Determination of In Situ Esterification Parameters of Citric Acid-Glycerol Based Polymers for Wood Impregnation

The development of wood treatments is of increasing industrial importance. A novel technique for improving the properties of lodgepole pine and white pine through modification of the microstructure is described. The present investigation is devoted to the synthesis and determination of in situ parameters of citric acid and glycerol based polymers for wood impregnation. This solvent free approach is environmentally friendly and achieved through an esterification condensation reaction under acidic conditions. Crude glycerol and citric acid reactants were cross-linked via a curing process at 160?°C creating a polymer with only water as the byproduct. The ester bonds and crosslinking levels were controlled using different catalysts and citric acid contents and related to the reaction time and temperature. The nature of bonding within the polymers and at the wood cell walls was determined by FT-IR analysis. The thermal properties such as glass transition temperature (T_g) were studied using TGA/DSC and the effect of citric acid content and catalyst type determined. Dimensional stability of impregnated wood samples improved above 50% for each sample with HCl and p-TSA catalysts compared to control samples. FTIR spectra were studied to show the presence of the ester linkages of the polymer in situ at the wood cell walls. Bonding between the polymer and wood macromolecules were observed by scanning electron microscopy and interpreted as evidence of chemical bonds at the wood cells. When prepared using a catalyst, the polymer was intimately incorporated into wood structure significantly improving the substrate dimensional stability. Enhanced stability makes this approach of particular interest for exterior wood products especially as a green renewable option for the wood industry.     

Active and Intelligent Films Made from Starchy Sources/Blackberry Pulp

Functional, active and intelligent films were prepared from biopolymeric matrices (plantain starch and pre-gelatinized plantain flour) with and without the addition of a natural filler (blackberry pulp) using the casting methodology. A thorough examination of the physicochemical, antioxidant and antimicrobial properties of the both the matrices used and the developed films was then carried out. The films developed from matrices incorporating the blackberry pulp were more amorphous, thicker, less sensitive to moisture, and with higher melting temperatures than the films made without this natural filler. The degree of substitution, average molecular weight and attenuated total reflectance Fourier transform infrared spectroscopy of the films made with blackberry pulp suggest that the starch chains were cross-linked. This is probably because the citric acid contained in the pulp functions as a cross-linking agent. Films with added blackberry pulp responded to changes in pH, i.e. were pH-sensitive, and also showed antimicrobial activity especially against Escherichia coli. In general, the addition of blackberry pulp improved the physicochemical and mechanical properties of the films developed due to cross-linking, as well as increasing their antioxidant activity.     

Role of Hydrophilic and Hydrophobic Interactions in Structure Development of Zein Films

Zein has been studied for its potential as a biobased polymeric material. Due to the fact that films made exclusively from zein are brittle, composites of zein and oleic acid were prepared in our lab and formed into flexible films. Film properties were believed related to their structure. X-ray scattering measurements on zein films suggested the formation of layers along the plane of the film. Oleic acid seemed to play an important role in layer formation. However, X-ray measurements could not yield information on the nature of the interface between oleic acid and zein. Surface plasmon resonance (SPR) was used to further investigate interaction between zein and oleic acid. Dynamic adsorption of zein from alcoholic solutions onto hydrophilic and hydrophobic surfaces generated by self-assembled monolayers of 11-mercaptoundecanoic acid or 1-octanethiol was monitored by SPR. It was observed that zein had a greater affinity for hydrophilic than for hydrophobic surfaces under the prevalent experimental conditions. A mechanism for structure development of zein-oleate films was proposed based on these results and previous X-ray measurements. It is suggested that the structure development involves hydrophilic adsorption of fatty acids onto the zein surface followed by hydrophobic associations leading to a layered film structure organization.     

PANI-TiO_2光催化剂的制备及其降解甲基橙的性能

采用溶胶-凝胶法和原位氧化聚合法制备了新型聚苯胺修饰纳米TiO_2(PANI-TiO_2)复合光催化剂。以甲基橙溶液模拟有机染料废水,考察了过硫酸钾加入量、苯胺加入量、盐酸浓度及反应温度对PANI-TiO_2复合光催化剂降解甲基橙性能的影响。采用XRD,UV-vis,FTIR技术对PANI-TiO_2复合光催化剂进行了表征。实验结果表明:PANI-TiO_2复合光催化剂降解甲基橙的最适宜工艺条件为:n(过硫酸钾):n(钛酸四丁酯)=0.1,n(苯胺):n(钛酸四丁酯)=0.11,盐酸浓度2 mol/L,反应温度20℃,在此最适宜条件下,反应时间为60 min时,甲基橙降解率为97%。表征结果显示:与TiO_2相比,PANI-TiO_2复合光催化剂明显发生了红移现象,带隙变窄,有利于光催化反应效率的提高;与PANI相比,PANI-TiO_2复合光催化剂的红外特征峰向低波数的方向发生偏移;PANI-TiO_2复合光催化剂为锐钛矿型。     

Preparation of Cationic/Anionic Chitin Nanofiber Composite Materials

In this study, we investigated the preparation of cationic/anionic chitin nanofiber (CNF) composite materials by electrostatic interaction. An aqueous dispersion of amidinium CNF was prepared by a top-down approach, and a maleylated CNF film was obtained by a bottom-up approach from a chitin ion gel in an ionic liquid with subsequent maleylation on the CNFs. The resulting film was dispersed in ammonia (aq), which was then mixed with the aqueous cationic CNF dispersion to give the composite film. The composition of the two CNFs was evaluated by scanning electron microscopy and X-ray diffraction measurements. Tensile testing results indicated that the mechanical properties of the composites were enhanced with increasing degrees of substitution of the cationic and anionic groups on CNFs, and also when the molar ratio of these groups approached 1:1. The dissociation of the two kinds of CNFs by alkaline treatment of the composite film was achieved, suggesting the presence of an electrostatic interaction among the interactions between them.     

ZnO的制备及其光催化性能

分别采用草酸沉淀法和柠檬酸络合法制备了纤锌矿型ZnO,通过X射线粉末衍射仪、扫描电子显微镜和透射电子显微镜对ZnO的结构和形貌进行了表征,并研究了所制备的ZnO对溶液中甲基橙的光催化降解性能.实验结果表明:草酸沉淀法制备的ZnO为小颗粒堆积而成的空心类柱状体,柠檬酸络合法制备的ZnO为小球形颗粒；草酸沉淀法制备的ZnO...     

Transdermal Delivery of Nicotine Using Pectin Isolated from Durian Fruit-Hulls-Based Polymer Blends as a Matrix Layer

Many natural polymers with various chemical structures are used to prepare transdermal patches. Pectin is a one interesting type of polymer because it can control drug release when used in transdermal patches. In Thailand, the waste from durian fruit-hulls is a major problem for the environment. However, the pectin from it can be isolated under acid conditions and used to prepare transdermal patches for nicotine delivery which has not yet been reported. As the isolated pectin is a natural polymer, the film made from isolated pectin is a brittle; therefore, adding a low protein natural rubber latex (LPNRL) polymer was needed to increase its flexibility. The transdermal patches were amorphous and had T_g values ranging from 81.0 to 93.3 °C. Moisture uptake, swelling ratio, and erosion values of the patches were significantly decreased after addition of LPNRL, which resulted in low hydrophilicity. The in vitro release and permeation of nicotine depends on the hydrophilicity of the patches. The kinetic models for in vitro release and permeation of nicotine were Higuchi model and zero order, respectively. In conclusion, pectin isolated from fruit-hulls of Mon Thong durians is an effective polymer to control the release of nicotine. It also is an option that could solve the environmental problems caused by durian fruit-hulls waste.     

The Properties of PLA/Oxidized Soybean Oil Polymer Blends

Novel polymer blends based on completely renewable polymers were reported. Polymer blends based on polylactic acid (PLA) and oxidized and hydroxylated soya bean oil polymers were prepared. Plasticization and mechanical strength effect of the soya bean oil polymers on the PLA were observed. Fracture surface analysis of the polymer blends was carried out by using scanning electron microscopy. The PLA blends showed more amorphous morphologies compared to pure PLA. The blends had better elongation at break in view of the stress–strain measurement. Blend of PLA with the hydroxylated polymeric soya bean oil indicated the slightly antibacterial properties.     

Fabrication and Characterization of Biodegradable Composite Films Made of Using Poly(caprolactone) Reinforced with Chitosan

Chitosan was dissolved in 2?% aqueous acetic acid solution and the films were prepared by solution casting. Values of tensile strength (TS), tensile modulus (TM), elongation at break (Eb?%) and water vapor permeability (WVP) of the chitosan films were found to be 30?MPa, 450?MPa, 8?% and 4.7?g?mm/m²?day?kPa, respectively. Poly(caprolactone) (PCL) films were prepared from its granules by compression molding and the values of TS, TM, Eb and WVP were 14?MPa, 220?MPa, 70?% and 1.54?g?mm/m²?day?kPa, respectively. PCL was reinforced with chitosan films, and composite films were prepared by compression molding. Amount of chitosan in the composite films varied from 10 to 50?% (w/w). It was found that with the incorporation of chitosan films in PCL, both the values of TS and TM of composite films increased significantly. The highest mechanical properties were found at 50?% (w/w) of chitosan content. The Oxygen transmission rate (OTR) of composite film was found to decrease significantly than PCL films. Thermal properties of the composite were also improved as compared to PCL. The water uptake test of the composite also showed promising results with a good stability of composite films. The interface of the composite was investigated by scanning electron microscopy and showed good interfacial adhesion between PCL and chitosan films.     

壳聚糖复合吸附剂对油的吸附性能

以天然可生物降解的壳聚糖和硬脂酸为原料,通过壳聚糖2位氨基与硬脂酸的羧基相互作用,引入疏水烷基链,制备了疏水的壳聚糖-硬脂酸复合吸附剂(简称复合吸附剂),采用傅立叶红外光谱、X射线衍射对复合吸附剂的结构进行表征,并考察了复合吸附剂对油的回收性能.实验结果表明:壳聚糖和硬脂酸以离子形式结合得到复合吸附剂;当硬脂酸与壳聚糖质量比为0.7时,硬脂酸的结合量最大;复合吸附剂对油的吸附量、保油率、脱附率的顺序分别为花生油(14.93 g/g)>甲基硅油(10.71 g/g)>液体石蜡(9.37 g/g),花生油(94.51%)>液体石蜡(90.74%)>甲基硅油(78.69%),花生油(95.62%)>液体石蜡(93.27%)>甲基硅油(90.73%).     

Dielectric and Material Properties of Poly (Vinyl Alcohol): Based Modified Red Mud Polymer Nanocomposites

Red mud emerges as the major waste material during production of alumina from bauxite by the Bayer??s process. Based on economics as well as environmental related issues, enormous efforts have been directed worldwide towards red mud management issues i.e. of utilization, storage and disposal. The present research work has been undertaken with an objective to explore the use of red mud as a reinforcing material in the polymer matrix as a low cost option. The silicate layered red mud was organophilized by aniline formaldehyde and to know the effect of various filler loading on the material properties of PVA-organophilized red mud composites, prepared by a conventional solvent casting technique and comparison of the same with that of the virgin poly (vinyl alcohol) (PVA), various characterizations was done. The modified red mud was typically characterized by X-ray diffraction. The X-ray diffraction pattern of the composite materials was also studied. The morphological image of the composite materials was studied by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was used to characterize the dispersion of the red mud within the composite materials. The surface topography of the composite materials was studied by Atomic Force Microscopy (AFM). The dielectric properties of composite materials were investigated in wide frequency ranges from 1?MHz to 1?GHz.     

Properties of Starch/PVA Blend Films Containing Citric Acid as Additive

Starch/polyvinyl alcohol (PVA) blend films were prepared successfully by using starch, polyvinyl alcohol (PVA), glycerol (GL) sorbitol (SO) and citric acid (CA) for the mixing process. The influence of mixing time, additional materials and drying temperature of films on the properties of the films was investigated. With increase in mixing time, the tensile strength (TS), elongation (%E), degree of swelling (DS) and solubility (S) of the film were equilibrated. The equilibrium for TS, %E, DS and S value was 20.12 MPa, 36.98%, 2.4 and 0.19, respectively. The mixing time of equilibrium was 50 min. TS, %E, DS and S of starch/PVA blend film were examined adding glycerol (GL), sorbitol (SO) and citric acid (CA) as additives. At all measurement results, except for DS, the film adding CA was better than GL or SO because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA and additives. Citric acid improves the properties of starch/PVA blend film compared to glycerol and sobitol. When the film was dried at low temperature, the properties of the films were clearly improved because the hydrogen bonding was activated at low temperature.     

Characterization of Sorghum Bran/Recycled Low Density Polyethylene for the Manufacturing of Polymer Composites

The objective of the study was to investigate the suitability of using sorghum bran in recycled low density polyethylene (R-LDPE) composites manufacturing. In response to the disposal of environmental problematic agricultural and polymer waste, composite sheets using recycled low density polyethylene and sorghum bran of different loadings (5, 10, 15 and 20 wt%) were prepared by melt compounding and compression molding. The effects of sorghum bran loadings on the mechanical, thermal, water absorption, swelling and crystalline properties of the composites were determined. Characterization of composites was carried out using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermo gravimetric (TGA/DTG) and mechanical analyses. It was found that increasing fiber loadings resulted to increased moduli and tensile strength while hardness was decreased. XRD indicated that fiber addition to R-LDPE did not change characteristic peak position. DSC results showed that the R-LDPE had significantly larger peak heat flow during cooling run than the blank R-LDPE, showing higher crystallization rates for R-LDPE. The results obtained confirmed that sorghum bran particles showed some potential as a good reinforcement in polymer matrix composites and indicate its thermal stability for possibly future composite applications.     

Biomass Carbon Ratio of Polymer Composites Measured by Accelerator Mass Spectrometry

The evaluation method of biomass carbon ratio of polymer composite samples including organic and inorganic carbons individually was investigated. Biodegradable plastics and biobased plastics can have their mechanical properties improved by combining with inorganic fillers. Polymer composites consisting of biodegradable plastics and carbonate were prepared by two different methods. Poly(lactic acid) (PLA) composite was prepared by synthesis from l-lactide with catalyst and calcium carbonate (CaCO₃) powders from lime. Poly(butylene succinate) (PBS) composite was prepared by hot-pressing the mixture of PBS powder and CaCO₃ powders from oyster shells. The mechanical properties of composite samples were investigated by a tensile test and a compression test using an Instron type mechanical tester. Tensile test with a dumbbell shape specimen was performed for PBS composite samples and compression test with a column shape specimen for PLA composite samples. Strength, elastic modulus and fracture strain were obtained from the above tests. Biomass carbon ratio is regulated in the American Standards for Testing and Materials (ASTM). In ASTM standards on biomass carbon ratio, it is required that carbon atoms from carbonates, such as CaCO₃, are omitted. Biomass carbon ratio was evaluated by ratio of ¹⁴C to ¹²C in the samples using Accelerator Mass Spectrometry (AMS). The effect of pretreatment, such as oxidation temperature and reaction by acid, on results of biomass carbon ratio was investigated. Mechanical properties decrease with increasing CaCO₃ content. The possibility of an evaluation method of biomass carbon ratio of materials including organic and inorganic carbons was shown.     

Polyvinyl Alcohol (PVA)/Starch Bioactive Packaging Film Enriched with Antioxidants from Spent Coffee Ground and Citric Acid

The bioactive packaging polyvinyl alcohol (PVA)/starch films were prepared by incorporating combined antioxidant agents i.e. extracted spent coffee ground (ex-SCG) and citric acid. Effect of citric acid content on chemical compatibility, releasing of antioxidant, antibacterial activities, and physical and mechanical properties of PVA/starch incorporated ex-SCG (PSt-E) films was studied. The results of ATR-FTIR spectra showed that antioxidant agents of ex-SCG can penetrate into the film and the ester bond of blended films by citric acid was also observed. The presence of ex-SCG increased efficiency of antioxidant release and antimicrobial activity. The PSt-E film incorporated 30 wt% citric acid showed minimum inhibitory concentration against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The incorporation of ex-SCG and citric acid into film showed a synergistic effect on antibacterial activity. The water resistance and kinetic moisture sorption improved with incorporation of citric acid. The tensile strength and biodegradability of samples were in range of 5.63–7.44 MPa and 65.28–86.64%, respectively. Based on this study, PSt-E film incorporated 30 wt% citric acid can be applied as novel food packaging materials.     

Cellulose–Polymer Based Green Composite Fibers by Electrospinning

Green composite fibers (339?C612?nm in diameter) have been developed from wood pulp, acetylated wood pulp and polyethylene oxide under various concentrations by electrospinning process. A polymer solution concentration of 7 wt% with 5 wt% wood pulp have been found to produce uniform composite fibers. Scanning electron microscopy micro-images demonstrated that composite fibers diameter and morphology depended on the processing parameters, such as solution concentration and molecular weight of polymer. Transmission electron microscopy and laser confocal microscopy observations indicated that the acetylated wood was well dispersed and oriented along the length of composite fibers axis. X-ray diffraction studies revealed that the structure of electrospun composite fibers became more non-crystalline.     

Utilization of Porous Carbons Derived from Coconut Shell and Wood in Natural Rubber

The porous carbons derived from cellulose are renewable and environmentally friendly. Coconut shell and wood derived porous carbons were characterized with elemental analysis, ash content, X-ray diffraction, infrared absorbance, particle size, surface area, and pore volume. The results were compared with carbon black. Uniaxial deformation of natural rubber (NR) composites indicate the composites reinforced with the porous carbon from coconut shell have higher tensile moduli at the same elongation ratio than the composites reinforced with wood carbon. 40 % coconut shell composite showed a fivefold increase in tensile modulus compared to NR. Polymer–filler interactions were studied with frequency dependent shear modulus, swelling experiments and dynamic strain sweep experiments. Both linear and non-linear viscoelastic properties indicate the polymer–filler interactions are similar between coconut shell carbon and wood carbon reinforced composites. The swelling experiments, however, showed that the polymer–filler interaction is greater in the composites reinforced with coconut shell instead of wood carbon.     

Properties of Poly(Vinyl Alcohol)/Chitosan Nanocomposite Films Reinforced with Oil Palm Empty Fruit Bunch Amorphous Lignocellulose Nanofibers

The objective of this study was to investigate the properties of poly(vinyl alcohol)/chitosan nanocomposite films reinforced with different concentration of amorphous LCNFs. The properties analyzed were morphological, physical, chemical, thermal, biological, and mechanical characteristics. Oil palm empty fruit bunch LCNFs obtained from multi-mechanical stages were more dominated by amorphous region than crystalline part. Varied film thickness, swelling degree, and transparency of PVA/chitosan nanocomposite films reinforced with amorphous part were produced. Aggregated LCNFs, which reinforced PVA/chitosan polymer blends, resulted in irregular, rough, and uneven external surfaces as well as protrusions. Based on XRD analysis, there were two or three imperative peaks that indicated the presence of crystalline states. The increase in LCNFs concentration above 0.5% to PVA/chitosan polymer blends led to the decrease in crystallinity index of the films. A noticeable alteration of FTIR spectra, which included wavenumber and intensity, was obviously observed along with the inclusion of amorphous LCNFs. That indicated that a good miscibility between amorphous LCNFs and PVA/chitosan polymer blend generated chemical interaction of those polymers during physical blending. Reinforcement of PVA/chitosan polymer blends with amorphous LCNFs influenced the changes of T_g (glass transition temperature), T_m (melting point temperature), and T_max (maximum degradation temperature). Three thermal phases of PVA/chitosan/LCNFs nanocomposite films were also observed, including absorbed moisture evaporation, PVA and chitosan polymer backbone structural degradation and LCNFs pyrolysis, and by-products degradation of these polymers. The addition of LCNFs 0.5% had the highest tensile strength and the addition of LCNFs above 0.5% decreased the strength. The incorporation of OPEFB LCNFs did not show anti-microbial and anti-fungal properties of the films. The addition of amorphous LCNFs 0.5% into PVA/chitosan polymer blends resulted in regular and smooth external surfaces, enhanced tensile strength, increased crystallinity index, and enhanced thermal stability of the films.     

锰锌铁氧体/SiO_2复合磁性材料的制备和表征

以正硅酸乙酯(TEOS)作为包覆材料,对锰锌铁氧体纳米颗粒进行SiO2包覆,制备出锰锌铁氧体/SiO_2复合磁性材料。利用FTIR,XRD,SEM等技术对其进行了表征,并研究了其对模拟亚甲基蓝废水的吸附脱色效果。实验结果表明:当SiO_2质量分数为40%1时,采用先将锰锌铁氧体在柠檬酸溶液中搅拌分散3 h后,加人氨水调节溶液pH,再继续搅拌分散3 h的分段分散方法制备的复合磁性材料对亚甲基蓝废水的处理效果更好,处理亚甲基蓝质量浓度为50 mg/L、COD为160 mg/L的废水,废水脱色率为97.2%,COD去除率为19.3%。表征结果显示:复合磁性材料锰锌铁氧体/SiO_2为球形颗粒,平均粒径为100 nm;SiO_2包覆前后锰锌铁氧体的晶型均为尖晶石型结构,在复合磁性材料中SiO_2以无定型的形态存在。     

Hybrid Composites from Waste Materials

Hybrid composites of thermoplastic biofiber reinforced with waste newspaper fiber (NF) and poplar wood flour (WF) were prepared. The weight ratio of the lignocellulosic materials to polymer was 30:70 (w:w). Polypropylene (PP) and maleic anhydride grafted polypropylene (MAPP) were also used as the polymer matrix and coupling agent, respectively. The mechanical properties, morphology and thermal properties were investigated. The obtained results showed that tensile and flexural modulus of the composites were significantly enhanced with addition of biofibers in both types (fiber and flour), as compared with pure PP. However, the increasing in WF content substantially reduced the tensile, flexural and impact modulus, but improved the thermal stability. This effect is explained by variations in fiber morphological properties and thermal degradation. Increasing fiber aspect ratio improved mechanical properties. The effect of fiber size on impact was minimal compared to the effects of fiber content. Scanning electron microscopy has shown that the composite, with coupling agent, promotes better fiber–matrix interaction. The largest improvement on the thermal stability of hybrid composites was achieved when WF was added more. In all cases, the degradation temperatures shifted to higher values after addition of MAPP. This work clearly showed that biofiber materials in both forms of fiber and flour could be effectively used as reinforcing elements in thermoplastic PP matrix.