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Enhancement of tensile strength and biodegradation resistance of jute

Materials Science CentreIIT Kharagpur

Debasis Roy, Prosenjit Saha, Suvendu Manna

Reagent preparation

• Phenol-formaldehyde (PF) resin

• Vegetable oil emulsion

• Alkaline surfactant

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Treatment

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Geotextiles manufacture

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Treated geotextiles

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Parameters UntreatedFiber level

Fabric level

Standard

Area density (g/m2)

700 690 720 ASTM D5261-10

Thickness (mm)

1.4 1.3 1.4 ASTM D5199-11

Yarn linear density (ktex)

0.68(a), 0.99(b)

0.46(a), 0.46(b)

0.68(a), 0.99(b)

ASTM D861-07

Fabric mesh (threads/mm)

5.5(a), 3.9(b)

7.1(a), 3.9(b)

5.5(a), 3.9(b)

BIS 1963-81

Weave pattern1 up 1 down

1 up 2 down

1 up 1 down

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AOS95 (m) 235 255 245 ASTM D4751-04Permittivity

(cm/sec)0.083 0.090 0.083 ASTM D4491-99

(a) Machine direction, (b) cross machine direction

Geotextiles specifications

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SampleTensile strength

(kN/m) ± CLElongation at break

(kN/m) ± CL

MD CD MD CDUntreated 22±6 21±5 11±1 08±2

Fiber level 19±2 21±3 12±5 09±3Fabric level 25±4 23±3 13±4 09±2

MD: machine direction, CD: cross machine direction,CL: 95%confidence limit, narrow width tensile strength and elongation at break were measured as per ASTM D-751, 2006

Mechanical properties: Geotextiles

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Sample Water absorption (% by wt.) ± CL

Initial 120-d chemical exposure

120-d physical exposure

200-d biological exposure

Untreated 270±35 380±52 310±71 387±58Fiber level

90±22 110±20 120±21 109±13

Fabric level

120±30 140±34 124±35 136±22

Water absorption was estimated as per Alvarez et al., 2006

Short and long term water absorption of geotextiles

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Durability: GeotextilesSoil burial (IS: 1623, 1992):• Soil burial test: 31° C, 90 % rel. hum., soil : fiber :: 100 :

1 (w:w), soil water cont. 30%• Regular changes of soil compost to supply fresh

nutrient

Saline exposure:• Periodic exposure to 30 ppt NaCl saline solution

Physical weathering, AAW (ASTM D-4355:07):• 500 h exposure to UV light and cyclic water spray

pH exposure:• Dipping of samples to the solution with pH ranges from

3 to 10 for prolonged days

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Durability: Geotex…

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Durability in pH exposure: Geotex…

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Effect of biodegradation in soil burial

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Effect of physical weathering

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Service life estimation: From AAW• From AAW results the service lives for

geotextiles were estimated• Data from AAW were fitted with the equation

Y= Axexp(bt), where Y is the narrow strip tensile strength at time t, A, b are constant.

• Half life was estimated by calculating time of exposure to reach the 50% strength of initial strength by best-fit relationship (Koerner et al., 2005)

• Total AAW UV irradiation was scaled with total yearly UV irradiation in Kolkata (Wypych, 2003)

Service life estimation: From biodegradation…

• Laboratory based compost environment is more severe than typical outdoor environment

• Untreated geotextile degrades within 90 days in laboratory while in outer environment it lasts for 18-21 months

• Laboratory results were scaled up with factor of 8 with outer environmental results

• Hence laboratory based half life was scaled up by 8 times to simulate environmental half life

Treatment

Half life in AAW Half life in soil burial

Laboratory (h), r2

Field(months)

Laboratory (days), r2

Field(months)

Raw 357, 0.99 11 45, 0.98 12

Fiber level

1613, 0.99 46 198, 0.99 52

Fabric level

1226, 0.99 35 137, 0.99 36

Life expectancy of geotextiles

Industrial trial

Field trials

Field trials

Field trials

Summary and Conclusions• A non-hazardous, non-expensive chemical

treatment process has been developed for enhancing hydrophobicity, tensile strength and resistance to biological, chemical and physical degradation of jute

• An alkaline solvent free emulsion of neem oil and mostly plant based phenolic resin were used for fiber treatment

• Vegetable oil was found to transesterify the cellulose chain of jute

Summary and Conclusions…• After degradation study long term tensile strength

retention for treated fabrics was found remarkably higher than that of untreated fabric

• Developed treatment process was applied to manufacture industrial textile such as jute geotextile within an industrial set up of a jute mill

• The feasibility of proposed treatment process was found satisfactory

• The process was found to enhance service life of treated geotextiles upto 3-4 times compared to untreated geotextiles without compromising strength, porometry and flexibility of the textiles

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