Pencirian Ultrasonik Bag) Batang Kelapa Sawit (Elaeis Guineensis Jacq.)

Ciri-ciri ultrasonik terhadap batang pokok kelapa sawit telah dikaji dengan menggunakan pelbagai parameter fizikal seperti kandungan kelengasan, ketumpatan dan arah butiran. Tiga arah anisotropik, iaitu arah membujur (L), jejarian (R) dan tangen (T) terhadap susunan serabut dan berkas vaskular telah dipertimbangkan untuk pengukuran ciri-ciri tersebut. Sifat-sifat ini telah ditentukan dengan menggunakan penguji komersial ultrasonik pada 45 kHz. Halaju ultrasonik dan pemalar kekenyalan berbeza mengikut susunan membujur > tangen > jejarian (L>T>R). Sebarang lencongan daripada paksi membujur mengurangkan halaju ultrasonik dan pemalar kekenyalan pada semua kandungan kelengasan. Corak pengurangan halaju dan pemalar kekenyalan pada arah L, R dan T adalah berbeza berbanding pada arah LR, LT dan RT. Kaedah ultrasonik berupaya mengesan pereputan pada pokok kelapa sawit hidup ia berdasarkan kepada surihan gelombang ultrasonik dan transduser penghantar kepada transduser penenma di sekeliling batang pokok Sistem kemudian diuji melalui perbandingan tomogram dengan memotong keratan rentas batang pokok pada satah yang sama selepas pengukuran pereputan mengurangkan halaju ultrasonik dan meninggikan masa transit sehingga tidak boleh dikesan oleh isyarat alat ultrasonik BPV Kaedah ini juga berupaya mengesan kecacatan pada kayu kelapa sawit halaju ultrasonik, pemalar kekenyalan, ketumpatan dan kandungan kelengasan kayu sawit reput sentiasa lebih rendah berbanding kayu sawit sihat Anatomi asas seperti taburan berkas vaskular dan susunan serabut pada kawasan zon periferal dan zon tengah sangat mempengaruhi ciri-ciri ultrasonik seperti halaju dan pemalar kekenyala

Elastic, Optical and Thermal Properties of Teo2-Zno and Teo2-Zno-Alf3 Glass Systems

This thesis presents the study of binary zinc tellurite, TeO2-ZnO and ternary oxyfluorotellurite, TeO2-ZnO-AlF3 glass system which have been prepared using melt quenching technique. The TeO2, ZnO and AlF3 contents have been changed based on their mole fraction. The physical properties were measured and their amorphous nature was confirmed by x-ray diffraction technique. Additional increment of ZnO in binary and ternary glass systems caused the decreasing of ultrasonic velocity. The values of velocity in ternary glass system are higher as compared to the values in binary glass system. Addition of fluorine into TeO2-based glass system resulted the reduction of Te-O-Te linkages due to a gradual transformation of trigonal bipyramid TeO4 (tbp) through TeO3+1 to trigonal pyramid TeO3 which decreasing the connectivity of the tellurite glass former network. Similar pattern in elastic moduli in both glass systems was observed where the values decreased linearly. Both Young’s modulus and bulk modulus were related to the cross-linking density with large influence on the propagation of ultrasonic velocities. All glass samples were found to have high cross-link densities. The values of Poisson’s ratio lie between 0.1 to 0.2. The elastic properties of these glasses are closely related to the strength of glass networks and structures. The refractive index of the TeO2-ZnO glasses was found to increase from 1.99 – 2.07 for mole fraction of 0.10-0.40 ZnO content with an interval of 0.05. The refractive indices for ternary glass system show an increasing trend in all series of glass and varying between 2.01 – 1.76. The behaviour of the refactive index can be explained in either electron density or polarizability of the ions. In this study, the positions of the fundamental absorption edge shift to higher energy (shorter wavelength) with increasing ZnO content in binary tellurite glasses. The shifting of wavelength was related to the amount of production of the non-bridging oxygen (NBO) in TeO2-ZnO glass system and the effect of fluorine ions replacement to the non-bridging oxygen ions in ternary glass system. Experimental data shows that the values of Eopt decreased with increasing content of ZnO for both glass systems where the values of Eopt for binary glass system varied from 2.34 eV to 1.88 eV for indirect allowed transition. The variation of Eopt with glass composition can be explained by suggesting that the non-bridging oxygen ion content increases with increasing ZnO content, shifting the band edge to lower energies and leading to a decrease in the value of Eopt. FTIR spectra revealed broad, weak and strong absorption bands in the investigated range of wavenumbers from 4000 to 400 cm-1 which associated with their corresponding bond modes of vibration and the glass structure. For pure TeO2 glass, the strong absorption band is located at 626 cm-1. The addition of ZnO to TeO2 shifted the major band from 626 cm-1 to the band at around 669 cm-1. AlF3 greatly affects the binary structure of TeO2-ZnO glasses by shifting the absorption bands to the lower wavenumbers. The thermal properties such as thermal expansion coefficient, glass transformation temperature, Tg, acoustic Debye temperature and softening temperature were collected for both glass systems. Generally, the increase of the thermal expansion coefficient in both glass systems might be due to the changes of the coordination number of TeO2 from 4 to 3 and associated with the creation of non-bridging oxygen that caused the decrease in rigidity. Experimental results showed that values for glass transition temperature were closely related to the chemical bond in the system. The decrease in the glass transition temperature, acoustic Debye temperature and softening temperature values implies that number of bridging oxygen group decreases. This is mainly due to the addition of ZnO which weaken the bond between each atom sample (increases the number of NBOs atom). The bond easier to break and hence the Tg of the sample decreased. The fluorine ions tend to break up the strong TeO2 covalent netrwork of the glass by forming ionic, non-bridging M-F bonds, where M is a metal cation

Synthesis and optical properties of ZnO-TeO2 glass system

Problem statement: Systematic series of ZnO-TeO2 glasses with mole fraction of 0.10-0.40 ZnO content with an interval of 0.05 were studied to obtain their physical and optical properties. Approach: All the glass samples were synthesized by rapid melting quenching method under controlled conditions, while their refractive indices (n) were measured by the EL X-02C high precision ellipsometer. The room temperature absorption of all glass samples were determined using Camspec M350 double beam UV-visible spectrophotometer. The infrared (IR) spectra of each glass samples were recorded with Thermo Nicolet Fourier Transform-Infrared (FT-IR) spectrophotometer. Their physical properties were measured and the amorphous nature was confirmed by the x-ray diffraction technique. Results: The increase of refractive index of the TeO2-ZnO glasses with the addition of ZnO was best explained in terms of either electron density or polarizability of the ions. The absorption edge shift to higher energy (shorter wavelength) with increasing ZnO content was observed in this glass. The optical band gap (Eopt) of zinc tellurite glass decreases with increasing of ZnO content probably due to the increment of Non-Bridging Oxygen (NBO) ion contents which eventually shifted the band edge to lower energies. Conclusion/Recommendation: The physical and optical properties of zinc tellurite glasses were found generally affected by the changes in the glass composition. FTIR spectra of zinc tellurite glass revealed broad, weak and strong absorption bands in the investigated range of wave numbers from 4000-400 cm-1 which associated with their corresponding bond modes of vibration and the glass structure. The addition of ZnO into TeO2 glass network shifted the major band from 626 cm-1 (for pure TeO2 glass) to the band at around 669 cm-1

Effect of ZnO on the thermal properties of tellurite glass

Systematic series of binary zinc tellurite glasses in the form (where to 0.4 with an interval of 0.05 mole fraction) have been successfully prepared via conventional melt cast-quenching technique. Their density was determined by Archimedes method with acetone as buoyant liquid. The thermal expansion coefficient of each zinc tellurite glasses was measured using L75D1250 dilatometer, while their glass transition temperature () was determined by the SETARAM Labsys DTA/6 differential thermogravimetric analysis at a heating rate of 20 K min−1. The acoustic Debye temperature and the softening temperature () were estimated based on the longitudinal () and shear ultrasonic () wave velocities propagated in each glass sample. For ultrasonic velocity measurement of the glass sample, MATEC MBS 8000 Ultrasonic Data Acquisition System was used. All measurements were taken at 10 MHz frequency and at room temperature. All the thermal properties of such binary tellurite glasses were measured as a function of ZnO composition. The composition dependence was discussed in terms of ZnO modifiers that were expected to change the thermal properties of tellurite glasses. Experimental results show their density, and the thermal expansion coefficient increases as more ZnO content is added to the tellurite glass network, while their glass transition, Debye temperature, and the softening temperature decrease due to a change in the coordination number (CN) of the network forming atoms and the destruction of the network structure brought about by the formation of some nonbridging oxygen (NBO) atoms

Effect of concurrent ZnO addition and AlF3 reduction on the elastic properties of tellurite based glass system

New ternary zinc oxyfluorotellurite (ZOFT) with the composition (ZnO)x –(AlF3)y –(TeO2)z, where 5 ≤ x < 35; 5 ≤ y ≤ 25; 60 ≤ z ≤ 70, has been successfully prepared by the conventional rapid melt quenching technique. Density, molar volume, and glass transition temperature have been assessed for each ZOFT glass sample. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system at 5 MHz frequency and room temperature. The longitudinal modulus (L), shear modulus (G), Young’s modulus (E), bulk modulus (K), and Poisson’s ratio (σ) are assessed from both velocity data and their respective density. The compositional dependence of the ultrasonic velocities and related parameters are discussed to understand the rigidity and compactness of the glass system studied

Effect of Zinc on the Physical Properties of Tellurite Glass

A series of binary tellurite glass samples containing zinc oxide, ranging from 10 to 40 mol%, were successfully prepared. Longitudinal and shear ultrasonic wave velocities were measured at room temperature and were taken at 5 MHz. Elastic properties, Poison`s ratio, microhardness, Debye temperature and fractal bond connectivity have been calculated from the measured density and ultrasonic wave velocities. Results from the studies show that the densities of all glasses increase from 5098 to 5283 kg m-3, molar volumes decrease from 29.773 to 24.287 m3 mol-1 and the transition temperature, Tg decreases from 381.17 to 360.52°C with the substitution of TeO2 by ZnO content. Both the longitudinal and shear wave velocities decrease with increase of ZnO composition. The experimental results indicated that the elastic constants depend upon the composition of the glasses. The role of the ZnO inside the glass network is also discussed. Quantitative analysis based on bond compression model has been carried out, in order to obtain more information about the structure of these glasses

Effect of Concurrent ZnO Addition and AlF3 Reduction on the Elastic Properties of Tellurite Based Glass System

New ternary zinc oxyfluorotellurite (ZOFT) with the composition (ZnO)x-(AlF3)y-(TeO2)z, where 5≤x<35; 5≤y≤25; 60≤z≤70, has been successfully prepared by the conventional rapid melt quenching technique. Density, molar volume, and glass transition temperature have been assessed for each ZOFT glass sample. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system at 5 MHz frequency and room temperature. The longitudinal modulus (L), shear modulus (G), Young’s modulus (E), bulk modulus (K), and Poisson’s ratio (σ) are assessed from both velocity data and their respective density. The compositional dependence of the ultrasonic velocities and related parameters are discussed to understand the rigidity and compactness of the glass system studied

Effect of AlF3 on the density and elastic properties of zinc tellurite glass systems

This paper presents the results of the physical and elastic properties of the ternary zinc oxyfluoro tellurite glass system. Systematic series of glasses (AlF3)x(ZnO)y(TeO2)z with x = 0–19, y = 0–20 and z = 80, 85, 90 mol% were synthesized by the conventional rapid melt quenching technique. The composition dependence of the physical, mainly density and molar volume, and elastic properties is discussed in term of the AlF3 modifiers addition that are expected to produce quite substantial changes in their physical properties. The absence of any crystalline peaks in the X-ray diffraction (XRD) patterns of the present glass samples indicates the amorphous nature. The addition of AlF3 lowered the values of the densities in ternary oxyfluorotellurite glass systems. The longitudinal and transverse ultrasonic waves propagated in each glass sample were measured using a MBS8020 ultrasonic data acquisition system. All the velocity data were taken at 5 MHz frequency and room temperature. The longitudinal modulus (L), shear modulus (G), Young’s modulus (E), bulk modulus (K) and Poisson’s ratio () are obtained from both velocities data and their respective density. Experimental data shows the density and elastic moduli of each AlF3-ZnO-TeO2 series are found strongly depend upon the glass composition. The addition of AlF3 modifiers into the zinc tellurite causes substantial changes in their density, molar volume as well as their elastic properties

Correction: Effect of AlF3 on the Density and Elastic Properties of Zinc Tellurite Glass Systems. Materials 2012, 5, 1361-1372.

Due to an oversight, the data of the last column “Vs” in Table 1 was missing in the original version of this article [1]. [...