Composite materials of thermoplastic starch and fibers from the ethanol-water fractionation of bagasse

The aim of this study was to evaluate the potential of the fibrous material obtained from ethanol-water fractionation of bagasse as reinforcement of thermoplastic starches in order to improve their mechanical properties. The composites were elaborated using matrices of corn and cassava starches plasticized with 30 wt% glycerin. The mixtures (0, 5, 10 and 15 wt% bagasse fiber) were elaborated in a rheometer at 150 °C. The mixtures obtained were pressed on a hot plate press at 155 °C. The test specimens were obtained according to ASTM D638. Tensile tests, moisture absorption tests for 24 days (20-23 °C and 53% RH, ASTM E104), and dynamic-mechanical analyses (DMA) in tensile mode were carried out. Images by scanning electron microscopy (SEM) and X-ray diffraction were obtained. Fibers (10 wt% bagasse fiber) increased tensile strength by 44% and 47% compared to corn and cassava starches, respectively. The reinforcement (15 wt% bagasse fiber) increased more than fourfold the elastic modulus on starch matrices. The storage modulus at 30 °C (E_30 °C′) increased as the bagasse fiber content increased, following the trend of tensile elastic modulus. The results indicate that these fibers have potential applications in the development of biodegradable composite materials.     

Thermal tolerance of propagative anthurium stem cuttings to disinfestation by heat treatment for burrowing nematodes and bacterial blight

Hot water and hot air treatments were evaluated for disinfesting anthurium, Anthurium andraeanum Lind., stem cuttings of the bacterial blight pathogen, Xanthomonas axonopodis pathovar dieffenbachiae (Xa pv. dieffenbachiae), and burrowing nematodes, Radopholus similis, and their effect on viability of the cuttings. Xa pv. dieffenbachiae suspended in distilled water in 1.5 ml microcentrifuge tubes, lost at least 6 logs of viability when exposed to hot water at 50 °C for 12 min or hot air at 50 °C, 60% RH for 35 min administered in commercial-sized heat treatment facilities. Stem cuttings exposed to hot air at 50 °C, 60% RH were disinfested of R. similis when their core temperatures attained 50 °C. Plant response to heat treatments varied among cultivars; however, all evaluated cultivars exhibited high tolerance to hot water at 50 °C for up to 24 min with equal or enhanced sprouting rates as compared to untreated checks. Sprouting rates of three of the four cultivars treated with hot air at 50 °C, 60% RH for up to 125 min were equal to or higher than untreated checks, while cuttings from the less tolerant cultivar ‘Tropic Fire’ registered lower sprouting rates for all hot air treatment durations as compared to untreated checks, Flower quality parameters, including average spathe size, stem diameter and number of flowers harvested from plants heat-treated as cuttings, were comparable to or higher than untreated checks for all treatments and cultivars. Disinfestation of anthurium stem cuttings for bacterial blight and the burrowing nematode can be achieved in hot water at 50 °C for 24 min without loss of sprouting rate or flower quality.     

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.     

Changes in gelatinization and rheological characteristics of japonica rice starch induced by pressure/heat combinations

Rice starch suspensions of 10% dry matter (DM) were treated by heat (0.1 MPa at 20–85 °C) or pressure/heat combinations (100–600 MPa at 20, 40 and 50 °C) for 15 min to investigate their gelatinization and rheological characteristics. The maximum swelling index of about 12 g water per gram of DM was obtained by thermal treatment at 85 °C, meanwhile, that of 7.0 g was observed by 600-MPa pressurization at 50 °C. The higher temperatures or pressures resulted in the higher degrees of gelatinization. Furthermore, treatments of 0.1 MPa at 85 °C, 500 MPa at 50 °C and 600 MPa at various temperatures caused complete gelatinization of rice starch. The consistency index (K) and storage modulus (G′) dramatically increased from 70 °C or 400 MPa. The G′ values were higher in pressure-treated samples than those in thermal-treated samples. Therefore, an application of pressure/heat combinations as a processing method to improve the quality of rice starch products would be possible.     

Temperature-induced structural and chemical changes in cork from Quercus cerris

The effects of temperature on anatomical and chemical characteristics of Quercus cerris cork were examined. Cork samples were subjected to isothermal air heating between 150 °C and 400 °C and analyzed for mass loss, cellular structure and chemical composition.The thermal decomposition of Q. cerris cork is similar to that of Q. suber cork. Cork is thermally stable below 200 °C and after that degradation depended on temperature and heating time with increasing mass loss, i.e. 3% at 200 °C 10 min and 46% at 350 °C 60 min. With temperature and starting at 200 °C, cells expanded, cell wall thickness was reduced and corrugations were lost.Extractives degraded at lower temperatures, although aliphatic extractives were found to be more stable. Suberin from Q. cerris was more heat resistant than Q. suber suberin, while lignin showed similar resistance.These results provide a basis for studies on the production of Q. cerris bark expanded cork agglomerates for insulation purposes.     

Sugarcane bagasse whiskers: Extraction and characterizations

This work evaluates the use of sugarcane bagasse (SCB) as a source of cellulose to obtain whiskers. These fibers were extracted after SCB underwent alkaline peroxide pre-treatment followed by acid hydrolysis at 45 °C. The influence of extraction time (30 and 75 min) on the properties of the nanofibers was investigated. Sugarcane bagasse whiskers (SCBW) were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) in air atmosphere. The results showed that SCB could be used as source to obtain cellulose whiskers and they had needle-like structures with an average length (L) of 255 ± 55 nm and diameter (D) of 4 ± 2 nm, giving an aspect ratio (L/D) around 64. More drastic hydrolysis conditions (75 min) resulted in less thermally stable whiskers and caused some damage on the crystal structure of the cellulose as observed by XRD analysis.     

Effect of alkali and silane treatments on mechanical and thermal behavior of Phormium tenax fibers

The effect of different treatments on the mechanical (tensile), thermal behavior (TGA), FTIR, and morphology of Phormium tenax fibers has been studied with the aim to investigate methods to improve their compatibility with polymer matrices. Applied treatments included sodium hydroxide (NaOH), silane (APTES, 3-aminopropyltriethoxysilane), and the combined application of silane treatment after NaOH. The effectiveness of the treatments in the removal of non-structural matter from the fibers was confirmed by FTIR investigation and TGA measurements, suggesting also that the alkali treatment has a strong effect on their thermal behavior. The study of tensile properties of the fibers performed using Weibull statistics indicates that the tensile properties are somewhat reduced by chemical treatment. The morphological investigation of treated fibers through scanning electron microscopy indicates that silane treatments, both on raw fibers and on alkalized ones, result in limited fiber degradation.     

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.     

Improving the barrier and mechanical properties of corn starch-based edible films: Effect of citric acid and carboxymethyl cellulose

The films produced from pure starch are brittle and difficult to handle. Chemical modifications (e.g. cross-linking) and using a second biopolymer in the starch based composite have been studied as strategies to produce low water sensitive and relatively high strength starch based materials. A series of corn starch films with varying concentrations (0-20%, W/W) of citric acid (CA) and carboxymethyl cellulose (CMC) were produced by casting method. The effects of CA and CMC on the water vapor permeability (WVP), moisture absorption, solubility and tensile properties were investigated. The water vapor barrier property and the ultimate tensile strength (UTS) were improved significantly (p < 0.05) as the CA percentage increased from 0 to 10% (W/W). At the level of 15% (W/W) CMC, the starch films showed the lowest WVP values (2.34 × 10⁻⁷ g Pa⁻¹ h⁻¹ m⁻¹) and UTS increased from 6.57 MPa for the film without CMC to 16.11 MPa for that containing 20% CMC.     

Thermochemical characterisation of straws and high yielding perennial grasses

The research is concerned with thermochemical characterisation of straws and high yielding perennial grasses. Crops selected for this study include wheat straw (Triticum aestivum), rape straw (Brassica napus), reed canary grass (Phalaris arundinacea) and switch grass (Panicum virgatum). Thermogravimetric analysis (TGA) was used to examine the distribution of char and volatiles during pyrolysis up to 900 °C. Utilising multi-heating rate thermogravimetric data, the Friedman iso-conversional kinetic method was used to determine pyrolysis kinetic parameters. Light and medium volatile decomposition products were investigated using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) up to 520 °C. The 22 highest yielding identifiable cellulose, hemicellulose and lignin biomass markers were semi-quantified taking into consideration peak areas from GC chromatograms. Notable differences can be seen in butanedioic acid, dimethyl ester (hemicelluloses decomposition products), 2-methoxy-4-vinylphenol (lignin marker) and levoglucosan (intermediate pyrolytic decomposition product of cellulose) content when comparing perennial grasses with straw. From results presented in this study, perennial grasses such as switch grass, have the most attractive properties for fast pyrolysis processing. This is because of the observed high volatile yield content of 82.23%, heating value of 19.64 MJ/kg and the relatively low inorganic content.     

Effects of flax lignin addition on enzymatic oxidation of poly(ethylene adipate) urethanes

Lignin use in polymer industry has recently become very attractive from both economical and environmental reasons. In the specific case of blending, the addition of low lignin amounts was found to improve the properties and extends the application field of other natural or synthetic polymers, but the effects of oxidative enzymes on resulting blends are widely unknown. Thereby, the current study was carried out to determine some potential effects of small flax lignin concentrations (4.2 and 9.3 wt%) on the enzymatic degradation of a poly(ethylene adipate) urethane (PU). Thin cast films of PU and its lignin blends were incubated for 3 days at 30 °C with buffered solutions of fungal peroxidase and laccase extracted from Aspergillus sp., and compared with the untreated ones. Changes in surface structure and morphology were investigated by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM), while the impact on bulk was assessed from tensile tests and thermogravimetry analysis (TGA). Although the addition of flax lignin reduces the surface structural modifications after enzyme treatment, the morphology, tensile and thermo-oxidative characteristics are still affected, with laccase showing the higher degradative efficiency. The lignin concentration, its high impact on the resulting blends morphology and relative low resistance to laccase and peroxidase degradation was the most important factors proved to driven the enzymatic oxidation.     

10-Undecenoic acid-based polyol esters as potential lubricant base stocks

A new class of polyol esters were prepared by esterification of 10-undecenoic acid (UDA) with three polyols namely trimethylolpropane (TMP), neopentyl glycol (NPG) and pentaerythritol (PE) in 92-96% yields. The esters were characterized by IR, ¹H NMR, HPLC and mass spectral studies. Polyol esters were evaluated for basic lubrication properties and found to be: viscosity at 40 °C, 11.2-36.1 cSt; at 100 °C, 3.2-7.3 cSt; viscosity index (VI), 162-172; pour point +3 to −36 °C; flash point, 254-296 °C. All the three polyol esters synthesized exhibited good thermal stability with TGA onset temperatures above 260 °C. The lubricating properties of the products compared well with polyol esters based on oleic acid.     

Characterization of light weight epoxy composites from short Sansevieria Cylindrica fibers

Sansevieria (genus) cylindrica (species) belongs to Agavaceae family plant fiber first time used as a reinforcing agent in the epoxy system. Fibre extracted from leaves, fairly lesser density, porosity, higher strength to weight ratio (hereafter called SCF) and these fibers were alkali-treated and yet impregnated on the epoxy system using wet hand lay up technique in order to compare with untreated fiber on performance. DMA, TGA, DSC, FTIR, SEM, degradation temperature, flexural and tensile tests were performed for untreated and alkali-treated epoxy composites using different SCF volumes viz. 1 vol.%, 5 vol.%, 7 vol.% and 9 vol.%. Alkali treated fibre were found to have higher initial and final degradation temperatures and flexural and tensile strength. The removal of the amorphous hemi-cellulose on alkali treatment was played an instrumental in improving properties. A 3 °C increase in glass transition temperature and decomposition temperature were recorded respectively and over all treated SCF composites reinforced on the epoxy were shown significant results than untreated. Storage modulus and tan ?? were observed well at 9 vol.% treated SCF while flexural and tensile were increased by 35 and 13 % for SCF treated composites respectively.     

Effect of boron phosphate on the mechanical, thermal and fire retardant properties of polypropylene and polyamide-6 fibers

The effect of boron phosphate (BPO₄) nanoparticles on the mechanical, thermal, and flame retardant properties of polypropylene (PP) and polyamide 6 (PA-6) fibers are investigated by tensile testing, thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and micro combustion calorimeter (MCC). The addition of BPO₄ reduces the mechanical properties of the both PP and PA-6 fibers. According to the TGA results, the addition of BPO₄ does not change the thermal behavior of PP fiber and slightly reduces the thermal stability of PA-6 fiber by about 30 °C. According to MCC results, the addition of BPO₄ does not change the effective total heat evolution and heat release rate (HRR) peak for PP fibers. Although the inclusion of BPO₄ does not change the total heat evolution of PA-6 fiber, it reduces the HRR peaks due to increase in barrier effect of char.     

Synthesis and physical properties of petroselinic based estolide esters

A new series of petroselinic (Coriandrum sativum L.) based estolide 2-ethylhexyl (2-EH) esters were synthesized, as the capping material varied in length and in degrees of unsaturation, in a perchloric acid catalyzed one-pot process with the esterification process incorporated into an in situ second step to provide the coriander estolide 2-EH ester. The kinematic viscosities ranged from 53 to 75 cSt at 40 °C and 9.1 to 14.6 cSt at 100 °C with a viscosity index (VI) ranging from 151 to 165. The caprylic (C8) capped coriander estolide 2-EH ester had the lowest low-temperature properties (pour point = −33 °C and cloud point = −33 °C), while the coco-coriander estolide 2-EH ester produced an estolide with modest low-temperature properties (pour point = −24 °C and cloud point = −25 °C). The coco-coriander estolide 2-EH ester was explored for the ability to resist oxidative degradation with the use of an biodegradable additive package added in 1.5%, 3.5%, or 7.0% units based on weight. The oxidative stability increased as the amount of stability package increased (rotating pressurized vessel oxidation test (RPVOT) times 65-273 min). Along with expected good biodegradability, these coriander estolide 2-EH esters had acceptable properties that should provide a specialty niche in the U.S. as a biobased lubricant.     

Extrusion process improves the functionality of soluble dietary fiber in oat bran

Extrusion processing is a thermal process applied to food preparation. However, its effects on food ingredients are ambiguous. The aim of this study was to elucidate the effects of extrusion processing on soluble dietary fiber (SDF) in oat bran. The yield, composition, thermal properties, rheological behavior and functionality of SDF in extruded oat bran were compared with those of SDF in untreated oat bran. The results showed that SDF in extrude oat bran had higher yields (14.2%), mean particle diameter (1718.1 nm), peak temperature (T_p = 69.0 °C), solubility, swelling capacity, solvent retention capacity, foam ability, apparent viscosity and consistency coefficient, and lower flow behavior index than those of SDF in untreated oat bran. The extrusion process improves some properties of SDF from oat bran.     

Fique fibers: Enhancement of the tensile strength of alkali treated fibers during tensile load application

Fique fibers were treated using Na(OH) solution at 5 w/v%, slack and under 1 N of tension, at room temperature, for 4 and 24 h respectively. Changes in their structure and composition were monitored using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Additionally their mechanical properties were evaluated and analyzed. Results showed that tensile load application during alkali treatment improves their tensile strength and modulus. The most important change in mechanical properties was achieved in fibers treated for 24 h under tension. However, these fibers presented a high standard deviation; due to this treatment causing an important defibrillation. Moreover, fibers treated for 4 hours under tension, enhance their tensile strength around 56 %, while slack treated fibers improve only 38 %. When fibers were treated under tension, cellulose microfibrills were rearranged in the direction of tensile application and the spiral angle decreased, increasing the molecular orientation.     

Effect of thermal modification on the properties of narrow-leaved ash and chestnut

The concept of thermal modification has evolved from a challenging research program to commercial reality in several European countries in recent years. The aim of this study is to determine the change of various physical properties (oven-dry density, air-dry density, weight loss, swelling and anti-swelling efficiency (ASE)), compression strength parallel to grain, colour difference (ΔE), glossiness and surface roughness of narrow-leaved ash (Fraxinus angustifolia Vahl.) and chestnut (Castanea sativa Mill.) woods after heat treatment under different temperatures and durations. For this study two different temperatures (160 °C and 180 °C) and two different durations (2 h and 4 h) were considered. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements by the stylus method were made in the direction perpendicular to the fiber. Four main roughness parameters which are mean arithmetic deviation of profile (R_a), mean peak-to-valley height (R_z), root mean square roughness (R_q), and maximum roughness (R_y) obtained from the surface of wood were used to evaluate the effect of heat treatment on the surface characteristics of the specimens. The properties studied were significantly different (p = 0.05) at two temperatures and two durations of heat treatment. Based on the findings of this study, the results showed that oven-dry density, air-dry density, swelling, compression strength parallel to grain and surface roughness decreases with increasing heat treatment temperature and time.     

Microwave-enhanced alkali treatment of Pinus yunnanensis: Physiochemical characterization of the dissolved lignins

Pinus yunnanensis was subjected to water-bath and microwave treatments in 1% NaOH aqueous solutions at 100 °C with various ratios of bath heating time to microwave heating time (0/120, 20/100, 40/80, 60/60, 80/40, 100/20 and 120/0 min). The lignins dissolved in the alkali liquors were separated and purified, and their physicochemical features were comparatively characterized by sugar analysis, GPC, FT-IR, ¹³C and HSQC NMR, as well as thermogravimetric analysis (TGA). The results showed that the lignin fractions extracted with microwave heating (20-120 min) had high molecular weights and polydispersities (M_w 3150-5710 g/mol, M_n 2130-3020 g/mol, M_w/M_n 1.48-2.00) as compared to those prepared without microwave heating (M_w 3080 g/mol, M_n 2080 g/mol, M_w/M_n 1.48). The most striking characteristic of all lignin fractions was the almost absence of associated sugars (0.16-3.25%). The TGA results indicated that the thermal stability of the lignin fraction increased with the increment of the molecular weight. FT-IR and NMR spectra suggested that the lignin fractions showed similar structures which were mainly composed of guaiacyl (G) and minor amounts of p-hydroxyphenyl (H) units. Moreover, HSQC NMR spectrum of a typical lignin fraction (prepared with microwave heating for 120 min) revealed that it contained dominant amounts of β-O-4′ linkages (64.6%) and phenylcoumaran (β-5′) substructures (25.8%) together with small amounts of resinol (β-β′) substructures (6.7%) and coniferyl alcohol end groups (2.9%).     

Performance of three thermally treated tropical wood species commonly used in Turkey

Thermally modified wood is being increasingly offered in Europe as an alternative to preservative-treated timber. The aim of this study is to determine the change of various physical properties (oven-dry density, air-dry density, weight loss, swelling and anti-swelling efficiency (ASE)), compression strength parallel to grain, colour difference (ΔE), glossiness and surface roughness of sapele (Entandrophragma cylindricum), limba (Terminalia superba) and iroko (Chlorophora excelsa) woods after heat treatment under different temperatures and durations. For this study wood specimens were subjected to heat treatment under atmospheric pressure and air at two different temperatures (160 °C and 180 °C) and two different times (2 h and 4 h). Multiple physical properties (oven-dry density, air-dry density, and swelling), compression strength parallel to the grain and surface roughness of the heat-treated wood and control samples were tested. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements using the stylus method were made in the direction perpendicular to the fiber. Four main roughness parameters which are mean arithmetic deviation of profile (Ra), mean peak-tovalley height (Rz), root mean square roughness (Rq), and maximum roughness (Ry) obtained from the surface of wood were used to evaluate the effect of heat treatment on the surface characteristics of the specimens. Significant difference was found (P = 0.05) between physical and technological properties, and surface roughness parameters (Ra, Rz, Ry, Rq) at two temperatures and two durations of heat treatment. Based on the findings of this study, the results showed that oven-dry density, air-dry density, swelling, compression strength parallel to grain and surface roughness values decreased with increasing treatment temperature and treatment time. Thus, sapele, iroko, and limba wood can be utilized with proper heat treatment techniques for outdoor and indoor applications.