Investigation of Crystallization and Relaxation Effects in Coarse-Grained Polyethylene Systems after Uniaxial Stretching

In this study, we investigate the thermo-mechanical relaxation and crystallization behavior of polyethylene using mesoscale molecular dynamics simulations. Our models specifically mimic constraints that occur in real-life polymer processing: After strong uniaxial stretching of the melt, we quench and release the polymer chains at different loading conditions. These conditions allow for free or hindered shrinkage, respectively. We present the shrinkage and swelling behavior as well as the crystallization kinetics over up to 600 ns simulation time. We are able to precisely evaluate how the interplay of chain length, temperature, local entanglements and orientation of chain segments influences crystallization and relaxation behavior. From our models, we determine the temperature dependent crystallization rate of polyethylene, including crystallization onset temperature.

Mechanical and Physical Properties of Cross-Laminated Timber Made from Batai using Different Glue Spread Amounts

This study aimed to determine the mechanical and physical properties of the Cross-Laminated Timber (CLT) glued with different amounts of glue. Cost of glue is the outmost importance where it will help in reducing the CLT manufacturing cost. Four different amounts of glue spread were used where the glue that used was phenol-resorcinol formaldehyde (PRF);150, 200, 250 and 300g/m2. The testing of the CLT was conducted by following BS EN 408:2010, BS EN 16351:2015, ASTM D 2718 method B, ASTM D 143-94 and Japanese Agricultural Standard (JAS) 1152:2007. The analysis of physical tests that have been carried out are density, moisture content, shrinkage and swelling of the CLT’s thickness. Meanwhile, the mechanical tests were compression parallel and perpendicular to the grain, three-point bending test (flatwise and edgewise of CLT) and shear test. The highest density was shown by the CLT that using 300 g/m2 which the value was 316.41 kg/m3. Whereas the highest moisture content was shown by CLT that used 250 g/m2 with 15.49% in value. The highest thickness shrinkage percentage was 2.50%, CLT with 200g/m2 while the highest thickness swelling percentage was 5.60% which the CLT used 150 g/m2. For the flatwise bending test, it shows that the CLT that used 300 g/m2 has the highest MOE and MOR value which were 510.63N/mm2 and 8.39 N/mm2. The MOE and MOR value for edgewise bending also shows that CLT that used 300 g/m2 was the best with 1528.70 N/mm2and 13.48 N/mm2. In compression perpendicular to grain test, the CLT with 150 g/m2 shows the highest value of MOE which was 5.89 N/mm2 while CLT that used 200 g/m2 has the highest value of compressive strength with 9.10N/mm2. However, for compression parallel to grain test, the CLT that used 300 g/m2 shows the best performance with 1002.78 N/mm2 and 13.75 N/mm2 of MOE and compressive strength value. Lastly, for the shear test, the highest shear strength value was 0.39 N/mm2 which belongs to CLT that used 150 g/m2. Thus, CLT that used 300 g/m2 of glue spread amount is the best CLT which, the more the amount of glue, the better the performance of the CLT.

Stabilization of soil using industrial wastes

Soil is the most important and basic element of earth. In India which have more type of soil which have low or high bearing capacity like black cotton soil which have high montmorillonite and kalinite. These are those type of soil which have high shrinkage and swelling property. This type of soil cannot withstand heavy load. So, to overcome such problem treatment of soil is needed to be done using plastic materials or volcanic ash, cement kiln dust(CKD) particles for stabilizing this soil. Soil stabilization is the process which improve the physical effects of soil shearing and bearing capacity which is use of adding the admixture like cement, fly ash, lime volcanic ash CKD. Engineers are develop new technique for soil stabilization. It is really big deal to use these type of waste to stabilization of soil. India is developing country build new building and break the old building. All this process many type of waste are generate and in Indian survey nearly 7.46 million tonnes of hazardous waste is generated in India annually So the engineers are think the all waste are used in soil stabilization This paper write for two reason, one is recycle the waste materials and other one is increase the soil stabilize. Some type of industrial waste are including the gravel and dirt concrete and masonry, oils, metals, industrial waste like gasses or solids and also count vegetables matters from restaurants. In other words the industrials waste is two type one is non-hazardous and 2nd is hazardous

Moisture swelling and shrinkage of pine wood versus susceptibility to robotic assembly of furniture elements

Moisture swelling and shrinkage of pine wood and susceptibility to robotic assembly of furniture elements. Background and Objectives. Processing technology, storage conditions and wood properties affect the actual dimensions of wooden elements. It was decided to experimentally check how the dimensions of samples, made of the selected wood species, will change under the influence of different storage conditions, typical for industrial environments. And especially how these changes will affect the susceptibility to assembly of upholstery frame rails that form a box joint. Materials and Methods. The tests were performed on three series of rails made of Scotch pine wood. Each tested series consisted of 12 elements. First, the five dimensions forming the box joint were measured. Then, each series was exposed to different conditions: in the industrial hall (air of RH = 29-48% and t = 16-24°C), in the compressor room (RH = 24-51%, t = 13-27°C) and outside in a covered shed (RH = 20-50%, t = 3-23°C). After 35 days the dimensions were measured again. Results. It was found that the average moisture content decreased and the dimensional deviations increased in the samples stored in the production hall and in the compressor room. In samples stored outside, the mean moisture content did not change, but the dimensional deviations increased significantly. Discussion. The storage of wooden elements increases the deviations from assigned dimensions. Exposure to repeated changes in moisture content and ambient temperature, even without changing the final moisture content of the elements, results in greater dimensional changes than storage under more stabilized conditions that reduce wood moisture content. Conclusions. The shrinkage and swelling of wood due to changes in its moisture content are not fully reversible, therefore, apart from maintaining the appropriate temperature and air humidity during storage, it is important to keep these conditions unchanged.

Soil Stabilization Using Plastic Chips, Granules & Sugarcane Bagasse Ash Mixture

Soil is mainly the foundation of structure, that actually supports the structure from its beneath and hold it for a life long time and spread the load uniformly. If the stability of a soil would not be proportionate enough to hold or to support the structure then the chances of the breakdown of the structure might occur in the true form of its settlement and development of cracks. So, the soil stabilization will help in enhancing the shear strength of the soil as well as it enhancing the shrinkage and swelling properties of soil. It will also help in increasing the load bearing capacity of our soil in support of foundations and pavements. Soil stabilization can also be done by using the various admixtures such as lime, fly ash, cment etc. but in present day, these admixtures happen to be more expansive to be use as soil stabilizing mixture. So this problem is demanding an alternative solution in making the soil stabilizing process cheap and economic by using wastes as a stabilizer.This research work present the use of excess waste generated in our present and make it hazardeous. India generates nearly around 2600-2700 tons of plastic wastes everyday which is seriously one of the major problems not too for the India but also for the whole world. The harmful gases being generated by the various plastics such as furnace, dioxin, mercury e.t.c. into the open atmosphere and have a threat to our vegetation, humans life and animals as well. In the past recent years, the researchers from the various fields have attempt their best to solved the ecological problems occurred by plastic. But our major motive of this project is to properly analyse the potential capabilities of using plastic types as a stabilizer as well as sugarcane bagasse and its ashes. Bagasse ash as we all know, spread generally over the farms and dumped in ponds which causes severe environmental problems and also many researchers stated that ashes being dumped in the open workplace exposure can cause chronic lung infections. So there is seriously a major concern to reuse the sugarcane bagasse ash. This new techniques of soil stabilization could be essentially meet the various challenges in terms environmental concern. Plastic wastes being converted into chips will be used as a reinforcement in stabilizing the soil. So recommendation of using plastic waste and bagasse ash as a soil stabilizer will reduce the problem of disposing wastes and also helps to reduce the environmental problems.

Hydraulic and Swell–Shrink Characteristics of Clay and Recycled Zeolite Mixtures for Liner Construction in Sustainable Waste Landfill

This paper presents research considering hydraulic as well as swelling and shrinkage characteristics of potential recycled fine particle materials for compacted clay liner for sustainable landfills. Five locally available clay soils mixed with 10% (by mass) of NaP1 recycled zeolite were tested. The performed analysis was based on determined plasticity, cation exchange capacity, coefficient of saturated hydraulic conductivity after compaction, several shrinkage and swelling characteristics as well as, finally, saturated hydraulic conductivity after three cycles of drying and rewetting of tested specimens and the reference samples. The obtained results showed that addition of zeolite to clay soils allowed reduction in their saturated hydraulic conductivity to meet the required threshold (≤1 × 10−9 m/s) of sealing capabilities for compacted clay liner. On the other hand, an increase in plasticity, swelling, and in several cases in shrinkage, of the clay–zeolite mixture was observed. Finally, none of the tested mixtures was able to sustain its sealing capabilities after three cycles of drying and rewetting. Thus, the studied clayey soils mixed with sustainable recycled zeolite were assessed as promising materials for compacted liner construction. However, the liner should be operated carefully to avoid extensive dissication and cracking.

Effect of hot-water extraction on the hygroscopicity, shrinkage, and swelling of Paulownia tomentosa wood

Liquid water and water vapor absorption on each separate surface and all surfaces at once, as well as the oven-dry shrinkage before and after the hot-water extraction of the wood, were examined using Korean Standards. The extractives content was examined using American Society for Testing and Materials (ASTM) standards. The highest water absorption and moisture adsorption were found in the transverse sections of both unextracted and extracted wood samples. There was no change in the equilibrium moisture content (EMC) in the unextracted vs. extracted wood samples at a relative humidity (RH) of 75%. However, the EMC in the extracted sample was higher than that in the unextracted sample at a RH of 90%. Swelling per 1% moisture content remained unchanged in the radial direction before and after extraction, while it increased in the tangential direction. The linear and volumetric shrinkage, as well as the coefficient of anisotropy, considerably increased after extraction. There was no difference in the extractive content between sapwood and heartwood. In conclusion, it was confirmed that the extractives in wood considerably affect the hygroscopicity and shrinkage of Paulownia wood.

The current state and tendencies of using rheological models for self-forming wooden structures

Wood is a natural and ecological material. Exceptional mechanical properties of wood allow it to be used in building structures subject to chemically active substances. However some changes in mechanical characteristics of wood under the influence of water and temperature, as well as its anisotropy, limit the application areas of this material. Based on the results of the research by S.P. Timoshenko, foreign scientists proposed a method that makes it possible to use these shortcomings of wood to create wooden structures of unique shapes. This article considers the self-forming process of glued layered wooden structures, which is based on various rheological processes taking place in wood. In order to predict the shape of a glued layered wooden structure obtained with the self-forming method, an accurate rheological model is required, which takes into account all wood deformation mechanisms. We analyzed the available rheological models of wood proposed or described both by Russian and foreign scientists, as well as the international experimental studies and numerical modeling results of the self-formed glued layered wooden structures. Based on the analysis results, it was found that the present rheological models do not take into account a number of factors that influence the process of self-forming of glued layered wooden structures. The rheological model, which includes a complete list of factors affecting wood deformation (elastic and plastic deformation, wood shrinkage or swelling, viscous-elastic creep deformation and mechanical and sorption deformation), is the most promising for creating unique architectural objects from glued wood. But it also has a number of shortcomings, mainly due to inconsideration of some factors and few experimental studies. Such factors include the geometric parameters of layers of the glued wooden structures, the surface treatment of layers, temperature, as well as wood species. These factors influence the process of wood shrinkage and swelling, thus the final shape of a wooden structure. It is necessary to have additional experimental and theoretical studies of the mechanical behavior of glued wooden structures which will take into account these factors, as well as to study other species of wood including their combinations.

PREDICTION OF THE BREAKING STRESS OF CLAYEY SOILS FROM TCHI DEPRESSION TO BENIN.

The phenomena of shrinkage and swelling of clay soils depending on the water content are manifested by disorders affecting mainly individual houses, often not very rigid and superficially founded. The superficial foundations of infrastructures built on swelling soils are subjected to several stresses due to shrinkage and swelling phenomena. These stresses are the cause of damage to the frames in the form of cracks, or even lead to the partial or total breakage of the structure when it is built without special precautions. In order to control these induced stresses and to safeguard these infrastructures, it is necessary to control the breaking stress so that the dimensioned foundations do not cause the structure to break. The objective of this study is to develop a model to estimate the breaking stress thanks to the physical parameters of these soils. To achieve this, we performed several physical and mechanical tests on swelling soil samples taken from the study area, the results of which we used to use the established non-linear least squares method of swelling pressure prediction models. The models were based on test results from 24 soil samples. The tests were carried out in accordance with the French NF standards. This study has shown that the shear strength of a soil is a function of several physical parameters, mainly: pre-consolidation stress and plasticity index. We obtained the model qu=(2.9-1.181.IP). σ'p allowing us to predict the shear strength for the study area. This model is obtained with a regression coefficient precision r2 = 98.50%.