Effect of Moisture and Heat on Mechanical Properties of Wood and Wood-Plastic Composite

Wood-plastic composite (WPC) has been made by impregnating methylmethacrylate (MMA) monomer into simul, a native timber of Bangladesh, under Co-60 γ radiation. The effect of moisture and heat and humidity on simul and its WPC is investigated as a simulating phenomenon of the sunlight, rain, and moisture to which timber is generally exposed. Mechanical properties measured under variable conditions of moisture, heat, and humidity reveal that the WPC is a much improved product, suitable for use as a substitute for the good-quality timber normally applied for household goods.     

Characterization of Wood and Wood-Plastic Composite

Wood-plastic composites (WE) were prepared with low-grade wood (kadom, simul, and mango) of Bangladesh and MMA (methyl methacry-late) under Co-60 gamma irradiation with a 3-Mrad dose (800 krad/h). Polymer loading and tensile properties of the composites were determined and the effect of urea and N-vinyl pyrrolidone (NVP) on these properties was studied. The polymer loading (PL) increases slightly (2-3%) with the addition of urea to the MMA + MeOH solution: however, this increment is 616% with NVP addition and 12-54% with urea + NVP, depending on the type of wood. Similarly, the tensile strength (TS) increased by 11-25%, the bending strength (BS) by 31-48%, and the compressed strength (CS) by 40-67%. To further characterize the composite, the samples were investigated with infrared (IR), electron-spin resonance (ESR), and thermally simulated luminescence (TSL) techniques. IR studies reveal that MMA was grafted with the wood substrate; ESR and TSL investigations detected the residual free radicals (not the primary free radicals) in the composites.     

Role of Photoinitiators in the UV Curing of Urethane Acrylate

Polymeric films were prepared under UV radiation with tetraacrylated urethane oligomer in combination with N-vinyl pyrrolidone (NVP) using a set of four photoinitiators (Irg 907, Irg 651, Irg 369, and Irg 184). The study evaluates optimum photoinitiator concentration and radiation dose. Various film properties such as gel content, swelling ratio in acetone, pendulum hardness, tensile strength, and elongation at break were determined. These formulated solutions were coated on wood substrates, and gloss and hardness of the film cured on the wood substrate were determined. Some of these properties are compared with those of the films cured on the glass plates. Irg 369 is found to be the best photoinitiator to produce better films, both on glass plate and on wood substrate.     

Thermal,Mechanical and Morphological Characterization of Jute/Gelatin Composites

Jute fabrics/gelatin biocomposites were fabricated using compression molding. The fiber content in the composite varied from 20–60 wt%. Composites were subjected to mechanical, thermal, water uptake and scanning electron microscopic (SEM) analysis. Composite contained 50 wt% jute showed the best mechanical properties. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength of the 50% jute content composites were found to be 85 MPa, 1.25 GPa, 140 MPa and 9 GPa and 9.5 kJ/m², respectively. Water uptake properties at room temperature were evaluated and found that the composites had lower water uptake compared to virgin matrix.     

Effect of Pretreatment with Ultraviolet Radiation on the Physicomechanical Properties of Photocured Coir (Cocos nucifera) Fiber with 1-Ethyl-2-Pyrrolidone (1-E-2-P) Monomer

Coir fiber (Cocos nucifera) was modified with 1-ethyl-2-pyrrolidone (1-E-2-P) monomer by photocuring. A series of formulations of different concentration of 1-ethyl-2-pyrrolidone (3, 5, 10, 20, 30, and 70%) in methanol was prepared along with 2% photoinitiator (Darocur-1664). Concentration of 1-E-2-P, soaking time, and radiation doses were optimized and found that 5% 1-E-2-P, 7 min soaking time, and 5th pass of UV radiation was the optimized condition that gave the maximum values as polymer loading (PL) (21%) and 71% higher tensile strength over virgin one. The coir fiber was pretreated with ultraviolet (UV) radiation of various intensities for further improvement of mechanical properties. The mechanical properties, such as TS (tensile strength), Eb (elongation at break), and modulus (σ) of the pretreated fiber, were monitored. Fiber treated with 130th pass of radiation showed the higher TS, Eb, and σ. The fiber irradiated at 130th pass of UV radiation gave the maximum values as PL (35%) and 74% and 18% higher tensile strength and elongation at break, respectively. The fiber, both treated and untreated, was subjected to water absorption. The pretreated and cured coir fiber showed the minimum water uptake behavior.     

Surface Modification of Sisal (Agavae sisalana) Fiber by Photocuring: Effect of Additives

The sisal fiber (Agavae sisalana) was grafted with methacrylonitrile (MAN) under UV radiation in order to modify its mechanical and degradable properties. A number of MAN solutions of different concentrations in methanol (MeOH) along with photoinitiator Darocur-2959 were prepared. The soaking time, radiation dose and monomer concentration were optimized. Sisal fiber soaked for 60 min in 50% MAN and irradiated at 8th UV pass achieved highest values of tensile properties like tensile strength (TS = 140.2 MPa), and elongation at break factor (Ef = 8) with 8% polymer loading (PL). To further improve the properties of sisal fiber, a number of additives (1%) such as urea (U), polyvinylpyrrolidone (PNVP), tripropelene glycol diacrylate (TPGDA), hexanediol diacrylate (HDDA), trimethyl propane triacrylate (TMPTA), ethylene glycol dimethacrylate (EGDMA) were used in the 50% MAN formulation to graft at the optimized condition. Among the additives used, urea has significantly influenced the PL (9%), TS (190 MPa), and Ef (9) values of the treated sisal fiber. Water uptake and accelerated weathering test were also performed.     

Textile industry dye-house water recovery and reuse

This case study details a UK-based wool-dyeing and yarn-spinning company's quest for a suitable water recovery system which could offer economic benefits to its business and deal with its environmental constraints.     

Intelligent measurement methods in technical diagnosis and quality assurance - a comparison

Faults in technical systems cannot be measured directly. Thus, a variety of intelligent measurement methods has been developed to detect faults. Two widely used procedures-the vibration analysis and the parameter estimation method, and their applications to technical diagnosis - will be described and compared.The paper deals with the application of the vibration analysis to the fault detection in a gear and the application of the parameter estimation to the fault detection in an electric drive system. The paper shows that faults in auxiliary systems canbe detected better by the vibration analysis, whereas faults in the drive system can be detected by the parameter estimation method. A combination of both methods provides better test results than conventional procedures.     

Stability analysis of a toroidal pipe-reducer under uniform external pressure

The stability of a toroidal pipe-reducer system is determined here from the solution of non-linear governing equations of axisymmetric deformations of shells of revolution. Numerical solutions are obtained by a modified version of the computer program developed by Uddin for solving the governing equations of axisymmetric shells by the multisegment method of integration. The interpretation of instability of the toroidal reducers is based on Thompson's theorems I and II. Critical pressures for the toroidal reduers are calculated over useful ranges of the curvature ratio, the thickness ratio, and the diameter ratio. It has been found that the critical pressure of these reducers varies almost linearly with the diameter ratio and that the long toroidal reducers are prone to local instability near the larger end. But this critical zone occurs near either one of the two ends as the reducer becomes shorter. The results of stability and stress analysis of toroidal pipe-reducers are compared here with those of conical reducers obtained by Ali and parabolic reducers obtained by Rahman. Comparison shows that toroidal reducers develop uniform stresses of lower magnitude compared to the other two. Further, toroidal reducers are found to sustain higher critical pressure than parabolic reducers except at higher diameter ratio.     

A case study and troubleshooting experience of safety power channel of instrumentation and control system of the BAEC TRIGA Research Reactor

Microsystem Technologies - Bangladesh Atomic Energy Commission TRIGA Research Reactor (BTRR) is a MK II type nuclear research reactor with a maximum thermal output power of 3 MW. Nuclear...