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Table 1: Comparative properties of PLA, PGA and CA
Parameter Polylactic acid Polyglycolic acid Cellulose diacetate Cellulose triacetate
Density[1][2][3] 1.24-1.50 g/cc 1.50 g/cc (for amorphous)
1.71 g/cc (for crystalline) 1.25-1.35 g/cc 1.31-1.35 g/cc
Melting point[1][2][3] 175°C 224-230°C 230°C 295°C
Tenacity [1][4][5][6] 3-6 g/den 5.5-7 g/den 1.2-1.8 g/den 3-5 g/den
single piece that did not biodegrade? acetate. About 200-kt of ethyl acetate however, pose a problem of separa-
Has anyone tried to collect the used is exported annually, consuming about tion.
cigarette fi lters with a view to recycle 140-kt of acetic acid. If the industry
these in any other application? What can import 230-kt of acetic anhydride, Concluding remarks
these mean is that CTA is fully bio- use it for acetylation of cellulose, PLA is a biodegradable plastic that
degradable; otherwise, it would have manufacture of 140-kt of CTA would requires (per tonne) 1.05-acres land,
accumulated like many other industrial be possible. This can meet a signifi - 60-kl water, and 89,200-megajoules
waste materials and single use plastics. cant requirement of single use plastics of energy for production. The polymer
in the form of fi lms used in packaging. takes anywhere from six months to
CTA has been used as fi bre, for It can also substitute polyvinyl chlo- 80 years for biodegradation, and costs
cinematographic fi lms and can be pro- ride (PVC), polyester and PP fi lms in Rs. 300-350 per kg.
cessed by all major plastics forming multi-layer packaging.
processes including injection moulding Cellulose derivatives – half natural
and extrusion. But in many applica- The dilute acetic acid obtained as a and half synthetic – are, on the other
tions, CTA have been replaced by petro- product of acetylation, can be converted hand, environmentally friendly.
chemicals over time. CTA fi lms, for to ethyl acetate for exports. Since the
example, have been replaced by poly- existing process for making ethyl REFERENCES
ester fi lms, even though CTA continues acetate utilises wet ethyl alcohol, water 1. What is PLA? (everything you need
to be used for cigarette fi lter, spectacle in acetic acid would not be objection- to know); https://www.twi-global.
frames, high quality combs and even able. The ethyl acetate industry, which com/technical-knowledge/faqs/
some membranes. is struggling to make ends meet, can get what-is-pla#HowisitMade
a fresh lease of life and can make 2. Bioabsorbable PGA, PGLA, or
For many years, CAB was used in profi ts by sale of high value CTA. PLLA yarn; https://www.telefl ex-
combs and in slide rules (for its dimen- medicaloem.com/bioresorbable-
sional stability), door handles, steering Physical properties of CTA make it resinsfi bersand-sutures/yarn/
wheels and grips of the gear stick of a perfect substitute to PLA (Table 1). 3. Hindeleh, A.M., & Johnson, D.J.,
expensive cars. Presently, the use of Correlation crystallinity and physical
CAB is restricted to clear coats in Cellulose availability properties of heat-treated cellulose
automobiles. Cellulose can be obtained from triacetate fi bres. Polymer, 11(12),
cotton linters, combing waste or de- 666-680. https://doi.org/10.1016/0032-
All these uses of cellulose deriva- rived from bagasse of which sugar 3861(70)90019-4
tives are time tested and proven. But, industry has adequate surplus. India 4. Liu, N., Wang, B., Chen, S., Ke, F.,
despite this existing body of know- exports about 60-kt of cotton linters, a Chen, Y., Pei, Q., & Wang, H. (2016).
ledge, India does not produce CTA, high-quality cellulose, and about 100-kt Improving the mechanical properties
CAB and even NC at suffi ciently large of fabric waste from hosiery industry. of cellulose diacetate fi bres via using
scale. Some of it may be coloured. White an ionic liquid as processing solvent,
waste, which could represent about RSC Advances, 6 (1), 1-7. https://doi.
One reason could be availability 40-50% of total waste, is a valuable org/10.1039/c5ra21583h
of acetic anhydride, which is locally resource. It is pre-processed, bleached 5. Life Cycle Assessment (LCA) of
produced only in small quantities. On and mercerised, and hence is a very Biodegradable Polymers; https://
the other hand, the Indian chemical pure form of cellulose. The presence nichem.solutions/2024/04/28/life-
industry is importing huge quantities of spandex, which has become an im- cycle-assessment-lca-of-biodegrad-
of acetic acid and exporting ethyl portant fi bre in hosiery fabric, may, able-polymers/

Chemical Weekly February 25, 2025 175

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