Alkali Silane Treatment Research Articles

Investigations on structure and properties of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced by diss fibers: Effect of various surface treatments

The paper reports some experimental results on the effect of different chemical modifications of Diss fibers on the properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites involving alkaline, combined alkaline/peroxide and combined alkaline/silane treatments. The biocomposite samples loaded at 20 wt% were prepared by melt compounding. Scanning Electron Microscopy (SEM) showed a better fiber-matrix interaction between Diss fiber and matrix after surface fiber treatment. Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD) results indicated an increase in crystallinity index of the biocomposites. In addition, the incorporation of Diss fibers treated with alkali-silane resulted in an improvement in Heat Deflection Temperature (HDT) and shore D hardness from 141.1 °C and 75.1–145.7°C and 86.2, respectively, in comparison with the neat matrix. This also agreed with the flexural properties results, which showed a significant increase in flexural modulus by almost 30 % compared to the neat PHBV. The same trend was observed for water absorption. Overall, combined alkali-silane treatment was found to be most efficient surface treatment method to develop strong interfacial adhesion between PHBV and Diss fiber, increasing the scope of application in manufacturing of light weight green composites.

Optimization of the Alkali-Silane Treatment of Agave lechuguilla Fibers (Ixtle) for Potential Reinforcement in Polymeric Composites

Reinforced polymeric composites with natural fibers have garnered significant interest in recent years due to the need for biomass utilization and the requirements of various industries, such as automotive and construction. Among these natural fibers, Agave lechuguilla fiber, commonly known as ixtle (FIx) or Tampico fiber, exhibits important characteristics such as length, high strength, and durability. However, there is limited literature on its conditioning, functionalization, and utilization as a reinforcing material in polymeric composites (CP). This study presents the optimization of the alkali-silane treatment of FIx, identifying the most suitable reaction conditions to enhance their thermal stability, tensile strength, and silane coupling agent (ACSi) grafting on the fiber surface. The chemical treatment with ACSi proved highly effective, resulting in a significant grafting content, which was confirmed through FTIR and SEM–EDS analyses. The high level of functionalization did not compromise the mechanical performance of the fibers, suggesting that functionalized FIx holds great potential as a reinforcing material in CP. These findings open new paths for the sustainable use of Agave lechuguilla fibers, contributing to the development of environmentally friendly and high-performance polymeric composites in various industrial applications.

Effect of optimized alkali-silane treatment on mechanical and fatigue behavior of maize husk fiber epoxy composites: a strength factor approach

Effect of optimized alkali-silane treatment on mechanical and fatigue behavior of maize husk fiber epoxy composites: a strength factor approach

Surface modification of Momordica angustisepala fiber using temperature-activated amino-functionalized alkali-silane treatment

Momordica angustisepala fiber (MAf) is like other natural fibers that usually have weak interfacial bonding when used in the production of polymer composites. Natural fibers are usually treated to improve their properties. This present work investigates surface modification of Momordica angustisepala fiber using temperature-activated amino-functionalized alkali-silane treatment. The fibers were soaked in an 80 ml sodium hydroxide (OH) solution before silane functionalization in 2 ml of aminopropyltriethoxysilane in 100 ml ethanol (OH-APS). The temperature of the APS solution was 75 and 150 °C with soaking time of 3 and 6 h. Optimized properties were obtained at a treatment temperature of 150 °C and a time of 3 h. It was established that the combined effect of activated temperature and OH-APS chemical treatment of MAf is promising and can be used to improve the interfacial bonding during polymer composite production.

Fatigue and impact strengths of kenaf fibre reinforced polypropylene composites: effects of fibre treatments

The effects of two fibre treatments (alkali-alone treatment and combined alkali-silane treatment) on the fatigue and impact strengths of kenaf fibre reinforced polypropylene composites are investigated. Test results showed that fibre treatments improve the fatigue and impact strengths of the composites, with alkali-silane treatment being the most effective one. Alkali concentration of 5% to 6% is found to be the optimal concentration for both alkali-alone and combined alkali-silane treatments. Microscopy examination revealed that the damage mechanisms of the composites are significantly influenced by the fibre treatment. The failure modes of alkali-alone treated kenaf/PP composites are predominantly characterized by fibre pull-outs, suggesting poor fibre-matrix adhesion; whereas the failure modes of alkali-silane treated kenaf/PP composites are characterised by fibre breakage and matrix cracks indicating improved fibre-matrix adhesion due to the additional silane treatment.

The Influence of Manufacturing Factors in the Short-Fiber Non-Woven Chestnut Hedgehog Spine-Reinforced Polyester Composite Performance

ABSTRACT One of the most important agricultural products in the northeast of Portugal is sweet chestnuts. In this region only, several tons of this product are produced every year. Sweet chestnuts are enclosed in a hedgehog covered with a large number of short and fine spines and containing more than one nut. This hedgehog, with long spines, does not have any commercial value, and they are considered an agricultural waste that is left in the fields to be incorporated into the soil. In this work, the authors propose to study the influence of some factors in the short-fiber non-woven chestnut hedgehog spine-reinforced polyester composite performance. For this purpose, the tensile properties of chestnut spines were determined by implementing a design of experiments (DOE) approach developed by Taguchi. Thus, the factors that will be controlled are the fiber dispersion which is defined by fiber/matrix mass ratio or weight fraction, the interfacial strength that could be improved using an alkali–silane treatment and, finally, the moisture level in the fibers. For each factor, three levels were used, an L9 orthogonal array of experiments was implemented to evaluate tensile and flexural properties. These properties were determined based on results of 54 tests, and the maximum mean values for tensile and flexural strength were 23.5 MPa and 33.6 MPa, respectively. The most influential factor for maximizing the tensile strength was the volume fraction of fiber with a contribution of 30%, and most influential factor for maximizing the flexural strength was the moisture level with a contribution of 65%. The determined mean value of tensile strength of the spines was 148 MPa.

High flow polypropylene/SEBS composites reinforced with differently treated hemp fibers for injection molded parts

Polypropylene/hemp fibers (PP/HF) composites for injection molded car parts show several advantages compared to similar composites containing glass fibers (GF), however they have low impact strength, tensile strength and modulus. Here, hemp fibers modified by alkali and alkali-silane treatment were used to reinforce a polypropylene matrix modified with maleic anhydride grafted polypropylene (MAPP) and SEBS. The addition of HF in PP modified with MAPP and SEBS has increased not only the tensile strength and modulus (by 45% and 230%) but also the impact strength. Double tensile strength and triple Young's modulus were obtained in PP composites with alkali-silane treated HF (HFs) in the presence of MAPP and SEBS. Similarly, the HFs led to a significant increase of storage modulus, with about 100% at room temperature and with about 200% at 120 °C. Moreover, the onset degradation temperature increased with 51 °C for HFs containing composites compared to neat PP. PP/HFs composites modified with MAPP and SEBS showed improved mechanical and thermal properties, being considered as a viable alternative to PP/GF composites for injection molded parts in the automotive industry.

Effect of Ramie Fabric Chemical Treatments on the Physical Properties of Thermoset Polylactic Acid (PLA) Composites

Ramie fabric-reinforced thermoset polylactic acid (PLA) composites were prepared by using heat pressing technology. Fabrics were treated with alkali, silane, and alkali–silane respectively, expecting an improvement of the interface between the fabric and the matrix. Scanning electron microscopy (SEM) results indicated that after alkali treatment, impurities on the fiber surface were removed and its diameter became finer. After the silane, and alkali–silane treatments, the contact angles of the ramie fibers increased by 14.26%, and 33.12%, respectively. The contact angle of the alkali–silane treated fiber reached 76.41°; this is beneficial for the adhesion between ramie fiber and the PLA. The research revealed that the tensile strength of the fiber increased after the alkali and silane treatments. A slight decrease was noticed on the tensile strength of fibers treated with alkali–silane. After all, three chemical treatments were done, the flexure strength of the ramie fabric-reinforced PLA composites, improved in all cases. Among the three treatments, the alkali–silane treatment demonstrated the best result, as far as the flexure strength and modulus of the fabricated composites were concerned. On the other hand, water absorption of the related composites decreased by 23.70%, which might contribute to the closer contact between the ramie fiber and the matrix. The ramie fabric-reinforced PLA composites, prepared in this study, can meet the standard requirements of aircraft interior structures and have favorable application foreground.

Comparative Thermal and Physical Investigation of Chemically Treated and Untreated Oil Palm EFB Fiber

Natural fiber (NF) as a reinforcement is capable of playing a remarkable role in fiber reinforced polymeric composites (FRPC) owing to its low cost, low density, flexibility, CO2-neutrality, renewability, availability and eco-friendliness. In order to substitute for synthetic fiber, oil palm empty fruit bunch (EFB) fiber could be a potential candidate. This study aims to investigate the effect of chemical treatment on the morphological, thermal and structural properties of EFB fibers. Pulverized EFB fibers of 1-3 mm in length with a diameter of 100∼400 µm and density of 1.07 g/cm3 were used. Surface modification of fibers was carried out by conducting alkali treatment for three different soaking periods of 1, 13 and 24 hours, sodium bicarbonate treatment and alkali-silane treatment, and subsequently fibers were neutralized by rinsing with distilled water to the pH level of 7. The fibers were then dried at 70 °C for 24 hours in an oven. To examine the physical and thermal properties of the fibers, Scanning Electron Microscope (SEM), Energy-Dispersive X-ray (EDX) spectroscopy, Fourier Transformed Infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA) tests were conducted. SEM was employed to investigate the morphology of fibers. The rougher and cleaner surface of treated EFB fibers were observed relative to those of untreated ones. EDX analysis showed the amount of carbon and oxygen in the fibers. FTIR revealed chemical structure of fibers. TGA tests were performed and showed greater thermal degradation temperature of alkali and alkali-silane treated fibers compared to those of sodium bicarbonate and untreated fibers for the entire temperature increment from 30 °C to 600 °C.

The Influence of Chemical Treatments on Cantala Fiber Properties and Interfacial Bonding of Cantala Fiber/Recycled High Density Polyethylene (rHDPE)

ABSTRACTThe influence of chemical treatments on the properties of cantala fiber as well as on the quality of the interfacial bonding of cantala fiber/rHDPE was investigated. The fibers were treated with alkali, silane, and a combination of both. The results showed that the loss of hemicellulose and lignin after the alkali treatment, and the presence of a silane layer on the fiber surface after the silane or alkali-silane treatment, improved the thermal stability, surface energy, and IFSS. The highest surface energy of 45.37 mN/m was obtained during the alkali treatment (NF12). The alkali-silane treatment with 0.75% wt of silane (NSF075) gave the highest thermal stability and IFSS value.

The effect of chemical treatment methods on the outdoor performance of waste textile fiber-reinforced polymer composites

In this study, weathering effect on untreated textile fiber-reinforced polymer composites and the effect of different chemical treatments for better interfacial adhesion on the outdoor performance were investigated. Degradation of physical, mechanical, and chemical properties of textile fiber-reinforced polymer composites was evaluated through common chemical treatments such as maleated coupling, alkaline treatment, silane treatment, and alkali–silane treatment. Untreated and chemically treated textile fiber-reinforced polymer composites were subjected to water uptake and UV exposure up to 1000 h. Tensile and impact properties were mechanically examined, and the changes on the physical properties due to water uptake, swelling, and color change were investigated. In addition, Fourier transform infrared spectrum analysis was performed in order to evaluate the chemical changes after exposure.

The effects of different chemical treatment methods on the mechanical and thermal properties of textile fiber reinforced polymer composites

In this study, the effects of improvement methods on the mechanical and thermal properties of textile fiber reinforced (T-FRP) composites were investigated. Five different chemical methods namely, silane treatment, alkaline treatment, alkali–silane treatment, maleic anhydride, and alkali–maleic anhydride coupling agents were applied to evaluate the suitable process parameters (concentration, soaking time, ratio by weight) for the enhanced properties of T-FRP composites. Tensile, three-point flexural and impact tests were performed on both untreated and treated composites for comparison purpose. Treated and untreated T-FRP composites were characterized using scanning electron microscopy, differential scanning calorimetry, and Fourier-transform infrared spectroscopy to evaluate thermomechanical properties of composites. Results show that a significant improvement up to 60–70% can be seen on the mechanical properties of T-FRP composites via improving the interfacial adhesion and compatibility between fiber and matrix.

Effects of surface treatment on mechanical and thermal properties of jute fabric-reinforced poly(butylene succinate) biodegradable composites

Biodegradable composites based on poly(butylene succinate) (PBS) and unidirectional plain jute fabrics have been developed. These composites were fabricated by compression molding of sandwiching 4–7 jute fabric layers between five and eight layers of PBS sheets. Surface modification of the jute fabric by alkali and combined alkali-silane treatments was investigated. The effects of surface modification on the mechanical and thermal properties of jute fabric/PBS biodegradable composites were studied. The mechanical properties of surface-treated jute fabric/PBS biodegradable composites were significantly higher than those of untreated ones. Compared with the alkali treatment, the combined alkali-silane treatment showed higher mechanical properties of the jute fabric/PBS biodegradable composites. The alkali-silane-treated jute fabric/PBS biodegradable laminated composite with six reinforced fabric layers (47.5 wt.%) achieved the best mechanical properties in this study, which showed an increase in tensile strength by 16.4%, tensile modulus by 10.8%, flexural strength by 24.2%, and flexural modulus by 21.9% compared with those of untreated one. Fractured surface morphologies of tensile specimens exhibited an improvement of interfacial fiber-matrix adhesion in the PBS biodegradable composites reinforced with surface-treated jute fabric. Thermal stability of the jute fabric/PBS biodegradable composites was remarkably to be intermediate between the PBS resin and the jute fabric. Surface-treated jute fabric/PBS biodegradable composites having good interfacial fiber-matrix adhesion resulted in stable composites with better thermal stability than that of untreated ones.

The effects of alkali–silane treatment on the tensile and flexural properties of short fibre non-woven kenaf reinforced polypropylene composites

Kenaf fibre reinforced polypropylene composites were manufactured by compression moulding. The kenaf fibre was considered in three forms; untreated, treated with sodium hydroxide solution and treated with sodium hydroxide solution followed by three-aminopropyltriethoxysilane. The effects of these chemical treatments on the tensile and flexural properties of the composites were investigated. Mechanical test results show that alkali treatment followed by three-aminopropyltriethoxysilane treatment (alkali–silane treatment) significantly improves the tensile and flexural properties of short fibre non-woven kenaf polypropylene composites. In particular, the specific tensile and flexural strengths of alkali–silane treated kenaf composites with 30% fibre mass fraction are, respectively, only 4% and 11% lower than those of composites made using glass fibre. Scanning electron microscopy examination shows that the improvements in the tensile and flexural properties resulting from alkali–silane treatment can be attributed to better bonding between the fibres and matrix.