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Variation of basic density,calorific value and volumetric shrinkage within tree height and tree age of Ugandan grown Eucalyptus grandis wood

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Journal of Forestry Research 2021年第2期32卷 503-512页

作者： Owen Emmanuel Sseremba P.Mugabi A.Y.Banana B.C.Wessels M.Plessis Department of Forestry Biodiversity and TourismMakerere UniversityKampalaUganda Department of Forestry and Wood Science Stellenbosch UniversityStellenboschSouth Africa

Insufficient knowledge on Ugandan grown Eucalyptus grandis *** ex Maiden wood properties,high demand,and processing challenges led to a study into its physical *** obtained the variation of basic density(BD),calorific value(CV)and volumetric shrinkage(VS)within tree height and tree-age of ***,and its appropriate use based on these *** with good boles were harvested from Kabarole District in western Uganda to produce specimens as prescribed by British Standards and ASTM standard wood testing *** data reviews and statistical analysis using ANOVA,Tukey’s test and multivariate analysis were done to obtain property estimates and their variation within trees and amongst tree *** mean BD of *** is 413.6,380.5,471.0,and 501.1 kg m^(−3)at 3,6,9,and 12 years,respectively,showing significant increase with tree age(p=0.003).The pattern of BD with tree height showed a reduction with tree height although with higher values in the middle portion of the *** CV increases(p=0.014)with tree age and reduces with tree height with values of 14,560.32,15,447.3,16,079.11,and 16,932.6 kJ kg^(−1)at 3,6,9,and 12 years,*** percentage VS was 11.02,9.84,12.31,and 14.45 for 3-,6-,9-,and 12-year-old trees,respectively,and it did not vary significantly(p=0.088)with tree *** on these property values,*** wood could be used for scaffolding,light constructions and fuel wood *** seasoning needs to be longer with well monitored drying schedules to reduce seasoning defects caused by the high *** studies on strength properties,seasoning schedules,panel products properties and tree-age chemical variations would improve the knowledge about its wood quality and would enhance its efficient utilization.

关键词： Eucalyptus grandis Age Calorificvalue Basic density volumetric shrinkage Wood

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Properties of a New Dental Photocurable Matrix Resin with Low shrinkage

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Journal of Wuhan University of Technology(Materials Science) 2011年第2期26卷 236-241页

作者：付静 State Key Laboratory of Oral Diseases West China College of StomatologySichuan University

In order to reduce the amount of volumetric shrinkage that occurs in dental composites as a result of curing,a new kind of dental matrix resin combining bisphenol-S-bis（3-meth acry late-2-hydroxy propyl）ether（BisS-GMA） with the expanding monomer unsaturated spiro orthoesters 2-methylene-1,4,6-trispiro[4,4] nonane （SOE） was prepared,with triethylene glycol dimethacrylate （TEGDMA） as *** （camphorquinone） of 1wt% and DMAEMA （2-（dimethylamino） ethyl meth acrylate） of 2wt% were used as photoinitiation system to initiate the copolymerization of the matrix *** performance including volumetric shrinkage,degree of conversion and condition of the ring-opening reaction of SOE,as well as curing time and the tensile bond strength were investigated respectively by the dilatometer,Fourier transfer infrared,the universal testing machine,and so *** ring-opening polymerization of SOE ***,the obtain copolymers were *** matrix resin containing BisS-GMA and SOE showed a reduced amount of volumetric shrinkage at 1.52%,which is a promising strategy for obtaining a polymer with a low amount of volumetric ***,the other properties were not compromised.

关键词： unsaturated spiro orthoester dental matrix resin volumetric shrinkage bisphenol-S-bis (3-methacrylato-2-hydroxy propyl) ether

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Effect of site and elevation on wood density and shrinkage and their relationships in Carpinus betulus

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Forestry Studies in China 2012年第3期14卷 229-234页

作者： Majid KIAEI Department of Wood Science and Paper Technology Chaloos BranchIslamic Azad UniversityChaloos46615/397Iran

This study examined the effect of site and elevation on the oven-dry density and volumetric shrinkage of hornbeam （Carpinus betulus） wood. For this purpose, 45 normal hornbeam trees from three different sites （Mazandaran, Guilan and Golestan） at three elevations, 300 m （low elevation）, 700 m （intermediate elevation） and 1100 m （high elevation） from natural forest in northern Iran were selected. Disks were cut at breast height from mature wood and test samples were prepared to determine physical proper- ties, i.e., wood density and volumetric shrinkage. The results show that there are significant differences between site and elevation on these physical properties of wood. The interaction effects between site ~ elevation on wood density and volumetric shrinkage were also statistically significant. At any fixed site, wood density and volumetric shrinkage increased with elevation. As well, their values at Guilan were higher than those at the other two sites. The relationship between wood density and volumetric shrinkage was deter- mined by simple regression equations. Strong, positive relationships between wood density and volumetric shrinkage at each site were found. Again, these were stronger at the Guilan site than at the other two sites. Given a fixed site, the correlation at high eleva- tion was stronger than at the other two elevations.

关键词： Carpinus betulus site elevation wood density volumetric shrinkage

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Properties of a New Dental Photocurable Resin based on the Expanding Monomer and Threecomponent Photoinitiator System

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Journal of Wuhan University of Technology(Materials Science) 2014年第2期29卷 384-390页

作者：付静 LIU Wenjia LIU Xiaoqing Sapna laxmi tuladhar WAN Qianbing 王航 State Key Laboratory of Oral Diseases West China Hospital of Stomatology Sichuan University Department of Prosthodontics West China College of Stomatology Sichuan University

The purpose of this study was to use. a three-component photoinitiation system comprising 1wt% CQ （camphorquinone）, 2wt% DMAEMA （2-（dimethylamino） ethyl meth acrylate） and 2wt% ph^2I^＋PF6^- （diphenyliodonium hexafluorophosphate） to initiate the copolymerization of the matrix resins which combine bisphenol-S-bis （3-methacrylate-2-hydroxy propyl） ether （BisS-GMA） with the expanding monomer unsaturated spiro orthoesters 2-methylene-l,4,6-tdspiro[4,4] nonane （MTOSN）, for minimizing the volumetric shrinkage that generally occurs during polymerization. It was hypothesized that MTOSN would expand volumetrically during polymerization under the three-component photoinitiator system and further reductions in volumetric shrinkage would be obtained. The performance study which consists of degree of conversion and condition of the ring-opening reactions of MTOSN, volumetric shrinkage and mechanical properties including tensile bond strength, compressive strength and Vicker＇s hardness were carried out respectively by Fourier transfer infrared, the dilatometer and the universal testing machine. The results supported that the dental composites based on the expanding monomer and three-component photoinitiator system engendered a greater decrease of volumetric shrinkage and better mechanieal properties.

关键词： 2-methylene-1, 4, 6-trispiro [4, 4] nonane light-curing dental matrix resin volumetric shrinkage mechanical properties

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Minimizing Warpage for Macro-Size Fused Deposition Modeling Parts

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Computers, Materials & Continua 2021年第9期68卷 2913-2923页

作者： Thanh Thuong Huynh Tien V.T.Nguyen Quoc Manh Nguyen Trieu Khoa Nguyen Department of Mechanical Engineering Can Tho UniversityCampus IICan ThoVietnam Faculty of Mechanical Technology Industrial University of Ho Chi Minh CityHo Chi Minh70000Vietnam Mechanical Engineering Department National Kaohsiung University of Science and TechnologyKaohsiung80778Taiwan Faculty of Mechanical Engineering Hung Yen University of Technology and EducationHung Yen16000Vietnam

In this study,we investigated warpage and corner lifting minimization for three-dimensional printed parts generated by macro-size fused deposition modeling(FDM).First,the reasons for warpage were theoretically *** approach revealed that the thermal deformation and differential volumetric shrinkage of the extruded molten plastic resulted in warpage of FDM *** addition,low adhesion between the deposited model and the heated or non-heated printing bed may intensify warpage *** a next step,initial small-size and medium-size models were used to identify parameters to manage and minimize warpage in a way that would reduce material consumption and running ***,a macro-size model was built to experimentally investigate and verify the technical solutions to minimize the warpage of FDM *** conclusion,an improved part with reduced warpage was efficiently produced after detailed consideration of thermal effects and adhesion *** exists to widen the application scope of FDM technology in manufacturing for processes like thermoforming that involve mold core fabrication with *** technology,which has applications not only in mechanical engineering but also in related engineering fields,is convenient and could readily be applied to practical manufacturing industries.

关键词： Fused deposition modeling corner lifting volumetric shrinkage thermal deformation acrylonitrile butadiene styrene filament

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The Simulation and Optimization of Aspheric Plastic Lens Injection Molding

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Journal of Wuhan University of Technology(Materials Science) 2005年第2期20卷 86-89页

作者：温家伶 School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Assoc.Prof

For the purpose of reducing the volumetric shrinkage and volumetric shrinkage variation, the process in injection molding of aspheric plastic lens was simulated, and several process parameters which include holding pressure, melt temperature, mold temperature, fill time, holding pressure time and cooling time were optimized by using an orthogonal experimental design method. Finally, the optimum process parameters and the influence degree of process parameters on the average volumetric shrinkage and the volumetric shrinkage variation are obtained.

关键词： injection molding volumetric shrinkage volumetric shrinkage variation orthogonal experimental design

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