In the world, there are more than 370 million indigenous and tribal people with especial culture and traditions. The Chakma’s is one of the groups of indigenous people dwelling Chittagong hill tracts in Bangladesh. C...In the world, there are more than 370 million indigenous and tribal people with especial culture and traditions. The Chakma’s is one of the groups of indigenous people dwelling Chittagong hill tracts in Bangladesh. Chakma’s has its own culture, tradition, literature, and costume designs. The design costumes of the Chakma’s play an essential role. The Chakma’s preserved their textile design in “Alam”. Alam is a kind of cloth embroidered with various designs carrying the heritage of the Chakma. The use of Alam began approximately 500 years ago. All used clothing in Chakma society is weaved manually in the back-strap loom, which is generally very time-consuming— this limits its design aesthetics and universal use. Because of globalisation, the use of the traditional design of Chakma’s are threatened today. Till today in our country and overseas, no attempts were taken for research of the traditional Chakma’s design. The purpose of this research is to upgrade and digitise Chakma’s designs. Furthermore, efforts were made for the automatization of the traditional process to preserve traditional Chakma’s designs. In this study analysis of the fabric designs, pattern structure, colour applications of the traditional Aalam design were constructed using small prototype Rapier loom technology. We found that most of the single designs of the Alam were possible to weave in small prototype modern loom. On the other hand, intricate designs were not possible to weave in small prototype loom but are possible in the jacquard loom. The key idea is to establish an approach to modernise the traditional weaving process in order to make it convenient, economical and less time-consuming.展开更多
The nanophotocatalytic process using semiconducting oxides with a nanostructure is one of the technologies used for the destructive oxidation of organic compounds such as dyes. The photocatalytic oxidation of a textil...The nanophotocatalytic process using semiconducting oxides with a nanostructure is one of the technologies used for the destructive oxidation of organic compounds such as dyes. The photocatalytic oxidation of a textile dye—C. I. Basic Blue 41 (BB41) in aqueous solution was assessed by UV ray irradiation in the presence of TiO2 nanoparticles. The effect of initial dye concentration, pH and TiO2 loading were investigated and the optimized conditions for maximum amount of degradation were determined. Analysis of the kinetics showed pseudo-first-order model. The mineralization of the dye was reported by measuring the initial and final chemical oxygen demand of the solution that was irradiated under optimized conditions.展开更多
Heterogeneous photocatalysis is an advanced oxidation process (AOP), which can be successfully used to oxidize many organic pollutants present in aqueous systems. This research studied the photocatalytic degradation o...Heterogeneous photocatalysis is an advanced oxidation process (AOP), which can be successfully used to oxidize many organic pollutants present in aqueous systems. This research studied the photocatalytic degradation of C. I. Basic Blue 66 (BB 66) in the presence of TiO2 P-25 Degussa as a photocatalyst. The influence of various parameters, such as mass of catalyst, initial concentration of dye and pH on the degradation process was examined. The degradation of the dye followed a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model and decolourization was achieved within 80 min of light exposure. The mineralization of organic carbon was also evaluated by measuring the dissolved organic carbon (DOC) of the dye solutions.展开更多
This article describes the results of an investigation on the influence of loading silane treated sugar cane bagasse (SB) on the morphology and properties of recycled polypropylene (rPP). The samples are prepared thro...This article describes the results of an investigation on the influence of loading silane treated sugar cane bagasse (SB) on the morphology and properties of recycled polypropylene (rPP). The samples are prepared through melt extrusion followed by injection moulding. The Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) results show that SB-rPP composites have a fairly strong interfacial interaction and a change in crystallization for the highest containing SB composite, however, some fibre pull-outs are observed as the SB content is increased. The interaction influences the thermal and mechanical properties of the samples in a complex way. There are strong indications of a stronger interfacial interaction on the highest containing SB composite, which is supposedly accountable for the increased crystallinity and melting temperature.展开更多
Polyethylene （PE） films are treated using an atmospheric pressure plasma jet （APPJ） with He or He/O2 gas for different periods of time. The influence of gas type on the plasma polymer interactions is studied. The ...Polyethylene （PE） films are treated using an atmospheric pressure plasma jet （APPJ） with He or He/O2 gas for different periods of time. The influence of gas type on the plasma polymer interactions is studied. The surface contact angle of the PE film can be effectively lowered to 58° after 20 s of He/O2 plasma treatment and then remains almost unchanged for longer treatment durations, while, for He plasma treatment, the film surface contact angle drops gradually to 47° when the time reaches 120 s. Atomic force microscopy （AFM） results show that the root mean square （RMS） roughness was significantly higher for the He/O2 plasma treated samples than for the He plasma treated counterparts, and the surface topography of the He/O2 plasma treated PE films displays evenly distributed dome-shaped small protuberances. Chemical composition analysis reveals that the He plasma treated samples have a higher oxygen content but a clearly lower percentage of COO than the comparable He/O2 treated samples, suggesting that differences exist in the mode of incorporating oxygen between the two gas condition plasma treatments. Electron spin resonance （ESR） results show that the free radical concentrations of the He plasma treated samples were clearly higher than those of the He/O2 plasma treated ones with other conditions unchanged.展开更多
Wool keratin has broad application prospects in biomedical materials, tissue engineering, and other fields. To obtain porous wool keratin membrane with good performance, and lay the foundation for its application in b...Wool keratin has broad application prospects in biomedical materials, tissue engineering, and other fields. To obtain porous wool keratin membrane with good performance, and lay the foundation for its application in biological fields in the future, wool keratin aqueous solution and sponge were prepared and their characters were discussed. Wool fiber was dissolved with a mixture of urea, β-mercapitoethanol, sodium dodecyl sulfate(SDS) and water, and stable keratin aqueous solution was prepared through filtration and dialysis. Dissolution rate under different conditions was discussed. The results show that dissolution rate increases with the increase of dissolving temperature, reduction β-mercaptoethanol and assistant agent urea concentration and the addition of SDS. SDS polyacrylamide gel electrophoresis (SDS PAGE) shows the major molecular weight of the aqueous keratin solution is between 44300 u and 66400 u. Amino acid analysis shows the cysteine acid content of the keratin solution decreases obviously. Wool keratin sponge was made from the keratin solution with freeze drying method and its structure and characters were studied with scanning electron microscopy(SEM) and Fourier transform infrared spectrometer (FTIR). The results indicate that keratin sponge has evident pores structure, and the conformation of the sponge is β-sheet.展开更多
The fate of end-of-life electronics (e-wastes) is of increasing concern because of their toxicity and ever increasing volumes. Addressing these concerns requires proper management plans and strategy which in turn requ...The fate of end-of-life electronics (e-wastes) is of increasing concern because of their toxicity and ever increasing volumes. Addressing these concerns requires proper management plans and strategy which in turn requires reliable estimates of e-waste generation in the present as well as future times. In this study, a material flow model for the analysis of e-waste generation from computer equipments inNigeriahas been developed. Data used to develop the model are the sales data from major distributors of electronics, usage time of computer equipments and transfer coefficients of the electronics from one stage to another. The analysis of individual flows of computer from the material flow model showed that the fate of obsolete computer equipments were storage (41%), reuse (35%) and direct disposal (24%). The projections of the flows for a period of 15 years also indicated that storage and reuse of computer equipments would be preferred over direct disposal;and computer equipments would continue to remain in either storage, re-use or gradually disposed off for about 11 years after its inflow. This delay or staggering disposal is of advantage as it would reduce the amount of e-waste disposed yearly and also afford the country some time to make plans to accommodate and manage the e-wastes generated more efficiently.展开更多
Many researchers have shown interest in the reinforcement of commodity thermoplastic with natural fibers. However, the drawback of natural fibers is their low thermal processing temperatures, that border around 200℃....Many researchers have shown interest in the reinforcement of commodity thermoplastic with natural fibers. However, the drawback of natural fibers is their low thermal processing temperatures, that border around 200℃. In this investigation, we tried to improve the thermal stability of natural fibers with the use of flexible epoxy surface coating that could facilitate processing with engineering thermoplastics. Jute fabric and Polyamide 6 (PA6) composites were prepared by compression molding. The thermal decomposition characteristics of the jute fabric were evaluated by using thermo gravimetric analysis (TGA). Mechanical analysis was conducted to evaluate tensile test and three point bending test of composite. It was found that thermal degradation resistance of jute fabric was improved by coating with flexible epoxy resin. Moreover, the flexural modulus improved with increasing curative concentration. The interfacial interaction between the epoxy and PA6 was clearly indicated by the photo micrographs of the polished cross sections of the coated and uncoated jute fabric/PA6 composites.展开更多
The synthesis of a series of 3-(p-substituted phenylazo)-6-pyridone dyes which is suitable for the dyeing of polyester fabrics, is described. Visible absorption spectra of the dyes were examined in various solvents an...The synthesis of a series of 3-(p-substituted phenylazo)-6-pyridone dyes which is suitable for the dyeing of polyester fabrics, is described. Visible absorption spectra of the dyes were examined in various solvents and the compounds in solution exhibited hydrazone-common anion equilibrium. The electronic absorption spectra cover a λmax range of 404 - 464 nm in DMF at uniformly high absorption intensity between 5.33 × 104 - 8.55 × 104 lmol–1cm–1 and gave bright intense hues of yellow to orange on polyester fabrics. The colour parameters of the dyed fabrics were measured and the dyes have excellent exhaustion between 72% - 79% for polyester fabrics, more intense and of very good fastness properties on polyester fabrics. The remarkable degree of levelness and brightness after washing is indicative of good penetration and excellent affinity of these dyes for the polyester fabric.展开更多
Nitrosonaphthol dyes and other corresponding analogues were synthesised from 1-Naphthol. The dyes were applied onto chrome and vegetable tanned leather upon characterization. The results indicate that the dye bath exh...Nitrosonaphthol dyes and other corresponding analogues were synthesised from 1-Naphthol. The dyes were applied onto chrome and vegetable tanned leather upon characterization. The results indicate that the dye bath exhaustion was better on chrome tanned leather than on vegetable tanned leather. This may be attributed to the chelating effect of chrome on leather and the higher temperature of dyeing the chrome tanned leather compared with the vegetable tanned leather. The fastness properties of the dyes of washing ranging from (3 - 5), perspiration on acid (4 - 5), alkaline (4 - 5) and light (4 - 7) were impressive on both vegetable and chrome tanned leather respectively.展开更多
In this work, thermosetting resin, epoxy and fibre loading were used in optimizing the strength at which ABS/epoxy coated kenaf fibre (EKF) composites would perform apparently during mechanical stress. Kenaf bast fibr...In this work, thermosetting resin, epoxy and fibre loading were used in optimizing the strength at which ABS/epoxy coated kenaf fibre (EKF) composites would perform apparently during mechanical stress. Kenaf bast fibres were resin coated before incorporated into engineering thermoplastic ABS at its processing temperature (230°C), cured in-situ at internal mixer and later compression moulded at 210°C under 65 kg/cm2pressure. The results showed the optimum level of tensile strength with thermoset and fibre loading as well as increase in strong interfacial bonding while the hardness values increased with increasing thermosetting and fibre contents. Both the tensile and flexural modulus apparently increased as the fibre contents increased.展开更多
Novel polymeric pigments were synthesized in xylene by cross linked epoxy resin with 1,4 and 1,5-diaminoanthraquinones, by varying weight fractions from 5% to 20% of the diaminoanthraquinone derivatives. FTIR, UV and ...Novel polymeric pigments were synthesized in xylene by cross linked epoxy resin with 1,4 and 1,5-diaminoanthraquinones, by varying weight fractions from 5% to 20% of the diaminoanthraquinone derivatives. FTIR, UV and solubility tests were carried out. The pigments were then used to colour PLA, PMMA, PE and also in emulsion paints using polyvinyl alcohol as binder. Their light fastness, surface drying time and surface hardening time were assessed. It was found that λmax of the 1,4-diaminoanthraquinone shifted towards longer wavelength after the cross linkage, in contrast to the 1,5-diaminoanthraquinone which suffered a blue shift. However in all the cases, the λmax was not affected by the weight fractions of the anthraquinones, but the absorptivity coefficients was significantly increased as the weight fractions of the anthraquinones increased. The light fastness properties of the coloured plastics varied from 4 to 7, indicating a trend of increase with the weight fractions of the anthraquinones. Similar observations were seen with the emulsion paints produced. In all the cases, the 1,4-diaminoanthraqunione produced better result.展开更多
In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and therm...In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and thermal properties were then characterised. The synthesis was achieved by reacting equimolar solutions of the amine and the acid halides. The structure and thermal properties of the products were characterised. FT-IR Spectra of all the three products revealed the formation of amide due to the presence of strong bands at 1565 and 3390 cm?1 assignable to C=O stretching and N-H vibrations. Differential Scanning Calorimetry revealed high melting exotherms for the products. Thermogravimetry revealed moderate thermal stabilities for Poly NAM and Poly NAS and low thermal stability for Poly NAA which indicated 5.9%, 7.1% and 61.2% weight losses at 285℃, 285℃ and 374℃ for the three products respectively. The wavelengths of maximum absorbance for the dye samples are 601.5, 591 and 589 nm respectively with absorptivity coefficients (a1cm1% ) of 11640000, 11610000 and 11560000 respectively.展开更多
The aim of this study was to investigate the use of effect of pulveriser and extraction of cellulosenanowhiskers (CNWs) on Maize stalks. Maize stalk residues were first subjected to a cutting mill for size reduction p...The aim of this study was to investigate the use of effect of pulveriser and extraction of cellulosenanowhiskers (CNWs) on Maize stalks. Maize stalk residues were first subjected to a cutting mill for size reduction purified using mechanical, chemical extraction and bleaching. After chemical extraction, high quality cellulose resulted and cellulose nanowhiskers (CNW) were then extracted using chemical acid hydrolysis. The chemical compositions and mechanical properties of the maize stalk residues were examined before and after purification by using standard methods, Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and thermo gravimetric analysis (TGA). The morphology and dimensions of the isolated cellulose nanowhiskers were characterized using atomic force microscope (AFM). The crystallinity index increased upon mechanical and chemical extraction. Thermal stability of cellulose derived from maize stalk improved with chemical treatment due to new functional groups introduced on the surface and enhancement in crystallinity. Highly dispersed cellulose nanowhiskers (CNWs) were successfully extracted from maize stalk residues with diameters ranging between 3 and 7 nm, length ranges between 150 - 450 nm, respectively.展开更多
文摘In the world, there are more than 370 million indigenous and tribal people with especial culture and traditions. The Chakma’s is one of the groups of indigenous people dwelling Chittagong hill tracts in Bangladesh. Chakma’s has its own culture, tradition, literature, and costume designs. The design costumes of the Chakma’s play an essential role. The Chakma’s preserved their textile design in “Alam”. Alam is a kind of cloth embroidered with various designs carrying the heritage of the Chakma. The use of Alam began approximately 500 years ago. All used clothing in Chakma society is weaved manually in the back-strap loom, which is generally very time-consuming— this limits its design aesthetics and universal use. Because of globalisation, the use of the traditional design of Chakma’s are threatened today. Till today in our country and overseas, no attempts were taken for research of the traditional Chakma’s design. The purpose of this research is to upgrade and digitise Chakma’s designs. Furthermore, efforts were made for the automatization of the traditional process to preserve traditional Chakma’s designs. In this study analysis of the fabric designs, pattern structure, colour applications of the traditional Aalam design were constructed using small prototype Rapier loom technology. We found that most of the single designs of the Alam were possible to weave in small prototype modern loom. On the other hand, intricate designs were not possible to weave in small prototype loom but are possible in the jacquard loom. The key idea is to establish an approach to modernise the traditional weaving process in order to make it convenient, economical and less time-consuming.
文摘The nanophotocatalytic process using semiconducting oxides with a nanostructure is one of the technologies used for the destructive oxidation of organic compounds such as dyes. The photocatalytic oxidation of a textile dye—C. I. Basic Blue 41 (BB41) in aqueous solution was assessed by UV ray irradiation in the presence of TiO2 nanoparticles. The effect of initial dye concentration, pH and TiO2 loading were investigated and the optimized conditions for maximum amount of degradation were determined. Analysis of the kinetics showed pseudo-first-order model. The mineralization of the dye was reported by measuring the initial and final chemical oxygen demand of the solution that was irradiated under optimized conditions.
文摘Heterogeneous photocatalysis is an advanced oxidation process (AOP), which can be successfully used to oxidize many organic pollutants present in aqueous systems. This research studied the photocatalytic degradation of C. I. Basic Blue 66 (BB 66) in the presence of TiO2 P-25 Degussa as a photocatalyst. The influence of various parameters, such as mass of catalyst, initial concentration of dye and pH on the degradation process was examined. The degradation of the dye followed a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model and decolourization was achieved within 80 min of light exposure. The mineralization of organic carbon was also evaluated by measuring the dissolved organic carbon (DOC) of the dye solutions.
文摘This article describes the results of an investigation on the influence of loading silane treated sugar cane bagasse (SB) on the morphology and properties of recycled polypropylene (rPP). The samples are prepared through melt extrusion followed by injection moulding. The Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) results show that SB-rPP composites have a fairly strong interfacial interaction and a change in crystallization for the highest containing SB composite, however, some fibre pull-outs are observed as the SB content is increased. The interaction influences the thermal and mechanical properties of the samples in a complex way. There are strong indications of a stronger interfacial interaction on the highest containing SB composite, which is supposedly accountable for the increased crystallinity and melting temperature.
基金supported by the Fundamental Research Funds for the Central Universities of China(Nos.JUSRP1044 and JUSRP1045)National Natural Science Foundation of China(Nos.51203062 and 51302110)the Cooperative Innovation Fund,Project of Jiangsu Province,China(Nos.BY2012064,BY2013015-31 and BY2013015-32)
文摘Polyethylene （PE） films are treated using an atmospheric pressure plasma jet （APPJ） with He or He/O2 gas for different periods of time. The influence of gas type on the plasma polymer interactions is studied. The surface contact angle of the PE film can be effectively lowered to 58° after 20 s of He/O2 plasma treatment and then remains almost unchanged for longer treatment durations, while, for He plasma treatment, the film surface contact angle drops gradually to 47° when the time reaches 120 s. Atomic force microscopy （AFM） results show that the root mean square （RMS） roughness was significantly higher for the He/O2 plasma treated samples than for the He plasma treated counterparts, and the surface topography of the He/O2 plasma treated PE films displays evenly distributed dome-shaped small protuberances. Chemical composition analysis reveals that the He plasma treated samples have a higher oxygen content but a clearly lower percentage of COO than the comparable He/O2 treated samples, suggesting that differences exist in the mode of incorporating oxygen between the two gas condition plasma treatments. Electron spin resonance （ESR） results show that the free radical concentrations of the He plasma treated samples were clearly higher than those of the He/O2 plasma treated ones with other conditions unchanged.
基金Natural Science Foundation of Hubei Province,China ( No. 2008CDA059)
文摘Wool keratin has broad application prospects in biomedical materials, tissue engineering, and other fields. To obtain porous wool keratin membrane with good performance, and lay the foundation for its application in biological fields in the future, wool keratin aqueous solution and sponge were prepared and their characters were discussed. Wool fiber was dissolved with a mixture of urea, β-mercapitoethanol, sodium dodecyl sulfate(SDS) and water, and stable keratin aqueous solution was prepared through filtration and dialysis. Dissolution rate under different conditions was discussed. The results show that dissolution rate increases with the increase of dissolving temperature, reduction β-mercaptoethanol and assistant agent urea concentration and the addition of SDS. SDS polyacrylamide gel electrophoresis (SDS PAGE) shows the major molecular weight of the aqueous keratin solution is between 44300 u and 66400 u. Amino acid analysis shows the cysteine acid content of the keratin solution decreases obviously. Wool keratin sponge was made from the keratin solution with freeze drying method and its structure and characters were studied with scanning electron microscopy(SEM) and Fourier transform infrared spectrometer (FTIR). The results indicate that keratin sponge has evident pores structure, and the conformation of the sponge is β-sheet.
文摘The fate of end-of-life electronics (e-wastes) is of increasing concern because of their toxicity and ever increasing volumes. Addressing these concerns requires proper management plans and strategy which in turn requires reliable estimates of e-waste generation in the present as well as future times. In this study, a material flow model for the analysis of e-waste generation from computer equipments inNigeriahas been developed. Data used to develop the model are the sales data from major distributors of electronics, usage time of computer equipments and transfer coefficients of the electronics from one stage to another. The analysis of individual flows of computer from the material flow model showed that the fate of obsolete computer equipments were storage (41%), reuse (35%) and direct disposal (24%). The projections of the flows for a period of 15 years also indicated that storage and reuse of computer equipments would be preferred over direct disposal;and computer equipments would continue to remain in either storage, re-use or gradually disposed off for about 11 years after its inflow. This delay or staggering disposal is of advantage as it would reduce the amount of e-waste disposed yearly and also afford the country some time to make plans to accommodate and manage the e-wastes generated more efficiently.
文摘Many researchers have shown interest in the reinforcement of commodity thermoplastic with natural fibers. However, the drawback of natural fibers is their low thermal processing temperatures, that border around 200℃. In this investigation, we tried to improve the thermal stability of natural fibers with the use of flexible epoxy surface coating that could facilitate processing with engineering thermoplastics. Jute fabric and Polyamide 6 (PA6) composites were prepared by compression molding. The thermal decomposition characteristics of the jute fabric were evaluated by using thermo gravimetric analysis (TGA). Mechanical analysis was conducted to evaluate tensile test and three point bending test of composite. It was found that thermal degradation resistance of jute fabric was improved by coating with flexible epoxy resin. Moreover, the flexural modulus improved with increasing curative concentration. The interfacial interaction between the epoxy and PA6 was clearly indicated by the photo micrographs of the polished cross sections of the coated and uncoated jute fabric/PA6 composites.
文摘The synthesis of a series of 3-(p-substituted phenylazo)-6-pyridone dyes which is suitable for the dyeing of polyester fabrics, is described. Visible absorption spectra of the dyes were examined in various solvents and the compounds in solution exhibited hydrazone-common anion equilibrium. The electronic absorption spectra cover a λmax range of 404 - 464 nm in DMF at uniformly high absorption intensity between 5.33 × 104 - 8.55 × 104 lmol–1cm–1 and gave bright intense hues of yellow to orange on polyester fabrics. The colour parameters of the dyed fabrics were measured and the dyes have excellent exhaustion between 72% - 79% for polyester fabrics, more intense and of very good fastness properties on polyester fabrics. The remarkable degree of levelness and brightness after washing is indicative of good penetration and excellent affinity of these dyes for the polyester fabric.
文摘Nitrosonaphthol dyes and other corresponding analogues were synthesised from 1-Naphthol. The dyes were applied onto chrome and vegetable tanned leather upon characterization. The results indicate that the dye bath exhaustion was better on chrome tanned leather than on vegetable tanned leather. This may be attributed to the chelating effect of chrome on leather and the higher temperature of dyeing the chrome tanned leather compared with the vegetable tanned leather. The fastness properties of the dyes of washing ranging from (3 - 5), perspiration on acid (4 - 5), alkaline (4 - 5) and light (4 - 7) were impressive on both vegetable and chrome tanned leather respectively.
文摘In this work, thermosetting resin, epoxy and fibre loading were used in optimizing the strength at which ABS/epoxy coated kenaf fibre (EKF) composites would perform apparently during mechanical stress. Kenaf bast fibres were resin coated before incorporated into engineering thermoplastic ABS at its processing temperature (230°C), cured in-situ at internal mixer and later compression moulded at 210°C under 65 kg/cm2pressure. The results showed the optimum level of tensile strength with thermoset and fibre loading as well as increase in strong interfacial bonding while the hardness values increased with increasing thermosetting and fibre contents. Both the tensile and flexural modulus apparently increased as the fibre contents increased.
文摘Novel polymeric pigments were synthesized in xylene by cross linked epoxy resin with 1,4 and 1,5-diaminoanthraquinones, by varying weight fractions from 5% to 20% of the diaminoanthraquinone derivatives. FTIR, UV and solubility tests were carried out. The pigments were then used to colour PLA, PMMA, PE and also in emulsion paints using polyvinyl alcohol as binder. Their light fastness, surface drying time and surface hardening time were assessed. It was found that λmax of the 1,4-diaminoanthraquinone shifted towards longer wavelength after the cross linkage, in contrast to the 1,5-diaminoanthraquinone which suffered a blue shift. However in all the cases, the λmax was not affected by the weight fractions of the anthraquinones, but the absorptivity coefficients was significantly increased as the weight fractions of the anthraquinones increased. The light fastness properties of the coloured plastics varied from 4 to 7, indicating a trend of increase with the weight fractions of the anthraquinones. Similar observations were seen with the emulsion paints produced. In all the cases, the 1,4-diaminoanthraqunione produced better result.
文摘In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and thermal properties were then characterised. The synthesis was achieved by reacting equimolar solutions of the amine and the acid halides. The structure and thermal properties of the products were characterised. FT-IR Spectra of all the three products revealed the formation of amide due to the presence of strong bands at 1565 and 3390 cm?1 assignable to C=O stretching and N-H vibrations. Differential Scanning Calorimetry revealed high melting exotherms for the products. Thermogravimetry revealed moderate thermal stabilities for Poly NAM and Poly NAS and low thermal stability for Poly NAA which indicated 5.9%, 7.1% and 61.2% weight losses at 285℃, 285℃ and 374℃ for the three products respectively. The wavelengths of maximum absorbance for the dye samples are 601.5, 591 and 589 nm respectively with absorptivity coefficients (a1cm1% ) of 11640000, 11610000 and 11560000 respectively.
文摘The aim of this study was to investigate the use of effect of pulveriser and extraction of cellulosenanowhiskers (CNWs) on Maize stalks. Maize stalk residues were first subjected to a cutting mill for size reduction purified using mechanical, chemical extraction and bleaching. After chemical extraction, high quality cellulose resulted and cellulose nanowhiskers (CNW) were then extracted using chemical acid hydrolysis. The chemical compositions and mechanical properties of the maize stalk residues were examined before and after purification by using standard methods, Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and thermo gravimetric analysis (TGA). The morphology and dimensions of the isolated cellulose nanowhiskers were characterized using atomic force microscope (AFM). The crystallinity index increased upon mechanical and chemical extraction. Thermal stability of cellulose derived from maize stalk improved with chemical treatment due to new functional groups introduced on the surface and enhancement in crystallinity. Highly dispersed cellulose nanowhiskers (CNWs) were successfully extracted from maize stalk residues with diameters ranging between 3 and 7 nm, length ranges between 150 - 450 nm, respectively.
