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Test Bank for Campbell Biology 12th Edition ||All Chapters 1-56||Full Complete||Latest 2024
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Prime dogo1
Carbon Fibers
Carbon fibers are mostly composed of carbon atoms, and they are about 5-10
micrometers in size. They are said to contain about 92 wt% carbon, while, on the other hand, the
fiber contained is about 99 wt%, normally referred to as graphite fiber. They are characterized by
tensile properties, high chemical, and high thermal stabilities when constituted in the absence of
oxidizing agents. Besides, it also has good electrical and thermal conductivities (Bhatt et al.,
2017). It also has good creep resistance and is featured with low densities. These characteristics
have made it more popular in civil engineering fields, aerospace models, motorsports, and other
competition facilitations.
Carbon fiber is made from a raw material known as the precursor. In about 90% of it is
made from polyacrylonitrile. The other portion of about 10% consists of petroleum products
pitch or the rayon. These raw materials used are mainly polymers and featured by larger
molecule strings bound by carbon atoms together. Moreover, several gases and liquids are also
used in the manufacturing process, with the aim of these materials reacting with fiber to achieve
a certain product. A steady production has also been encouraged regarding the high rate of
consumption of these carbon fibers within the industrial demand.
Furthermore, the carbon fibers manufacturers have extensively ventured into expanding
their products to meet the growing market demand. However, there has been a hindrance to large
applications in the automotive industry due to the high cost of purchasing this carbon fiber. Also,
dissatisfaction and lack of high-speed fabrication composite techniques have hindered the large
application of carbon fiber. For instance, the figure below shows the estimated consumption of
carbon fiber globally.
Regarding the plate carbon fiber capacity consumption in the year 2005, the below table
shows the estimated capacity.
, 2
Structures and Properties of Carbon Fiber
Carbon fiber is considered to be similar to that of graphite and where it is said to consist
of graphene sheets. It is mainly referred to as the carbon atom layers arranged in a hexagonal
pattern, but they are regular. Besides, looking into manufacturing processes and precursors, the
layer planes in these carbon fibers are either graphitic, turbostratic, to even in a hybrid structure.
Regarding the regions in graphic crystalline, these layer planes are arranged parallel to each of
the regular arrangement (Huang, 2009). These atoms are bonded together covalently with sp2
bonds, while Vander walls interactions characterize the relationship between the sheets in their
interaction. While featuring a single graphitic crystal, the graphene layers are about 0.335 nm in
d-spacing.
The parallel grapheme sheets are irregularly stacked and folded haphazardly, split, and
tilted in a structure featuring the turbostratic structure. It is significant to note that the presence of
sp2 bonding and stacking in an irregular arrangement can lead to an increase in d-spacing from
0.335-0.344 nm. A proper stacked graphitic structure, which is crystalline, can be viewed in
vapor characterized carbon fibers. However, the turbostratic structures can be viewed from other
precursors, such as PAN, regarding the carbon fibers. When stabilized graphically in PAN
fibers, the crystals grow by incorporating disorganized environments of carbon and coalescing
with opposite crystallites. Below is the structure of graphitic crystals and their directions.
Additionally, the layer planes constituted within the crystals are made so that they rotate
and shift. However, the extent of these arrangements is minimal, and the existing graphite fibers
tend to be turbostratic, with the being of extensive misalignment rotational of the planes in their
layers.
, 3
Manufacturing Process PAN Spinning
In its manufacturing process, the acrylonitrile powder, which is in plastic form, is mixed
with other plastics such as methyl acrylate and methyl methacrylate. It is then reacted with under
a convectional suspension with a catalyst and may also be polymerized to form a
polyacrylonitrile product in the form of plastic. The produced plastic is then made to spin making
fibers. Regarding various steps, the plastic is then mixed with other chemicals. It is then pumped
via very tiny poles into a clean bath of chemicals and sometimes in a quench chamber where the
plastics are made to coagulate and solidifies making the expected fibers.
Regarding other methods, the mixture containing the plastics is heated and pumped via
jets, which are tiny into a bath where the solvent is made to evaporate. After it evaporates, a solid
fiber is left at the bath surface. The fiber is then spun to form an internal atomic structure of the
fiber. According to the manufacturer, the fibers produced after the above processes are cleaned
and stretched to the proper and desired diameter of the fiber. This stretching step helps align the
fiber molecules and execute the basics in an attempt to form a tightly bonded crystals of the
carbon after it undergoes the carbonization process.
Several processes are used to replenish the final steps of carbon fibers. These processes
include stabilizing these carbon fibers, usually carbonized. They are supposed to be chemically
changed to integrate their linear atomic bonding to produce a more thermally ladder bonding,
which is stable. Besides, it undergoes carbonizing where they are heated to a certain temperature
for some time inside a furnace with gas with oxygen deficiency. The product is then treated on
its surface to ensure excellent bonding through oxidizing to ensure that its epoxies and other
constituted materials bond effectively. After treating the surfaces, the fibers are then coated to
prevent them from their damage. The below figure shows the processes involved in the precursor
method
, Campbell Biology, 11e (Urry)
Chapter 1 Evolution, the Themes of Biology, and Scientific Inquiry
1.1 Multiple-Choice Questions
1) Cells are ________.
A) only found in pairs, because single cells cannot exist independently
B) limited in size to 200 and 500 micrometers in diameter
C) characteristic of eukaryotic but not prokaryotic organisms
D) characteristic of prokaryotic and eukaryotic organisms
Answer: D
Bloom's Taxonomy: Knowledge/Comprehension
Section: 1.1
2) In comparison to eukaryotes, prokaryotes ________.
A) are more structurally complex
B) are larger
C) are smaller
D) do not have membranes
Answer: C
Bloom's Taxonomy: Knowledge/Comprehension
Section: 1.1
3) Which of the following types of cells utilize deoxyribonucleic acid (DNA) as their genetic
material but do not have their DNA encased within a nuclear envelope?
A) animal
B) plant
C) archaean
D) fungi
Answer: C
Bloom's Taxonomy: Application/Analysis
Section: 1.1
4) To understand the chemical basis of inheritance, we must understand the molecular structure
of DNA. This is an example of the application of which concept to the study of biology?
A) evolution
B) emergent properties
C) reductionism
D) feedback regulation
Answer: C
Bloom's Taxonomy: Application/Analysis
Section: 1.1
1
Copyright © 2017 Pearson Education, Inc.
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