Showing papers on "Natural fiber published in 2001"
TL;DR: In this paper, a critical review on the physical and chemical treatment methods that improve the fiber-matrix adhesion and their characterization methods is given, as well as a detailed characterization of these methods.
Abstract: An Important aspect with respect to optimal mechanical performance of fiber reinforced composites in general and durability in particular is the optimization of the interfacial bond between fiber and polymer matrix. The quality of the fiber-matrix interface is significant for the application of natural fibers as reinforcement for plastics. Since the fibers and matrices are chemically different, strong adhesion at their interfaces is needed for an effective transfer of stress and bond distribution throughout an Interface. A good compatibilization between cellulose fibers and non-polar matrices is achieved from polymeric chains that will favor entanglements and interdiffiusion with the matrix. This article gives a critical review on the physical and chemical treatment methods that improve the fiber-matrix adhesion and their characterization methods.
1,071 citations
TL;DR: A review of biocomposites highlighting recent studies and developments in natural fibers, bio-polymers, and various surface modifications of natural fibers to improve fiber-matrix adhesion is presented in this paper.
Abstract: A review of biocomposites highlighting recent studies and developments in natural fibers, bio-polymers, and various surface modifications of natural fibers to improve fiber-matrix adhesion is presented. One of the most important factors which determine the final performance of the composite materials is the quality of the fiber-matrix interface. A sufficient degree of adhesion between the surface of hydrophilic ligno-cellulosic natural fibers and the polymer matrix resin is usually desired to achieve optimum performance of the biocomposite. Dewaxing, alkali treatment, isocyanate treatment, peroxide treatment, vinyl grafting, bleaching, acetylation, and treatment with coupling agents are useful ways to improve fiber-matrix adhesion in natural fiber composites. Two major areas of biocomposites will be discussed in this article. One is the most predominant biocomposite currently being commercialized for semi-structural use in the durable goods industries, e.g. auto-industries, i.e. natural fiber-polypropylen...
911 citations
TL;DR: In this paper, the state-of-the-art knowledge on structure formation of fibers and films via the NMMO-route comprising the cellulose-NMMO-water phase system, the state of solution, the dry jet-wet shaping, the precipitation, and the drying stages.
861 citations
TL;DR: In this paper, cellulosic fibers from Eucalyptus urograndis pulp were used as reinforcement for thermoplastic starch in order to improve its mechanical properties.
429 citations
TL;DR: In this paper, the degradation behavior of flax fibers and their mechanical properties were investigated, and the results showed that upgraded Duralin flax fiber absorbed less moisture than untreated Green flax fibre.
Abstract: The environmental degradation behaviour of flax fibers and their mechanical properties were investigated Upgraded Duralin flax fibers, which have been treated by a novel treatment process for improved moisture and rot sensitivity, were studied Results showed that upgraded Duralin flax fibers absorbed less moisture than untreated Green flax fibers, whereas the mechanical properties of the upgraded fibers were retained with moisture absorption, if not improved In addition electrochemical studies were conducted on these fibers These data agreed well with conventional moisture absorption data Zeta (ζ)-potential measurements at different pH-levels showed differences for Duralin fibers, which can be attributed to differences in morphological features
382 citations
TL;DR: In this article, the use of high quality natural fibres as reinforcements was studied using the resin transfer molding (RTM) processing technique and the results from mechanical testing showed that the (50/50) high quality ArcticFlax/epoxy composite has a stiffness of about 40 GPa compared to the stiffness in pure epoxy of 3.2 GPa.
Abstract: In this work the use of high quality natural fibres as reinforcements was studied using the resin transfer moulding (RTM) processing technique. The fibres were unidirectional high quality ArcticFlax and the matrix was an epoxy resin. The mechanical properties of the composites were compared to conventional RTM manufactured glass fi- bre composites, traditionally retted UD-flax fibre composites and to the pure epoxy. The results from mechanical testing showed that the (50/50) high quality ArcticFlax/epoxy composite has a stiffness of about 40 GPa compared to the stiffness in pure epoxy of 3.2 GPa. The same composite has a tensile strength of 280 MPa compared to 80 MPa of the ep- oxy. RTM showed to be a suitable processing technique for natural fibre composites when high quality laminates are preferred.
219 citations
TL;DR: In this article, the structure-property relationship of kenaf fiber reinforced polypropylene (PP) and its impact copolymers was investigated and a significant improvement in impact strengths was observed when the maleated polypropylenes (MAPP) was used in the composites.
Abstract: Although lignocellulosic, fiber-thermoplastics composites have been used for several decades, recent economic and environmental advantages have resulted in significant commercial interest in the use of these fibers for several applications. Kenaf is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. This paper reports the structure-property relationships of kenaf fiber reinforced polypropylene (PP) and its impact copolymers. The use of maleated polypropylenes (MAPP) is important to improve the compatibility between the fiber and matrix. A significant improvement in impact strengths was observed when the MAPP was used in the composites. Results also indicate that the impact copolymer blends with coupling agent have better high temperature moduli and lower creep compliance than the uncoupled systems. The coupling agent also changes the crystallization and melting behavior of these blends. Because of the better adhesion between the polymer molecules and kenaf fibers, the coupled samples have more restricted molecules than the uncoupled blends. As a result, the crystallization of the coupled high molecular weight blends is slower than the uncoupled blends, resulting in a lower crystallization temperature (T C ) and reduced crystallinity. For the lower molecular weight blends, the coupling agent enhances the crystallization of polymer matrix and results in a higher crystallization temperature and increased crystallinity of the coupled blend. The coupled blends also have more defects in the polymer crystals, and the crystallinity of coupled blends is also lower than the uncoupled blends. This could explain the lower melting temperatures of the coupled samples as compared to uncoupled samples.
185 citations
TL;DR: In this article, the effects of thermal exposure on mechanical properties (tenacity) as well as on fiber fine structure (degree of polymerization and degree of crystallinity) of jute and flax fibers were studied in detail.
Abstract: The thermal degradation of jute and flax fibers under temperatures between 170 and 210°C for a maximum of 120 min was studied in detail. This article will analyze the effects of the thermal exposure on mechanical properties (tenacity) as well as on fiber fine structure (degree of polymerization and degree of crystallinity). It was found that temperatures below 170°C only slightly affects fiber properties, while temperatures above 170°C significantly dropped tenacity and degree of polymerization. Because of chain scissions, a slight increase in degree of crystallinity was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1417–1422, 2001
174 citations
TL;DR: In this article, the thermal stability of flax fibres was evaluated with thermogravimetric analyses and determination of the mechanical properties after thermal exposure was carried out on individual fibres and on bundles.
Abstract: Scutched and hackled long flax fibres varying in retting degree, namely green, under-retted and normally retted flax, and elementary fibres were tested for their mechanical and thermal properties. Tensile tests were performed on individual fibres and on bundles. The thermal stability is evaluated with thermogravimetric analyses (TGA) and determination of the mechanical properties after thermal exposure. For the investigated samples, no significant influence of the retting degree on tensile strength can be determined. Exposure to different temperatures results in a weight decrease and affects the mechanical properties of the fibres.
118 citations
TL;DR: The mechanical performance of natural fiber reinforced polymers is often limited owing to a weak fiber-matrix interface as discussed by the authors, and melamine-formaldehyde resins are well known to have a stro...
Abstract: The mechanical performance of natural fiber reinforced polymers is often limited owing to a weak fiber-matrix interface. In contrast, melamine-formaldehyde (MF) resins are well known to have a stro ...
69 citations
TL;DR: In this paper, composites were prepared from waste wood flour, sisal fiber and polypropylene (PP) and the surface of the filler was modified to enhance the chemical affinity between hydrophilic cellulosic and hydrophobic polymer.
Abstract: Composites were prepared from waste wood flour, sisal fiber and polypropylene (PP) The surface of the filler was modified to enhance the chemical affinity between hydrophilic cellulosic and hydrophobic polymer The treatments studied were: a) The addition of a coupling agent; b) chemical treatment with NaOH; and c) the addition of functionalized polypropylene (Polybond 3150 and 3200) After treatment, mixtures of PP with 40% and 20% of the filler, wood flour and sisal fiber respectively, were extruded and injection molded In the case of wood flour, a mixture of two particle sizes (mesh 20 and 40, 50% each) was used, and in the case of sisal, 10 mm long fibers were selected Results showed that, regardless of the treatment to which the filler was previously submitted, Young’s modulus was always higher for mixtures prepared with wood flour, with values varying between 2839 and 3150 MPa Whereas for mixtures with sisal fiber, the modulus’ values varied between 1704 and 2220 MPa Values of breaking strength, elongation at break and impact strength for PP mixtures with treated sisal fiber were always higher than those for mixtures of PP with wood flour Based on these results, we can conclude that sisal fiber is an organic filler which, due to its mechanical and morphological characteristics, has a reinforcing effect higher than that of wood flour
TL;DR: In this article, a di-functional and tri-functional poly(propylene oxide)-based polyol was investigated as the synthetic components with a polyol-miscible isocyanate resin serving as a crosslinking agent.
Abstract: Whereas lignocellulosic fibers have received considerable attention as a reinforcing agent in thermoplastic composites, their applicability to reactive polymer systems remains of considerable interest. The hydroxyl-rich nature of natural lignocellulosic fibers suggests that they are particularly useful in thermosetting systems such as polyurethanes. To further this concept, urethane composites were prepared using both unused thermomechanical pulp and recycled newsprint fibers. In formulating the materials, the fibers were considered as a pseudo-reactant, contributing to the network formation. A di-functional and tri-functional poly(propylene oxide)-based polyol were investigated as the synthetic components with a polyol-miscible isocyanate resin serving as a crosslinking agent. The mechanical properties of the composites were found to depend most strongly on the type of fiber, and specifically the accessibility of hydroxy functionality on the fiber. Dynamic mechanical analysis, swelling behavior, and scanning electron micrographs of failure surfaces all provided evidence of a substantial interphase in the composites that directly impacted performance properties. The functionality of the synthetic polyol further distinguished the behavior of the composite materials. Tri-functional polyols generally increased strength and stiffness, regardless of fiber type. The data suggest that synthetic polyol functionality and relative accessibility of the internal polymer structure of the fiber wall are dominant factors in determining the extent of interphase development. Considerable opportunity exists to engineer the properties of this material system given the wide range of natural fibers and synthetic polyols available for formulation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 546–555, 2001
TL;DR: In this article, conifer fibers were used to reinforce polypropylene (PP) to improve the thermal and mechanical properties of the resultant composites compared with the composites filled with untreated conifer fiber.
Abstract: Conifer fibers were used to reinforce polypropylene (PP). To improve the compatibility between the conifer fibers and the PP matrix, the fibers were either grafted with maleated PP (MAPP), treated by adding MAPP, or mixed with ethylene/propylene/diene terpolymer (EPDM). The treatments resulted in improved processing, as well as improvements in the thermal and mechanical properties of the resultant composites compared with the composites filled with untreated conifer fibers. Moreover, MAPP grafting and MAPP treating displayed more obvious benefits than EPDM treating in terms of thermal properties, processing flowability, and tensile strength improvements. EPDM treating also produced more significant benefits than either MAPP grafting or MAPP treating in terms of impact strength and tensile elongation improvements. These improvements were attributed to surface coating of the fibers when EPDM was used. In addition, the effect of the concentration of the conifer fibers on the properties of the composites and the difference between MAPP grafting and MAPP treating were evaluated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2833–2841, 2001
TL;DR: In this paper, Hessian cloth was modified with 2hydroxy ethylmethylacrylate (HEMA) and 2-ethylhexylacrylated (EHA) by soaking in solution of different concentration of monomer in methanol for 5 min.
Abstract: The modern technology relies heavily on the development of new materials having superior properties, such as mechanical and thermal properties along with toughness. Fiber reinforced composites have successfully proven their versatile qualities because of their specific properties e.g. high mechanical properties, stiffness, light weight etc. The potential of natural fiber based composites prepared mainly from jute as reinforcing fiber in polymer matrix has received much attention among the composite scientists [1–3]. Jute fibers are polar and of hydrophilic nature due to the presence of several hydroxyl groups in their cellulosic backbone. However, this is the most important disadvantage of using natural fiber in non-polar polymer like polypropylene (PP). Selection of proper coupling agents is important to improve the fiber-matrix interaction. The purpose of this study reported here is to investigate the effect of two monomers HEMA and EHA used as coupling agents on the performance of jute fabric (hessian cloth) PP composite. Hessian cloth (jute fabrics) was modified with 2hydroxy ethylmethylacrylate (HEMA) and 2-ethylhexylacrylate (EHA) by soaking in solution of different concentration of monomer in methanol for 5 min. Dicumyl peroxide was used as thermal initiator. The treated hessian cloth (HC) was dried at ambient temperature. Hessian cloth-polypropylene (Vestolen GmbH, Germany) composite was prepared by sandwiching two layers of HC and three layers of PP. The prepreg temperature, pressure and pressing time were 180 ◦C, 0.2 MPa and 5 min, respectively. The prepreg samples were cooled to room temperature, then cut to desired size in the mold and again heat-pressed at 130 ◦C for 5 min under 20 MPa pressure to get final composite. Tensile strength (TS) and three point bending strength (BS) of the composites were studied following DIN 53455 and DIN 53452 standard methods, respectively. The tensile as well as bending strength of the composite thus formed are shown in Fig. 1 as a function of monomer concentration. It is observed that
TL;DR: In this article, the effects of different fiber surface treatments and fiber amounts on the performance of resulting bio-composites are investigated, and the remarkable achievement of the present investigation is that a low strength coir fiber, through optimal surface modifications, on reinforcement with BAK show an encouraging level of mechanical properties.
Abstract: Biocomposites are prepared from a cheap, renewable natural fiber, coir (coconut fiber) as reinforcement with a biodegradable polyester amide (BAK 1095) matrix. In order to have better fiber-matrix interaction the fibers are surface modified through alkali treatment, cyanoethylation, bleaching and vinyl grafting. The effects of different fiber surface treatments and fiber amounts on the performance of resulting bio-composites are investigated. Among all modifications, cyanoethylated coir-BAK composites show better tensile strength (35.50 MPa) whereas 7% methyl methacrylate grafted coir-BAK composites show significant improvement in flexural strength (87.36 MPa). The remarkable achievement of the present investigation is that a low strength coir fiber, through optimal surface modifications, on reinforcement with BAK show an encouraging level of mechanical properties. Moreover, the elongation at break of BAK polymer is considerably reduced by the incorporation of coir fibers from nearly 400% (percent elongation of pure BAK) to 16-24% (coir-BAK biocomposites). SEM investigations show that surface modifications improve the fiber-matrix adhesion. From biodegradation studies we find that after 52 days of soil burial, alkali treated and bleached coir-BAK composites show significant weight loss. More than 70% decrease in flexural strength is observed for alkali treated coir-BAK composites after 35 days of soil burial. The loss of weight and the decrease of flexural strength of degraded composites are more or less directly related.
TL;DR: In this paper, a method of blending natural-fiber with polypropylene to form a mat and then consolidated into a sheet by hot pressing was presented. But the results showed that the tensile and flexural modulus were positively influenced by fiber length.
Abstract: Natural fiber based composites have the potential to improve the mechanical properties of plastics while reducing the cost and weight. This study shows a practical method of blending natural-fiber with polypropylene to form a mat and then consolidated into a sheet by hot pressing. The natural fibers assessed were Pinus radiata and Eucalyptus regnan high temperature thermomechanical pulps and sisal (Agave sisalana) fibers. The tensile strength was shown to decrease with an increase in fiber content, while the tensile modulus was shown to increase. Tensile and flexural modulus were positively influenced by fiber length. The water performance tests of the sheets generally showed approximately 20% weight gain and approximately 3% thickness swell at 30% fiber content. The natural fiber surface chemical composition was determined by X-ray photoelectron spectroscopy and shown to be primarily covered with hydrophobic material such as lignin and extractives, while polypropylene was shown to be partially oxidized.
TL;DR: In this paper, the chemical resistance of these fibres to some acids, alkalis and solvents was studied, and the tensile load at break was determined for the bamboo fibres belonging to the family of Dendrocalamus strictus.
Abstract: The bamboo fibres belonging to the family of Dendrocalamus strictus were coated with a blend of epoxy/polycarbonate with varying polycarbonate content. The chemical resistance of these fibres to some acids, alkalis and solvents was studied. The tensile load at break for these fibres was determined. The coated fibres showed higher tensile load at break, and were resistant to acids and alkalis. However, the solvent resistance of the coated fibres was found to be minimal.
TL;DR: In this article, raw and dewaxed jute felt composites were prepared with resol and lignin modified phenol formaldehyde resin, and the thermal stability of the composites was assessed by DSC and TGA.
Abstract: Raw and dewaxed jute felt composites were prepared with resol and lignin modified phenol formaldehyde resin. Four different types of lignin modified resins were used by replacing phenol with lignin. The lignin modified resins were prepared from purified lignin obtained from paper industry waste black liquor. To investigate bonding between jute and resin, IR spectroscopy of jute felts and composites was carried out. The thermal stability of the composites was assessed by DSC and TGA. It was found that the lignin resin jute composite is thermally more stable than resol composite. XRD of jute felt and composite shows that the crystallinity of the jute fiber increases after composite preparation. The lignin resin composites were tested for water absorption and thickness swelling, and it was found that the results are comparable with those of resol jute composite. Composites prepared from lignin phenol formaldehyde resin with 50% phenol replacement has shown 75% tensile strength retention to that of pure resol jute composite.
TL;DR: In this paper, the poly-L-lysine (PLL) and gellan gum via polyion complex (PIC) formation is used for spinnable polypeptide fiber.
Abstract: Different characteristic surface structures such as capsules, regularly spaced droplets, and fibers are formed by electrostatic interaction between poly-L-lysine (PLL) and gellan gum via polyion complex (PIC) formation. Spherical droplet PIC capsules of varying diameters form in solutions. Some dyes adsorb on the surface of the capsules, and other dyes penetrate into the capsules. The strong PIC fiber can be spinnable by gravity and by wet spinning in ethanol. This fiber possesses a counterion pairing structure and exhibits the nervation/veining pattern and hollow yarn. The tensile strength of the fiber is 27.8 kg/mm2 [1.40 g/denier (d)] and the knotting strength is 9.98 kg/mm2 (1.13 g/d). By using an organic crosslinking agent, epichlorohydrin, the tensile strength can be increased to 38.5 kg/mm2 (2.46 g/d) and the knotting strength can be increased to 12.2 kg/mm2 (1.99 g/d). The PIC fiber can be dyed by five different dyeing procedures such as direct and vat dyeings. The PLL PIC fiber is water insoluble and has potential as a new synthetic polypeptide fiber technology. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 437–446, 2001
TL;DR: In this article, a systematic analysis of structure characteristics and the influence of aqueous medium on the mechanical properties of lyocell fibers was performed. But the results showed that the water influence on mechanical properties is considerably smaller compared to the viscose and modal fibers.
Abstract: Comparative investigations between the new lyocell fibers and the regular viscose and modal types were made in order to explain the reasons for the differences in the mechanical properties of the fibers. The purpose was a systematic analysis of structure characteristics and of influence of aqueous medium on the mechanical properties. The properties determined in the wet state reflect the effect of the aqueous medium on the changes in the supermolecular structure during wet treatments [1, 2]. The new lyocell fibers consist of longer molecules and have a higher degree of crystallinity. Smaller but longer crystallites are oriented in the fiber axis direction and the voids structure is similar to that of viscose fibers [3]. Good mechanical properties are conditioned by the structure of the lyocell fibers, above all by high values of the orientation factor and crystallinity index. Sorption properties place lyocell fibers between the viscose and modal fibers. The water influence on the mechanical properties of lyocell fibers is considerably smaller compared to the viscose and modal fibers.
TL;DR: In this article, regenerated cellulose fibers from rice straws with a diameter of 10 to 25 μm and initial modulus of 11 to 13 GPa were prepared by wet spinning in rice straw/N-methylmorpholine-Noxide (MMNO) solution.
Abstract: Regenerated cellulose fibers from rice straws with a diameter of 10 to 25 μm and initial modulus of 11 to 13 GPa were prepared by wet spinning in rice straw/N-methylmorpholine-N-oxide (MMNO) solution. X-ray diffraction analysis indicates that the rice straw regenerated fibers are classified as cellulose (II). This observation indicates a potential utility of rice straw as an alternative to wood pulp as a cellulose-based fiber material.
Patent•
13 Mar 2001TL;DR: In this paper, the quality stability and strength performance of fiber-reinforced thermoplastic resin pellets with natural fiber fiber as the reinforcing fiber were investigated using yarns with No. 5 to 80 counts.
Abstract: Disclosed is fiber-reinforced thermoplastic resin pellets that satisfy the quality stability (homogeneous impregnation, deterioration prevention of reinforcing fiber) of the molding material and the strength performance of the molded product, using natural discontinuous fiber as the reinforcing fiber, and a manufacturing method of the pellets. A plurality of spun yarns with No. 5 to 80 counts are twisted 10 to 200 turns/m and pultruded when fiber-reinforced thermoplastic pellets containing natural fiber as the reinforcing fiber are manufactured by the impregnating pultrusion method.
TL;DR: In this paper, a kinetic model for the crystallization behavior of PCL/starch and their composites with sisal fibers was developed, taking into account the effects of nucleation and crystal growth.
Abstract: Calorimetric results obtained by differential scanning calorimetry (DSC) have been used to develop a kinetic model for the crystallization behavior of PCL/starch and their composites with sisal fibers. The model takes into account the effects of nucleation and crystal growth, and it is able to describe the isothermal and non-isothermal conditions, especially for the low cooling rates. The effect of the sisal fiber has also been analyzed. The Avrami exponent was 2.0 for the crystallization of PCL/starch and sisal fiber reinforced composite. The activation energy of the crystallization process was 4.3 and 4.0 kJ/mol for PCL/starch and sisal composite, respectively. The induction time of the crystallization and the crystallization rate was not influenced by the presence of sisal fiber.
TL;DR: In this article, the dynamic mechanical behavior of jute fiber-reinforced epoxy foams was investigated, and the influence of various fiber and microvoid content on shear modulus, frequency and log decrement was discussed.
Abstract: In this work, the dynamic mechanical behavior of jute fiber-reinforced epoxy foams was investigated. The influence of various fiber and microvoid content on shear modulus, frequency and log decrement was discussed. Experimental results showed that the 42 vol.% fiber content significantly enhances the shear modulus. The shear modulus and frequency were decreased with increasing microvoid content in the epoxy matrix. The jute fiber as reinforcement affects the temperature of the log decrement peak. Increasing fiber and microvoid content induced a decrease and an increase of the log decrement peak values, respectively.
TL;DR: It is concluded that nonequilibrium phenomena necessitate a more severe form of precaution toward surface energy component theories when these are used for interpreting plant fiber wetting than what is currently at issue.
TL;DR: In this article, several types of flax were used as reinforcement in poly(propylene) based unidirectional composites, including non-treated as well as treated (boiled) samples.
Abstract: In this work several types of flax were used as reinforcement in poly(propylene) based unidirectional composites. These flax types included non-treated as well as treated (boiled) samples. On the other hand, two types of poly(propylene) were used as matrix: non-modified poly(propylene) (PP), and maleic anhydride modified poly(propylene) (MAAP-PP). The influence of both fibre and matrix modification was studied through mechanical (flexural) and physical (density, sorption, and drying) tests. Combination of boiled flax with MAAP-PP proved to yield the best mechanical properties, combined with good physical properties. A 100% stress transfer between fibre and matrix could be calculated in this optimised case. Interlaminar shear strentgh tests were done in order to confirm this improved fibre-matrix adhesion.
Patent•
30 Apr 2001TL;DR: In this article, a method of forming a multicomponent mat is described, which is formed from glass fibers and natural fibers, and the next step involves using a surfactant to disperse glass fibers in white water.
Abstract: The invention relates to a method of forming a multicomponent mat, the multicomponent mat which is formed from glass fibers and natural fibers and methods of making a multicomponent mat. Initially in the method of forming a multicomponent mat, a natural fiber slurry is formed. The next step involves using a surfactant to disperse glass fibers in white water. The natural fiber slurry and the slurry of glass fibers are generally compatible and are combined to form a multicomponent slurry which is used to form a multicomponent mat.
TL;DR: In this paper, Silk fibers from Bombyx mori silkworms were grafted using a novel grafting monomer, vinyltrimethoxysilane (VTMSi), with various grafting initiators.
Abstract: Silk fibers from Bombyx mori silkworms were grafted using a novel grafting monomer, vinyltrimethoxysilane (VTMSi), with various grafting initiators. The effects of these grafting initiators were evaluated. It was possible to successfully copolymerize VTMSi within the silk fiber matrix without disturbing the fine structure of the fiber matrix, which was shown by FTIR analysis and refractive index measurements. The physical properties of VTMSi grafted silk were analyzed and compared to fibers grafted with conventional monomers such as methyl methacrylate, methacrylamide, and 2-hydroxyethyl methacrylate. No trend in the tensile strength and elongation at break was observed when grafting silk fibers with VTMSi. Crease recovery in the wet state improved significantly, suggesting that this new grafting technique is important for the production of washable silk fabrics. The thermal stability of VTMSi grafted silk fibers was improved as shown by the shift of the endothermic peak for the thermal decomposition toward higher temperatures. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1764–1770, 2001
TL;DR: In this paper, the mechanical and optical properties of cellulose-based composite films are investigated and it is shown that the use of toluene diisocyanate as a coupling agent and Avicel fibers as reinforcing elements give films with the highest mechanical characteristics.
Abstract: The mechanical and optical properties of cellulose-based composite films are investigated.It is shown that the use of toluene diisocyanate as a coupling agent and Avicel fibers as reinforcing elements give films with the highest mechanical characteristics. Using differential scanning calorimetry, it is also found that the glass transition temperature Tg of all the materials studied is below the room temperature and that the Tg increased with cross-linking and introduction of Avicel.
TL;DR: In this article, the reactivity of these modifying agents toward silk fibers was examined as a function of the reaction solvent, temperature, time, and isocyanate chemistry, showing that the fine structure of silk remained unchanged regardless of chemical modification.
Abstract: Bombyx mori silk fibers were chemically modified with various kinds of isocyanates and diisocyanates, including phenyl isocyanate and hexamethylene diisocyanate. The reactivity of these modifying agents toward silk fibers was examined as a function of the reaction solvent, temperature, time, and isocyanate chemistry. The use of DMSO as the solvent, bifunctional isocyanates, such as hexamethylene diisocyanate, and a temperature of 75°C resulted in higher weight gains of modified silk fibers. The physical and chemical properties of the modified silk fibers were studied as well. The moisture regain tended to decrease as the weight gain increased, the extent depending on the kind of isocyanate used. The resistance of silk toward attack by hot acid and alkali was generally enhanced by a reaction with isocyanates, the only exception being phenyl isocyanate, which induced a drop of alkali solubility. The tensile strength remained almost unchanged, regardless of chemical modification, while elongation at break decreased. The optical properties and the thermal stability of the modified silk fibers were not influenced by the reaction with isocyanates, suggesting that the fine structure of silk remained unchanged, regardless of chemical modification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1756–1763, 2001