A laboratory study in Bangladesh shows that cotton knit cutting waste, sawdust and biological ETP sludge combined with epoxy resin can be made into composite garment buttons, at a batch cost of about Tk249, or roughly Tk2.49 per button.

Key points

  • Sample S2 (5% sawdust + 5% ETP sludge) reached a peak stress of 34.80 N/mm², Young's modulus of 2616 N/mm² and elongation at break of 4.80%, outperforming S1, which contained only sawdust.
  • Raw materials came from Interstoff Apparels Ltd's knit cutting waste and biological ETP sludge, while the sawdust came from a furniture factory in Rampura.
  • Each batch contains Tk144 of epoxy resin, Tk54 of hardener and Tk1 of sawdust, plus Tk50 in processing costs, working out to about Tk2.49 per button based on 100 buttons, compared with Tk2–5 for ordinary plastic buttons.

Turning waste into buttons
Buttons are small fasteners on garments and accessories, commonly made from plastic, metal, shell, wood and resin. Plastic buttons such as ABS, polyester and nylon dominate because they are cheap, durable and easy to design, but they degrade poorly and bring microplastic and chemical problems. The study cites data showing that about 60 billion buttons are produced worldwide each year, the textile industry generates nearly 5% of global waste, and millions of tonnes of textile waste are landfilled annually.

According to the study, the cotton knit cutting waste was collected from Interstoff Apparels Ltd's cutting floor, the biological ETP sludge also came from the company, and the sawdust came from a furniture factory in Rampura. The ETP sludge was first sun-dried, then oven-dried at 105°C for 6–8 hours, ground and sieved through 300 microns; the sawdust was taken below 300 microns and dried at 80°C for two hours; the cotton knit fabric was soaked in 5% sodium hydroxide for one hour to increase surface roughness and resin adhesion, washed to neutrality and dried at 70°C. The matrix used epoxy resin with LAPOX hardener in a 2:1 ratio.

Preparation used hand lay-up: both formulations used eight layers of 17×17 cm knit fabric impregnated with the resin and filler mixture, stacked and pressed to remove air bubbles, cured at room temperature for 24 hours, then pressed with an automatic hydraulic press, and the cured composite panels were machined into button specimens. S1 was knit fabric + 5% sawdust, and S2 was knit fabric + 5% sawdust + 5% ETP sludge.

Performance and shortcomings
Mechanical testing followed ASTM D3039. S2 outperformed S1 in all main indicators, with peak stress of 34.80 N/mm², Young's modulus of 2616 N/mm², elongation at break of 4.80% and fracture energy of 2.427 N·m, and was described as a composite with both strong stiffness and practical flexibility, suitable for non-load-bearing garment trims.

Water absorption was tested under ASTM D570. S2 absorbed 1.00% after one day in distilled water at room temperature, rising to 1.87%, 2.27% and 2.84% after two, three and seven days. The samples showed no delamination or cracking but did bend, which the study attributed to fibre swelling and matrix softening. Chemical resistance was tested under ASTM D543. After seven days, absorption was 2.41% in 5% hydrochloric acid and 2.09% in 5% sodium hydroxide, again with bending but no cracking. The study considers the performance promising under those conditions, but says testing under actual garment processing and washing conditions is still needed.

Cost and application prospects
Preliminary cost accounting shows economic appeal: textile waste and ETP sludge carry no purchase cost as waste, 50 g of sawdust costs Tk1, 180 g of epoxy resin Tk144 and 90 g of hardener Tk54, giving a raw material cost of Tk199 per batch, plus Tk50 in processing costs (including Tk20 in management and Tk30 in labour), for a total of Tk249; based on 100 buttons per batch, that is about Tk2.49 per button. The concept could be used for casual shirts, trousers, jackets and denim, as well as sustainable fashion products and decorative trims such as bag and belt buttons, and the research team has already demonstrated a finished shirt.

The study stresses that its value lies in bringing three waste streams — textile cutting waste, sawdust and ETP sludge — into the same product development path, turning them from a disposal burden into reinforcement and filler materials and supporting a "waste to resource" manufacturing approach; if it can be scaled and validated, it could reduce reliance on virgin plastic trims.

Still a proof of concept
The study's main limitation is that it remains at laboratory scale: hand lay-up has limits in consistency and precision, the composition and properties of natural and industrial fillers may fluctuate, and advanced characterisation equipment and large-scale production validation are lacking. Further work should examine automated standard production, optimise filler ratios and particle size, and test repeated washing, abrasion, impact, heat exposure, long-term ageing and dimensional stability; because ETP sludge composition may vary, safety characterisation and leaching assessment are also needed before commercialisation, along with life cycle assessment to quantify environmental performance. The study therefore positions its results as a proof of concept rather than a ready replacement for conventional buttons. Even so, it shows a practical direction for Bangladesh's textile industry: waste streams can be engineered into useful garment components, and circularity can extend from fibres and fabrics to a garment's small parts.

Source: Sustainable composite buttons from textile waste · Originally published 2026-10-03