Constructing Cellulose Diacetate Aerogels with Pearl-Necklace-Like Skeleton Networking Structure

Cellulose and its derivative aerogels have attracted much attention due to their renewable and biodegradable properties. However, the significant shrinkage in the supercritical drying process causes the relatively high thermal conductivity and low mechanical property of cellulose and its derivatives aerogels. Considering the pearl-necklace-like skeleton network of silica aerogels, which can improve thermal insulation property and mechanical property. Herein, we propose a new strategy for fabricating cellulose diacetate aerogels (CDAAs) with pearl-necklace-like skeletons by using tert-butanol (TBA) as exchange solvent after experiencing the freezing-drying course. CDAAs obtained have the low density of 0.09 g cm−3, the nanopore size in the range of 10–40 nm, the low thermal conductivity of 0.024 W m−1 K−1 at ambient conditions, and the excellent mechanical properties (0.18 MPa at 3% strain, 0.38 MPa at 5% strain). Ultimately, CDAAs with moderate mechanical property paralleled to cellulose-derived aerogels obtained from supercritical drying process are produced, only simultaneously owning the radial shrinkage of 6.2%. The facile method for fabricating CDAAs could provide a new reference for constructing cellulose/cellulose-derived aerogels and other biomass aerogels.

Influence of Chrysoporthe deuterocubensis Canker Disease on the Physical and Mechanical Properties of Eucalyptus urograndis

Eucalyptus hybrid has been planted rigorously in wet tropical regions including Malaysia. Recently, there was a report on the occurrence of stem canker on these trees. However, the extent of the infections by this stem canker is unknown. The aim of this study was to evaluate the influence of stem canker disease, Chrysoporthe deuterocubensis, on the physical and mechanical properties of 11-year-old E. urophylla × E. grandis or also known as E. urograndis. The samples were taken from infected and healthy trees that were segregated into different classes based on the severity of the attack, i.e., healthy (class 1), moderately infected (class 2), severely infected (class 3) and very severely infected (class 4). A total of 1440 samples from four infection classes were used in this study. The physical and mechanical properties were determined according to the standard test procedures specified by the International Organization for Standardization (ISO) 13061:2014 (Parts 1 to 4, 13, 14 and 17) and British Standard (BS 373: 1957). From the result, a significant effect by the infection classes was observed on physical and mechanical properties of E. urograndis. All infected wood experienced less shrinkage compared to that of a healthy one, particularly the volumetric (Volsh) and radial shrinkage (Rsh). Wood from class 2 and class 3 was less affected by the infection while the majority of wood from class 4 had significantly lower density and poorer strength. Based on the strength data, wood from infection class 2 can be considered to be used for non-structural applications such as furniture, interior finishing, window frames and doors since reduction in mechanical properties was observed. Wood from class 3 would need further investigation to examine its suitability for structural applications.

Variation in wood physical properties and effects of climate for different geographic sources of Chinese fir in subtropical area of China

Chinese fir is one of the most important commercial timber species in China, with many geographic sources. However, little is known of the variation in wood physical properties among them. To explore the differences in wood physical properties and their influencing factors, five geographic sources of Chinese fir were selected. The variance inflation factor, stepwise regression, and principle component analysis were used to reduce multicollinearity and dimensions of the 19 wood physical properties (including density, shrinkage, and mechanical properties). The results showed that the wood density differed significantly among five geographic sources. The tangential shrinkage rate and radial shrinkage rate reached maximum values in black-heart Chinese fir (HNYX-T) but accompanied by the lowest value for difference dry shrinkage. The wood density and mechanical properties of HNYX-T was exceeded to that of others geographic sources. Fast-growth Chinese fir (FJYK-P) had the lowest value for all mechanical properties. The precipitation and temperature had significant correlations with the wood physical properties of this five geographic sources. The temperature in summer was mainly positive correlated with physical properties, while precipitation was negatively correlated with them. HNYX-T had the highest comprehensive score of PCA, followed by JXCS-R, emerged as higher-quality geographic source, which is important for selecting and utilizing geographic sources in forest management.

Full-field tracking and analysis of shrinkage strain during moisture content loss in wood

Anisotropic shrinkage is a typically feature in wood, which is of critical importance in wood drying. In this study, the shrinkage strains over each growth ring were determined by a full-field strain measurement system during moisture content (MC) loss. Color maps were used to visualize the full-field distribution of displacement and shrinkage strain under different MC conditions. The variation of tangential and radial shrinkage strain from pith to bark, as well as the anisotropic shrinkage in heartwood and sapwood were studied. Both of the displacement and strain values increased as the MC decreased. From pith to bark, the tangential strains were higher at two poles as compared to the center, showing a parabolic distribution below fiber saturation point. While for radial shrinkage strain, a minor difference was observed except for the MC of 10%. An intersection between tangential and radial shrinkage ratio curve was observed at the MC of 28%. Both expansion and shrinkage in tangential direction were larger than radial counterparts, and the transformation from expansion to shrinkage occurred at the MC region of 32–28%. In addition, the shrinkage in heartwood was larger than sapwood, whereas anisotropic shrinkage in sapwood was more pronounced as compared to heartwood.

Clamping Effect on the Welding Deformations in Dissimilar Welded Pipes (Joints) With Varied Thicknesses: Axial and Radial Shrinkage

This study investigates and evaluates the welding residual stresses and deformations in the dissimilar material MSSS metals in order to verify the clamping effect on the residual stresses and deformations and entails comparison with the finite element simulation, the critically reflected longitudinal ultrasonic stress measurement and the hole-drilling residual stresses in a Butt-welded plate courtesy of Javadi et al [1]. The angular shrinkage measurement and vertical displacement were used to achieve this objective. The outcome of the study proved that the measurement of residual stress using protractor is an effective way of differentiating the influence of clamps on the longitudinal stresses.

The Effect of Traditional Fumigation on Physical, Mechanical and Anatomical Properties of Wooden Handicraft in West Kalimantan

West Kalimantan wooden craft is internationally well known and its export is increasing. Currently, high durability and attractive color of wood material such as belian (Eusideroxylon zwageri Teysm & Binnend) is rarely available, then alternatively mangium (Acacia mangium Willd.) and laban wood (Vitex pubescens Vahl.) are used for handicraft. Fumigation is one possible way to improve wood service life and color shades. This paper determines the impact of traditional fumigation on wood raw material on physical, mechanical and anatomical properties. The timber fumigation technique was conducted for one week, with curing time from early morning until late afternoon. After treatment, the physical, mechanical and anatomical properties of wood were evaluated. The different of color before and after treatment was measured by image processing scanner Canon P 145. Physical and mechanical properties refer to the British standard method. Result shows that fumigation improves the quality of wood, especially on color of wood. The wood became dark and more shining. It’s good for the handicraft materials. The quality of wood on moisture content value, both on mangium and laban wood was increased with average 30-50%. The average value of wood density of mangium wood after treatment with fumigation was 0.52, meanwhile laban wood was 0.55. The average value of radial shrinkage of mangium wood after fumigation treatment was 3.96% and tangential shrinkage was 6.34%. The average value of radial shrinkage of laban wood after fumigation was 6.43% and tangential shrinkage was 6.08%. The average value of hardness of mangium wood after fumigation treatment was 470.13 kg/cm2 and laban wood was 625.46 kg/cm2. The Fumigated wood color was darker and more attractive for decorative and craft products than non-fumigated wood. In general, this method could be used to preserve wood and to increase the physical performance of wood as raw material for handicraft.

Influence of the w/c ratio and aggregate composition on the autogenous shrinkage in self-consolidating concrete

Paper presents the analysis of shrinkage development in selfconsolidating concretes (SCC). Concretes were cured for 28 day in an insulated environment. The shrinkage was tested on 35x150x1150 mm samples. The specimen had the same volume as ring specimen proposed in the ASTM method of testing the susceptibility of concretes to cracking caused by the restricted radial shrinkage. Linear deformation of concrete samples was measured in constant periods of 500 s using dial gauges with digital data loggers. Conducted tests showed the influence of w/c ratio of 0.28, 0.34, 0.42 and aggregate composition on the development of the autogenous shrinkage in self-consolidating concretes. Additionally, rheological properties of the concrete mixes were tested and compressive and splitting strength was determined. Conducted research allowed to evaluate the influence of w/c ratio and natural aggregate composition on the development of autogenous shrinkage in different stages of curing of SCC.

Intriguing uniform elongation and accelerated radial shrinkage in an amorphous SiOxnanowire as purely induced by uniform electron beam irradiation

The nanowire demonstrates a tensile pulling-free uniform plastic elongation and an accelerated radial shrinkage at nanoscale under uniform e-beam irradiation.