Water-repellent efficiency of thermally modified wood as affected by its permeability

This study shows how the air permeability of thermally modified wood contributes to its water-repellent efficiency. For this purpose, freshly cut boards of hornbeam(Carpinus betulus), poplar(Populus nigra), and heartwood of oak(Quercus castanifolia) were modified at a steam temperature of 180 °C for 3 h inside a Thermo Wood kiln.The porous structure, permeability, and water uptake of wood were affected differently by thermal modification,depending on the wood species. The creation of microcracks in the cell walls, due to collapsing of fiber cells,resulted in a noticeable increase in the permeability of hornbeam. Despite checking in the poplar wood structure,its permeability was negatively affected by thermal modification. In contrast to oak and poplar, a negative waterrepellent efficiency was observed for the modified hornbeam, caused by an increase in the permeability.

Research Progress on Corrosion Resistance of Magnesium Alloys with Bio-inspired Water-repellent Properties:A Review

Thanks to its excellent mechanical properties,magnesium alloys have many potential applications in the aerospace and other fields.However,failure to adequately solve corrosion problems of magnesium alloy becomes one of the factors restricting its wide use in many industrial fields.Inspired by nature,researchers designed and fabricated bio-inspired water-repellent(superhydrophobic and slippery liquid-infused porous surface)surfaces with special wetting properties by exploring the surface microstructures of plants and animals such as lotus leaf and nepenthes pitcher,exhibiting excellent corrosion-resistant performance.This article summarizes the research progress on corrosion resistance of magnesium alloys with bio-inspired water-repellent properties in recent years.It mainly introduces the corrosion reasons,types of corrosion of magnesium alloys,and the preparation of magnesium alloys with bio-inspired water-repellent properties to improve corrosion resistance.In particular,it is widely used and effective to construct water-repellent and anti-corrosion coating on the surface of magnesium alloy by surface treatment.It is hoped that the research in this review can broaden the application range of magnesium alloys and provide a powerful reference for the future research on corrosion resistance of magnesium alloys.

Organo-silane compounds in medium density fiberboard:physical and mechanical properties

We studied the effects of nanoparticles of organo-silane（NOS） compounds in the size range of20–80 nm on physical and mechanical properties in medium density fiberboard,and used NOS at four consumption levels of 0,50,100,and 150 g kg-1dry wood fibers.Density of all treatments was kept constant at 0.67 g cm-3.The water-repellent property of organo-silane significantly reduced water absorption（WA） and thickness swelling but mechanical properties declined due to the reduced proportion of wood-fiber as organo-silane was added to the matrix：the compression ratio of MDF panels and the integrity among wood-fibers both declined,resulting in reduced mechanical properties.We recommend use of 50 g of NOS/kg wood-fiber to improve WA and thickness swelling while retaining acceptable mechanical properties.

Fabrication of highly water-repelling paper by surface coating with stearic acid modified calcium carbonate particles and reactive biopolymers

Cellulose paper is the most attractive green packaging material due to its recyclability, renewability, sustainability and biodegradability. In some applications, paper with a high level of water resistance is desirable to meet specific requirements in modern packaging fields. This research aimed to develop a water-repelling paper with cost-effective and nontoxic materials. Commercial precipitated calcium carbonate (PCC) particles were modified by stearic acid (SA) and incorporated with soybean oil-based binder as a water repelling coating agent. The water-repelling efficiency of the coated paper was highly dependent on the ratio of SA / PCC as well as the binder content in the coating formula. PCC particles modified with 12wt% SA were efficient in increasing the water contact angle (WCA) of the coated paper to 146° at a coating weight of 5 g/m2. The binder for the coating was synthesized with acrylated epoxidized soybean oil (AESO) through Michael addition reaction. The triglyceride structure in the polymer chain imparted good bio-degradability to the binder polymer. It was found that surface modification of PCC with stearic acid played an important role in improving the WCA of paper. A super hydrophobic paper with a WCA of 162° was fabricated with a coating formula of 60% SA-modified PCC and 40 wt% AESO-binder.

Tonic Immobility Behavior Used by Lobella sokamensis to Adapt Water-saturated Environment in Marshes

Collembola is well known as one of the most important soil meso-faunas of terrestrial ecosystem. As terrestrial arthropods, some water-dependent Collembola live in or near water environment. However, hydrodynamic analysis of water-walking showed that Collembola individuals retain smooth end of claw which are barely high efficient for water walking. The high abundance of Collembola habiting in the wetlands implies an important water-adaptive way of water moving that exists in these animals. This study chose Lobella sokamensis as sample; it is uniquely distributed in and near standing water in the marshes in Northeast China. In order to test the function of water to habitat selecting, free choice behavior experiment was set at a water gradient arena and the effect of the plants in the marshes was analyzed through double choice test. The numbers of the animals stayed at dry, mediated, wet areas were recorded after 0.5 hour, 11 hours, 23 hours, and 32 hours in free choice behavior and analyzed the data with SPSS software. Analogue method and data analysis was applied at double choice test. In order to describe the movement feature of Lobella sokamensis on the water, the activity on the water surface was observed. The results showed that the species had water-repellent and moss-attractive behavior. Tonic immobility gesture was observed when the animal floating on water surface and it was quite efficient for escaping from water when water level was fluctuating. The water flow increased Lobella sokamensis' s transferring in the wetlands. The results illustrated that the moss in the wetlands was vital for distribution of Lobella sokamensis, but tonic immobility was basic for population diffusing for this inactive Collembola. The importance of close connection of moss and water was indicated in the paper, which should be concerned during Collembola biodiversity preserving in the Sanjiang Plain. This is the first demonstration of immobility behavior for water adaptation in Collembola from the wetlands.