Optimization of the silane treatment of cellulosic fibers from eucalyptus wood using response surface methodology

Viscose cellulosic fibers from eucalyptus wood were treated with organosilanes to introduce specific functionalities on the fibers and enhance their wettability and adhesion with phenolic matrices in composites. Modeling procedures were employed to optimize the conditions of the treatments of the fibers with the silanes (3‐aminopropyl) trimethoxysilane (APS) and 3‐(2‐aminoethylamino) propyltrimethoxysilane (AAPS). The analyzed responses were relative intensities of the bands 1565/897 and 1120/897 cm⁻¹, measured by Fourier transform infrared spectroscopy, and the silicon amount incorporated into the cellulosic fibers, which was determined by energy dispersive X‐ray analysis. In addition, surface morphology of the silane treated fibers was observed using scanning electron microscopy. The treatments of the cellulosic fibers with 2.2% APS for 120 min and 1.5% AAPS for 100 min were selected as optimums. According to contact angle measurements, both treatments enhanced the wettability between the fibers and a resol‐type phenolic resin, revealing the possible use of the silane treated fibers as reinforcement in phenolic composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42157.     

Surface treatment of eucalyptus wood for improved HDPE composites properties

In this study, the effect of Eucalyptus globulus wood (UE) used as a filler (5–20% w/w) on the physical and thermal properties of high-density polyethylene (HDPE) composites was evaluated. To improve the compatibility with HDPE, the wood was modified (TE) using crude glycerol derived from biodiesel production. The addition of 20% (w/w) of UE or TE led to more rigid and durable composite materials compared to neat HDPE (about 50 or 100% increase in tensile strength, respectively). Composites also revealed 55–75°C higher temperatures at maximal degradation rates. The advantageous behavior of TE over UE in composites was attributed to the improvement of surface morphology of modified wood and it is better compatibility with the HDPE as revealed by surface energy analysis. The changes in wetting behavior of HDPE and ensuing HDPE-TE composites (contact angles of ca 72 and 80°, respectively) explain the matrix-filler interactions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48619.     

Alkali treatment of jute fibers: Relationship between structure and mechanical properties

The mechanical properties of tossa jute fibers were improved by using NaOH treatment process to improve the mechanical properties of composites materials. Shrinkage of fibers during this process has significant effects to the fiber structure, as well as to the mechanical fiber properties, such as tensile strength and modulus. Isometric NaOH‐treated jute yarns (20 min at 20°C in 25% NaOH solution) lead to an increase in yarn tensile strength and modulus of ∼ 120% and 150%, respectively. These changes in mechanical properties are affected by modifying the fiber structure, basically via the crystallinity ratio, degree of polymerization, and orientation (Hermans factor). Structure–property relationships, developed for cellulosic man‐made fibers, were used with a high correlation factor to describe the behavior of the jute fiber yarns. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 623–629, 1999     

Silk‐inspired polyurethane containing glyalaglyala tetrapeptide. III. morphological,thermal, and mechanical features of electrosprayed and electrospun deposition

Morphological, thermal, and mechanical features of electrosprayed and electrospun deposition of the silk‐inspired polyurethane (PU) containing GlycineAlanineGlycineAlanine (GlyAlaGlyAla, the featured peptide sequence of silkworm silk fibroin) tetrapeptide, which was synthesized by the traditional liquid‐phase peptide synthesis method and the classical two‐step polymerization method using Boc‐protected amino acids and diisocyanates as starting materials, were characterized. The results show that the synthesized silk‐inspired PU dissolved in tetrahydrofuran (THF) can be easily electrosprayed or electrospun into the film form, although its molecular weight ranging from 13,000 to 15,000 is quite low. Elastomeric fibrous membranes with surface morphologies of “droplets,” “bead‐on‐string,” and “nonwoven fibers” have been obtained by electrospraying and electrospinning the silk‐inspired PU/THF solution of varying concentrations. The thermograms confirm high thermostability of the silk‐inspired PU between 350 and 400°C due to the polar peptide linkages. The tanδ peak of dynamic mechanical analysis curve corresponding to its glass transition temperatures is detected at ?34.3°C. Its elongation at break is about 140–150%, and the breaking tensile strength ranges from 22 to 27 MPa, which is consistent with the data of other PUs containing l ‐alanine residue. Information provided by this study can be used to better understand the correlation between the natural and man‐made silk polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40245.     

Comparison of direct solvents for regenerated cellulosic fibers via the lyocell process and by means of ionic liquids

Because new technology using ionic liquids (ILs) for cellulose processing enables the spinning of cellulose with various techniques, the resulting fiber property profiles differ significantly, depending on the process parameters. ILs are thermally stable, nontoxic, environmentally friendly solvents and dissolve cellulose directly; this leads to a high flexibility in the complete process chain for man‐made cellulosics. A comparison of the manufacture of cellulosic fibers according to the Lyocell process and by means of ILs is presented. The rheological behavior of the spinning dopes, the structures, and the physical textile properties of the prepared fibers were determined. The fibers spun from solutions of cellulose in N‐methyl morpholin‐N‐oxide monohydrate, 1‐ethyl‐3‐methyl imidazolium acetate, and 1‐ethyl‐3‐methyl imidazolium diethyl phosphate were compared. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fibrillation tendency of cellulosic fibers,part 6: Effects of treatments with additive polymers

The influences of the treatments with various polymers on fibrillation and abrasion resistances of lyocell materials were investigated with respect to the type of polymer, the polymer concentration, and the drying temperature. Fibril number, generated with agitation using ball‐bearings (FN_ball), was decreased with increasing the concentration of aminofunctional polysiloxane because of reduction in water retention capacity (WRV) in fibers. The never‐dried lyocell fiber showed smaller decrease in FN_ball because of its higher WRV when compared to dried fibers. The treatment with aminofunctional polysiloxane enhanced not only the fibrillation resistance but also abrasion resistance, which was indicated as rotation number of abrasive bar in the abrasion test (RN_abr). No fibrillation was obtained in the fiber treated with 10 g/L aminofunctional polysiloxane at 120°C for 20 min, while the fibers treated at 60 and 170°C for 15 min were fibrillated in the agitation and abrasion tests. The addition of secondary polyethylene derivative also reduced the fibrillation tendency of lyocell; however, the extent of the reduction was lesser when compared with aminofunctional polysiloxane. The treatments with polyacrylate, polyurethane, and polyisocyanate derivatives improved the fibrillation resistance in lyocell fabrics, while fiber abrasion resistance was not significantly improved by the treatment with those additives, except in polyisocyanate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4140–4147, 2006     

Acoustical,thermal, and morphological properties of zein reinforced oil palm empty fruit bunch fiber bio‐composites

In this research, biodegradable composites were prepared with zein as a polymer matrix and oil palm empty fruit bunch (OPEFB) as fiber reinforcement. The fibers were treated with sodium hydroxide (NaOH). The effects of sodium hydroxide treatment on sound absorption, thermal stability, and fiber‐polymer matrix interaction in composites were examined. The acoustical sound absorption coefficients of the composites were evaluated using two‐microphone transfer function impedance tube method. The spectral, thermal, and morphological studies of the composites were analyzed and characterized using scanning electron microscope (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. It was found that in all the biodegradable composites, the sound absorption coefficients increased as the frequency increased. Increases in fiber loading caused sound absorption coefficients of the composites to increase. The sodium hydroxide treatment showed a better interface adhesion on fiber and zein matrix. It was also found that this treatment increased the sound absorption coefficients. This was supported by qualitative analysis on the SEM micrographs and FTIR spectrum. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44164.     

Impact toughness,viscoelastic behavior,and morphology of polypropylene–jute–viscose hybrid composites

In this investigation, we studied the impact toughness and viscoelastic behavior of polypropylene (PP)–jute composites. In this study, we used viscose fiber as an impact modifier and maleated PP as a compatibilizer. The toughness of the composites was studied with conventional Charpy and instrumental falling‐weight impact tests. The composites’ viscoelastic properties were studied with dynamic mechanical analysis. The results show that the incorporation of viscose fibers improved the impact strength and toughness to 134 and 65% compared to those of the PP–jute composites. The tan δ peak amplitude also increased with the addition of the impact modifier and indicated a greater degree of molecular mobility. The thermal stability of the composites was evaluated with thermogravimetric analysis. The addition of 2 wt % maleated polypropylene (MAPP) to the impact‐modified composite improved the impact strength and toughness to 144 and 93%, respectively. The fiber–matrix morphology of the fracture surface and the Fourier transform infrared spectra were also studied to ascertain the existence of the type of interfacial bonds. Microstructural analysis showed the retention of viscose fibers in the composites compared to the more separated jute fibers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42981.     

Alkali pretreatment and resin finishing of lyocell: Effect of sodium hydroxide pretreatments

Lyocell fabric samples were pretreated with 2–8 mol/L sodium hydroxide (NaOH) and then resin‐finished with dimethyloldihydroxyethylene urea, dimethyl dihydroxyethylene urea, and dimethylol urea based products. The resin‐finishing treatments caused changes in the substrate properties, such as reduced accessibility, improved crease recovery, and reduced work of rupture and abrasion resistance. Differences were observed between resin‐finished substrates as a function of the crosslinker type, and they were attributed to the influence of the crosslinker content and crosslink length in the substrates. The alkali pretreatments influenced the effects of resin finishing. A significant enhancement of the crosslinker penetration appeared within the substrates pretreated with 4 mol/L NaOH. Pretreatments with 6 and 8 mol/L NaOH also enhanced the crosslinker penetration, but the depth of catalyst penetration appeared to exceed that of the crosslinker; leading to demixing between the two components within the substrates. The penetration depth of a direct dye, C.I. Direct Red 81, appeared lower than that of the crosslinker in the alkali‐pretreated substrates. Pretreatments with NaOH in the range of 4–8 mol/L appeared to create gradients of accessibility within fibers and yarns of lyocell fabrics, with the depth of reagent penetration increasing in the following order: C.I. Direct Red 81 < crosslinker < catalyst. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characterization and modeling of the moisture diffusion behavior of natural fibers

Natural fibers have good properties to be used as reinforcement in composite materials. The main issue is their hydrophilic behavior. So we propose here to investigate the diffusion phenomenon in such fibres. First, a brief characterization of four vegetal fibers has been achieved. We show that all fibers have a similar composition and structure despite their different origin. Then, their moisture diffusive behavior was investigated. The samples were submitted to hygro‐thermal aging either in total water immersion at room temperature or in an environmental chamber at 80% relative humidity and 23°C. Various predictive models were used to simulate experimental curves. Results show that all fibers exhibit a similar diffusive behavior in a same environment. In immersion, specimens show anomalous absorption kinetics and Langmuir theory actually describes very well the diffusion kinetics in such conditions, whereas the same fibers follow a Fickian diffusion when they are exposed to vapor during relative humidity aging. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Carboxymethylcellulose (CMC) as a model compound of cellulose fibers and polyamideamine epichlorohydrin (PAE)–CMC interactions as a model of PAE–fibers interactions of PAE‐based wet strength papers

Carboxymethylcellulose (CMC) is a cellulose derivative obtained by the carboxymethylation of some hydroxyl groups in the cellulose macromolecules. In this article, we use CMC as a model compound of cellulose fibers to study polyamineamide epichlorohydrin (PAE)–fibers interactions during the preparation of PAE‐based wet strength papers. The main advantages of the use of CMC to replace cellulose fibers are its water‐soluble character and the homogeneous reaction medium during mixing with PAE resin. Based on ¹³C cross‐polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) and Fourier transformed infra‐red (FTIR) spectroscopy, we prove the formation of ester bonds in PAE–CMC films boosted by a thermal posttreatment at 105°C for 24 h. These ester bonds are derived from a thermally induced reaction between carboxyl groups in the CMC structure and azetidinium ions (AZR) in the PAE resin. PAE‐based handsheets were prepared from 100% Eucalyptus fibers. After preparation, some samples were thermally posttreated (TP) at 130°C for 10 min and stored under controlled conditions (25°C and 50% relative humidity or RH). For lowest PAE dosage, storage of the not thermally posttreated (NTP) PAE‐based handsheets does not allow them to reach the tensile strength values of TP PAE‐based handsheets (at 130°C for 10 min), but the difference in terms of breaking length remains low. For the highest PAE addition level, NTP and TP PAE‐based handsheets exhibit close values of the breaking length from 30 days of storage under controlled conditions (25°C and 50% RH). When a thermal posttreatment is applied, the wet strength development of PAE‐based papers is a combined effect of homo‐ and co‐cross‐linking mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42144.     

Biodegradable composites: Morphological,chemical, thermal,and mechanical properties of composites of poly(hydroxybutyrate‐co‐hydroxyvalerate) with curaua fibers after exposure to simulated soil

Composites produced from biodegradable polymeric matrixes reinforced with vegetable fibers have attractive mechanical properties and are environmentally friendly. This work is directed to the biodegradation of a composite made of a poly(hydroxybutyrate‐co‐hydroxyvalerate) matrix reinforced with curaua fibers (with and without alkaline treatment) in simulated soil. The composites were developed by extrusion and injection and were later buried in simulated soil according to the ASTM G160‐03 method. Scanning electron microscopy showed evidence of microbial attack on the samples surfaces. Infrared spectra showed that the composites biodegradation was mainly caused by erosion of the surface layer resulting from microorganisms activity. Thermogravimetric analysis pointed out reduced thermal stability of the samples, and results of differential scanning calorimetry showed that the degree of crystallinity increases and then decreases progressively throughout the degradation period, indicating that enzymatic degradation primarily occurs in the amorphous phase material and thereafter in the crystalline phase. For curaua composite fibers, reductions in tensile strength and elastic modulus are more significant, indicating that the presence of fibers promotes biodegradation of the curaua fiber. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40712.     

碱处理对棉秆皮纤维木质素的影响

棉秆皮纤维中的木质素影响纤维的柔软性。采用正交实验分析碱性处理条件对棉秆皮纤维木质素的影响。实验结果表明:H2O2浓度对棉秆皮纤维的木质素影响最大,且对木质素含量的影响最显著。在NaOH质量浓度8 g/L,温度80℃,时间45min,H2O2质量浓度7 g/L条件下,棉秆皮纤维中木质素含量较少。     

Performance of nylon 6 composites reinforced with modified agave fiber: Structural,morphological, and mechanical features

Nylon 6 (Ny6) composites reinforced with treated agave fiber (AF) at different concentrations (5–20 wt%) were achieved by melt mixing process at 250°C, without the addition of any compatibilizing or coupling agents, and characterized in terms of their structural, morphological, and mechanical properties. The alkaline-ultrasound (NaOH-U) treatment in AF resulted in the removal of the low thermal stability components (pectin and hemicellulose), concentrating the cellulose fraction, and favoring the crystallinity percentages (X_c) of the Ny/AF composites. Moreover, the interfacial interactions between functional groups of agave fiber and Ny6 resulted in the increase Young's modulus (18.8%), flexural strength (11.3%), and density (3.7%). These findings could be useful when looking for potential applications in the mobility industry.     

Mechanical,thermal, and burning properties of viscose fabric composites: Influence of epoxy resin modification

The influence of epoxy resin modification by 3‐aminopropyltriethoxysilane (APTES) on various properties of warp knitted viscose fabric is reported in this study. Dynamic mechanical, impact resistance, flexural, thermal properties, and burning behavior of the epoxy/viscose fabric composites are studied with respect to varying content of silane coupling agent. The results obtained for APTES‐modified epoxy resin based composites reinforced with unmodified viscose fabric composites are compared to unmodified epoxy resin based composites reinforced with APTES‐modified viscose fabric. The dynamic mechanical behavior of the APTES‐modified resin based composites indicates improved interfacial adhesion. The composites prepared from modified epoxy resin exhibited a twofold increase in impact resistance. The improved adhesion between the fiber and modified resin was also visible from the scanning electron microscope analysis of the impact fracture surface. There was less influence of resin modification on the flexural properties of the composites. The 5% APTES modification induced early degradation of composites compared to all other composites. The burning rate of all the composites under study is rated to be satisfactory for use in automotive interior applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46673.     

Pilling in man‐made cellulosic fabrics,part 1: Assessment of pilling formation methods

Despite the pills appear similarly in fabric surfaces, their structure and mechanism of formation are distinct depending on material categories and handling conditions. The lyocell and viscose knitted fabrics were abraded with short cycles in the wet state as an assessment method for pilling formation called rapid pilling test (RPT). The samples were immersed in different wetting agents and subsequently padded before short abrasion in Martindale tester. The results were compared with long abrasion, besides 5–25 cycles of washing and drying (W‐D). The samples were rated and these results were correlated with the changes in the physical parameters obtained in the dry and wet state. The correlation showed the feasibility of RPT in wet state with short‐abrasion cycles, in lieu of long cycles and W–D cycles. Furthermore, the image analysis of single pills formed by different methods and the inner/outer pill structure may reflect the pilling mechanism and yield a comprehensive view of the whole process. Instead of conventional Martindale test, the easy‐handling RPT can be applied for cellulosic fabrics, in which wet samples are abraded in short cycles fulfilling two important demanding factors during test performance: test of material in the wet state and reduced testing time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polyvinylbutyral‐assisted synthesis and characterization of SnS mesoporous fibers via electrospinning process

Tin sulfide (SnS) has the potential to be used as a low‐cost absorber material for applications in thin film photovoltaic solar cells. In this study, polyvinylbutyral/SnS (PVB/SnS) composite fibers were synthesized through a relatively simple electrospinning process. SnS mesoporous fibers were obtained from PVB/SnS composite fibers after sintering treatment at 500°C for 1 h in N₂ atmosphere. The SnS mesoporous fibers were then characterized using X‐ray powder diffraction, scanning electron microscopy, thermogravimetric analysis, and transmission electron microscopy. The optical properties of SnS mesoporous fibers were also recorded by UV–vis absorption spectroscopy. The results showed that the synthesized SnS mesoporous fibers exhibited a single phase, stoichiometric composition, with good crystallinity, a size ranging from 100 to 200 nm, and a band gap of 1.49 eV. The as‐prepared SnS mesoporous fibers are thus a suitable material to achieve visible light absorption in a thin film solar cell. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42388.     

Fibrillation tendency of cellulosic fibers. VII. Combined effects of treatments with an alkali,crosslinking agent,and reactive dye

Lyocell woven fabrics were treated with crosslinking agents [1,3‐dimethyl‐4,5‐dihydroxyethylene urea (X1) and 1,3‐dimethylol‐4,5‐dihydroxyethylene urea (X2)], binders [polyacrylate (B1), anionic polyacrylate (B2), anionic polyurethane (B3), and aliphatic polyisocyanate (B4)], and polyfunctional reactive dyes in combination with alkali treatments. The effects of the treatment conditions, including the reagent types, the reagent concentrations, the process types (pretreatments or posttreatments with alkali), and the treatment combinations, on the fibrillation tendency and dyeing behavior in treated samples were investigated. Generally, the fibril number decreased with an increasing concentration of additives and decreased further with reactive dyeing. Fabrics treated with 45 g/L X1 (34 g/kg of fiber) or with 28 g/L X2 (21 g/kg of fiber) and dyed thereafter exhibited no fibrillation. Posttreatments with alkalis caused no changes in either the color shade or fibrillation tendency of crosslinked fabrics, although they enhanced the water retention capacity. The use of mixtures of binders B3 and B4 minimized the fibrillation, but the use of B4 led to changes in the color shade. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:1176–1183, 2006     

Rheology of natural fibers thermoplastic compounds: Flow length and fiber distribution

The presented study investigates the flow length and the corresponding fiber content distribution in the injection‐moulded natural fiber reinforced thermoplastics and its relation to fiber type and processing parameters such as injection pressure, temperature, injection rate and mould tempering by increasing die temperature. In this research, polypropylene compounds with nominally 30 wt % hemp and sisal fibers are investigated. The influence of the injection pressure (500 and 1000 bar), melt temperature (180°C, 200°C, and 220°C), and die temperature (23°C and 80°C) on the fiber content distribution all over the sample is investigated. An increasing linear trend of fiber content along the spiral length is observed as an evidence of a fiber/polymer multiflow system. A pattern for fiber content distribution with respect to the fiber length along the injected spiral can be distinguished, where the longer fibers are usually found at the end of the injected part and the shorter fibers remain near mould entrance point. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39861.     

Some studies on thermal treatments of polyester fibers: Structural changes

The development of the changes of structure during thermal treatment of polyester fiber is studied. Critical dissolution time (CDT) was evaluated to trace the changes in crystallinity and crystal morphology of polyester fibers. CDT increased as the time of thermal treatment was increased. The change in CDT was less effective for samples thermally treated at temperatures up to 160°C, which may indicate a nucleation tendency of tiny crystals. CDT of polyester treated at 200°C in air was found to be relatively high, while silicon oil medium can affect both amorphous and crystalline regions, increasing the structure disorder. The effect of treatment under constant length revealed smaller CDT values than those attained by samples treated in free conditions. An indication to crystal size increase was traced by a decrease in peak width in X-ray diffraction pattern. Thermal treatment increased the crystallinity of polyester fibers up to 160°C. Dry air medium was more effective in increasing the disorder in amorphous regions than silicon oil medium. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2773–2780, 1997