The effect of adding natural materials waste on the mechanical properties and water absorption of epoxy composite using grey relations analysis

Recently, there has been a tendency for scientific studies to deal with natural materials as fillers and reinforcement for polymer composites, which are used in many different applications due to their environmentally friendly properties when compared to synthetic materials. The current study aims to preserve the environment by dealing with natural materials and their influence on the mechanical properties and water absorption property of the polymer composites. In this study, epoxy composites were produced from local natural sourced non-hazardous raw natural materials using grey relational analysis (GRG). The materials used for fabrication include micro-filler of pollen palm 50 μm, seashell 75 μm and epoxy resin. Nine different composites were prepared using pollen palm and seashell as reinforcement material by varying the wt % of the micro-filler. Rule of the mixture was used for formulation and wt % of (0.5, 1 and 1.5) % reinforcement and 99.5, 99 and 98.5 % epoxy (binder) were used for composites. Grey relational analysis was conducted in order to scale the multi-response performance to a single response. The results indicate that optimum performance can be achieved with the addition of 1.5 wt % micro-filler of seashell, which achieved the first rank, while the second rank achieved by 0.5 wt % micro-filler of palm pollen and seashell when compared to other composites. The addition of micro-fillers has improved greatly the mechanical properties of epoxy composites. The loading of micro-fillers has influenced the water absorption property of composites based epoxy in ascending order

A Dual/Single Wideband Switchable Metamaterial Absorber at Low Frequency

Based on PIN diode and resistive film, a dual/single wideband switchable metamaterial absorber at low frequency is presented in this paper. Its absorption is over 90% from 0.8GHz to 1.5GHz and from 4.2GHz to 5.2GHz while the PIN diode operates in forward biased condition. On the contrary, with the PIN diode acting in reverse biased condition, the above 90% absorption occurs from 1.1GHz to 3.2GHz. The surface current distributions at the absorption frequencies are monitored to explain the reason of wideband absorption. The simulation results show that the absorption property of the metamaterial absorber is polarization-sensitive. The metamaterial absorber possesses the advantages of simple structure, wideband, dual/single band, and switchable performance.

Experimental Investigation on Sound Absorption Property of a Panel Board Using Maize Stem

In this project our aim is to produce a soundproofing board which is made out of Maize stem (stalk). Due to increase in number of industries, factories and vehicle traffic cause serious noise pollution. So to overcome this, use of Sound proofing panels in the structural elements could significantly help to reduce the sound as well as gives a good environment to work. People nowadays demand for a better working environment. Many commercialized sound proofing materials are available in the market, the cost of these materials would be much higher and also it could cause health issues when people are exposed with the material. So use of sound proofing panels made with agro-waste could be a better solution, an attempt has been made to produce a soundproofing board which is made out of stalk portion of maize plant. The board’s sound absorption property is studied in this research by using Impedance test and the cost of maize stem board is cheap enough so that everyone can afford it.

Terahertz Wave Absorption Property of all Mixed Organic–Inorganic Hybrid Perovskite Thin Film MA(Sn, Pb)(Br, I)3 Fabricated by Sequential Vacuum Evaporation Method

All mixed hybrid perovskite (MA(Sn, Pb)(Br,I)3) thin film was fabricated by sequential vacuum evaporation method. To optimize the first layer with PbBr2 and SnI2, we performed different annealing treatments. Further, MA(Sn, Pb)(Br, I)3 thin film was synthesized on the optimized first layer by evaporating MAI and post-annealing. The formed hybrid perovskite thin film exhibited absorptions at 1.0 and 1.7 THz with small absorbance (<10%). Moreover, no chemical and structural defect-incorporated absorption was found. In this study, the possibility of changing terahertz absorption frequency through the mixture of metal cations (Sn+ and Pb+) and halogen anions (Br− and I−) was verified.

Effects of wetting and compression/recovering time on the compressionalbehaviour of sanitary napkin layers

Sanitary napkins are technical textile products which are used by women. They are designed as layered structures to fulfil several end–use properties at the same time. One of the most important properties of sanitary napkins is absorption property and this is widely studied in the literature. On the other hand, formability and sensorial comfort of sanitary napkins are of great importance but they are ignored during scientific researches. During daily life, women sit or sleep for certain time intervals and their sanitary napkins are exposed to compressional forces. If the sanitary napkin will squeeze and not recover, this can result with poor sensorial comfort and low formability. Also, wetting of sanitary napkins during usage can worsen the compressional properties. Therefore in this study, effect of wetting and compression/recovering time on the compressional behaviours of sanitary napkins was evaluated. Study was focused on separate sanitary napkin layers in order to detect the most problematic layers. Two compression times and four recovering times were applied to samples for compression tests. Also, sanitary napkin layers were characterised by scanning electron microscopy, unit mass, thickness and bending measurements. According to results, top sheet layer was the most compressible layer in dry and wet states. This is expected to give a soft and resilience sense to the sanitary napkin. Absorbent layer was responsible for low compressibility of sanitary napkins under different compression/recovering times. Bending rigidity of absorbent layer was the highest in dry state but it exhibited a dramatic decrement after wetting