Wear Behavior of Wood/PVC Composite for Woodlike Flooring Products

AbstractThe work is to study the effects of load, sliding distance and water absorption on wear properties and mechanism ofwood/PVC composites. The experimental results indicated that the weight loss increased with an increasing load from 250 to 500g. When applying the load at 1000g, the weight loss increased at sliding distance of 0.5-1.5 kilometers followed by stability at sliding distance of 1.5-2.0 kilometers. The longer sliding distance resulted in the greater the weight loss in the wood/PVC composites. The worn surface of wood/PVC composites at loading 250g and 500g at 0.5-1.5 kilometers for sliding distanceshowed wear mechanism of Polyvinylchloride, and that ago 1.5-2.0 kilometers sliding distance, the wear mechanism result from wood flour effect. The three-body abrasion occurred at the load of 1000g at 0.5-1.5 kilometers sliding distance. The transfer film improved wear properties at 1.5-2.0 kilometers sliding distance. In case of the water absorption, the unscrubed specimens had more water absorption than the scrubbed specimens. The weight loss increased due to the increasing of specimen volume and density by water absorption. As a result, the weight loss was high at 3% water absorption. The mechanical wear involved with chemical reactions on the PVC surface. The wear mechanism at 6% and 9% water absorption involved wood resistance effect andabrasive three-body effect, respectively

การปรับปรุงเครื่องขูดหินปูนแบบอัลตร้าโซนิคสาหรับชุดทันตกรรมเคลื่อนที่

วิทยานิพนธ์ (วศ.ม.) -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2563This research presents the development of ultrasonic scaler for mobile dental unit. The operation of the scaler uses a phase-locked loop circuit to generate high frequency electrical signal. Then, the signal is amplified with a Darlington amplifier circuit to feed to the coil in the Hand Piece, resulting in Magnetostriction. This phenomenon causes the stretching and shrinking of the magneto-strictive stack with high frequency, which causes the tip of the scaling head to vibrate more than 20,000 times/second. Traditional ultrasonic scaler for mobile dental unit has thermal problem of the amplifier circuit due to use of the transistors as the switching devices. When used for a period of time, the scaler is necessary to stop working, resulting in not much scaling per day. This research solved the problem by using MOSFETs as switching devices and adding cooling system to the amplifier circuit. The experiment was carried out using actual conditions. The experimental results show that the developed scaler has increased the number of scaling per day. In addition, it will still remove plaque and dirt in the gumline around the base of the teeth similar to the scaler used by general dentists.Rajamangala University of Technology Phra Nakho

Bamboo scraps and hardwood chips biochar derived from a cone-truncated open fire kiln for use as a nutrition medium for agricultural purpose

An experiment on the production of biochar from bamboo scraps and hardwood chips for use as materials to improve soil was done by burning the biomass of the bamboo scraps and hardwood chips in Pyrolysis conditions at a temperature range of 500 - 700C with a cone-truncated open fire kiln which reduces burning time to 45-60 min. Experimental results revealed that the average bamboo-scrap biochar of 2.5 kg resulted from burning 15 kg of the bamboo scraps; likewise, the average hardwood-chip biochar of 2.2 kg resulted from burning 15 kg of the hardwood chips. According to analyses, the bamboo-scrap biochar was composed of 8.6% moisture content, 8.0% volatile substance, 9.0% ash, 83% fixed carbon, 250mg/g iodine and pH 10.3; whereas, the hardwood-chip biochar was composed of 6% moisture content, 8.2% volatile substance, 3% ash , 88.8% fixed carbon, 300 mg/g iodine, and pH 10.1. The result of planting experiments showed that after mixing the biochar for soil nourishment and compost into the planting soil, the morning glory and kale can grow better than those planted in normal soil and soil with compost

AN ANALYSIS OF THE MULTI – WORD EXPRESSIONS USED IN SPORTS NEWS STORIES: A CASE STUDY OF TEN SPORTS NEWS STORIES SELECTED FROM THE BANGKOK POST

The purposes of the study were to analyze the structure of the multi – word expressions used in sports news stories and to study types of the multi – word expressions used in sports news stories. The subjects of this study were10 sport news stories including five football news, three tennis news and two boxing news collected from the Bangkok Post from 27 September to 14 November 2014.The percentage was used for data analysis. The study found that the patterns of the multi-word expressions in those news stories could be detailed as follows. The structure used with the highest occurrence was Adjective + Noun, Asian Games; it accounts for 43.02% in ten news stories. The pattern mostly used in a second ranking was Noun + Noun, season-ending tournament; it accounts for 12.83 %. The structure ranked third in its use in the selected news stories was Noun +’s+ Noun, Spain’s Ferrer; it made up 18.11%. The structure came in fourth was Noun +of + Noun, Kuldep Singh of India; it represented 12.45 %. The structure came in fifth was Noun +Noun + Noun, World number three; it represented 7.17 %. Last, the structure Adjective + Noun+ Noun, Five Thai fighters, was the least used; it accounts for only 6.42 % in ten subjects

Effect of carbon nanotube lengths on the mechanical properties of epoxy resin: an experimental study

Batches of multi-walled carbon nanotubes having an average length of 2091 nm were aggressively tip-ultrasonicated to produce shortened carbon nanotubes having average lengths of 1689 nm, 1332 nm, 992 nm and 503 nm. Raman spectroscopic analysis confirmed that the shortened carbon nanotubes retained their crystallinity after the shortening process. Carbon nanotubes were then dispersed in the epoxy matrix using high-shear mixing technique (calendering). The mechanical properties were measured for the cured epoxy–0.1 wt% carbon nanotube nanocomposites having carbon nanotubes of different lengths. It was found that the nanocomposites containing long carbon nanotubes (2091 nm and 1689 nm) possess higher tensile strength, elastic modulus, fracture strain and fracture toughness as compared to nanocomposites containing short carbon nanotubes (1332 nm, 992 nm and 503 nm)