Polymer Reaction Engineering and Processing

Polymer reaction engineering and processing is an engineering field that modifies, analyzes, and designs polymer materials. This article covers the structure-property relations, major polymers, processing and compounding of polymers, and more. Find study materials and solved assignments on Desklib.

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Polymer Reaction Engineering and Processing
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INTRODUCTION
Polymer reaction engineering and processing is generally an engineering field that modifies,
analyses, and designs polymer materials. Polymer reaction engineering covers structure property
application and relations, description of major polymers, processing and compounding of
polymers, properties of polymers, and aspects of the characterization, structure, polymerization,
and petrochemical industry.
1.
a) Fibres used as Reinforcement for Composites
Fibreglass
Fibreglasses are glasses that have spun into the form of fibres and are not as stiff or strong as
fibres of carbon but with features that make glassfibres more appropriate in numerous uses.
Fiberglasses is an insulator since it is non-conductive and is normally invisible to majority of
transmission types. There are five categories of fiberglass, namely alkali glass, electrical glass,
electrical glass, and chemical glass1.
Carbon Fibres
Carbon fibres offer good resistance to high temperature, have a low CTE, high tensile strength,
high modulus, and are also conductive. They exists in five different types, namely ultra-high
modulus, low modulus, high modulus, standard modulus, and intermediate modulus. The fibre
tend to get more brittle as the modulus increases, harder to handle and more expensive2.
Aramid
1 Kausar, A. Strategies in Polymeric Nanoparticles and Hybrid Polymer Nanoparticles. NanoWorld Journal. 2019. Vol 5
2 Kausar, A. Strategies in Polymeric Nanoparticles and Hybrid Polymer Nanoparticles. NanoWorld Journal. 2019. Vol 5

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The chemical structure of aramid shows the benzene rings of aramid along the polymeric
backbone. Modulus and strength of aramid are very good, shear strength and compression
similar to E glass, UV resistance low, and low density.
Coupling Agents in Composites
Coupling agents are chemicals which improve the interfacial properties of polymers and mineral
fillers. They minimize the interfacial tension which is inconvenient rather than beneficial,
however, simultaneously minimize the agglomeration tendency of particle of filler, hence
improving their polymer molecules accessibility. Adding bi-functional coupling agents to the
composites, commonly tetrasulphide, promotes compatibility of filler-matrix3.
b) Conventional Composites and Nanocomposites
Nanocomposites is a structures having nano-scale recurrence distances between diverse phases
that constitute the material, or multiphase solid material where a single phase has three, two of
one dimensions of less than 100nm. Nanocomposites differ from conventional composites
materials because of the exceptional high aspect ratio of nanocomposites and also the
exceptional volume to surface ratio of the reinforcing phase. The material for reinforcement can
be made up of fibres (such as electrospun or nanotubes fibres) minerals or particles. The area of
the interface between reinforcement phase and matrix is generally an order of magnitude greater
compared to the conventional composites4.
Dispersion of the Reinforcement in Nanoparticles
3 Kausar, A. Strategies in Polymeric Nanoparticles and Hybrid Polymer Nanoparticles. NanoWorld Journal. 2019. Vol 5
4 Kausar, A. Strategies in Polymeric Nanoparticles and Hybrid Polymer Nanoparticles. NanoWorld Journal. 2019. Vol 5

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Multi-objective optimization method: This method of improving dispersion of reinforcement in
nanoparticles is based on the basis of the ratio analysis and is defined as the process of
optimization of a single or more conflicting attributes simultaneously subject to some
constraints. The procedure of this method begins with computation of normalized decision
matrix through vector method and then calculating the composite score.
Procedure for preference order by similarity to perfect solution: This technique is depend on the
perception that the selected option should have a shorter geometric distance from positive perfect
solution. The first step is normalization of weights and then determining the negative ideal
solution and ideal solution5.
VIKOR method: This method is an applicable approach of finding the solution close to negative
ideal solution and ideal solution. This approach aims at ranking the set of alternatives from
different problems measures that assist the decision-makers to reach an ultimate solution.
2
a) Synthetic polymers
Some of the synthetic polymers used for manufacturing rubber include:
 Santoprene
 Styrene-Butadiene rubber (SBR)
Similarities
Both have great resistance against weathering
Both are used in the manufacture of rubber
Both are synthetic polymers
5 Kausar, A. Strategies in Polymeric Nanoparticles and Hybrid Polymer Nanoparticles. NanoWorld Journal. 2019. Vol 5

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Differences
Santoprene can withstand temperatures up to 275oC while Styrene-Butadiene rubber (SBR) have
low temperature performance.
Santoprene has superior defense against ozone, weathering and UV rays6 while Styrene-
Butadiene rubber (SBR) exhibits heat resistance
Santoprene has a perfect resistant against chemicals while Styrene-Butadiene rubber (SBR) has a
perfect Aarasion resistant
b) Vulcanization or Curing of Rubber
Vulcanization of rubber induced by sulfur is the chemical process of natural rubber conversion
into materials that are durable through heating them with sulfur. The most common agent of
vulcanization of rubber is sulfur and it forms bridges between individual molecules of polymer
when heated with rubber. Normally an initiator or catalyst is added to accelerate the process of
vulcanization. The process of cross-linking is rather complicated and entail a sequence of
reactions. The process begin with the formation of isoprene unit with sulfur molecule polarized
(Kruželák & Sýkora, 2017). The ion of persulfonium reacts with allylic hydrogen abstraction
than with other isoprene to produce a polymeric allylic carbocation. In the last step, molecule of
sulfur combines with the allylic cation to generate another sulfonium ion which releases sulfur.
The crosslink of polysulfide formed by the various reactions may possess four to six sulfur atoms
at low temperatures whereas at higher temperatures of reactions shorter sulfur bridges are
formed7.
c) Roles of Carbon Black and Clay in Rubber
6 Rabiei, S., & Shojaei, A. Vulcanization kinetics and reversion behavior of natural rubber/styrene-butadiene rubber
blend filled with nanodiamond – the role of sulfur curing system. European Polymer Journal. Vol 81. 2016. pp. 98-
113.
7 Rabiei, S., & Shojaei, A. Vulcanization kinetics and reversion behavior of natural rubber/styrene-
butadiene rubber blend filled with nanodiamond – the role of sulfur curing system. European
Polymer Journal. Vol 81. 2016. pp. 98-113.

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Carbon black and clay when added to the automobile tires, carbon expands the solidness and
quality of the tires hence extending the life expectancy of the tires by reducing the heat from
parts of the tires that have tendency of getting hot especially when driving. Carbon black and
clay maintains the nature of tires by shielding them from ozone and UV light which are known to
break down the tires. The carbon also additively influence the safety of the drive by ensuring
safety drive through reducing the rolling resistance by 40% which in turn minimizes the amount
of consumption of fuel and provide better economy8.
3. Stimuli-responsive polymers
A responsive polymer-based material has the ability of changing their physical and chemical
properties after external stimuli exposure. Stimuli-responsive polymers have been used to
improve the quality of life in the following ways:
Biosensing and sensing: Biosensor is a device with the ability of quantifying and detecting
species of interest and at point of care to increase the efficiency of treating patients. These
polymers are capable of converting the presence of analytes into a chemical and physical change
that a user can relate to status of a system9.
Controlled drug delivery: Smart polymers have portrayed promise for biomedical applications,
and have found application as targeted, and controlled drug delivery, artificial muscles, triggered,
biodeparation apparatus, cell culture supports, and tissue engineering scaffolds.
Artificial actuators and muscles: Natural muscles are biological organs which have the capability
of transforming chemical energy into mechanical energy. Photoresponsive polymer-based
8 Zhang, X., Li, H., & Wang, F. Upgrading pyrolytic residue from waste tires to commercial carbon black. Waste
Management & Research. Vol 36. 2018. pp. 436-444
9 Ian, T. Stimuli-Responsive Phosphorus-Based Polymers. European Journal of Inorganic Chemistry. 2018. pp. 1445-1456.

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polymer material can be used to liquid crystalline polymers, polymer gels, and shape memory
polymers10.
Types of Smart or Responsive Polymers
Microgels and Hydrogels: These polymers have proved to be significant variety of biomedical
applications due to their water swellability and porous structure. Their porosity allows drug
loadings into gel matrix and consequent release of drug at a dependency on the coefficient of
diffusion of micromolecule or minute molecule in gel networks.
Amphiphilic hyaluronic acid: This polymer can be synthesized and used to form vesicles that are
self-assembled, which encapsulate both GOx and human insulin. When the level of blood
glucose is high, the oxygen dissolved is consumed rapidly because of reaction of glucose
oxidation11.
4.
a) Power Law
The shear rate and shear stress relationship for fluids that are non-Newtonian can be expressed
mathematically as:
Therefore, the power law fluid apparent viscosity is given by;
For;
n > 1, the fluid shows the behavior of shear-thickening
10 Casolaro, M., & Casolaro, I. Multiple Stimuli-Responsive Hydrogels for Metal-Based Drug Therapy. Polymers. Vol
4. 2012. pp. 946-985.
11 Vidyasagar, A. Stimuli Responsive Polymers for Biophysical Applications. Journal of Physical
Chemistry & Biophysics. Vol 3. 2013.

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n = 1, the fluid shows Newtonian behavior
n < 1, the fluid exhibits the properties of shear-thinning
In this above equation, n and K are tow empirical curve fitting parameters and are referred to as
the flow behavior index and fluid consistency coefficient respectively. The index may have any
value between 1 and 0 for a behavior of shear thinning. The larger the value of n, the larger is the
shear-thinning degree. For a shear-thickening fluid, the n index will be larger than unity. When n
= 1, the above equation becomes the Newtonian fluid constitutive equation12.
b)
c) Why plastics behave as shear thinning fluids
This is because plastics have viscosity that decreases under shear strain. A shear thinning
plastics’ apparent viscosity reduces with increase in shear rate. The viscosity behavior of plastics
changes according to microstructure13.
5. Fabrication of bottle cap
12 Kirwan, A. On Objectivity, Irreversibility and Non-Newtonian Fluids. Fluids. Vol 1. 2016. pp. 3.
13 Rodríguez, A., & Radilla, G. Non-Darcian flow experiments of shear-thinning fluids through
rough-walled rock fractures. Water Resources Research. Vol 52. 2016. pp. 9020-9035.

Polymers 9
Stretch blow molding is the first phase during the manufacture of bottle cap. The Polyethylene
Terephthalate (PET) is heated and then positioned in a mold where it assumes the shape if a thin,
long bottle top. PET is a thermoplastic polymer that may either be transparent or opaque
depending on the precise composition of the material. PET is first polymerized to create long
chain of molecules to produce plastic bottle cap. Injection molding is the procedure by which
plastic is forced into the mold. A thin steel rod referred to as mandrel is then slid in the parison
where it fills air in the parison that is pressurized highly and stretch blow molding starts. Due to
pressure, heat and pressurized air, the parison is stretched and blown into the mold, taking the
shape of the bottle. The mold is then quickly cooled so that the bottle cap is properly set14.
14 Ning, M., & Xin, M. Design and Research of Cap Sorter Mechanism of PET Bottle Automatic Cap Screwing
Machine. Advanced Materials Research. Vol 411. 2011. pp. 25-28

Polymers 10
REFERENCES
Casolaro, M., & Casolaro, I. Multiple Stimuli-Responsive Hydrogels for Metal-Based Drug Therapy.
Polymers. Vol 4. 2012. pp. 946-985.
Ian, T. Stimuli-Responsive Phosphorus-Based Polymers. European Journal of Inorganic Chemistry. 2018.
pp. 1445-1456.
Kausar, A. Strategies in Polymeric Nanoparticles and Hybrid Polymer Nanoparticles. NanoWorld Journal.
2019. Vol 5.
Kirwan, A. On Objectivity, Irreversibility and Non-Newtonian Fluids. Fluids. Vol 1. 2016. pp. 3.
Kruželák, J., & Sýkora, R. VULCANIZATION OF RUBBER COMPOUNDS WITH PEROXIDE CURING SYSTEMS.
Rubber Chemistry and Technology. Vol 90. 2017. pp. 60-88.
Ning, M., & Xin, M. Design and Research of Cap Sorter Mechanism of PET Bottle Automatic Cap Screwing
Machine. Advanced Materials Research. Vol 411. 2011. pp. 25-28.
Rabiei, S., & Shojaei, A. Vulcanization kinetics and reversion behavior of natural rubber/styrene-
butadiene rubber blend filled with nanodiamond – the role of sulfur curing system. European
Polymer Journal. Vol 81. 2016. pp. 98-113.
Rodríguez, A., & Radilla, G. Non-Darcian flow experiments of shear-thinning fluids through rough-walled
rock fractures. Water Resources Research. Vol 52. 2016. pp. 9020-9035.
Vidyasagar, A. Stimuli Responsive Polymers for Biophysical Applications. Journal of Physical Chemistry &
Biophysics. Vol 3. 2013.
Zhang, X., Li, H., & Wang, F. Upgrading pyrolytic residue from waste tires to commercial carbon black.
Waste Management & Research. Vol 36. 2018. pp. 436-444