variables. The incompressible three-dimensional Navier-Stokes equations were applied to describe the fluid motion. Numerical simulation results showed that an increased inlet flow rate could improve the efficiency by enhance of the centrifugal force on particles. Secondary swirling patterns were predominant for centrifugal cleaners with smaller lower outlets. The crowding effect played an important role in the separation of heavy contaminants, and the separating efficiency was proportional to the inlet flow rate and inverse proportional to the lower outlet diameter.
Thermo-responsive cellulose papers grafted with poly (di(ethylene glycol) methyl ether methacrylate)
2016, 1(3): 127-131.
doi: 10.21967/jbb.v1i3.42
Abstract:
Novel thermo-responsive cellulose papers were prepared via grafting poly (di(ethylene glycol) methyl ether methacrylate) (PDEGMA) by activators regenerating electron transfer (ARGET) and atom transfer radical polymerization (ATRP). Attenuated total refraction Fourier-transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) measurements of the modified paper showed that PDEGMA brushes were successfully grafted on the paper surface. The thermal stability of the papers before and after grafting was evaluated by thermogravimetric analysis (TGA). The PDEGMA-grafted paper exhibited a two-step thermal degradation process, and presented thermo-responsive characteristics. It was hydrophilic at room temperature but changed rapidly to highly hydrophobic when the temperature rose above 50℃.
Novel thermo-responsive cellulose papers were prepared via grafting poly (di(ethylene glycol) methyl ether methacrylate) (PDEGMA) by activators regenerating electron transfer (ARGET) and atom transfer radical polymerization (ATRP). Attenuated total refraction Fourier-transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) measurements of the modified paper showed that PDEGMA brushes were successfully grafted on the paper surface. The thermal stability of the papers before and after grafting was evaluated by thermogravimetric analysis (TGA). The PDEGMA-grafted paper exhibited a two-step thermal degradation process, and presented thermo-responsive characteristics. It was hydrophilic at room temperature but changed rapidly to highly hydrophobic when the temperature rose above 50℃.
2016, 1(3): 132-138.
doi: 10.21967/jbb.v1i3.47
Abstract:
Partially deacetylated chitin nano-fiber (DAChN) dispersions were prepared using mechanical treatment of partially deacetylated crab shell α-chitin under acidic conditions mediated by various protonic acids. The representative organic acids had a better efficiency in terms of mediating the nanofibrillation of chitin fibers in comparison to the inorganic acid (HCl). The DAChN dispersed in water at a pH of 3.5 mediated by gluconic acid exhibited the highest yield of nano-fibers (88.6%), followed by succinic, itaconic, and ascorbic acids with a nano-fiber yield of 79.9%, 73.3% and 66.0%, respectively. The pH, conductivity, viscosity, and light transmittance of dispersions were assessed under different storage times. All of the tested DAChN dispersions were stable for at least 15 weeks at 4℃.
Partially deacetylated chitin nano-fiber (DAChN) dispersions were prepared using mechanical treatment of partially deacetylated crab shell α-chitin under acidic conditions mediated by various protonic acids. The representative organic acids had a better efficiency in terms of mediating the nanofibrillation of chitin fibers in comparison to the inorganic acid (HCl). The DAChN dispersed in water at a pH of 3.5 mediated by gluconic acid exhibited the highest yield of nano-fibers (88.6%), followed by succinic, itaconic, and ascorbic acids with a nano-fiber yield of 79.9%, 73.3% and 66.0%, respectively. The pH, conductivity, viscosity, and light transmittance of dispersions were assessed under different storage times. All of the tested DAChN dispersions were stable for at least 15 weeks at 4℃.
2016, 1(3): 139-144.
doi: 10.21967/jbb.v1i3.51
Abstract:
The effects of concentration and sonication on the liquid crystalline phases of collagen were investigated by several methods, especially by the atomic force microscopy (AFM). The X-ray diffraction (XRD) results revealed that the triple-helical structure of the collagen was nearly unchanged after sonication. Moreover, the differential scanning calorimetry (DSC) examinations indicated that the thermal stability of the sonicated collagen was close to that of native collagen. The AFM observations showed that collagen with a concentration of 60 mg/mL had more ordered arrays compared to that of 30 mg/mL when both samples were treated by sonication. Furthermore, the 60 mg/mL collagen solution without sonication could still form pre-cholesteric patterns, while the liquid phase could not be observed for the 30 mg/mL collagen solution under the same conditions. Generally, AFM was an effective tool for the study of the liquid crystalline phases of collagen.
The effects of concentration and sonication on the liquid crystalline phases of collagen were investigated by several methods, especially by the atomic force microscopy (AFM). The X-ray diffraction (XRD) results revealed that the triple-helical structure of the collagen was nearly unchanged after sonication. Moreover, the differential scanning calorimetry (DSC) examinations indicated that the thermal stability of the sonicated collagen was close to that of native collagen. The AFM observations showed that collagen with a concentration of 60 mg/mL had more ordered arrays compared to that of 30 mg/mL when both samples were treated by sonication. Furthermore, the 60 mg/mL collagen solution without sonication could still form pre-cholesteric patterns, while the liquid phase could not be observed for the 30 mg/mL collagen solution under the same conditions. Generally, AFM was an effective tool for the study of the liquid crystalline phases of collagen.
2016, 1(3): 145-151.
doi: 10.21967/jbb.v1i3.50
Abstract:
A significant amount of lignin and hemicellulose are dissolved in the hydrothermal treatment of biomass. The hemicellulose can be recovered and utilized for value-added products. The dissolved lignin can undergo depolymerization and condensation reactions, and interferes with the separation and purification process for hemicellulose recovery. This paper investigated the behavior of the lignin extracted from the hydrothermal pretreatment of bamboo and its contributions to the physical characteristics of the hydrolysate. It was found that the turbidity of the hydrolysate was strongly associated with the lignin fragments and suspended long chain hemicelluloses. As the lignin depolymerization and condensation reactions occurred simultaneously, the dissolved lignin fractions in the hydrolysate increased first and then decreased. The molecular weight (MW) of the dissolved lignin fragments ranged from 3342~5611 g/mol, with mainly guaiacyl (G) and syringyl (S) unit in the structure.
A significant amount of lignin and hemicellulose are dissolved in the hydrothermal treatment of biomass. The hemicellulose can be recovered and utilized for value-added products. The dissolved lignin can undergo depolymerization and condensation reactions, and interferes with the separation and purification process for hemicellulose recovery. This paper investigated the behavior of the lignin extracted from the hydrothermal pretreatment of bamboo and its contributions to the physical characteristics of the hydrolysate. It was found that the turbidity of the hydrolysate was strongly associated with the lignin fragments and suspended long chain hemicelluloses. As the lignin depolymerization and condensation reactions occurred simultaneously, the dissolved lignin fractions in the hydrolysate increased first and then decreased. The molecular weight (MW) of the dissolved lignin fragments ranged from 3342~5611 g/mol, with mainly guaiacyl (G) and syringyl (S) unit in the structure.
2016, 1(3): 152-158.
doi: 10.21967/jbb.v1i3.52
Abstract:
The use of magnesium hydroxide (Mg(OH)2) was proposed as a filler to replace part of the calcium carbonate (CaCO3) in cigarette paper and reduce the toxicity of the smoke from cigarettes. Physical property changes and smoke reducing ability of this possible substitution were effectively studied. The results showed that adding 10% Mg(OH)2 could meet the requirements of the physical property of the cigarette paper. Moreover, with the addition of Mg(OH)2 as a filler in the cigarette paper, the pyrolysis temperature of the cigarette paper decreased, while the porosity and specific surface area increased. As a result, the main-stream smoke had a lower smoke total particle matter (STMP), tar, nicotine and carbon monoxide content, and the side-stream smoke also had a lower STMP.
The use of magnesium hydroxide (Mg(OH)2) was proposed as a filler to replace part of the calcium carbonate (CaCO3) in cigarette paper and reduce the toxicity of the smoke from cigarettes. Physical property changes and smoke reducing ability of this possible substitution were effectively studied. The results showed that adding 10% Mg(OH)2 could meet the requirements of the physical property of the cigarette paper. Moreover, with the addition of Mg(OH)2 as a filler in the cigarette paper, the pyrolysis temperature of the cigarette paper decreased, while the porosity and specific surface area increased. As a result, the main-stream smoke had a lower smoke total particle matter (STMP), tar, nicotine and carbon monoxide content, and the side-stream smoke also had a lower STMP.
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