CBSE Class 8 / VIII General Ccience Power Point Presentation
Prepared By
Praveen M Jigajinni
DCSc & Engg,PGDCA,ADCA,MCA,MSc(IT),MTech(IT), M.Phil (Comp Sci)
For Any Queries Please feel free to contact:
Email Id : praveenkumarjigajinni@gmail.com
Cell No: 9431453730
Synthetic fibres are man-made fibres. Synthetic fibres are made from different chemicals. Each kind of synthetic fibres have their own properties. Synthetic fibres are more in length and are long lasting. The only limitation in synthetic fibres is that they are poor absorbents of moisture and they catch fire easily.
CBSE Class 8 / VIII General Ccience Power Point Presentation
Prepared By
Praveen M Jigajinni
DCSc & Engg,PGDCA,ADCA,MCA,MSc(IT),MTech(IT), M.Phil (Comp Sci)
For Any Queries Please feel free to contact:
Email Id : praveenkumarjigajinni@gmail.com
Cell No: 9431453730
Synthetic fibres are man-made fibres. Synthetic fibres are made from different chemicals. Each kind of synthetic fibres have their own properties. Synthetic fibres are more in length and are long lasting. The only limitation in synthetic fibres is that they are poor absorbents of moisture and they catch fire easily.
Synthetic polymers - a content written by Dr.Lali Thomas Kotturan about man ...lalikotturan
A polymer is a giant molecule made from small identical repeating molecules called monomers joined together by covalent bonds. The process of interlinking the monomers to form a polymer is called polymerization. The Classification of Polymers is possible based on different parameters. Origin, thermal processing Behavior, Mechanism of polymerization, line structure, physical property, Crystallinity, and Degradability are such parameters. The spatial arrangements of substituents like alkyl, phenyl, chloro groups on the carbon chain of polymer are called tacticity. Based on tacticity polymers are classified into isotactic, syndiotactic, and atactic polymers. Tacticity depends on the temperature of formation and solvent used. Steps involved in addition polymerization or chain-growth polymerization are initiation, propagation, and termination. Polythene is an addition polymer that exists as LDPE or HDPE.LDPE is formed from ethylene at a high pressure of 1500-3000 atmosphere at a temperature range of175-250oC in presence of some oxygen, peroxide, or azocompounds as initiators.LDPE has nearly 20–50 branches (both long and short branches) per 1000 linear carbon atoms in the chain molecules. The polymerization at a low temperature and pressure in presence of metal oxide catalyst results in HDPE. 2–5 short branches or side chains per 1000 carbon atoms in the main chain, thus having a higher density range (0.945–0.96) and high melting temperature (125–130°C) compared to LDPE. Polystyrene is a transparent, amorphous addition polymer of styrene.PMMA is an addition polymer of methyl methacrylate.PAN is an acrylic fiber obtained by addition polymerization of acrylonitrile. Condensation polymerization or step-growth polymerization happens by the intermolecular reaction with the elimination of water, HCl, etc. Monomers of nylon 66 are hexamethylene diamine and adipic acid.
The first 6 in 66 denotes the number of carbon atoms in diamine and the second 6 denotes the number of carbon atoms in diacid. Nylon 6 is formed from caprolactam which has 6 carbon atoms in its ring. Bakelite is a three-dimensional phenol-formaldehyde polymer. Kevlar is an aromatic polyamide formed from-phenylene diamine and terephthaloyl chloride. Terylene is the condensation polymer from ethylene glycol and terephthalic acid. A typical Ziegler Natta catalyst is a mixture of titanium tetrachloride and triethyl Aluminium. This catalyst permits the synthesis of unbranched, stereospecific, high molecular weight polyolefins. The process is coordination polymerization and the product is the cis product. Biodegradable polymers get decomposed by bacteria into natural byproducts such as gases (CO2, N2), water, biomass, and inorganic salts. These polymers are esters, anhydrides or amides. PLA(polylactic acid), PGA (Poly(glycolic acid), and PHBV -Poly(β-hydroxybutyrate-co-hydroxy valerate) are examples of biodegradable polymers. The plastic identification code identifies the type of plastic.
Polymer science revolves around the study of macromolecules known as polymers, which are formed by linking together repeating units called monomers. Understanding the relationship between polymers and monomers is fundamental to grasping the diverse properties and applications of these materials.
Additionally, we'll delve into the nomenclature of polymers, which involves the systematic naming conventions used to describe their structure and composition. Clear and standardized nomenclature ensures effective communication within the scientific community and facilitates the classification of polymers based on their chemical structure, properties, and applications.
The royal fibers, silk have a long history and legends around its manufacture. the process of silk worm rearing, properties and uses of the fiber are discussed in this ppt
Rayons are regenerated cellulosic fibers. this presentation explores viscose rayon and cuprammonium rayon, discussing their manufacturing process, properties and uses.
This ppt gives an introduction to the types of fibers along with the primary and secondary properties needed by any material to be classified as a fiber
This ppt shares information on types of care labels and the various symbols and colors used for care labels. This can be referred to for understanding common symbols used on apparel
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
2. The TFPIA (Textile Fiber Products
Identification Act) defines polyester
as: “a manufactured fiber in which
the fiber forming substance is any
long chain synthetic polymer
composed of at least 85% by
weight of an ester of a dihydric
alcohol and terepthalic acid.”
3. The first work on polyester
was done by the
CAROTHERS team of
chemist during the early
stages of their fundamental
research for Dupont.
When polyamides (NYLON)
appeared to show more
promise they were selected
for their development and
the polyesters were set
aside.
The early polyesters were
poor in quality and
threatened to be too
expensive.
4. Later, chemist in
Britain began
experimenting with
polyester fibers. In
1941, ‘calico
Printers’ Association
introduced a
successful polyester
fiber in 1946.
Dupont’s polyester
fiber was made
available to the
American consumers
in small quantities
and was known as
fiber V, Amilan and
then Dacron.
While the fiber
known as Dacron
was becoming
popular in the U.S.,
the same fiber called
TERYLENE, was
gaining status in
England and several
European countries.
5. Terylene
Dimethyl terepthalate and
ethylene glycol
React in the presence of N2
atmosphere and sodium as a
catalyst.
The polymerization takes place
at 196°C for three hours
Dacron
Terepthalic acid and ethylene
glycol
React in the presence of N2
atmosphere and dil. HCl as
catalyst at a definite time and
temperature
Forms a low molecular weight
polyethylene terepthate
6. The low molecular weight
Polyethylene terepthalate is
obtained
It is white, hard, flaky, solid
polymer.
PET is then heated at 280°C for
30 min. at atmospheric
pressure.
7. The polymer is then transferred to an ester changing vessel where it is kept
for 10 hours in vacuum.
Excess ethylene glycol is distilled off and the polymer is kept in the absence
of oxygen as it affects the stability of the polymer.
The low molecular weight PET is converted to high molecular weight PET
and obtained in the form of chips.
8. The chips
are mixed
and
conveyed to
an
autoclave
where they
are heated.
The molten
polymer is
filtered.
Delustering
agents,
optical
brighteners,
antistatic
agents, etc.
may be
added in
this step
The polymer
is fed to the
melt
spinning
tank.
9. The hot solution
is forced
through the
spinneret and
the fibers are
spun in air.
The fibers
solidify upon
contact with air.
11. Mixing of
chemicals
• Terepthalic acid +
ethylene glycol
Heating low mol.
Wt. polymer
• 280 C for 30 min
Ester changing
vessel
• Vacuum for 10
hours
Melting
• Chips are
meted
Spinning
12. The longitudinal view of
the fibers exhibit uniform
diameter, smooth surface,
and a straight rod like
appearance. The cross
section is usually round
but variations are
encountered in the form of
trilobal, pentalobal or oval
cross sections.
The inclusion of pigment
in the melt solution
produces fibers that are
dull or semi dull in
appearance and has a
speckled appearance
since the pigment causes
changes in light reflection.
13. • Regular &
high tenacity
fibers
available
Strength
• Better than
cellulosics
• Poor than
nylon
Elasticity
• Excellent
• Heat setting
Resiliency
• 1.38 – 1.42
Density
• Poor
Moisture
• Good when
heat set
• Shrinks
otherwise
Dimensional
stability
14. Polyester fibers melt at
temperatures from 238°- 290°C
depending upon type. As the
fiber melts, it forms a hard and
non - crushable gray or tawny
colored bead. Polyesters burn
with dark smoke and an aromatic
odor. But they do not burn as
rapidly as other fibers,. The fibers
melt and drip away form the
source of ignition
There is a minimal loss of
strength at high temperatures.
Heat setting of yarns and fabrics
is essential. Permanent pleats in
polyester fabrics once heat set in
the desired location will hold as
long as the maintainence
temperatures do not exceed the
heat set temperature
15. • Conc. H2SO4
can dissolve
the fibers
Acids
• Strong
alkalies for
prolonged
exposure
degrade
Alkalies
• Dissolve in
hot
metacresol
Organic
solvents
• No effect
Bleaches
• No effect
Sunlight /
Ageing
16. • No effect
Sunlight /
Ageing
• No effect
Biological
• Absorbs oil / oily soil
and holds it
Oleophilic
