Bioplastics
Bioplastics are plastic materials produced from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, woodchips, sawdust, recycled food waste, etc.
Bioplastic can be made from agricultural by-products and also from used plastic bottles and other containers using microorganisms. Common plastics, such as fossil-fuel plastics (also called petrobased polymers) are derived from petroleum or natural gas.
Bioplastics are usually derived from sugar derivatives, including starch, cellulose, and lactic acid.
Points to Note
- They may or may not be biodegradable.
- Some are only partially biobased, that is they contain both renewable and fossil-fuel-based carbon.
- Do not necessarily biodegrade more readily than commodity fossil-fuel derived plastics.
- Although bioplastics save more nonrenewable energy than conventional plastics and emit less GHG compared to conventional plastics, bioplastics also have negative environmental impacts such as eutrophication and acidification.
- Bioplastics induce higher eutrophication potentials than conventional plastics.
Examples
- Polylactic acid (PLA)
- Polyamide 11.
- Polyhydroxyalkanoate.
- Bio-derived polyethylene.
- Starch-based plastics.
- Cellulose-based plastics.
- Protein-based plastics.
- Lipid-derived polymers
Quantum Dots
Quantum dots (QDs) are man-made nanoscale crystals that that can transport electrons. When UV light hits these semiconducting nanoparticles, they can emit light of various colors. These artificial semiconductor nanoparticles that have found applications in composites, solar cells and fluorescent biological labels.
Applications
Use in bioanalytics and biolabeling has found the widest range of applications for colloidal QDs.
Quantum dots have found applications in composites, solar cells (Grätzel cells) and fluorescent biological labels.
Quantum dots in medicine
Quantum dots enable researchers to study cell processes at the level of a single molecule and may significantly improve the diagnosis and treatment of diseases such as cancers. QDs are either used as active sensor elements in high-resolution cellular imaging, or in passive label probes where selective receptor molecules such as antibodies have been conjugated to the surface of the dots.
Quantum dots in photovoltaics
Quantum dot TVs and displays
Graphene quantum dots
(Graphene itself is an important topic-asked in UPSC Prelims earlier)
Superalloys
Superalloys are an important group of high-temperature materials used in the hottest sections of jet and rocket engines where temperatures reach 1200–1400 °C.
Superalloys are based on nickel, cobalt or iron with large additions of alloying elements to provide strength, toughness and durability at high temperature.
Characteristics of Superalloys
- Excellent mechanical strength and creep resistance at high temperatures
- Good surface stability
- Corrosion and oxidation resistant
Applications of Superalloys
- Aerospace
- Turbine blades and jet/rocket engines
- Marine industry
- Submarines
- Chemical processing industry
- Nuclear reactors
- Heat exchanger tubing
- Industrial gas turbines
Superalloy Trivia
The term “superalloy” was first used shortly after World War II to describe a group of alloys developed for use in turbosuperchargers and aircraft turbine engines that required high performance at elevated temperatures.
Carbon Nanotubes
Carbon nanotubes (CNTs) are cylindrical large molecules consisting of a hexagonal arrangement of hybridized carbon atoms, which may by formed by rolling up a single sheet of graphene (single-walled carbon nanotubes, SWCNTs) or by rolling up multiple sheets of graphene (multiwalled carbon nanotubes, MWCNTs).
Carbon nanotubes (CNTs) are an allotropic form of carbon related to the fullerene family.
Properties
- remarkable electrical conductivity
- exceptional tensile strength
- exceptional thermal conductivity
Applications
These properties are expected to be valuable in many areas of technology, such as electronics, optics, composite materials (replacing or complementing carbon fibers), nanotechnology, and other applications of materials science.
Nanoparticles are increasingly being considered in the medical field as an effective means to deliver drugs of interest or as diagnostic biosensors.Their exceptional thermal, mechanical, and electronical properties together with their tubular shape, offering a high surface area and enabling adsorption or conjugation of a wide variety of therapeutic drugs or diagnostic agents, make CNTs attractive platforms for the treatment of various diseases.
Graphene
-asked earlier in UPSC Prelims
Graphene is a single layer (monolayer) of carbon atoms, tightly bound in a hexagonal honeycomb lattice. It is an allotrope of carbon in the form of a plane of sp2-bonded atoms with a molecular bond length of 0.142 nanometres. Layers of graphene stacked on top of each other form graphite, with an interplanar spacing of 0.335 nanometres. The separate layers of graphene in graphite are held together by van der Waals forces, which can be overcome during exfoliation of graphene from graphite.
Properties which make Graphene Unique
- thinnest material known to man at one atom thick
- the lightest material known
- the strongest compound discovered
- the best conductor of heat at room temperature
- the best conductor of electricity known
- shows a large and nonlinear diamagnetism
Applications
- solar cells, light-emitting diodes (LED), touch panels, and smart windows or phones.
- areas including electronics, biological engineering, filtration, lightweight/strong composite materials, photovoltaics and energy storage.
