Surface modification of henequen (Agave fourcroydes) fibers by ultraviolet curing with 2‐hydroxyethylacrylate and ethylacrylate: Effect of additives on degradable properties

Henequen fibers were grafted with a double impregnating monomer 2‐hydroxyethylacrylate (HEA) and ethylacrylate (EA) to improve the physicomechanical properties. The fibers soaked in different concentration (1–10%) of monomer + MeOH solution along with photoinitiator Irgacure 907 [2%] were cured under ultraviolet (UV) lamp at different UV radiation intensities (2–14 passes). Concentration of monomer at different radiation intensities was optimized with extent of mechanical properties such as polymer loading, tensile strength, and elongation at break. Enhanced tensile strength (268%) and elongation at break (110%) were achieved by the polymer treated fibers than untreated virgin fibers. We observed that, henequen fibers treated by 3% EA showed better physico‐mechanical properties than those treated by 5% HEA. The tensile properties of henequen fibers treated by 3% EA can be enhanced by adding aloxysilane; 3‐(trimethoxysilyl) propylmethacrylate additives with bulk monomer EA (3%). The degradability of the treated and untreated fibers due to accelerated weathering were also studied and it has been found that surface modified henequen fibers produced more resistivity towards different weathering conditions than untreated fibers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4000–4006, 2006     

Effect of Pretreatment with Ultraviolet Radiation on the Physicomechanical Properties of Photocured Coir (Cocos nucifera) Fiber with 1-Ethyl-2-Pyrrolidone (1-E-2-P) Monomer

Coir fiber (Cocos nucifera) was modified with 1-ethyl-2-pyrrolidone (1-E-2-P) monomer by photocuring. A series of formulations of different concentration of 1-ethyl-2-pyrrolidone (3, 5, 10, 20, 30, and 70%) in methanol was prepared along with 2% photoinitiator (Darocur-1664). Concentration of 1-E-2-P, soaking time, and radiation doses were optimized and found that 5% 1-E-2-P, 7 min soaking time, and 5th pass of UV radiation was the optimized condition that gave the maximum values as polymer loading (PL) (21%) and 71% higher tensile strength over virgin one. The coir fiber was pretreated with ultraviolet (UV) radiation of various intensities for further improvement of mechanical properties. The mechanical properties, such as TS (tensile strength), Eb (elongation at break), and modulus (σ) of the pretreated fiber, were monitored. Fiber treated with 130th pass of radiation showed the higher TS, Eb, and σ. The fiber irradiated at 130th pass of UV radiation gave the maximum values as PL (35%) and 74% and 18% higher tensile strength and elongation at break, respectively. The fiber, both treated and untreated, was subjected to water absorption. The pretreated and cured coir fiber showed the minimum water uptake behavior.     

Effect of alkali and ultraviolet (UV) radiation pretreatment on physical and mechanical properties of 1,6‐hexanediol diacrylate–grafted jute yarn by UV radiation

To improve the physicomechanical properties of jute yarn, grafting with 1,6‐hexanediol diacrylate (HDDA) monomer was performed by a UV radiation technique. A series of HDDA solutions of various concentrations in methanol were prepared. A small quantity of photoinitiator (Darocur‐1664) was also added to HDDA solutions. To optimize the conditions for grafting, the effects of monomer concentration, soaking time, and radiation doses were studied by varying the number of soaking times along with variation of monomer concentrations and UV radiation intensities. The extent of polymer loading and the mechanical properties like tensile strength (TS), elongation at break (Eb), and tensile modulus of both treated and untreated jute were investigated. The highest tensile strength, polymer loading, and modulus were achieved with 5% HDDA concentration, 5 min soaking time, and the 4th pass of UV radiation. This set of conditions was selected as optimum and produced enhanced tensile strength (67%), modulus (108%), and polymer loading (11%) over those of virgin fiber. To further improve the mechanical properties the jute yarns were pretreated with alkali (5% NaOH) solution and after that the alkali‐treated yarn were treated under UV radiation of various intensities. The pretreated samples were grafted with optimized monomer concentration (5% HDDA). Increased properties of alkali + UV‐pretreated and grafted samples such as polymer loading (12%), tensile strength (103%), elongation at break (46%), and modulus (114%) were achieved over those of virgin jute yarn. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 18–24, 2004     

Surface Modification of Sisal (Agavae sisalana) Fiber by Photocuring: Effect of Additives

The sisal fiber (Agavae sisalana) was grafted with methacrylonitrile (MAN) under UV radiation in order to modify its mechanical and degradable properties. A number of MAN solutions of different concentrations in methanol (MeOH) along with photoinitiator Darocur-2959 were prepared. The soaking time, radiation dose and monomer concentration were optimized. Sisal fiber soaked for 60 min in 50% MAN and irradiated at 8th UV pass achieved highest values of tensile properties like tensile strength (TS = 140.2 MPa), and elongation at break factor (Ef = 8) with 8% polymer loading (PL). To further improve the properties of sisal fiber, a number of additives (1%) such as urea (U), polyvinylpyrrolidone (PNVP), tripropelene glycol diacrylate (TPGDA), hexanediol diacrylate (HDDA), trimethyl propane triacrylate (TMPTA), ethylene glycol dimethacrylate (EGDMA) were used in the 50% MAN formulation to graft at the optimized condition. Among the additives used, urea has significantly influenced the PL (9%), TS (190 MPa), and Ef (9) values of the treated sisal fiber. Water uptake and accelerated weathering test were also performed.     

Study on the mechanical and dielectric properties of photocured jute fabrics with 2‐hydroxyethyl methacrylate

Jute fabric (Hessian cloth) was treated with 2‐hydroxyethyl methacrylate (HEMA) under ultraviolet radiation in order to improve the mechanical and electrical properties. Concentration of the monomer 2‐hydroxyethyl methacrylate (HEMA), radiation dose, and soaking time were optimized with respect to mechanical properties such as tensile strength and elongation at break of the treated and untreated Hessian cloth. The 10% HEMA, 15 min soaking time, and 15th pass of radiation rendered the best tensile properties. The variations of dielectric properties with temperature were measured at 10 kHz frequency. It was observed that dielectric constant and loss tangent (tan Ω) increased with increasing temperature up to the transition temperature and then decreased, and at the end become almost constant. The surfaces of treated and untreated jute were characterized by scanning electron microscope. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 655–661, 2003     

Jute Reinforced Polymer Composite by Gamma Radiation: Effect of Surface Treatment with UV Radiation

Jute (Hessian cloth) reinforced polymer composites were prepared with a mixture of 2-hydroxy ethyl methacrylate (HEMA) and aliphatic urethane diacrylate oligomer (EB-204), and then cured under gamma radiation. Thick pure polymer films (2 mm thickness) were prepared by using the same monomer and oligomer at different weight ratios, and 500 krad of total gamma radiation dose at 600 krad/hr was selected for the curing of all composites. Total radiation dose, jute content, and monomer concentration were optimized with the extent of mechanical properties. Among all resulting composites, the composite of 38% jute content at monomer:oligomer = 50:50 (w/w) ratios showed the better mechanical properties, such as 108% increase in tensile strength (TS), 58% increase in bending strength (BS), 138% increase in tensile modulus (TM), and 211% increase in bending modulus (BM) relative to pure polymer film. The gel content values were also found to increase with the increase of jute content in the composite. But the elongation at break (Eb) for both tensile and bending was found to decrease with increasing jute content. The best mechanical properties were obtained when jute fibers were pre-irradiated with UV radiation, such as 150% increase in TS, 90% increase in BS relative to polymer film, 19% increase in TS, and 15% increase in BS relative to untreated jute-based composites. A water uptake behavior investigation of the resulting composites was also performed and composites based on UV-treated jute showed the minimum water uptake value.     

Photocuring of Empty Fruit Bunches of Oil Palm (Elaeis guineensis) Fibers with Allyl Methacrylate (AMA): Effect of Additives on Mechanical and Degradable Properties

Empty fruit bunches of oil palm fibers can be used as environmentally friendly alternatives to conventional reinforcing fibers, like glass, carbon, etc. In order to improve the interfacial properties, this fiber was subjected to grafting with bulk monomer allyl methacrylate (AMA) and cured under UV radiation. It was found that UV curing enhanced the physicomechanical properties to a large extent compared to the untreated virgin fiber. Among different AMA concentration, the fibers treated with 10% monomer showed the best mechanical properties after 15 passes of UV radiation. Different additives such as urea, acrylamide, and NVP were added with the 10% AMA solution, and the effect of additives was studied. It was found that fibers treated with 2% urea showed even better PL and tensile properties than those treated only with AMA. the treated and untreated fiber samples were also subjected to various weather conditions such as simulating weather, soil, and water aging to determine the degradable properties. It was observed that the minimum loss in each case was shown by the sample treated with the formulations that contain urea as additives with AMA and that fiber aged in soil showed higher loss of weight and tensile properties than that aged in water.     

Structure and properties of bombyx mori silk fibers grafted with methacrylamide (MAA) and 2-hydroxyethyl methacrylate (HEMA)

Silk fibers were graft-copolymerized with methacrylamide (MAA) and 2-hydroxyethyl methacrylate (HEMA) in aqueous media, using a chemical redox system as an initiator. High weight gains (300%) were obtained with both monomers, the weight gain being linearly related to the amount of monomer contained in the reaction system. The reaction efficiency attained 95–100%. The extent of homopolymerization was negligible for the MAA grafting system, while large amounts of poly-HEMA covered the surface of silk fibers beyond 70% weight gain. The fiber size increased linearly with the weight gain. The moisture content of MAA-grafted silk fibers was highly enhanced by grafting. The severe grafting conditions caused a partial degradation of the tensile properties of silk fibers, as well as of the degree of fiber whiteness. Following grafting, the breaking load slightly increased, while elongation at break and energy decreased. The decomposition temperature of grafted silk fibers shifted upwards. The Raman spectra of untreated silk fibers showed strong lines at 1667 (amide I), 1451, 1227 (amide III), 1172 and 1083 cm⁻¹. Overlapping of the lines characteristic of both silk fibroin and grafted polymer was observed in the spectra of grafted silk samples. The vibrational mode of the amide III lines of silk fibroin was significantly modified by grafting. © 1996 John Wiley & Sons, Inc.     

Physico-mechanical and degradation properties of biodegradable photografted coir fiber with acrylic monomers

Coir fibers were modified with 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA) and 2-hydroxyethyl acrylate (2-HEA) solutions under UV radiation. Monomer concentration and radiation dose were optimized in terms of grafting and tensile properties. It was found that 20 % HEMA at 20th UV pass, 30 % MMA at 15th UV pass and 25 % 2-HEA at 20th UV pass of radiation produced higher tensile properties over untreated sample. Urea of different concentrations (0.5–2 %) were incorporated into optimized solutions and 1 % urea showed the best properties of the fiber. Water uptake behavior and simulating weathering degradation properties were also performed.     

Effect of pretreatment with detergent on mechanical properties of photocured coir (Cocos nucifera) fiber with ethyleneglycol dimethacrylate

Coir fibers were treated with ethylene glycol dimethacrylate (EGDMA) mixed with methanol (MeOH) under UV radiation. A series of solutions of different concentrations of EGDMA in methanol along with a photoinitator, Irgacure‐500 (mixture of 1‐hydroxylcyclohexylphenylketone and benzophenonc), were prepared. Monomer concentration, soaking time, and radiation intensity were optimized in terms of polymer loading (PL) and mechanical properties. EGDMA (50%), 5 min soaking time at the 4th pass of radiation, produced higher PL and tensile strength (TS), and the values of PL is 17% and TS is 1.3 times of the nontreated one. Then, coir fiber was pretreated with detergent and then treated with the optimized monomer formulation, which exhibited a higher PL of 69% and produced TS of the coir fiber of 4.4 times of the nontreated one. Coir fiber pretreated with detergent along with UV radiation showed the highest TS, which is 18.2 times of nontreated one. Water uptake, degradable properties, and simulated weathering of treated and virgin fibers were also monitored, which showed that EGDMA treatment under UV radiation improved the degradable property. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1630–1636, 2006     

Comparison of mechanical and degradation properties of EG and EGDMA grafted gelatin films

Thin films of gelatin were prepared from gelatin granules in aqueous medium by casting and its mechanical properties like tensile strength (TS), tensile modulus (TM), and elongation at break (Eb %) were studied. Gelatin films were procured with two types of monomers such as 5% ethylene glycol (EG) and 5% ethylene glycol dimethacrylate (EGDMA) to increase the mechanical properties. Five percent of monomer solutions were prepared in MeOH along with 2% photoinitiator; Irgacure-651. Soaking time and UV radiation intensities were optimized with the extent of polymer loading (PL) and the mechanical properties of the cured films. Comparing the properties of EG and EGDMA treated gelatin film, EG showed the best performance. The EG-cured gelatin film with 5?min soaking time showed the highest tensile strength (58.6?MPa) and elongation at break (11.2%). The water uptake was determined for raw film (500.1%), EG grafted gelatin film (375.3%), and EGDMA grafted film (412.9%). The degradation properties in water and soil were determined for the raw and cured gelatin films. It was observed that the raw film degrades more than that of the treated films.     

Enhancement of PVC/ENR blend properties by poly(methyl acrylate) grafted oil palm empty fruit bunch fiber

Effect of oil palm empty fruit bunch (OPEFB) fiber and poly(methyl acrylate) grafted OPEFB on several mechanical properties of poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends were studied. The composites were prepared by mixing the fiber and the PVC/ENR blends using HAKEE Rheomixer at the rotor speed of 50 rpm, mixing temperature 150°C, and mixing period of 20 min. The fiber loadings were varied from 0 to 30% and the effect of fiber content in the composites on their ultimate tensile strength (UTS), Young's modulus, elongation at break, flexural modulus, hardness, and impact strength were determined. An increasing trend was observed in the Young's modulus, flexural modulus, and hardness with the addition of grafted and ungrafted fiber to the PVC/ENR blends. However the impact strength, UTS, and elongation at break of the composites were found to decrease with the increase in fiber loading. An increase in elongation at break and UTS and decrease in the flexural and Young's modulus was observed with the addition of PMA‐g‐OPEFB fiber compared to ungrafted fiber. This observation indicates that grafting of PMA onto OPEFB impart some flexibility to the blend. The morphology of cryogenically fractured and tensile fracture surfaces of the composites, examined by a scanning electron microscope shows that the adhesion between the fiber and the matrix is improved upon grafting of the OPEFB fiber. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and Mechanical Characterization of Gelatin-Based Films Using 2-Hydroxyethyl Methacrylate Cured by UV Radiation

Gelatin films were prepared from gelatin granules in aqueous medium by casting. Tensile strength, tensile modulus and elongation at break of the gelatin films were found to be 27 MPa, 100 MPa and 4%, respectively. Gelatin films were soaked in five different formulations containing 2-hydroxyethyl methacrylate (HEMA) (10–50%, by wt), methanol and photoinitiator and then cured under UV radiation. Again, a series of gelatin solutions was prepared by blending varying percentages (10–50% by wt) of HEMA and then films were prepared and UV cured. It was found that tensile properties of gelatin films improved significantly.     

Modification Jute Yarn with HEMA by Thermal Curing Method

Jute, an important lignocellulosic fiber, can be incorporated in monomer like HEMA in different ways for achieving desired properties and texture. But its high level of moisture absorption, poor wettability and insufficient adhesion between untreated fiber and the polymer matrix lead to debonding with age. In order to improve the above qualities, adequate surface modification is required. In our present work, jute yarn surface modification was done by graft copolymerization of 2-hydroxyethylmethacrylate (HEMA). Jute yarns soaked into HEMA (5–30%) + MeOH and benzoyl peroxide (2%) solution and were cured in an oven at different temperature (30–70°C) for different curing time (15–60 min). Concentration of monomer, soaking time, curing temperature and curing time were optimized with the extent of tensile properties and polymer loading (%PL). Enhanced tensile strength (137%) and polymer loading (36%) were achieved by 20% HEMA solution with 15 min soaking time, 30 min curing temperature at 50°C. The fiber surface was pretreated with 0.05–0.5% KMnO₄ solution and grafted with the optimized conditions. It was observed that KMnO₄ treatment only increases the PL while it decreases the tensile properties a lot, which is even lower than the raw fiber. An experiment involving water absorption capacity shows that water uptake by treated sample is much lower than that of the untreated samples. During weathering in accelerated weathering tester, the treated samples exhibited less loss of the physico-mechanical properties than untreated yarns.     

Role of Amino Acids on In Situ Photografting of Jute Yarn with Acrylamide Using Ultraviolet Radiation

Abstract

To improve the mechanical performance of jute yarn, grafting with acrylamide (AM) monomer has been performed on in situ UV radiation and optimized; the monomer concentration (30%) and irradiation time (60 min) attained 195% tensile strength with 22% polymer loading (PL). The effect of amino acids (1%) as additives in AM with photografted jute yarn at optimized system has been studied. The PL and tensile properties, such as tensile strength (TS) and elongation at break (Eb), of treated samples were enhanced by incorporation of amino acids, and the highest TS value (270%) and Eb value (300%) with 27% PL value were achieved by the sample treated with L‐arginine (Arg). Weak acid [3% acetic acid (Ace)] and strong acid [1% sulfuric acid (Sul)] were also incorporated in the optimized system of AM grafting to investigate their effect on the mechanical properties of photografted jute yarn. Water absorption and weathering resistance of treated untreated samples (TS₀) were also studied.     

Role of Urea on the Physico-Mechanical and Degradable Properties of Mercerized and Acid Hydrolyzed Coir (Cocos nucifera) Fibers Photocured with 1,6-Hexanediol Diacylate

Abstract

Coir fibers were modified with 1,6-hexanediol diacrylate (HDDA) by using ultraviolet (UV) radiation. Concentration of HDDA, soaking time, and radiation dose were optimized and found to be 30% HDDA in methanol along with photoinitiator Irgacure-500 (2%) and 120 min of soaking time the better performance registered as the optimum conditions, where polymer loading (PL) was 17% and tensile strength (TS) was 50%. Urea of different concentrations (0.5–2%) was incorporated with 30% HDDA to monitor its effect on the properties and 1% urea produced the enhanced PL (25%) and TS (82%). For the improvement of the properties, the fibers were subjected to surface treatment with alkali (5% potassium hydroxide) at various mercerizing times in hot and normal conditions. Among all the mercerized fibers, fibers treated with hot alkali for 6 h and cured under optimized condition demonstrated the maximum enhancement of PL (35.5%) and TS (130%). The fibers were also subjected to acid hydrolysis for different times with different acid (H₂SO₄) concentrations. Again the effect of urea (1%) on the properties of the pretreated fibers was scrutinized. Water uptake and degradable properties of the treated and virgin fibers were performed.     

Mechanical and thermal characterization of native brazilian coir fiber

Coir fiber native to the Brazilian northeast coast has been characterized by mechanical, thermal, and microscopy techniques. The tensile strength, initial modulus, and elongation at break were evaluated for untreated and alkaline‐treated fibers. The results showed an enhancement of mechanical properties after 48‐h soaking in 5 wt % NaOH. The thermal stability slightly decreased after this alkaline treatment. A thermal event was observed between 28 and 38°C. The heat capacity, C_p, as a function of temperature curves between −70 and 150°C, were obtained for the untreated and alkaline‐treated coir fibers. The morphologies of the coir‐fiber surfaces and cross sections were observed by scanning electron microscopy. The properties and the morphologies were discussed, comparing the native Brazilian coir fiber with the more extensively studied native Indian coir fiber. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1197–1206, 2000     

碳纤维改性HA/PMMA生物复合材料力学性能的研究

采用原位合成与溶液共混相结合的方法,制备了短切碳纤维增强纳米羟基磷灰石(HA)/聚甲基丙烯酸甲酯(PMMA)生物复合材料。研究了碳纤维的含量和长度对HA/PMMA复合材料结构和力学性能的影响。采用万能材料试验机和扫描电子显微镜对复合材料的力学性能及断面的微观形貌进行了测试和表征。结果表明:碳纤维在HA/PMMA复合材料中分布均匀,有效提高了复合材料的力学性能;碳纤维含量为4%时,复合材料的拉伸强度、弯曲强度、压缩强度和弹性模量等均达到最大值;复合材料的断裂伸长率随碳纤维含量的增加而减小;当碳纤维含量一定时,随其长度的增加,复合材料的拉伸强度、弯曲强度和弹性模量均增加,但断裂伸长率降低。     

竹纤维增强PP复合材料的研究

介绍了竹纤维增强聚丙烯(PP)复合材料的性能,初步探讨了竹纤维的处理、未处理以及纤维含量对增强PP的力学性能的影响因素。实验证明:与PP材料相比,添加竹纤维可使复合材料的力学性能有不同程度的改善,特别是对复合材料的冲击强度、拉伸强度及断裂伸长率影响较明显。     

Surface modification of ultra-high molecular weight polyethylene fibers by γ-radiation-induced grafting

A technique for grafting acrylic polymers on the surface of ultra-high molecular weight polyethylene (UHMWPE) fibers utilizing ⁶⁰Co gamma radiation at low dose rates and low total dose has been developed. Unlike some of the more prevalent surface modification schemes, this technique achieves surface grafting with complete retention of the exceptional UHMWPE fiber mechanical properties. In particular, poly(butyl acrylate) and poly(cyclohexyl methacrylate) were successfully grafted onto UHMWPE fibers with no loss in tensile properties. The surface and tensile properties of the fibers were evaluated using Fourier transform infrared/photoacoustic spectroscopy (FTIR/PAS), X-ray photoelectron spectroscopy (XPS), and tensile tests. The reinforcement efficiency of untreated, polymer-grafted, and plasma-treated UHMWPE fibers in polystyrene and a poly(styrene-co-butyl acrylate-co-cyclohexyl methacrylate) statistical terpolymer was characterized using mechanical tensile tests. The thermoplastic matrix composites were prepared with 4 wt% discontinuous (10 mm), randomly distributed UHMWPE fibers. An approximate 30% increase in composite strength and modulus was observed for poly(cyclohexyl methacrylate)-grafted fibers in the terpolymer and polystyrene matrices. A comparable improvement was realized with the plasma-treated fibers. On the other hand, poly(butyl acrylate) grafts induced void formation, i.e. energy dissipation through plastic deformation and volume expansion at the fiber/matrix interface in terpolymer composites. The latter resulted in a 75% increase in the elongation to failure. The effect of polymer grafts on fiber/matrix adhesion is discussed in terms of the graft and matrix chain interactions and solubility, graft chain mobility, and fracture surface characteristics as determined by scanning electron microscopy (SEM).