14-May-2019: Scientists develop new plastic that could be fully recycled
Scientists have created a next-generation plastic that can be fully recycled into new materials of any colour, shape, or form, without loss of performance or quality.
As plastics contain various additives, like dyes, fillers, or flame retardants, very few plastics can be recycled without loss in performance or aesthetics. Even the most recyclable plastic, PET -- or polyethylene terephthalate -- is only recycled at a rate of 20-30 per cent, with the rest typically going to incinerators or landfills, where the carbon-rich material takes centuries to decompose.
Now, a team of researchers at Berkeley Lab has designed a recyclable plastic that, like a Lego playset, can be disassembled into its constituent parts at the molecular level. Described in the journal Nature Chemistry, the plastic, called poly diketoenamine, or PDK, can be reassembled into a different shape, texture, and colour again and again without loss of performance or quality.
According to the researchers, the problem with many plastics is that the chemicals added to make them useful -- such as fillers that make a plastic tough, or plasticisers that make a plastic flexible -- are tightly bound to the monomers and stay in the plastic even after it is been processed at a recycling plant.
During processing at such plants, plastics with different chemical compositions -- hard plastics, stretchy plastics, clear plastics, candy-coloured plastics -- are mixed together and ground into bits. When that hodgepodge of chopped-up plastics is melted to make a new material, it is hard to predict which properties it will inherit from the original plastics.
With PDKs, the immutable bonds of conventional plastics are replaced with reversible bonds that allow the plastic to be recycled more effectively. Unlike conventional plastics, the monomers of PDK plastic could be recovered and freed from any compounded additives simply by dunking the material in a highly acidic solution.
The acid helps to break the bonds between the monomers and separate them from the chemical additives that give plastic its look and feel. After testing various formulations, the researchers demonstrated that not only does acid break down PDK polymers into monomers, but the process also allows the monomers to be separated from entwined additives.
29-Apr-2019: Seminar on ‘Use of Technical Textiles in Water Resources Works’ held
Technical Textiles are being used globally for last several decades. These materials have provided innovative engineering solutions for several applications in civil and geotechnical engineering, for infrastructure water resources projects. Even while Technical Textiles have been extensively used in developed as well as many developing countries, India has yet to capitalise the technical, economical and environmental benefits on large scale.
Various parts of India are subjected to floods and environmental degradation. In some of the terrains, the flood management and control can rely on Technical Textiles tubes, containers and bags. Technical Textiles have been found to perform better than concrete as water protection component because of permeability, flexibility and ease of underwater placement.
The Seminar highlighted various application areas, best practices and mechanisms for encouraging larger usage of Technical Textile in Water Resources Sector and created a platform for all the concerned stakeholders for brain-storming and creating a roadmap to take the Technical Textiles uses to the next level.
The speakers from various fields discussed issues of Standards, Benchmarking & Testing, Technical-textiles for Water Resources Conservation, Advanced methods in use of Technical Textiles, Contractual Matters related to Technical Textiles etc. in detail.
The event was organized by Ministry of Water Resources, River Development and Ganga Rejuvenation with participation from high level Officials from Central Departments, State Governments, Engineering Departments of States working in Water Resources, Institutions, Colleges, Universities, Manufacturers, Associations, Trade Associations, Consultants and Contractors.
5-Feb-2018: Indian scientists develop world’s thinnest material
A group of Indian scientists have synthesized a two-dimensional material of one-nanometer thickness using a novel method. The nanosheets synthesized by researchers at the Indian Institute of Technology, Gandhinagar, using Magnesium diboride – a compound of boron – represent a two-dimensional material that has never existed before. Such a material can find a range of applications – from next-generation batteries to ultraviolet absorbing films.
A human hair is about 80,000 nanometer wide, while the approximate diameter of human DNA is 2.5 nanometer. 2D planar materials are just a few micron (one-millionth of a meter) long and wide, and their thickness is one nanometer. Such materials are a hot topic of research since the discovery of graphene – a single layer of carbon arranged in a honeycomb – isolated from pencil graphite. The graphene discovery had won the Nobel physics prize in 2010.
Scientists are racing to develop such nanomaterials as they possess unique properties. Graphene, for instance, is 200 times stronger than steel though it is just one atom thick. The quest is to synthesize newer 2D materials which are similar to graphene but made from different elements.
The nanosheets developed by researchers are made of boron atoms arranged in the shape of a honeycomb, using a simple method. Scientists prepared boron-rich nanosheets by an extremely simple method, which merely involves dissolving a boride compound in water and letting it recrystallize for just the right duration of time. Other methods for preparing similar nanomaterial require a deposition from the vapor phase onto a substrate, which is quite expensive and limits the application.
The researchers have shown that a large fraction of Magnesium diboride crystals can undergo dissolution in water under ambient conditions to result in nanocrystal precursors, which recrystallize in a 2D fashion after some time. This non classical recrystallization can be used to obtain a high yield of boron-based nanostructures like nanodots, nanograins, and nanoflakes.
This discovery, according to the researchers, constitutes a fundamental set of findings in the science of Magnesium diboride, a material that has been primarily known for its superconductive properties.
The method yields an aqueous colloid of these nanosheets, which means that a drop of water from this colloid would contain thousands of ultrathin nanosheets swimming like micro-carpets. Boron has attracted nanotechnology researchers because of its rich properties – low density, high mechanical strength but lighter weight, high thermal resistance, high specific resistance at ordinary temperature, high melting point, ability to absorb neutrons, and high resistance to chemical attacks.
The ability of these boron-based nanostructures to selectively absorb UV radiation makes them promising candidates for developing transparent UV absorbing films. These functionalized magnesium boride nanostructures (containing hydrides, oxides, and hydroxide functional groups) are also promising candidates for engineering hydrogen storage materials.
The rich chemistry of boron is expected to make these nanosheets useful for not only storing energy but also for generating energy in a green way. Scientists are now working towards utilizing these nanosheets for developing the next generation batteries and Nano-catalysts.