Preparation and characterization of jute fabrics reinforced urethane based thermoset composites: Effect of UV radiation

Jute fabrics reinforced thermoset composites were prepared with different formulations using urethane acrylate oligomer, methanol, and benzyl peroxide. Jute fabrics were soaked in the prepared formulations and fiber content in the composites was optimized with the extent of mechanical properties. Among all the resulting composites, 55 wt% jute content at oligomer:methanol:benzyl peroxide=75:24.5:0.5 (w/w/w) ratio showed best mechanical properties. The optimized jute fabrics were cured under UV radiation at different intensities and their mechanical properties were measured. Jute fabrics were treated with potassium permanganate (KMnO₄) solution of different concentrations (0.01, 0.02, 0.03, and 0.05 wt%) for different soaking times (1–5 min) before the composite fabrication. Optimized jute fabrics (jute fabrics treated with 0.02 wt% KMnO₄ for 2 min soaking time) were soaked in the optimized formulation and cured under UV radiation at different intensities and measured their mechanical properties. Scanning electron microscopic investigation showed that surface modification improves fiber/matrix adhesion. Water uptake and soil degradation test of the treated and untreated composite samples were also performed.     

Role of potassium permanganate and urea on the improvement of the mechanical properties of jute polypropylene composites

Jute fabrics (hessian cloth) reinforced polypropylene (PP) matrix composites (45 wt% fiber) were fabricated by compression molding. Jute fabrics were treated with 2-hydroxyethyl methacrylate (HEMA) using ultraviolet radiation in order to improve the mechanical properties of the composites. Concentration of HEMA, soaking time and radiation dose were optimized. It was found that 15% HEMA in methanol along with photoinitiator Darocur-1173 (2 %), 10 min soaking time and 20th pass of radiation rendered better performance. Urea of different concentrations (0.5–2 %) was incorporated with 15 % HEMA to monitor its effect on the properties and 1 % urea revealed the best results. For the improvement of the properties, jute fabrics were treated with potassium permanganate (KMnO₄) solution in acetone of different concentrations (0.02, 0.03, 0.05, and 0.5 %) at different soaking times (1, 2, 3, and 5 min) before the composite fabrication. Optimized jute fabrics (jute fabrics treated with 0.03 % KMnO₄) were again treated with HEMA (15 %) solution along with urea (1 %) and promising improvement of mechanical properties of the composites was observed. Scanning electron microscopy, water uptake, soil degradation and thermal aging of the treated and untreated composites were also performed.     

Effect of chemical modifications on the performance of biodegradable photocured coir fiber

Coir fibers (Cocos nucifera) were treated with 1-ethyl-2-pyrrolidone (1-E-2-P) mixed with methanol (MeOH) under UV radiation. A series of solutions of different concentrations of 1-E-2-P in methanol along with a photoinitiator, Darocur-1173, were prepared. Monomer concentration, soaking time, and radiation dose were optimized in terms of grafting and mechanical properties. Ten percent 1-E-2-P, 6 min soaking time, and a 15th pass of radiation produced higher tensile strength (53 %) and elongation at break (230 %) than those of virgin fiber, as well as the highest grafting value (4.9 %). The effect of additives (1 %), such as urea and silane (3-trimethoxysilyl propyl methacrylate) on the properties of coir fiber was studied. Among the additives used, silane showed the best performance. For further improvement of the properties, the fibers were treated with alkali (potassium hydroxide) solution of different temperatures (0–60 °C). A 10 % alkali-treated fiber showed the best properties such as grafting (6.2 %), tensile strength (72 %) and elongation at break (330 %) over virgin fiber. The silane-treated fiber produced the minimum loss of the properties, as well as a lower water uptake than those of the untreated one. The effect of simulating weathering on the degradation properties of samples was also performed.     

不同处理方法对菜用黄麻种子萌发的影响

为了提高菜用黄麻种子的发芽率,保证出苗的整齐度,采用沙子研磨、热水浸种、98%浓硫酸浸种和40%氢氧化钠浸种共4种方法对菜用黄麻桂麻菜1号和桂麻菜2号种子进行处理。结果表明:沙子研磨、热水浸种、98%浓硫酸浸种处理对种子的发芽势和发芽率均有显著地影响。桂麻菜1号和桂麻菜2号在种子与沙子体积比1:4、研磨时间为8 min时,种子发芽率最高分别为78.0%、86.3%;热水80℃浸种8 min时,种子发芽率最高分别为86.3%、83.0%;98%浓硫酸浸种处理30 min时,桂麻菜1号发芽率最高达78.3%,桂麻菜2号在浸种10 min时,发芽率最高达87.3%。40%氢氧化钠浸种处理对菜用黄麻种子发芽率的影响不明显。在这4种菜用黄麻种子处理方法中,热水浸种方法易于操作,处理时间短,成本低廉,适合生产上推广运用。     

Effect of ionizing and non-ionizing preirradiations on physico-mechanical properties of coir fiber grafting with methylacrylate

Coir fibers were modified with methyl acrylate (MA) mixed with methanol (MeOH) under thermal curing method at different temperatures (40?C80 °C) for different curing times (20?C60 min). A series of solutions of different concentrations of MA in methanol along with 2 % benzoyl peroxide, were prepared. Monomer concentration, curing temperature, and curing time were optimized with the extent of grafting of monomer and mechanical properties of cured fiber and found to be 30 % MA, 60 °C and 40 min curing time registered as better performance (Grafting (Gr) = 5.7 %, tensile strength (TS) = 72 %, elongation at break (Eb) = 88 %) than those of untreated fiber. For further improvement of the properties, untreated coir fibers were pretreated with gamma and UV radiations at different doses and then pretreated fibers were soaked in the optimized monomer and cured under optimum conditions. Coir fiber pretreated with UV radiation and grafted with optimized monomer showed the best properties such as Gr (7.12 %), TS (132 %), and Eb (153 %) over raw fiber. Water uptake and simulated weathering test of untreated and treated coir fibers were studied.     

Effect of chemical softening of coconut fibres on structure and properties of its blended yarn with jute

Coconut fibres were subjected to chemical treatment to obtain softer and finer fibres, suitable to blend with other finer fibre like jute. The chemical softening recipe was optimized using Box-Behnken design of experiments as 40 % Na₂S, 10 % NaOH and 6 % Na₂CO₃, which notably reduced the fineness (33 %) and flexural rigidity (74 %) and improved tensile property of coconut fibre. Effect of softening of coconut fibre on its process performance was studied in high speed mechanized spinning system at different blend ratios with jute. Blending with jute assists in spinning of coconut fibre to produce yarn of 520 tex at production rate of 5-6 kg/h, as compared to 15 kg/day for hand spun 5300 tex raw coconut fibre yarn in manual system. Analysis of blended yarn structure in terms of packing density, radial distribution of fiber components (SEM) and mass irregularity were investigated. SEM shows yarns made from softened coconut fibre -jute blends are more compact than raw coconut fibre -jute blend yarns. Coconut fibres were preferentially migrated to core of the yarn. Major yarn properties viz., tensile strength, and flexural rigidity of raw and chemically softened blended yarns were compared against their finest possible 100 % coconut fibre yarn properties. Yarn made up to 50:50 chemically softened coconut fibre-jute blend showed much better spinning performance, and having superior property in terms of reduced diameter, higher compactness, strength, initial modulus and less flexural rigidity than 100 % raw, 100 % chemically softened coconut fibre rope, and raw coconut fibre-jute blend yarns.     

Effect of mercerization on mechanical, thermal and degradation characteristics of jute fabric-reinforced polypropylene composites

Jute fabric reinforced polypropylene composites were fabricated by compression molding technique. Fiber content in the composites was optimized at 45 % by weight of fiber by evaluating the mechanical parameters such as tensile strength, tensile modulus, bending strength, bending modulus. Surface treatment of jute fabrics was carried out by mercerizing jute fabrics with aqueous solutions of NaOH (5, 10 and 20 %) at different soaking times (30, 60 and 90 mins) and temperatures (0, 30 and 70 °C). The effect of mercerization on weight and dimension of jute fabrics was studied. Mechanical properties of mercerized jute-PP composites were measured and found highest at 20 % NaOH at 0 °C for 60 min soaking time. Thermal analytical data from thermogravimetric and differential thermal analysis showed that mercerized jute-PP composite achieved higher thermal stability compared to PP, jute fabrics and control composite. Degradation characteristics of the composites were studied in soil, water and simulated weathering conditions. Water uptake of the composites was also investigated.     

Preparation, characterization and bioactivity assessment of chitosan-acetylated jute blended green films

In recent years, there has been a great demand for artificial materials for biomedical applications, especially to bone growth. In the present study, the in vitro bioactivity of chitosan-acetylated jute blended film was investigated through biomimitic growth of bone-like apatite layer formation in simulated body fluid (SBF) on the surface of the film. Chitosan was prepared from crab shells and the blended film was prepared by solvent casting method using 10 % formic acid aqueous solution of in-house chitosan and mercerized, acetylated jute fiber. Water absorption characteristics (swelling test) and tensile strength (Universal testing machine) of the films were determined. Thermal behavior of the films were examined by TGA analysis. The biocompatibility of the chitosan-acetylated jute (CAJ) film was indicated by the formation of hydroxy apatite (HAp) bone-like layer formed on the surface when soaked in SBF solution for 14 days. The topography of the film was characterized by scanning electron microscope (SEM) and Ca/P ratio of the apatite layer was confirmed to be 50:50 by EDX analysis. The results showed that the CAJ film will be a promising bone substituting material.     

二氧化氯对剑麻外植体材料消毒的应用研究

为建立高效、环保的剑麻无菌繁殖技术,以H.11648剑麻的珠芽为外植体,以1 000 mg/L HgCl2溶液对外植体材料浸泡消毒灭菌20 min作对照,以不同浓度的ClO2溶液对外植体材料进行不同时间的浸泡消毒灭菌试验。结果表明,500~3 000 mg/L ClO2溶液对剑麻珠芽外植体浸泡消毒20~50 min,可显著降低培养材料的污染率,外植体生长好,腋芽萌动快,腋芽萌发率在14.175%~47.335%,显著高于对照的4.340%,最初3次继代的增殖率为5.685~11.325倍,显著高于对照的3.040倍。剑麻珠芽外植体材料消毒灭菌的最适宜方法是1 000 mg/LClO2溶液浸泡消毒30 min。     

Quality attributes of three new improved lines of Nigerian lima beans (Phaseolus lunatus L. Walp.)

Three promising new improved lines of lima beans (Tpl 1^B, Tpl 7^A and Tpl 175^A) were evaluated for physicochemical properties and cooking quality. The beans varied in seed dimensions and weights with Tpl 1^B and Tpl 7^A having smaller seed volume than Tpl 175^A. Seed coat percentages, leached solids and swelling capacities were within a range of 10.2–19.6% (w/w), 0.44–0.92 g/100 g and 94.0–121.0 g/100 g dry bean, respectively. Cooking times varied between 62 and 81 min without soaking and were reduced by about 34%following a presoaking treatment in water for 12 h at room temperature (28 ± 1 °C). Small seeds absorbed higher amounts of water during soaking and required more cooking time than larger seeds. No significant (p>0.05) difference in cooked texture was found between unsoaked beans cooked for 50 min and soaked beans cooked for 30 min,suggesting that cooking times and cooked texture for all lines were improved through soaking.     

Effect of processing on flatus producing oligosaccharides in cowpea (Vigna unguiculata) and the tropical African yam bean (Sphenostylis stenocarpa)

The effect of dehulling, soaking and soaking/cooking on sucrose, raffinose and stachyose in mature dry seeds of nine varieties of cowpea (Vigna unguiculata) and one variety of tropical African yam bean (Sphenostylis stenocarpa) were investigated. The results showed a progressive decrease in sucrose, raffinose, and stachyose contents. Soaking for 12 hours and cooking for 30 min eliminated most of the sucrose, raffinose and stachyose. The sugar contents in whole raw cowpea were sucrose 0.73–4.58%, raffinose 0.71–6.86% and stachyose 2.38–3.87%, and for tropical African yam bean sucrose 4.08%, raffinose 1.08% and stachyose 4.14% while the seeds soaked for 12 hours and cooked for 30 min had for cowpea sucrose 0.03–0.81%, raffinose 0.04–0.20% and stachyose 0.12–0.72%, and tropical African yam bean sucrose 0.70%, raffinose 0.40% and stachyose 0.41%.     

Preparation of regenerated cellulose fiber via carbonation (II)

Sodium cellulose carbonate (CC-Na) dissolved in 8.5 wt% NaOH/ZnO (100/2–3, w/w) aqueous solution was spun into some acidic coagulant systems. Diameter of regenerated cellulose fibers obtained was in the range of 15–50μm. Serrated or circular cross sectional views were obtained by controlling salt concentration or acidity in the acid/salt/water coagulant systems. Velocity ratio of take-up to spinning was controlled up to 4/1 with increasing spinning velocity from 5 to 40 m/min. Skin structure of was developed at lower acidity or higher concentration of coagulants. Fineness, tenacity and elongation of the regenerated cellulose fibers were in the range of 1.5–27 denier, 1.2–2.2 g/d, and 8–11.3%, respectively. All of CC-Na and cellulose fibers spun from CC-Na exhibited cellulose II crystalline structure. Crystallinity index was increased with increasing take-up speed.     

Mechanical and electrical properties of photocured jute fabric with 2-hydroxy ethylacrylate

Jute fabric (hessian cloth) was grafted with 2-hydroxy ethylacrylate (HEA) and aliphatic urethane diacrylate oligomer (M-1200) under UV radiation at different intensities (16, 20, 30, 40, 50, and 60 pass) in order to improve the mechanical and electrical properties. The concentrations of the monomer (HEA), and oligomer (M1200), radiation dose, and soaking time were optimized with respect to mechanical property such as tensile strength (TS) of the treated and untreated hessian cloth. The 73 % HEA, 25 % oligomer (M-1200) and 2 % photoinitiator (Darocur-1116) in 1 minute soaking time showed the highest TS at 50th UV pass. The electrical properties such as dielectric constant and loss tangent of both treated and untreated sample were measured at frequency 10 kHz with the variation of temperature. It was observed that dielectric constant and loss tangent increased with increasing temperature up to the transition temperature and then decreased.     

Effect of γ (Gamma)-radiation on the physico-mechanical properties of grafted jute fabric reinforced polypropylene (PP) composites

The bleached jute fabric (BJF) reinforced polypropylene (PP) composites with various contents of acrylic acid (AA)-treated BJF and un-AA-treated BJF were fabricated by compression moulding method at 190 °C. The AA-grafted BJF reinforced PP composites were then irradiated by γ-ray at various doses. The mechanical properties of neat PP (N-P), ungrafted-BJF and PP composites (UG-BJFPC), AA-grafted-BJF and PP composites (AA-BJFPC) and γ-ray cum AA-grafted-BJF and PP composites (γAA-BJFPC) show maximum tensile strength (TS) of 30, 46, 47 and 51 MPa, maximum flexural strength (FS) of 34, 49, 50 and 54 MPa and maximum Young’s modulus (E) of 280, 428, 436, and 680 MPa, respectively. The increase of TS, FS and E from UG-BJFPC are 2 %, 2 %, and 2 % for AA-BJFPC and 11 %, 10 % and 59 % for γAA-BJFPC. The TS, FS and E are found to increase with radiation dose up to 500Krad and then decrease. The water absorption (WA) for UG-BJFPC, AA-BJFPC and γAA-BJFPC is respectively about 14, 10 and 9 %, indicating a gradual development of hydrophobic character of the composites first by AA-treatment and then by γ-ray-treatment. AA treatment on jute fabric and gamma irradiation on composite result in significant change of morphology of the jute fabric composites surface and better mechanical bonding between fabric and polymer matrix, as a result improved mechanical properties are found.     

Preparation and characterization of melt-spun PVC filament yarns

Polyvinyl chloride (PVC) fibers were melt-spun to prepare mono and multifilament yarns. To find optimum spinning and drawing conditions, various parameters such as spinning temperature, spinneret diameter, drawing temperature, and drawing ratio were examined. From the observation of the spinnability under various conditions, we found that the optimum conditions were as following: the extrusion temperature and die temperature were 175–180°C and 185–190°C, and the drawing temperature and drawing ratio were 85–95°C and 3.4, respectively. Under these conditions, the spinneret diameter could be reduced to the minimum value, 0.5 mm. Spun PVC filament yarns were subjected to the different yarn texturing process of stuffing box and pin false-twist method. The PVC yarn fabric was prepared by the knitting of textured yarns. Finally, the anion-emission and antibiotic properties of the knitted PVC fabrics were precisely evaluated.     

Formulation and Sensory Evaluation of Prosopis alba (Algarrobo) Pulp Cookies with Increased Iron and Calcium Dialyzabilities

Prosopis alba (algarrobo) is an important indigenous specie, which fruits are used as food and feed since ancient times. Cookies containing algarrobo pulp (AP) with increased iron and calcium availabilities were formulated and sensory evaluated. AP is preferred as food ingredient because of its high sugar content and pleasant flavour. Formulated cookies mean proximal composition was 8.9 g/100 g protein, 7.2 g/100 g dietary fiber, 25 g/100 g total sugar, and 18.5 g/100 g crude fat with iron and calcium contents 30 ppm and 340 ppm, respectively. Ascorbic (AA) and citric (CA) acids at different mM acid: mM Fe were added in order to increase mineral availabilities being evaluated by an in vitro method. Those ratios were 5:1 and 10:1 for AA:Fe whereas for CA:Fe were 50:1 and 100:1 and combinations of them. After chosen the best AA:Fe and CA:Fe ratios (5:1 and 50:1, respectively), sensory evaluation with trained sensory panel and a consumer acceptability test with one hundred and seventy untrained judges were carried out. Acceptability test showed that 77.65% of the people (<25 years old 41.76%, 25–50 years old 20.00% and>50 years old 15.89%) tasting final formulated cookies indicated that they “like very much” or “moderately like” and there were not consumers rejecting them.     

浸泡介质及浸泡条件对豆浆中抗营养因子及品质的影响

为了最大程度降低豆浆中抗营养因子含量的同时保证品质优良,以干豆制浆为对照,利用不同浸泡介质(水、柠檬酸溶液、NaHCO_3溶液)及不同浸泡条件,探究前处理工艺条件以及介质的改变对豆浆中抗营养因子及营养品质的影响。结果表明:浸泡处理能有效降低豆浆中胰蛋白酶抑制因子活性和植酸含量,但不同介质对不同抗营养因子的效果不同。经浸泡处理后的胰蛋白抑制因子的最低活性为30.88±1.35 TIU·mg^-1,相对于未处理组降低了54%;植酸最低含量为3.46±0.15 mg·mL^-1,相对于未处理组降低了77.4%;而经浸泡处理后的单宁含量却显著上升(P<0.05)。从降低胰蛋白酶抑制因子活性的效果来看,NaHCO_3>水>柠檬酸;从降低单宁含量的效果来看,柠檬酸>NaHCO_3>水;从降低植酸含量的效果来看,柠檬酸>水>NaHCO_3。除抗营养因子外,豆浆的品质指标也发生了显著变化,NaHCO_3浸泡组的总体品质最优,除了个别品质指标(蛋白质含量)与水浸泡组相比差异不显著(P>0.05),其它品质成分含量均显著高于水浸泡组,而柠檬酸浸泡组的品质为3组中最差。选取NaHCO_3溶液作为浸泡介质进行正交工艺优化,当浸泡温度为25℃,浸泡时间为16 h,浸泡豆水比为1∶4,NaHCO_3浓度为0.45%时,豆浆的抗营养因子的去除效果最好,品质最优。     

Carbon dioxide and methane gas permeations in thermally annealed and chemically cross-linked commercial polyimide hollow fiber membrane

Two types of modifications were performed on a commercial polyimide (PI) hollow fiber membrane for carbon dioxide (CO₂) and methane (CH₄) gas permeations. Thermal annealing was conducted between 50- and 200 °C while chemical cross-linking was performed using 0.1- to 1.0 wt% of N, (1-Naphthyl) ethylene-diamine dihydrochloride (NED). Membrane characterization revealed densification of the thermally annealed PIs. But formation of macrovoids was observed in PIs annealed near its glass transition temperature (207 °C). Fourier transform infrared spectroscopy confirmed the successful cross-linking of NED with PI. Highest CO₂ permeance was obtained from pristine PI (P/L=225 GPU) but it also had the lowest selectivity (α=72). The performances of thermally annealed (P/L=160–219 GPU, α=76–106), NED crosslinked (P/L=68–139 GPU, α=65–95) and thermally induced NED cross-linked (P/L=51-91 GPU, α=98–138) PIs varied according to modification conditions. Among the modified membranes, highest CO₂ permeance was obtained from thermally annealed PI at 100 °C (P/L=211GPU, α=106) while thermally induced NED cross-linked PI (100 °C, 0.5 wt% NED) exhibited the highest selectivity (P/L=91, α=138). Both modified membranes are the best candidates for CO₂/CH₄ separation.     

Preparation of regenerated cellulose fiber via carbonation. I. Carbonation and dissolution in an aqueous NaOH solution

Cellulose carbonate was prepared by the reaction of cellulose pulp and CO₂ with treatment reagents, such as aqueous ZnCl₂ (20–40 wt%) solution, acetone or ethyl acetate, at −5–0°C and 30–40 bar (CO₂) for 2 hr. Among the treatment reagents, ethyl acetate was the most effective. Cellulose carbonate was dissolved in 10% sodium hydroxide solution containing zinc oxide up to 3 wt% at −5–0°C. Intrinsic viscosities of raw cellulose and cellulose carbonate were measured with an Ubbelohde viscometer using 0.5 M cupriethylenediamine hydroxide (cuen) as a solvent at 20°C according to ASTM D1795 method. The molecular weight of cellulose was rarely changed by carbonation. Solubility of cellulose carbonate was tested by optical microscopic observation, UV absorbance and viscosity measurement. Phase diagram of cellulose carbonate was obtained by combining the results of solubility evaluation. Maximum concentration of cellulose carbonate for soluble zone was increased with increasing zinc oxide content. Cellulose carbonate solution in good soluble zone was transparent and showed the lowest absorbance and the highest viscosity. The cellulose carbonate and its solution were stable in refrigerator (−5°C and atmospheric pressure).     

Antioxidant Capacity and Antimutagenic Activity of Natural Oleoresin from Greenhouse Grown Tomatoes (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis>)

Natural oleoresins rich in lycopene were obtained from two varieties of tomato (Zedona and Gironda) and their nutraceutical potential (antioxidant and antimutagenic capacity) was evaluated. Both oleoresins had a high content of lycopene, 58.33 ± 1.67 mg/g (Zedona) and 63.97 ± 0.80 mg/g (Gironda). The antioxidant activity (AA) of the oleoresins by β-carotene method were 56.4–74.5% (Zedona) and 51–72.8% (Gironda), while when using the free radical stable 2,2-diphenyl-picryl-hydrazyl (DPPH) method, the antiradical activity (ARA) was determined to be 18.2–32.7% (Zedona) and 16.6–26.7% (Gironda) for the concentrations tested that of 200–400 μM equivalents of lycopene. The antimutagenic activity of the oleoresins was tested against aflatoxin B₁ (AFB₁) using the microsuspension assay, both varieties had a very high antimutagenic potential against AFB₁ (60–66%).These results suggest the NCRT can be taken advantage to obtaining rich oleoresin in lycopene with a nutraceutical value.