Sciencedoze is a free learning platform where you can explore blogs of Science, Education and Technology. You can follow us on Facebook to be a member of this community.
Buna-S or SBR is a copolymer of 1,3-butadiene and styrene which is prepared by copolymerization of 1,3-butadiene and styrene along with sodium. In Buna-S, Bu stands for butadiene, Na for sodium which is the polymerizing agent and S stands for styrene.
It is tough and is a good substitute for natural rubber. It possesses high abrasion resistance, high load-bearing capacity and is used for the manufacture of automobile tires.
Styrene-butadiene rubber (SBR) or Buna-S can be prepared by copolymerization of a mixture of 1,3-butadiene and styrene in the ratio of 3:1 in the presence of sodium.
1. Buna-S has high abrasion resistance, high bearing capacity, and resilience.
2. Buna-S is very tough and is a good substitute for natural rubber
3. Buna-S swells in organic solvents up to a limited extent.
4. Buna-S gets oxidized in the presence of traces of ozone.
1. Buna-S is used for making floor tiles, footwear components, cable insulation, etc.
2. Buna-S is also used as a binder in the lithium-ion battery.
3. Buna-S is used as a part of cement-based waterproofing systems as it aids bond strength, reduces the potential shrinkage.
4. Latex Buna-S is widely used in the coated paper as it is the cheapest resin to bind pigmented coatings.
Styrene-maleic anhydride (SMA) is a synthetic copolymer that undergoes copolymerization with styrene in a highly symmetrical manner to form styrene-maleic anhydride.
1. SMA is a crystal clear and amorphous thermoplastic in nature.
2. SMA offers high heat and chemical resistance, high glass, and high melt velocity.
3. SMA is soluble in alkaline solutions and polar organic solvents.
4. SMA is also known for high functionality and reactivity.
1. SMA is used in the automobile industry for the manufacturing of car instrument panels and consoles.
2. SMA's surface provides excellent adhesion to polyurethane (PUR) foam which is used in padded instrument panels.
3. SMA (ester) resins are added in solvent-based coatings, adhesives, overprint varnishes, printing inks, etc because they act as dispersing and emulsifying agents.
Styrene-acrylonitrile (SAN) is a copolymer plastic that is produced by copolymerization of styrene and acrylonitrile.
1. SAN has very good tensile and flexural strength.
2. SAN has good abrasion resistance and impact strength.
3. SAN has high chemical resistance, better resistance to stress cracking and crazing.
4. SAN has good resistance to water, acid, and alkalis.
1. SAN is used in the kitchen in mixing bowls, basins, and fitting for refrigerators as it is resistant to oil and fats.
2. SAN is used in making thermally insulated jugs, tableware, cutlery, coffee filters, etc.
3. Due to its toughness, SAN is used in heavy machinery like winding cores, air-conditioners, etc.
4. Due to its pleasing appearance, SAN is used in the bathroom as premium bathroom fittings and cosmetic packaging.
What is a Crime Scene ? A place where the crime is committed or where the maximum physical evidence related to crime is found is known as a crime scene. A crime scene is a starting point of the investigation which provides information about the suspect and the victim. This helps to reconstruct the crime and fast resolution of the case. It is noted that the crime scene is not limited to a single place but may extend to a wider area depending upon the nature of the crime committed. For example, In a murder case where murder is done at one place and the body is disposed on another place. In this case, we have two crime scenes that give information about the crime. Types of Crime Scene Based on evidence found on the crime scene: 1. Primary Crime Scene The crime scene where the actual crime occurred or where more usable pieces of evidence were found is known as the primary crime scene. For example, A murder scene, theft, assault, etc. 2. Secondary Crime Scene The crime scene which is some
What are Conducting Polymers? As the name suggests organic polymers that conduct electricity are known as conducting polymers. They are also known as intrinsically conducting polymers (ICPs) and they have alternating single and double bonds along the polymer backbone (conjugated bonds) or that are composed of aromatic rings such as Phenylene, naphthalene, anthracene, pyrrole, and thiophene which are connected through carbon-carbon single bonds. Examples: Polyacetylene, Polypyrrole, Polyaniline, etc What is the reason behind conducting nature of these polymers? Conducting polymers comes in two forms that are doped conducting polymers and non-doped conducting polymers. The conductivity of non-doped conjugated polymers is due to the existence of a conductivity band similar to a metal. In a conjugated polymer, three of the four valence electrons form strong sigma bonds through sp² hybridization where electrons are strongly localized. The remaining unpaired electron of each carbon atom re
What is documentation of the crime scene and Why it is done? After securing the crime scene, the next most important step is documentation of the crime scene because documentation permanently records the crime scene and its physical evidence. Documentation should be done without any wastage of time as the scene and its evidence may get altered over time. The documentation should be done innovatively and the originality of the crime scene should be maintained and documentation should not have pauses or breaks, it should remain constant till the whole crime scene is documented. There are four main tasks of documentation that is note-making, photography, videography , and sketching . It should be noted that all four tasks are necessary and none is a substitute for another. For example, notes are not substitutes for photography, video is not a substitute for sketching, etc. Following are the sequence for crime scene documentation: 1. Note making Documentation of crime scene in the f
