Comparison of Ramie Degumming Processes

 

Ramie is a perennial herbaceous plant known for its strong, lustrous fibers with excellent moisture absorption and breathability. However, due to the presence of pectin, hemicellulose, and other gummy substances, raw ramie is stiff and difficult to spin. Degumming removes these impurities through chemical, biological, or physical means, allowing the fibers to separate, soften, and improve in spinnability and dyeability. Common degumming methods include chemical and biological processes. The chemical method offers complete and efficient degumming but causes pollution and may damage fibers, whereas the biological method is eco-friendly and produces high-quality fibers, though it requires longer time and higher cost. Degumming quality directly affects the softness, luster, and subsequent spinning performance of ramie fibers.
This study compares biologically degummed and chemically degummed refined dry ramie fibers in terms of chemical composition, physical properties, and microstructure, aiming to analyze the fundamental differences between the two methods. The results help reveal how degumming affects fiber properties during spinning, contributing to better control of the biological process for stable fiber quality.

Degumming Processes

Biological Degumming Process​
Raw ramie bundling → Pretreatment → Inoculation → Fermentation → Inactivation → Beating or Scutching → Washing → Oiling → Dehydration → Drying → Refined dry ramie.
  • Microorganism: Strain T85–260; slant culture for 12–16 h at 35 °C; fermentation tank (200 L) at 34–35 °C, air flow 0.3–0.6 m³/min, pressure 30 kPa, time 5–6 h.
  • Process details:
    • Inoculation: 500 kg per batch, 15 min.
    • Fermentation: No aeration, 8 h at 35–36 °C.
    • Inactivation: Pressure 19.6 N, 3 g/L NaOH, 1 h.
    • Beating: 4–5 rounds; synthetic oil used as lubricant; other steps follow conventional parameters.
Chemical Degumming Process
Acid soaking → Washing → First boiling → Washing → Second boiling → Washing → Acid washing → Washing → Refining → Washing → Oiling → Dehydration → Drying.
Parameters:
  1. Acid soaking: 1% H₂SO₄, 1 h, bath ratio 1:12, 50 °C.
  2. First boiling: 5% NaOH, 4% Na₂SiO₃, 1.5 h, bath ratio 1:12, 100 °C.
  3. Second boiling: 12% NaOH, 4% Na₂SiO₃, 2% Na₅P₃O₁₀, 2 h, bath ratio 1:12, 100 °C.
  4. Acid washing: 2 g/L, room temperature, 5 min, bath ratio 1:20.
  5. Refining: 2% NaOH, 3% Na₂SiO₃, 1% DBS, 3 h, bath ratio 1:10, 100 °C.
  6. Oiling: 1.5%, room temperature, 30 min, bath ratio 1:1.

Chemical Composition and Residual Gum Content of Ramie Fibers

Ramie fibers have the highest tensile strength and modulus among natural fibers, but due to their low elongation and small breaking work, they exhibit poor elasticity, crease recovery, and abrasion resistance, making fabrics somewhat stiff and prickly to wear.
The following table shows the measured tensile properties of the two types of refined dry ramie fibers. Tests were conducted using an electronic single-fiber strength tester under the following conditions: gauge length 30 mm, tensile speed 20 mm/min, pre-tension 0.196 cN, temperature 20 ± 2 °C, and relative humidity 65 ± 2 %. Each sample included 50 randomly selected fibers, and the average values are reported. YG005S Electronic Single Fiber Strength Tester

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