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1.
An investigation was conducted to study the effect of solvent composition and temperature on the efficiency of pretreatment prior to enzymatic hydrolysis. The aim was to improve the sugar recovery of oil palm empty fruit bunch fiber (EFBF) through enzymatic hydrolysis. Two types of pretreatments, namely, acidified-glycerol (AC-g) pretreatment and alkaline-glycerol (AL-g) pretreatment were conducted. The study proved that AL-g pretreatment promoted higher delignification and enzymatic hydrolyzed sugar yield compared to AC-g pretreatment. Total sugar recovery of 81.44 and 96.55 % was achieved from AL-g pretreatment at 80 and 120 °C respectively, following the enzymatic hydrolysis. However, downstream industrial processes, involving enzyme treatment along the processing line have the preference of acidic condition. Thus, AC-g pretreatment was favorable. Approximately 51.74 % total sugar had been recovered successfully from enzymatic hydrolysis of EFBF after 3 h of pretreatment by using solvent comprising of 50 % acetic acid and 80 % aqueous glycerol at a ratio of 97:3 at 120 °C.  相似文献   

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3.
A novel biodegradable adsorbent called pyrolysed empty fruit bunch fibres (PEF) was prepared by chemo-physical activation of empty fruit bunch fibres (EFB) biochar for removal of cibacron blue 3G-A (CB) dye from aqueous solution. PEF was characterized using FTIR, SEM-EDX, XRD and BET techniques. The N2 adsorption-desorption isotherms indicated PEF’s surface area to be 362.84 m2g−1 and XRD attributed amorphous nature to PEF. After adsorption process, PEF has smoother surface morphology, increase in carbon by weight and shift in functional groups. The established adsorption optimum conditions were pH 10, 45 min contact time and 0.10 g/100 mL adsorbent dosage with 99.05% CB dye removal capacity at 343 K and initial dye concentration 100 mg/L. Desorption ratio >90% after seventh cycle of adsorption-desorption experiments confirmed high reusability (regeneration) of PEF. Pseudo second order kinetic and Freundlich were better fitted with kinetic and isotherm model respectively, while mechanism of adsorption was controlled by film diffusion (external mass transfer). Thermodynamic studied revealed ΔG, ΔS and ΔH to be −3.12 MJ/mol K, 9.11 kJ/mol K, 6.83 kJ/mol respectively at 343 K. The negative value of ΔG, positive values of ΔS and ΔH indicated spontaneity, feasibility and endothermic nature of CB dye adsorption from aqueous solution onto PEF.  相似文献   

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5.
Fully biodegradable poly(butylene succinate) (PBS) and poly(butylene carbonate) (PBC) blends were prepared by melt blending. Miscibility, thermal properties, crystallization behavior and mechanical properties of PBS/PBC blends were investigated by scanning electron microscopy (SEM), phase contrast optical microscopy (PCOM), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and mechanical properties tests. The SEM and PCOM results indicated that PBS was immiscible with PBC. The WAXD results showed that the crystal structures of both PBS and PBC were not changed by blending and the two components crystallized separately in the blends. The isothermal crystallization data showed that the crystallization rate of PBS increased with the increase of PBC content in the blends. The impact strength of PBS was improved significantly by blending with PBC. When the PBC content was 40%, the impact strength of PBS was increased by nearly 9 times.  相似文献   

6.
This article discusses the extraction and characterization of new natural fiber extracted from red coconut empty fruit bunch. The physicochemical, mechanical, and thermal properties of alkali-treated red coconut empty fruit bunch fibers (ARCEFBFs) were reported and compared with other natural fibers for the first time. Cellulose content (65.02 wt%), wax (0.32 wt%), density (1.421 g/cc), and tensile strength (1299.49 MPa) were identified in ARCEFBFs. Fourier transform infrared spectroscopy and X-ray diffraction analysis confirmed that ARCEFBFs are rich in cellulose content with crystallinity index of 53.6%. Thermogravimetric analysis revealed that these fibers are thermally stable until 270.48°C.  相似文献   

7.
Activated carbon fibre (ACF) is a nanoporous material which is useful for various important applications such as safe biogas and natural gas storage as well as heavy/precious metals removal and recovery. It is commonly produced from synthetic fibres such as rayon, polyacrylnitrile and pitch mainly derived from petroleum products, which are less environmental friendly. Besides, cost of ACF production is high due to the high burnt off percentage of such expensive raw materials. As an alternative, natural fibre of oil palm empty fruit bunch was used as a raw material for ACF preparation. Thermogravimetric analysis was carried out with two different gases, i.e. nitrogen gas and oxygen gas in order to observe pyrolysis and combustion behaviours in different gases. Carbonisation temperatures were then identified from the peaks of derivative thermogravimetry results. Different carbonisation temperatures (85?C200?°C) were chosen to carbonise the EFB fibre to observe the effect of carbonisation temperatures on the nanoporous characteristics, i.e. surface area, pore size distribution and pore volume of the ACF produced. Good nanoporous characteristics such as surface area up to 2,740?m2/g of the ACF prepared were observed, suggesting EFB fibre as an excellent candidate to replace synthetic fibre for ACF production. The discussion of relationship between thermal characteristics and nanopores in ACF derived from EFB were also included in this study.  相似文献   

8.
Silkworm silk/Poly(lactic acid) (silk/PLA) biocomposites with potential for environmental engineering applications were prepared by using melting compound methods. By means of Dynamic mechanical analysis (DMA), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), Coefficient of thermal expansion test, Enzymatic degradation test and Scanning electron microscopy (SEM), the effect of silk fiber on the structural, thermal and dynamic mechanical properties and enzymatic degradation behavior of the PLA matrix was investigated. As silk fiber was incorporated into PLA matrix, the stiffness of the PLA matrix at higher temperature (70-160 °C) was remarkably enhanced and the dimension stability also was improved, but its thermal stability became poorer. Moreover, the presence of silk fibers also significantly enhanced the enzymatic degradation ability of the PLA matrix. The higher the silk fiber content, the more the weight loss.  相似文献   

9.
In this work, polymeric biocomposites of poly (butylene adipate-co-terephthalate), PBAT, were reinforced with Munguba fibers (Pseudobombax munguba). This tree is found in great abundance in the marshy areas of the Amazon forest. The motivation for using this fiber in polymer composites comes from the fact that although research for this fiber has not been reported in the scientific literature, it is commonly used by the local population because its bark is strong and flexible. Most important is that the extraction of Munguba fibers does not damage the supplier tree because as it is extracted from the bark, its regeneration starts as it is removed. The fibers were chemically treated by mercerization/acetylation and evaluated by Fourier transform infrared spectroscopy, thermogravimetric analysis and tensile tests. The Munguba fiber presented mechanical properties similar to those of other natural fibers traditionally used in composites, and the chemical treatment provided improvements of its thermal stability and stiffness. The biocomposites showed a better elastic modulus in relation to the pure PBAT. The addition of fibers caused changes in the T g, T m and T c of PBAT as observed by differential scanning calorimetry analysis. The Russel, Halpin-Tsai and Maxwell models were employed to provide the theoretical elastic modulus of the biocomposites.  相似文献   

10.
The concept of the drawing of a molecular network has been employed to derive a total network draw ratio from the combination of the two deformations occurring in the production of poly(butylene terephthalate), PBT, fibers by the consecutive processes of melt spinning and cold drawing. The mechanical properties of PBT can then be more readily explained in terms of increases in this total network draw ratio. However, the preorientation and crystallization that occurs in the melt-spinning process can occur at different strain rates and temperatures, depending on the wind up speed employed, on the extensional viscosity of the polymer, and on the variation of the extensional viscosity with temperature. Therefore, for polymers such as poly(butylene terephthalate), which can exist in two crystalline forms, the morphology of the final drawn fiber might be expected to depend on the first melt-spinning stage of the process as well as on the total network draw ratio. In this work, density, birefringence, mechanical measurements, and WAXD measurements, which have been made on the melt-spun fibers and on the drawn fibers, are described. Small differences in some of the drawn yarn mechanical properties at the same overall network draw ratio are related to the crystallinity and in particular to differences in the proportion of the α and β phases present in the drawn yarn. These in turn are related to differences in the temperature and stress during melt spinning and drawing. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2465–2481, 1997  相似文献   

11.
In the present study, chemical-physical properties of nanofibers isolated from rubberwood (Hevea brasiliensis) and empty fruit bunches (EFB) of oil palm (Elaeis guineensis) were analyzed by microscopic, spectroscopic, thermal and X-ray diffraction methods. The isolation was achieved using chemo-mechanical processes. Microscopy study showed that the diameters of the nanofibers isolated from the EFB ranged from 5 to 40 nm while those of the nanofibers isolated from rubberwood had a wider range (10–90 nm). Fourier transform infrared spectroscopy study demonstrated that almost all the lignin and most of the hemicellulose were removed during the chemical treatments. X-ray diffraction analysis revealed that the crystallinity of the studied nanofibers increased after the chemo-mechanical isolation process. The results of thermogravimetric analysis showed that the nanofibers isolated from both sources had higher thermal stability than those of the bleached pulp and untreated fibers.  相似文献   

12.
张会良 《高分子科学》2015,33(3):444-455
Poly(propylene carbonate)(PPC) was melt blended in a batch mixer with poly(butylene carbonate)(PBC) in an effort to improve the toughness of the PPC without compromising its biodegradability and biocompatibility. DMA results showed that the PPC/PBC blends were an immiscible two-phase system. With the increase in PBC content, the PPC/PBC blends showed decreased tensile strength, however, the elongation at break was increased to 230% for the 50/50 PPC/PBC blend. From the tensile strength experiments, the Pukanszky model gave credit to the modest interfacial adhesion between PPC and PBC, although PPC/PBC was immscible. The impact strength increased significantly which indicated the toughening effects of the PBC on PPC. SEM examination showed that cavitation and shear yielding were the major toughening mechanisms in the blends subjected the impact tests. TGA measurements showed that the thermal stability of PPC decreased with the incorporation of PBC. Rheological investigation demonstrated that the addition of PBC reduced the value of storage modulus, loss modulus and complex viscosity of the PPC/PBC blends to some extent. Moreover, the addition of PBC was found to increase the processability of PPC in extrusion. The introduction of PBC provided an efficient and novel toughened method to extend the application area of PPC.  相似文献   

13.
Biodegradable poly(butylene succinate-co-lactate) (PBSL)/starch blends that contain various amounts of starch were prepared. In addition, luffa fiber (LF) and kenaf fiber (KF) were incorporated, individually, into PBSL/starch (70/30) blend to achieve biocomposites. The LF and KF were treated with NaOH(aq) prior to their addition to the blend. The Young's modulus and flexural modulus of PBSL increased with the addition of starch and increased further after the formation of the biocomposites. The highest Young's modulus increment, which was found in the KF-added system, was up to a 2.2-fold increase compared with neat PBSL. The tensile/flexural/impact strength of PBSL declined after the formation of the blends. With the further addition of LF/KF, the said properties leveled off. The blends exhibited higher complex viscosity and dynamic storage modulus in the melt state than the neat PBSL, and the values further increased in the biocomposites. The crystallization temperature of PBSL slightly decreased in the blends. By contrast, the biocomposites showed an increment in PBSL crystallization temperature, from 73.0 °C (PBSL) to 75.3 °C (KF-added composite), thereby confirming the surface nucleation effect of LF/KF. The blends showed a higher degree of water absorption than PBSL. The formation of biocomposites led to an even higher degree of water absorption. The current approach of including LF/KF in the PBSL/starch blend to enhance the rigidity and biodegradability was advantageous in expanding the applications of PBSL.  相似文献   

14.
Phenyl side chains were introduced to poly(butylene succinate) and poly(ethylene adipate) by the polymerization of the respective monomers in the presence of mandelic acid. The increasing content of the phenyl side chains decreased the melting temperature and the crystallinity but increased the glass‐transition temperature of the aliphatic polyesters. The phenyl side branches reduced the crystallinity of poly(butylene succinate) more significantly than the ethyl or n‐octyl side branches did. The tensile strength, elongation, and tear strength of poly(ethylene adipate) decreased with an increase in the content of mandelic acid units. However, the increasing content of mandelic acid units enhanced the elongation and tear strength of poly(butylene succinate) considerably without a notable deterioration of tensile strength. The biodegradability of the copolyesters was increased as a result of the introduction of more mandelic acid units due to the decrease in the crystallinity. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1504–1511, 2000  相似文献   

15.
Summary A chemical method is described which provides a reproducible quantitative determination of hydroxyl end groups in poly(ethylene terephthalate) and poly (butylene terephthalate). It is based on esterification at 60° C of the hydroxyl end group with dichloroacetic anhydride as an acetylating reagent in dichloroacetic acid as a solvent. After removal of the excess of esterification reagent and solvent by precipitation techniques, the chlorine content of the modified polymer, which is a measure of the hydroxyl group content, is determined by X-ray fluorescence. The standard deviation of the method is 0.7 mmol OH/kg in the region of 10–200 mmol/kg.
Bestimmung von Hydroxyl-endgruppen in Polyäthylenterephthalat und Polybutylenterephthalat durch Reaktion mit Dichloressigsäureanhydrid
Zusammenfassung Die Methode basiert auf der Veresterung der Hydroxyl-Endgruppe mit Dichloressigsäureanhydrid als Acetylierungsreagens in Dichloressigsäure als Lösungsmittel bei 60° C. Nach Entfernung des Überschusses an Veresterungsreagens und Lösungsmittel durch Fälltechniken wird der Chlorgehalt des Derivats, der ein Maß für den Hydroxylgruppengehalt ist, mit Hilfe der Röntgenfluorescenz bestimmt. Die Standardabweichung der Methode beträgt 0,7 mmol OH/kg im Bereich von 10–200 mmol/kg.
  相似文献   

16.
When poly(butylene terephthalate) (PBT) is annealed, a second endotherm is often displayed in a subsequent scanning thermal analysis at a temperature below that of the original endotherm, and this new endotherm appears to grow with annealing at the expense of the original. This growth is not due to chemical changes, because the thermogram obtained before annealing is recovered after complete melting. But a physical change would also seem unlikely because the transformation of higher-melting into lower-melting crystals is generally prohibited by thermodynamics. Two hypotheses to explain the result were tested. The first is that higher-melting crystals are not transformed into lower-melting crystals. Instead, because of recrystallization during thermal analysis, the single endotherm that results without annealing overestimates the population of high-melting crystals present before the analysis. This hypothesis was tested by extending to annealing a mathematical analysis previously used to describe the thermal scanning behavior of specimens crystallized at different cooling rates. Though most features of the thermograms obtained after annealing were able to be described, the decrease in the higher-temperature endotherm concomitant with growth of the lower endotherm was not. The second hypothesis is that the transformation of higher-melting to lower-melting crystals during annealing is allowed because it is coupled to the crystallization of formerly amorphous material. The amount of such crystallization observed for PBT was found to be sufficient to satisfy thermodynamic requirements, suggesting that this hypothesis is correct. © 1994 John Wiley & Sons, Inc.  相似文献   

17.
Li  Yi  Sang  Lin  Wei  Zhiyong  Ding  Chen  Chang  Ying  Chen  Guangyi  Zhang  Wanxi  Liang  Jicai 《Journal of Thermal Analysis and Calorimetry》2015,120(1):261-267
Journal of Thermal Analysis and Calorimetry - Biodegradable poly(butylene succinate) (PBS)/basalt fiber (BF) composites were prepared by melt blending method using twin-screw extruder followed by...  相似文献   

18.
A solid-state mechanochemical processing,that is,pan-milling,was used to conduct the esterification of poly(vinyl alcohol) (PVA) with maleic anhydride (MA) through stress-induced reaction.FTIR spectrum study indicated the presence of ester linkages and olefinic double bonds in maleic anhydride cross-linked PVA.Thermal properties of the cross-linked product were characterized by DSC.The results showed its glass transition temperature was 20℃higher than the original linear PVA and the thermal stability was also improved.  相似文献   

19.
A new method to obtain composites of phenolic resin reinforced with microfibrillated cellulose with a wide fiber content was established and the mechanical properties were evaluated by tensile test. A linear increase in Young’s modulus was observed at fiber contents up to 40 wt%, with a stabilizing tendency for higher fiber percentages. These results were ratified by measurements of the coefficient of thermal expansion (CTE) relative to fiber content, which indicated a strong thermal expansion restriction rate below 60 wt% fiber content, indicating the effective reinforcement attained by the cellulose microfibrils. The low CTE achieved of 10 ppm/K is one of the important properties of cellulose composites.  相似文献   

20.
Organophilic montmorillonite was obtained by the reaction of montmorillonite (MON) and distearyldimethylammonium chloride (DSAC). The modified clay and poly(l-lactide), (PLLA), were solvent-cast blended using chloroform as cosolvent. The structure and properties of the PLLA-clay blends were investigated. Thermal measurements revealed that cold crystallization took place in the as-cast PLLA, and that the clay served as a nucleating agent. From small and wide-angle x-ray scattering measurements, it was found that silicate layers forming the clay could not be individually well dispersed in the PLLA-clay blends prepared by the solvent-cast method. In other words, the clay existed in the form of tactoids, which consist of several stacked silicate monolayers. However, these tactoids formed a remarkable geometrical structure in the blend films. That is, their surfaces lay almost parallel to the film surface, and were stacked with the insertion of PLLA crystalline lamellae in the thickness direction of the film. During the blend drawing process, fibrillation took place with the formation of plane-like voids developed on the plane parallel to the film surface. Furthermore, delamination of the silicate layers did not occur even under the application of a shearing force. Finally, Young's modulus of the blend increased with the addition of a small amount of the clay. © 1997 John Wiley & Sons, Inc.  相似文献   

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