NARAYANA GROUP OF SCHOOLS
BRANCH : KRISHNANAGAR
Name : Soubhik Biswas
Class: XI ( PCMB )
Roll number: 31
Subject: Chemistry
Admission number: 5914504
Project Title: To study the effect of acids and bases
on the tensile strength of fibres
Academic Year: 2024-25
ACKNOWLEDGEMENT
I would like to thank my chemistry teacher Mr
Somnath Das for guiding me throughout this project
work. I should also thank our lab assistant who
helped me to line up the project and helped me the
practical work related to this project.
A special acknowledgement goes to our principal Mr
Krishna Kishore Baddri who gave me the golden
opportunity of this project, which also helped me
doing a lot of research and I came to know about so
many new things.
CERTIFICATE
This is to certify that Soubhik Biswas, a student of
class XI has successfully completed the Chemistry
project on the topic of - To study the effect of acids
and bases on the tensile strength of fibres under the
guidance of Mr. Somnath Das during the year 2024 –
25.
INTRODUCTION
Fibers are integral to industries such as textiles,
construction, and engineering. Understanding how
chemical environments affect fibers is essential for
their efficient use and maintenance. This project
explores how acids and bases impact the tensile
strength of natural (cotton, silk, wool) and synthetic
(nylon, polyester) fibers.
OBJECTIVES
● To analyze the effect of acidic and basic
solutions on the tensile strength of various fibers.
● To understand the chemical reactions leading to
changes in strength.
● To compare the durability of natural vs. synthetic
fibers under chemical exposure.
MATERIALS AND METHODS
Materials Required :
● Fibers: Cotton, silk, wool, nylon, polyester.
● Chemicals: Dilute hydrochloric acid (HCl),
sodium hydroxide (NaOH), distilled water.
● Equipment: Tensile testing apparatus,
beakers, gloves, tongs.
PROCEDURE
1. Fibre Preparation : Cut fibers into 10 cm lengths
and divide into untreated (control), acid-treated,
and base-treated groups.
2. Chemical Treatment :
○ Immerse fibers in 0.1M and 1M solutions of
HCl and NaOH for 24 hours.
○ Rinse with distilled water and air dry.
3. Tensile Testing : Measure the tensile strength of
each sample using a tensile testing apparatus,
recording the force required to break the fiber.
4. Data Recording : Note the initial and final
tensile strengths to calculate percentage change.
OBSERVATION
1. Effect of Acidic Treatment:
• Natural Fibers (Cotton, Wool, Silk):
● Cotton fibers showed slight degradation in dilute
acids and significant weakening in concentrated
acids.
● Wool and silk, being protein-based, exhibited
hydrolysis of peptide bonds, leading to a
noticeable reduction in tensile strength.
• Synthetic Fibers (Nylon, Polyester):
● Nylon showed partial hydrolysis and a slight
reduction in strength.
● Polyester remained largely unaffected in dilute
acids but showed minor weakening in
concentrated acids.
2. Effect of Basic Treatment:
•Natural Fibers (Cotton, Wool, Silk):
● Cotton fibers were damaged significantly, as
alkalis degraded cellulose.
● Wool and silk showed loss of tensile strength due
to the breaking of peptide bonds in protein
structures.
•Synthetic Fibers (Nylon, Polyester):
● Nylon showed moderate degradation.
● Polyester exhibited high resistance to alkalis,
retaining most of its tensile strength.
RESULT TABLE
RESULTS
● Natural fibers (cotton, wool, silk) are more
vulnerable to both acids and bases compared to
synthetic fibers.
● Synthetic fibers like polyester exhibit high
resistance to chemical treatments, making them
more suitable for use in chemically harsh
environments.
● Tensile strength reduction is more significant in
strong acid and base solutions compared to
dilute ones.
DISCUSSION
● Effect of Acids:
Hydrolysis weakens the molecular structure of
natural fibers like cotton and wool, reducing their
tensile strength. Synthetic fibers such as
polyester are more resistant.
● Effect of Bases:
Alkalis degrade cellulose in cotton and proteins
in wool but have minimal effects on polyester.
Nylon shows moderate degradation.
APPLICATIONS
● Textile care and durability enhancement.
● Designing chemically resistant materials for
industrial use.
● Development of innovative fibers for harsh
environments.
CONCLUSION
● Natural fibers are more susceptible to chemical
damage than synthetic fibers.
● Polyester and nylon are relatively resistant to
both acidic and basic environments, making
them suitable for industrial applications.
● Proper care is required when using natural fibers
in chemically active environments.
REFERENCES
● Chatgpt.com
● Laboratory manuals for tensile strength testing
