INFLUENCE OF LIGNIN CONTENT ON PHOTODEGRADATION IN WOOD/HDPE COMPOSITES UNDER UV WEATHERING

The aim of this work was to examine the influence the lignin component of wood on the photodegradation of high-density polyethylene (HDPE) in wood/HDPE (WPE) composites. The neat HDPE and wood/HDPE composites were prepared using a twin screw extruder followed by an injection moulder. The lignin content was varied from 0 to 29 %wt. of wood by the addition of delignified wood pulp into wood flour. The results suggested that the photodegradation of HDPE in WPE composites was accelerated by the presence of lignin; the chromophoric groups in the lignin enhanced UV adsorption onto the WPE composite surface. The carbonyl and vinyl indices, color, percentage crystallinity, and the melting temperature increased when the lignin contents were increased. The color fading in WPE composites resulted from photobleaching of lignin. In addition, the presence of lignin led to the development ofl cracks in WPE composites, especially at high lignin contents. For the effect of UV weathering time, the carbonyl and vinyl indices, discoloration, and percentage crystallinity increased as a function of UV weathering times, whereas the melting temperature of HDPE in both neat HDPE and WPE composites and water absorption of specimens decreased; the wood index in WPE composites increased during the initial UV weathering times and then decreased at 720 h weathering time

การปรับปรุงความเหนียวของพอลิแลกติกแอซิดด้วยวัสดุธรรมชาติที่ผ่านการดัดแปร

รายงานวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2561This research work was to study the toughening modification of polylactic acid by the mixing with epoxidized natural rubber (ENR) and the increase of effectiveness of mechanical properties with a compatibilizer. Enhancement of properties in polylactic acid was evaluated by tensile and impact testings, Fourier-transform Infrared Spectroscopy (FTIR) technique, Differential Scanning Calorimetry (DSC) technique and Scanning Electron Microscope (SEM). For the addition of ENR, it was revealed that the increase of ENR contents improved elongation at break and impact strength but decreased tensile modulus and ultimate tensile strength. Glass transition temperature (Tg), percentage crystallinity and the melting point of polylactic acid tended to decrease with the addition of ENR. Chemical change was found that position of C=O peak in polymer blend was slightly shifted as compared to the spectrum of neat polylactic acid. The optimum formulation for toughening modification was ENR content of 30 wt%. Its impact strength was 1,982.55 % of neat polylactic acid. For increasing effectiveness of mechanical properties with a compatibilizer, it revealed that the addition of Joncryl ® ADR-4300 as compatibilizer improved both tensile and impact properties. The optimum loading of a compatibilizer for improving mechanical properties was 0.5 wt% of polylactic acid. The decreases of crystallinity and melting point of polylactic acid with adding Joncryl ® ADR-4300 might be because Joncryl ® ADR-4300 was also chain extender of polylactic acid and it might be obstructing crystallization. The presence of Joncryl ® ADR-4300 unaffected on Tg value and chemical change.Rajamangala University of Technology Phra Nakho

การปรับปรุงสมบัติทางกลและความสามารถในการขึ้นรูปของพลาสติกชีวภาพที่ทำมาจากโปรตีนกลูเตนโดยการใช้ยางธรรมชาติ

รายงานวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2560The aims of this research work were to enhance the impact resistance and processibilty of wheat gluten (WG) by the addition of epoxidized natural rubber (ENR) compared to glycerol. This work was divided into two parts: to study the optimum ENR content for improvement of WG and the effect of together functions between ENR and glycerol on the properties of WG. Tested specimens were mixed and prepared by internal mixer and compression molding machine, respectively. ENR and glycerol were varied from 10 to 40 phr. The effects of modifier types and contents on WG were evaluated by tensile, impact and water absorption testing and thermal analysis. Fracture behavior and rubber dispersion were investigate with scanning electron microscope (SEM). The result revealed that the increase of ENR or Glycerol contents led to the decreases in tensile modulus and strength except for modifier content of 10 phr, whereas elongation at break and impact strength increased. Glass transition temperature (Tg) of modified WG tended to decreased with the increase of ENR or glycerol contents, especially for glycerol. The presence of glycerol affected on the decomposition temperature (Td) values but those were unchanged for case of ENR. Water resistant of WG specimen was improved by the presence of ENR whereas the increase of glycerol led to weight loss at immersion time of 2880 min. For the effect of ENR : glycerol ratios, it indicated that glycerol enhanced tensile resistances but suppressed impact and water resistances of modified WG by ENR. Sizes and dispersion of ENR particles were improved by the addition of glycerol. Tg and Td values of modified WG by ENR and glycerol increased when ENR fractions were increased.Rajamangala University of Technology Phra Nakho

Development of bone replacement material via nanohydroxyapatite crystal growth on silk fibroin fiber

รายงานการวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2557The objective of this research is to propose a new way to fabricate a composite material for future bone replacement development via growing apatite crystal on silk fibroin fiber. Apatite crystallization on silk fibroin fiber was prepared by precipitation reaction between Ca(NO3)2 solution and (NH4)2HPO4 solution adjusted pH by NH4OH solution. In this work, Effect of solution concentration and initial pH values was investigated on apatite crystals. Chicken eggshells were used as calcium source by heating sufficiently powdered eggshells at 1300 °C for 4 h to acquire CaO powders, made Ca(NO3)2 solution by dissolving in 65% HNO3 solution. Prepared Ca(NO3)2 solutions were adjusted concentration as 3 levels and were adjusted different pH values of 7, 8 and 9, respectively. For processing of apatite crystallization, silk fibroin fibers were immersed in Ca(NO3)2 solutions for 30 min. After that (NH4)2HPO4 solutions were added in silk fibroin fibers immersed in Ca(NO3)2 solutions. Reaction time was fixed about 1 min before cleaning to remove impurity precipitates on surface of silk fibroin fiber. Finally, apatite crystallization on silk fibroin fibers occurred. The obtained result can conclude morphologies of apatite crystals on silk fibroin fibers was sheets sphere and flower. Solution concentrations and initial pH values directly influenced on Ca/P ratio of obtained apatite crystals by Ca/P ratio increases as increased solution concentrations or increased pH values. Finally research, silk fibroin fibers were woven as two patterns of plain weave and twill weave and they were investigated Young’s modulus and tensile strength. The result indicates that Young’s modulus of silk fibroin fiber sheets woven as twill weave and as plain weave were about 616 MPa and 425 Mpa and tensile strengths of them weave were about 40 Mpa and 72 Mpa, respectively. The optimum condition of growing apatite crystals on silk fibroin fibers was sample of CP19. Design of silk fibroin fiber with plain weave was an optimum pattern for future biomedical applicaions.Rajamangala University of Technology Phra Nakor

Measurement and mapping of noise level for Rajamangala University of Technology Phra Nakhon North Phra Nakhon Campus

รายงานการวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนครThe purpose of this research was characterized the noises at North Phra Nakhon campus, Rajamangala University of Technology Phra Nakhon,Thailand. The instrument of this study was instrument noises. Volume of noise levels were measured in terms of 15 hr and equivalent sound level (Leq 9 hr). 10 samples of noise levels were collected at Rajamangala University Technology Phra Nakhon from 10 stations. The results shown that the average noises volume of 9 hours were in range of 63.10 to 71.20 dBA by measuring station with highest mean of monitoring Station Building Civil Engineering in the area of Electrical Engineering and Mechanical Engineering were found 67.68 and 67.39 dBA, respectively. The results of this study indicated that volume of noises in Rajamangala University of Technology Phra Nakhon were a little bit more than the standard of Pollution Control Department of Thailand and weren’t affected to teaching and learning in North Phra Nakhon campus.Rajamangala University of Technology Phra Nakor

A study of chemical release of wook/PVC composites affecting on the physical and chemical water qualities

รายงานการวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2557This research work was to study the chemical release of wood/polyvinylchloride composites (WPVC) affecting the physical and chemical properties of water. WPVC specimens in ratio of PVC and wood (100:100 by weight) were prepared by using twin screw extruder. The water conditions for specimen immersion testing were varied for temperatures of 30-70 oC and specimen immersion time of 0-120 h. The water quality was estimated by measuring pH, electrical conductivity, turbidity and color of water after immersion of WPVC specimen as comparing with case of PVC specimen. The result suggested that pH values of water slightly decreased with increasing specimen immersion time whereas the change of temperature of water did not affect the pH value. The electrical conductivity remained unchanged with increasing specimen immersion time or temperature except for immersion of WPVC specimens at 70 oC. This might be attributed the weak interfacial bonds between PVC and wood and this led to more easily release the metal ions from additives of PVC. The turbidity and color of water for case of WPVC increased with increasing specimen immersion time whereas those for case of PVC did not change. From the results of water quality testing, it indicated that WPVC applications which contact with water are safety. This was because water quality after immersion of WPVC specimen is within the effluent standards of pollution control department.Rajamangala University of Technology Phra Nakor

STRUCTURAL AND THERMAL STABILIZATIONS OF PVC AND WOOD/PVC COMPOSITES BY METAL STERATES AND ORGANOTIN

Structural and thermal stabilizations of poly(vinyl chloride) (PVC) and wood/PVC (WPVC) composites were studied using lead stearate (PbSt2), calcium/zinc complex (Ca/Zn) stabilizers, and methyl tin mercaptide (MT). Thermal and structural stabilities of PVC and WPVC composites were assessed using FTIR spectrometer, thermogravimetric analysis (TGA) and UV-Vis spectrophotometry. The results indicated that the additions of thermal stabilizers into PVC and WPVC composites could promote the thermal stabilities under both un-aged and thermally aged conditions. The presence of wood particles resulted in increases in polyene and carbonyl sequences during processing and decreases in the decomposition temperature (Td). The presence of wood was found to accelerate the thermal degradation in PVC, and suppressed the efficiencies of the thermal stabilizers used. By increasing the stabilizer dosage, the thermal degradations of PVC and WPVC were moderated. Under thermally aged condition at 177oC, the additions of thermal stabilizer could decrease the increase in yellowness index (YI) and discoloration at different ageing times. In this work, MT was found to be the most suitable and promising stabilizer for PVC and WPVC composites, considering the polyene and carbonyl contents, Td, the shift of derivative thermogravimetric (DTG) curves, and changes in YI value and visual color

การเปลี่ยนแปลงสมบัติทางกลของวัสดุผสมพีวีซีและผงขี้เลื่อยไม้ ภายใต้สภาวะการใช้งานที่มีความชื้น

รายงานการวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2558This research work was to study the effect of moisture on mechanical properties of wood/polyvinylchloride composites (WPVC). WPVC specimens in ratio of PVC and wood (100:100 by weight) were prepared by using twin screw extruder. The water conditions for WPVC specimen immersion testing were varied for temperatures of 30-70 oC and specimen immersion time of 0-120 h. The moisture effect was investigated by measuring flexural properties and hardness of WPVC as comparing with case of PVC specimen. The result suggested that flexural modulus of WPVC tended to decrease with increasing time of water immersion and then remained unchanged at immersion time of more than 72 and 48 h for water temperature of 30 and 70 oC, respectively. The decrease rate in flexural modulus enhanced when water temperature increased. Flexural modulus of PVC slightly changed with increasing both immersion time and water temperature. Flexural strength for both PVC and WPVC specimens were found the change at water temperature of 70 oC only. Flexural strength of PVC tended to slightly increase with increasing immersion time whereas flexural strength of WPVC slightly decreased with increasing immersion time. Hardness of PVC specimen in cases of both water temperature of 30 and 70 oC slightly increased with increasing immersion time. For WPVC, hardness tended to decrease with increasing immersion time and water temperature.Rajamangala University of Technology Phra Nakho

ผลของเส้นใยธรรมชาติและการปรับปรุงผิวที่มีต่อสมบัติทางความร้อนและกายภาพของพอลิแลคติกแอซิด

รายงานวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2564his research work aimed to study the effects of the addition of sisal fiber and surface treatment by epoxy silane on the physical and thermal properties of polylactic acid (PLA). Specimens of PLA and unidirectional fiber-reinforced composite were processed by a compression molding machine and evaluated the physical and thermal properties by water absorption measurement and differential scanning calorimetry (DSC) analysis, respectively. The result showed that water absorption tended to increase by adding sisal fiber whereas surface treatment of sisal fiber by epoxy silane improved water resistance of composites. The water absorption values at immersion time of 5 days were 0.89, 1.13, and 1.26 % for PLA, PLA/treated sisal fiber composite, and PLA/untreated sisal fiber composite, respectively. For thermal properties, the addition of sisal fiber led to decreases in glass transition temperature and crystallinity. These were because the presence of continuous fiber might interfere with the crystallization of PLA. The surface treatment of continuous fiber with epoxy silane led to difficult crystallization. The good interfacial adhesion interrupted PLA alignment.Rajamangala University of Technology Phra Nakho

การผลิตวัสดุดูดซับเสียงจากวัสดุผสม ยางโฟมธรรมชาติและเส้นใยธรรมชาติ

รายงานการวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร, 2558This research work was to study the effect of surface treatment of natural fiber and the effects of type and content of natural fiber on the development of acoustic material from natural rubber foam /natural fiber composites. The surface treatment used for this research work was sodium hydroxide (NaOH) treatment. NaOH Concentrations and treatment times were varied from 0 to 15 %wt. and 0 to 30 min, respectively. Natural fibers used for this work were bagasse fiber (BF) and oil palm fiber (OPF). The suitable condition for surface treatment was estimated by fiber length and diameter (L/D) ratio and morphology of natural fiber. The result suggested that L/D ratios tended to increase when NaOH concentrations and/or treatment times increased except for NaOH concentration of 15 %wt. L/D ratios of OPF after surface treatment were changed more than those of BF. The suitable conditions of NaOH treatment for BF and OPF were NaOH concentration of 10 %wt. and surface treatment times of 30 and 10 min, respectively. The effects of fiber type and content on sound absorption properties of natural rubber foam /natural fiber composites were investigated by cell characteristics, sound absorption coefficient, DMA analysis and bulk density. Both treated BF and OPF with suitable treatment condition were varied from content of 0.0 to 10.0 %wt. The result showed that the cell size of composites tended to decrease with addition of natural fiber whereas number of foam cell per unit volume increased. After adding natural fiber more than 2.5 %wt., cell size of composite foam and number of foam cell per unit volume tended to change the inverse direction. Natural fiber in composites enhanced the sound absorption efficiency. Sound absorption coefficient of composites adding BF was more than that of composite adding OPF. The addition of natural fiber enhanced the elasticity of composites and that increased sound absorption efficiency. NaOH treatment led to creation of strong interfacial bonding between natural fiber and natural rubber and enhanced the sound absorption efficiency. Density of NR composite foam increased with increasing natural fiber content.Rajamangala University of Technology Phra Nakho