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Nylon (Chemistry, Properties and Uses)

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Nylon can be described as a ubiquitous polymer. It is a part of various applications which are paramount in our quotidian life. Hence it is important to study the chemistry and properties of nylon which are instrumental for its selection in various applications. The paper focuses on the chemistry of nylon and its different types. Maximum emphasis is placed on the synthesis of various nylons and their structure which influence its properties. The properties in turn widen the range of applications of this important entity. Possible additives if added to nylon could make it a better material for newer and more sophisticated applications are also discussed.
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IJSR - INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH 349
Volume : 5 | Issue : 9 |
September
2016 • ISSN No 2277 - 8179 | IF : 3.508 | IC Value : 69.48
Original Research Paper
Chemistry
Parth K. Vagholkar Department of Polymer & Surface Engineering, Institute of Chemical Technology.
Mumbai 400019. India.
Nylon
(Chemistry, Properties and Uses) KEYWORDS : Nylon, Chemistry,
structure, Properties
ABSTRACT Nylon can be described as a ubiquitous polymer. It is a part of various applications which are paramount in our
quotidian life. Hence it is important to study the chemistry and properties of nylon which are instrumental for its
selection in various applications. The paper focusses on the chemistry of nylon and its dierent types. Maximum emphasis is placed on
the synthesis of various nylons and their structure which inuence its properties. The properties in turn widen the range of applications
of this important entity. Possible additives if added to nylon could make it a beer material for newer and more sophisticated applications
are also discussed.
Introduction:
Before going to the synthesis and chemistry of nylon, one
needs to study the various types of nylon and their appli-
cation. The various types of nylon used in everyday life
are Nylon-6, Nylon-6,6, Nylon-6,10, Nylon-6,12, Nylon-11,
Nylon-12 and Nylon MXD6. Some common applications of
these nylons are electrical connectors, gear, slide, cams, and
bearings, cable ties and lm packaging, uid reservoirs,
shing line, brush bristles, automotive oil pans, fabric, car-
peting, sportswear, sports and recreational equipment [1,
2].
Chemistry:
Nylons are basically included in the class of polyamides
which also contains Kevlar [3]. Nylons, except for Nylon-6,
are all formed by condensation polymerisation between di-
carboxylic acids and diamines as shown in Figure 1. This
is an example of nucleophilic addition- elimination reaction
as shown in Figure2. [5]
Figure 1: Condensation polymerization reaction of Ny-
lons.
But usually this conventional method of forming a ny-
lon is replaced by a newer method. In the newer method,
a carbonyl chloride group is used to form an amide link-
age with an alcohol instead of a carboxylic acid group as
shown in Figure 2. This method of forming an amide link-
age is more eective than the conventional one. Sometimes
acid anhydrides are also used instead of carboxylic acid
groups as shown in gure 2. [4, 5]
Figure 2: Amide synthesis by three dierent compounds
all reacting with amine.
From gure 2, it is evident that these acyl and anhydride
groups render the carbonyl carbon atom more electroposi-
tive for a nucleophilic addition of the amine group to take
place.
The polymerization technique used for nylon is interfacial
condensation. In this technique, polymerization is allowed
to proceed at the interface between an aqueous and an or-
ganic medium.[6] Since the polymer formation at the inter-
face is a diusion controlled process, very high molecular
weight polymers can be achieved by this technique.
Nylon-6:
Nylon-6, Nylon-11, Nylon-12 are all homopolymers. But
Nylon-11 and Nylon-12 are formed by condensation po-
lymerization because their monomers (11-aminoundeca-
noic acid and ω-aminolauric acid respectively) contain both
amine and acid functionalities in a single molecule (mon-
omer) itself. [7] Nylon-12 can also be produced by ring-
opening polymerization of laurolactam at 260-300˚C. [8]
Nylon-6 however is only formed by ring opening polymeri-
zation of ε-Caprolactam [9] as shown in gure 3.
Figure 3 polymerization reaction of nylon-6
Structure and related properties:
As the separation of the amide groups increases (by adding
more methyl groups) and the polarity of the amide groups
is reduced, moisture absorbance is decreased. Resistance
to thermal deformation is lowered due to more exibility
and mobility in the methyl unit sections of the chain. In
the case of Nylon-6,6 and Nylon-6,12, one can clearly see
this relationship. Nylon-6,12 has a lower modulus, higher
elongation, lower strength, lower thermal distortion tem-
perature, lower hardness, and lower melting point than
Nylon-6,6. However, Nylon-6,12 absorbs half as much wa-
ter on Nylon-6,6. Thus, even though the properties may
not be as good as Nylon-6,6 in dry conditions; the proper-
ties of Nylon-6,12 will be much more consistent when it is
used in applications in which water may be present. The
absorption of water has a signicant eect on the proper-
ties of nylon. [2]
Chemical and Physical properties:
• Acid: Nylon 6, 6 is aacked by mineral acids is dis-
integrated or dissolved almost. But is inert to dilute
350 IJSR - INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH
Volume : 5 | Issue : 9 | September 2016 • ISSN No 2277 - 8179 | IF : 3.508 | IC Value
: 69.48
Original Research Paper
acetate acid and formic acids even of the boil. It is
dissolved in the concentrated formic acid. Nylon 6 is
aacked by mineral acid but resistant to dilute boiling
organic acid. [6,7]
• Bleaches: Not aacked by oxidizing and reducing
bleaches but may be harmed by chlorine and strong
oxidizing bleaches. [10,11]
• Alkali: Nylon is substantially inert to alkalis. [11]
• Organic solvent: Most of the solvent have lile or no
eect on nylon. Phenol metacressol and formic acid
dissolve the bre but solvents used in stain removal
and dry cleaning do not damage it. [12,13]
• Light: No discoloration. Nylon 6 gradually loss of
strength on prolonged extension.[6,10,11]
• Biological: Neither micro organism nor moth, larvae
aack nylon. [6]
• Electrical: High insulating properties leads to static
charges on the bre.
• Flammability: Burns slowly. [6]
Figure 4: The molecular structure of Nylon-6 versus Ny-
lon-6, 6 yields enhanced properties.
Nylon-6, 6 shows greater strength as compared to Nylon-6
because of the greater hydrogen bonding shown in Ny-
lon-6, 6 as shown in gure 4.
Melting point and crystallinity increase because of this
greater hydrogen bonding between adjacent chains. But
this eect is not a regular one. The increase in melting
point also depends on whether the number of -CH₂ groups
present in between the CONH groups is even or odd. The
odd number of -CH₂ groups between the amide groups
in Nylon-6 allows complete hydrogen bonding when the
amides in the adjacent chains have an opposed or an an-
tiparallel orientation but not when they have the same or
parallel orientation(as shown in the gure 4). Changing
from a parallel to an antiparallel array requires inverting
the entire molecular chain in the odd numbered case. But
only a segment lateral movement is needed if there is an
even number of -CH₂ groups, as in the case of Nylon-6, 6
with its intervening number of 4 and 6 -CH₂ groups. It is
this odd-even feature that accounts for the lower melting
point and percent crystallinity of Nylon-6 versus Nylon-6,
6. It is this reason in general why Nylon-odd and Nylon-
odd-even have lower melting points than comparable or
similar Nylon-even-even. [7]
Thus the crystalline behaviour of nylon is directly related
to its structure.
Increasing crystallinity increases
• Stiness
• Density
• Tensile and yield stress
• Chemical and abrasion resistance
• Beer dimensional properties.
However increasing crystallinity decreases
• Elongation
• Impact resistance
• Thermal expansion
• and Permeability.
Water absorption as discussed earlier is characteristic of
nylons. Unless compensated for by increased crystallinity,
a higher proportion of amide groups leads to higher water
absorption. Increased water content has an eect analo-
gous to that of increased temperature, i.e., enhanced seg-
mental mobility with concomitant loss in stiness and ten-
sile strength, gain in toughness and growth in dimensions
(elongation).
At very low temperature, however, water stiens the nylon.
Thus the brileness temperature (ASTM D746) of Nylon-6,
6 is-80°c if dry and - 65°c if conditioned to 50% relative
humidity. Properties are frequently reported in the “dry”,
as- molded condition corresponding to about 0.2% water or
less, and after equilibration to a specied relative humidity
such as 50 or 65% and occasionally to 100%.
Also nylons with fewer CONH groups and lower water ab-
sorption have a lower dry Tg, but shows less change of Tg
with relative humidity. [7] Thus we see that the mechanical
properties of nylon depend greatly on the crystallinity and
water absorption.
Applications:
1. Nylon is a high strength bre. It is used for making sh-
ing nets, ropes, parachutes and type cords. [6, 14]
2. It is used for making fabrics in textile industry. Nylon
creates draperies, ame-resistant products, and clothes. It is
often used for carpets. [15, 16]
3. Crinkled nylon bres are used for making elastic hosiery.
Most stockings for women are made from nylon. Used to
make and design clothing. [6, 15]
4. Nylon is widely used as plastic for making machine
parts. [15]
5. It is blended with wool to increase the strength. [14]
6. Military applications such as parachutes, ak vests, and
tires for vehicles.
7. Nylon threads are used for surgical suture, dresses, un-
der garments, ties, tapestry. [16]
Figure 5: Applications of Nylon-6, 6
IJSR - INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH 351
Volume : 5 | Issue : 9 |
September
2016 • ISSN No 2277 - 8179 | IF : 3.508 | IC Value : 69.48
Original Research Paper
References:
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[2] A GUIDE TO NYLON - PTS LLC. hp://ptsllc.com/intro/nylon_intro.aspx.
[3] Kevlar - Wikipedia, the free encyclopedia.
[4] T.W.Graham Solomons & Craig B. Fryhle. Carboxylic Acids and deriva-
tives in ORGANIC CHEMISTRY (tenth edition) International Student Ver-
sion (Wiley and Sons 2011).
[5] Learning Organic Chemistry Reactions as a Nursing Student | Caravel.
http://caravel.sc.edu/2014/10/learning-organic-chemistry-reactions-as-a-
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[6] V.R.Gowariker , N.V.Viswanathan and Jayadev Sreedhar. Polyamide (Pag-
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(by New Age International Publishers 1986)
[7] Ben Herzog, Melvin I. Kohan, Steve A. Mestemacher, Rolando U. Pagi-
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a21_179.pub3.
[8] Kubisa, P.; Matyjaszewski, K.; Penczek, S. (1985). Cationic Ring-Opening
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delberg. pp. 201–208. doi:10.1007/3-540-13781-5_11. ISBN 978-3-540-13781-
8.
[9] Polymerization of Nylon 6 and Nylon 6,10 hp://www.pslc.ws/macrog/
lab/lab01.htm.
[10] Physical and Chemical properties of Nylon| End uses of Nylon ~ Textile
Apex hps://textileapex.blogspot.in/2015/02/end-uses-properties-of-nylon.
html.
[11] hp://www.chemguide.co.uk/organicprops/amides/polyamides.html.
[12] Picking A Winning Nylon For The Roller Derby | Archive content from
Machine Design. hp://machinedesign.com/archive/picking-winning-ny-
lon-roller-derby.
[13] Preparation, Properties and Applications of Nylon 6,6 Fibers ~ Textile Era.
http://textileera.blogspot.in/2014/01/preparation-properties-and-applica-
tions.html.
[14] hp://www.slideshare.net/nashton/nylon-66-presentation-5487525,
[15] hp://syntheticsubstance.blogspot.in/2009/12/applications-common-uses-of-
nylon.html.
[16] Nylon - Wikipedia, the free encyclopedia. hps://en.wikipedia.org/wiki/
Nylon.
[17] “Nylons” (accessed Dec 2, 2011). hp://pslc.ws/macrog/nylon.htm.
... The description of these polymers is done by numbering the carbon atoms present in the respective structure [28]. Based on their structural geometries, nylons are categorized as nylon 6,6, nylon 6, nylon 6,10, nylon 6,12, nylon MXD6, nylon 4,6 and nylon 12 as shown in Table 1 Superior nylon properties reported include; good thermal stability, toughness and stiffness, moisture absorption and resistance to acids and metallic salts [32][33][34]. Sportswear, equipment, gears, fabrics, film packaging, bearings and electrical connectors are some applications of different types of nylons [34,35]. Nylon 6,6 is prepared by stepgrowth polymerization reaction between different diacids and diamines [32,34,36]. ...
... Based on their structural geometries, nylons are categorized as nylon 6,6, nylon 6, nylon 6,10, nylon 6,12, nylon MXD6, nylon 4,6 and nylon 12 as shown in Table 1 Superior nylon properties reported include; good thermal stability, toughness and stiffness, moisture absorption and resistance to acids and metallic salts [32][33][34]. Sportswear, equipment, gears, fabrics, film packaging, bearings and electrical connectors are some applications of different types of nylons [34,35]. Nylon 6,6 is prepared by stepgrowth polymerization reaction between different diacids and diamines [32,34,36]. ...
... Sportswear, equipment, gears, fabrics, film packaging, bearings and electrical connectors are some applications of different types of nylons [34,35]. Nylon 6,6 is prepared by stepgrowth polymerization reaction between different diacids and diamines [32,34,36]. Monofunctional acids such as acetic and aluric acids are added to the intermediate mixture to control the molecular weight of the polymer. ...
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Chapter
  • Nov 2022
Climate change, rigorously heralded more than thirty years ago as a real threat, has become the most pressing and pernicious global problem for the entire planet. In conjunction with local impacts such as fishing, eutrophication or the invasion of alien species, to give just a few examples, the acidification of the oceans and the warming of the sea began to show its effects more than twenty years ago. These signals were ignored at the time by the governing bodies and by the economic stakeholders, who now see how we must run to repair the huge inflicted damage. Today, different processes are accelerating, and the thermodynamic machine has definitely deteriorated. We see, for example, that the intensity and magnitude of hurricanes and typhoons has increased. Most models announce more devastation of flash floods and a decomposition in the water cycle, which are factors directly affecting ecosystems all over the world. Important advances are also observed in the forecasting of impacts of atmospheric phenomena in coastal areas with more and more accurate models. Rising temperatures and acidification already affect many organisms, impacting the entire food chain. All organisms, pelagic or benthic, will be affected directly or indirectly by climate change at all depths and in all the latitudes. The impact will be non-homogeneous. In certain areas it will be more drastic than in others, and the visualization of such impacts is already ongoing. Some things may be very evident, such as coral mortalities in tropical areas or in the surface waters of the Mediterranean, while others may be less visible, such as changes in microelement availability affecting plankton productivity. In fact, primary productivity in microalgae, macroalgae and phanerogams is already beginning to feel the impact of warmer, stratified and nutrient-poor waters in many parts of the planet. Nutrients are becoming less available, temperature is rising above certain tolerance limits and water movement (turbulence) may change in certain areas favoring certain species of microplankton instead of others. All these mechanisms, together with light availability (which, in principle, is not drastically changing except for the cloudiness), affect the growth of the organisms that can photosynthesize and produce oxygen and organic matter for the rest of the trophic chain. That shift in productivity completely changes the rest of the food chain. In the Arctic or Antarctic, the problem is slightly different. Life depends on the dynamics of ice that is subject to seasonal changes. But winter solidification and summer dissolution is undergoing profound changes, causing organisms that are adapted to that rhythm of ice change to be under pressure. The change is more evident in the North Pole, but is also visible in the South pole, where the sea ice cover has also dramatically changed. In the chapter there is also a mention about the general problem of the water currents and their profound change do greenhouse gas effects. The warming of the waters and their influence on the marine currents are also already affecting the different ocean habitats. The slowdown of certain processes is causing an acceleration in the deoxygenation of the deepest areas and therefore an impact on the fragile communities of cold corals that populate large areas of our planet. Many organisms will be affected in their dispersion and their ability to colonize new areas or maintain a connection between different populations. The rapid adaptations to these new changes are apparent. Nature is on its course of restart from these new changes, but in this transitional phase the complexity and interactions that have taken thousands or millions of years to form can fade away until a new normal is consolidated.
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Fishing and Overfishing-Sustainable Harvest of the Sea
Chapter
  • Nov 2022
The impacts of industrial fishing have been present in the oceans for over one hundred years, but the exponential increase all over the world and the systematic exploitation of different areas started after world war II. The phenomenon of fishing has to be understood in order to understand the changes in the oceans, and such deep transformation is essential to capture the essence of the resilience: the collapse of fish stocks, the lack of biodiversity, and the profound transformation of ecosystems due to overfishing is in part responsible for the ocean’s impacted functioning that we witness today. It now seems that the collapse of many habitats is to blame for rising acidification or temperature, but the reality is that the impact of overfishing on pelagic and benthic systems is largely responsible for the profound transformations we see today. Trawling has devastated entire ecosystems, destroying the complexity of marine forests, both those that are dominated by vegetal organisms (macroalgae and phanerogams) and those dominated by animals (corals, gorgonians, sponges, etc.). It has been possible to verify that it is not only the destruction of the structures, but the compaction of the sediment and the continuous resuspension that made possible the impoverishment of the communities and therefore of the impoverishment of the fishing stocks. Beyond these impacts, pelagic fisheries have seen profound changes in populations, which evolve to the sound of fishing pressure. The minimum size of successful reproduction (i.e. the size in which the fish is lying eggs to promote the continuity of the populations), for example, has been drastically changed in many species, making possible for populations to survive despite the immense pressure of the predator, us. In addition, these fisheries highlight the fact that many animals are trapped with nets and long lines (dolphins, turtles, birds, etc.). The solutions to these problems are sometimes difficult to apply. These large organisms are usually essential for the health status of the ecosystem and the maintenance of the biodiversity, but we are impacting them in such a way that they have become irrelevant from an ecosystem functioning point of view. The so-called by-catch of smaller organisms is another huge problem. Discards (sometimes more than 50% of fisheries) profoundly harm and transform the ecosystem, and are difficult to sell in the fishing market. Solutions have been sought for decades and this collateral damage has been denounced, but there is still a long way to go. There is also a long way to go to eliminate the high percentage (calculated in more than a quarter of the fish landings of the entire planet) of those known as illegal, unreported and unregulated fisheries. This type of mismanagement of the sea is at the heart of the active policies of many countries, but without transparency and transnational actions, it will it will be difficult to reach a good agreement to suppress or minimize them. In fisheries models, apart from direct impacts, the effects of climate change have long been implemented. As already explained in the previous chapter, rising temperatures and the effects of acidification are transforming the landscape of primary and secondary productivity. The most obvious of these changes is the fact that there will be less fishing, and therefore less production. The effect of lower productivity is already felt in several long-lasting time series, where fishing is being affected by the decrease in phytoplankton. But, in addition, there are less obvious effects. One is the substitution of species, because some are more vulnerable than others to the increase in temperature, so that in the same taxonomic and functional group those who are best adapted to the new conditions win. Another is the expansion of invasive species that directly affect the food chain, and that may feel more comfortable with the new “rules” of fisheries impact and climate change. Some animals are already undergoing these changes, such as cetaceans dying of starvation in certain areas where the synergistic effects of fishing and climate change are felt. The co-governance of fisheries, in which scientists, politicians and society work together, is essential to move forward. They are not hollow words; they are real needs in a world of an excessively accelerated change.
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Reinventing Marine Exploitaition—New Mariculture, Energy and Marine Products Approach
Chapter
  • Nov 2022
It is difficult to make a synthesis of the new trends in the so-called Blue Growth. This chapter opens a small window with some examples that can serve to understand a little bit the trends of some (not all) sectors that are in full expansion all over the world simultaneously, with their pros and cons. There is a need to change the rules of the game, the paradigms to which we have so far been working with. It is not a simple exercise. It needs a lot of will and a deep understanding of what are the limits and dangers of the old model in which we still live immersed. Many examples show that the actual model runs too fast and has a direct impact on natural resources and ecosystem functioning. In this framework, aquaculture is coming under specific scrutiny. We have gone from an almost negligible aquaculture figure in the ‘70s in terms of fisheries production, to almost half of the biomass extracted from the sea and continental waters from this “farming” activity. This is a considerable achievement, but it has its consequences. The impact of monocultures (salmon, shrimp, etc.) has been, in many places, equal to or worse than overfishing. Eutrophication, salinization, introduction of drugs to contain diseases, the use of wild fish to feed mariculture species or the systematic hunting of potential predators (eagles, seals, etc.) are only some of the problems associated with aquaculture nowadays. The impact on wild ecosystems such as mangroves or fjords is very relevant, and has been highlighted as one of the most important problems to be solved in coastal waters. A new vision is that of the Integrated Multitrophic Aquaculture. This is a method that is gaining strength and that may be the change we need, especially if we move from species of high energy and carbon investment (carnivores) to those species that require less energetic effort (such as bivalves, macroalgae, holothurians, etc.). To do this, one of the first things to do is a good forecast of the impact of climate change, selecting the most suitable organisms (and areas) according to the changing environmental conditions. The regional possibilities (i.e., those areas that may be suitable for a mariculture expansion) and the carrying capacity of the surrounding ecosystems according to different areas must also be taken into account if we want a significant paradigm change. Also, the inclusion of stakeholders and clear co-governance roles of these kind of infrastructures has to be understood as a tool to a successful management of the products that will be available for the local people. The Blue Growth related to the mariculture is not the only open front for the future. The use of microalgae is another type of approach to a future in which low-energy cost organisms are gradually taking center stage. The possibilities have a wide spectrum, and now these microorganisms are beginning to be applied industrially in nutraceuticals, biofuels or for the generation of interesting molecules for biomedical applications. The solutions are there, and changing the priorities and the way we apply the different discoveries to be in line with SDG14 in this Blue Growth strategy is a challenge. In fact, it is not all positive prospects in Blue Growth. There are cases in which excessive acceleration of production and inadequate management of “new generation” resources can cause stress on systems, especially in places with fragile ecosystem balances. In addition, considering the production of alternative energies such as offshore wind, or the new planning of maritime traffic, we have to deeply change our way to proceed. The Blue Growth roadmap must change the paradigm if we really want to consider it sustainable. New solutions and new perspectives in a changing world that require spatial planning and a very different model of resource management than the one we are now applying are urgently needed, considering new models of production, economy and social interaction.
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Cationic Ring-Opening Polymerization Advances in Polymer Science
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Kubisa, P.; Matyjaszewski, K.; Penczek, S. (1985). Cationic Ring-Opening Polymerization. Advances in Polymer Science. 68/69. Springer Berlin Heidelberg. pp. 201–208. doi:10.1007/3-540-13781-5_11. ISBN 978-3-540-13781- 8.
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Ben Herzog, Melvin I. Kohan, Steve A. Mestemacher, Rolando U. Pagilagan and Kate Redmond "Polyamides" in Ullmann's Encyclopedia of Industrial Chemistry 2013, Wiley-VCH, Weinheim. doi:10.1002/14356007. a21_179.pub3.
Carboxylic Acids and derivatives in ORGANIC CHEMISTRY (tenth edition) International Student Version
  • Jan 2011
  • T W Graham
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Polymerization Techniques (Page 79) in Polymer Science (by New Age International Publishers
  • Jan 1986
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  • Jayadev Sreedhar
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Advances in Polymer Science. 68/69. Springer Berlin Heidelberg
  • Jan 1985
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  • K Matyjaszewski
  • S Penczek
Kubisa, P.; Matyjaszewski, K.; Penczek, S. (1985). Cationic Ring-Opening Polymerization. Advances in Polymer Science. 68/69. Springer Berlin Heidelberg. pp. 201-208. doi:10.1007/3-540-13781-5_11. ISBN 978-3-540-13781-8.