Comparative study of Fourier transform infrared spectroscopy (FTIR) analysis of natural fibres treated with chemical,physical and biological methods

Polymer Bulletin - Kenaf and luffa fibres are hydrophilic due to the presence of water sensitive constituents, which tend to form a poor compatibility when binding with polymers. Thus, the surface...     

An investigation of sound absorption coefficient on sisal fiber poly lactic acid bio‐composites

In this research, the mechanical, acoustical, thermal, morphological, and infrared spectral properties of untreated, heat and alkaline‐treated sisal fiber‐reinforced poly‐lactic‐acid bio‐composites were analyzed. The bio‐composite samples were fabricated using a hot press molding machine. The properties mentioned above were evaluated and compared with heat‐treated and alkaline‐treated sisal fibers. Composites with heat‐treated sisal fibers were found to exhibit the best mechanical properties. Thermo‐gravimetric analysis (TGA) was conducted to study the thermal degradation of the bio‐composite samples. It was discovered that the PLA‐sisal composites with optimal heat‐treated at 160°C and alkaline‐treated fibers possess good thermal stability as compared with untreated fiber. The results indicated that the composites prepared with 30wt % of sisal had the highest sound absorption as compared with other composites. Evidence of the successful reaction of sodium hydroxide and heat treatment of the sisal fibers was provided by the infrared spectrum and implied by decreased bands at certain wavenumbers. Observations based on scanning electron microscopy of the fracture surface of the composites showed the effect of alkaline and heat treatment on the fiber surface and improved fiber‐matrix adhesion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42470.     

Riboflavin-mediated delivery of a macromolecule into cultured human cells

The effects of perivascular nerve stimulation and phenylephrine on osmolyte release were studied in the intact perfused rat liver and isolated liver parenchymal cells (PC) and nonparenchymal cells. In the perfused liver, electrical stimulation of perivascular nerves (20 Hz/2 ms/20 V) led to a phentolamine-sensitive increase of cell hydration by 6.5% +/- 1.2% (n = 3) and a transient phentolamine-sensitive stimulation of taurine and inositol, but not betaine, release. These nerve effects were mimicked by phenylephrine, but not prostaglandin F2alpha, and were not affected by sodium nitroprusside (SNP) or ibuprofen. Nerve stimulation-induced taurine, but not inositol, release was inhibited by 4, 4'-di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS) (50 micromol/L). Single-cell fluorescence studies with isolated liver PC, Kupffer cells (KC), sinusoidal endothelial cells (SEC), and hepatic stellate cells (HSC) revealed that phenylephrine induced an increase in cytosolic free Ca2+ only in PC and HSC, but not in KC and SEC, whereas extracellular uridine triphosphate (UTP) produced Ca2+ transients/oscillations in all liver cell types studied. Phenylephrine had no effect on osmolyte release from isolated KC and SEC, but increased taurine (but not inositol) release from PC and inositol (but not taurine) efflux from HSC. The data suggest that: 1) liver cell hydration and-consecutively-osmolyte content are modulated by hepatic nerves via an alpha-adrenergic mechanism, which does not involve eicosanoids or hemodynamic changes; 2) that PC and HSC are the primary targets for nerve-dependent alpha-adrenergic activation, whereas 3) KC and SEC probably do not express alpha-adrenoceptors coupled to Ca2+ mobilization or osmolyte efflux.     

Interface,thermal, and Fourier transform—infrared spectroscopy investigation on polylactic acid/polyhydroxyalkanoate composites with silane-treated aluminum particles and intercalated montmorillonite inclusions for semiconductor devices

In this investigation, the dielectric properties of silane-influenced aluminum conductive particles in polylactic acid, polyhydroxyalkanoates, and intercalated montmorillonite (MMT) composite were assessed for enhancing the dielectric constant, dielectric loss, and AC conductivities. Eight different sets of samples were fabricated with untreated and silane-treated batches of biopolymer composites where the highest recorded dielectric constant was 3.98 at relaxation frequency of 10 kHz. One of the notable observations in the dielectric loss was with PLA/PHA/iMMT/Al (10 wt%) (silane-treated) composites exhibited the lowest losses past relaxation frequencies. Furthermore, FT-IR spectra were conducted on the samples to identify stretching and bonds created by silane and aluminum particles. The IR spectra confirm the formation of the Si O Al bond when treated with 3-glycidyloxypropyl-trimethoxysilane (GPTMS) solution and confirm the bond of Al OH hydroxyl bonds in the untreated composite samples. Other IR spectra information that was gathered would include carbonyl group stretching at 1750 cm⁻¹ and absorption bands of hydroxy acids, between 3511 and 3640 cm⁻¹, respectively. Scanning electron microscopy was performed on the sample to observe the formation of matrix cracks and exfoliation. A rough surface can be seen on PLA/PHA blends and the crystallization of these polymer blends regions can be vividly seen from the micrographs. Lastly, thermogravimetry analysis on the composite samples shows a predominant mass loss at 300°C before complete degradation and the notable composite with the lowest mass loss would be PLA/PHA/iMMT/Al (10 wt%) (ST) composite samples and with the inclusion of a constant 5 wt% organoclay MMT fillers imposed a high-onset degradation temperature, which was remarkable for composites that were fabricated through standard hot-press compression molding and cooling procedures.     

Determination of dielectric properties of natural fiber reinforced polymer composite using adaptive neuro fuzzy inference system

In this study, the dielectric properties of polylactic acid reinforced with natural fibers are objectified by using adaptive neuro fuzzy inference system (ANFIS). This method is considered to be economically feasible as compared to fabricating dielectric samples and measuring dielectric properties with apt operating conditions and advanced equipment. Also, past research has focused primarily on polymer dielectric properties which does not involve any natural fiber inclusion, such that this research will focus on producing ANFIS models for natural fibers which will then be used to calculate dielectric permittivity ( ), dielectric loss ( ) with respect to frequency dependencies. Furthermore, experimental results of dielectric constants and losses of polylactic acid (PLA) based composites will be analyzed from past research which used physical techniques to fabricate composites and will be compared with the results from ANFIS models. It was found that error computation of both the properties are found to be low and the percentage difference in output data is considered less. In addition, the ANFIS neural network had predicted most of the data that was trained, and the crisp output values were found to correlate with the experimental dielectric properties which makes this prediction model possible to use as an alternative approach to fabricating composites and testing.     

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.     

Processing and characterization of chemically modified wood sawdust reinforced (diospyros,dialium) epoxy composites

Polymer composite materials based on natural fiber such as wood had been widely used for research purposes and engineering interests. The interest in wood reinforced polymer composites had grown quickly due to their better performance in aspects of mechanical properties compared to pure wood. In this study, wood sawdust of diospyros (kayu malam) and dialium (keranji) were chosen to be incorporated into an epoxy-based polymer composite. The wood is made into sawdust, which was treated with boric acid and hydrogen peroxide. Surface treatment with these reagents was used to improve the mechanical properties of the polymer composite compared to untreated wood polymer composite. Sawdust reinforced epoxy composite that was fabricated are with different weight percentages from 0 % (no wood), 5 %, 10 %, 15 % to 20 % wt % for comparison on their tensile, flexural, and impact strength properties. Tensile, flexural, and impact tests were performed to determine the changes in mechanical properties where it was found that tensile strength had increased by 34 percent with an optimum keranji and kayu malam fiber weight of 15 wt % for both boric acid and hydrogen peroxide treatments. For flexural strength, in both wood fibers, the optimum fiber weight was found to 15 wt %, and the addition of wood had increased the strength by 57 percent. As for impact strength, it decreased as the weight of fiber increased, where it was assumed that the addition of wood might have increased the crack initiation. Adhesive bonding between hydrophilic wood sawdust and the hydrophobic epoxy polymer was the phenomenon that was focused on this research. The range of optimum weight percentage of sawdust would be determined from the experiment result.     

Characterization study of flax/strontium titanate/polypropylene composite for low-k dielectric applications

This study demonstrates the characterization of flax fiber reinforced polypropylene-strontium titanate composite and dielectric study for low-k dielectric applications. The composite was studied through thermal, morphological, and compositional aspects. Thermogravimetry analysis, differential scanning calorimetry shows a higher thermal stability with low glass transition temperatures and lowered decomposition temperatures of 375°C. The morphological study on the surface of this composites had revealed closely packed layers of fiber, ceramic and polymer matrix, which deduces the increased dielectric constants between 3.92 and 4.25 after the addition of strontium titanate. The dielectric constant was found to be significantly higher with a 78% increase with strontium titanate inclusion at relaxation frequencies between 1 kHz and 2 MHz, respectively. Besides, the dielectric property data showed that dielectric permittivity of 4.2 (low k) with the inclusion of natural fibers and ceramic at higher frequencies and lowered corresponding dielectric losses. The infrared spectroscopy results also show a reduction in hydroxyl groups and confirms the presence of bonds that are subjected to high interfacial bonding.