ITR2012, Orlando, FL February 20-22, 2012

http://www.prolone.com/logo_earth_friendly_600x600.jpg http://thumbs.dreamstime.com/thumb_170/1185844728SVw3Es.jpg

Meltblown Ingo Nano-fibers: Current Status and Future Potential

Gajanan Bhat and Kokouvi Akato, The University of Tennessee, Knoxville TN

Issues

• Disposable Nonwovens • MSW • Recycling is Hard • Composting

-Biodegradability • Biodegradable Nonwovens

Poly(lactic acid) (PLA) Nonwovens - solution to sustainability

•PLA is obtained from renewable resources

•Biodegradable in nature

•Greener products

-compared to polypropylene etc.

PLA vs. other Biopolymers

•PLA is a thermoplastic polymer

•Easily processable

-Melt spinning, melt blowing etc.

•Economic advantage of melt processing

•Absence of chemicals during conversion processes

•Hence processing is comparatively eco-friendly

PLA polymer characterization - DSC thermo gram

* Heat of fusion of 100% crystalline PLA is taken as 93.7 j/gm

(Reference: B. Gupta et al, Journal of applied polymer science 2006, v100, n2, p1239-1246)

Peak melting temperature: 173°C

% DSC crystallinity: 47.2%*

Schematic of the melt blowing process

Melt Blowing Research At UTNRL Six-Inch line (HT Capable)

8

Nano and Sub-Micron Fibers

•Diameter

•High specific surface area

•Flexibility

•Enhanced reactivity of the Catalysts and

Biocides

9

Production Techniques for Nano and Sub-Micron Fibers

• Splitting

• Electrospinning

• Meltblowing??

10

Production Techniques for Nano and Sub-Micron Fibers

• Splitting of bi-/multi-component fibers – From multicomponent

spinning and dissolution of some components, one can produce fibers somewhat close to that of nanofibers

– Hard to control the fiber dimensions and solvent removal & recovery issues

11

Electrospinning

• Based on the current state of the art, nanofibers have a bright future and a large market potential, but only if – Cost of electrospun nanofibers – Extremely low production rate

• The commercial reality for electrospinning is still distant

New approach - Modified melt blowing process

12

Technology for Nano and Sub-Micron Fibers by Meltblowing

• Modular Dies on six inch line – AGR/NTI – Hills – AGR Die on twenty inch line

• Nanofiber production at commercially feasible rates – Throughput rates from 100-1100 gm/hour

13

Nanofiber Melt Blowing

• Nanofiber Die Module • Allows Trials With Small

Amounts of Material (Less Than 1 kg/trial)

• Capable of Reaching Polymer Melt Temps Above 750 Deg F.

• Capable of Air Temps In Excess of 750 Deg F

PLA and PP Submicron Fibers Samples ID Conditions Basis

Weight (gsm)

Thickness (mm)

Pore size (microns)

Air permeability

(cfm) Air

pressure (psi)

DCD (mm)

PLA

1 9 100 30 0.507 4.58 29.1 2 9 150 30 0.453 5.87 31.0 3 9 200 31 0.522 5.30 31.5 4 14 200 31 0.573 4.50 29.6 5 5 200 30 0.442 5.02 36.5

PP

1 9 100 29 0.508 3.57 15.1 2 9 150 30 0.658 4.18 16.7 3 9 200 31 0.483 4.58 21.3 4 14 200 29 0.501 5.93 25.5 5 5 200 30 0.517 4.55 17.7

SEM Images

SEM image of PLA sample 3 at 100x and 2Kx

SEM images

SEM image of PLA sample 5 at 100x and 2Kx

Fiber diameter

Samples 1 2 3 4 5

Fiber diameter (micron)

PLA

Avg. 0.452 0.504 0.550 0.474 0.662

Std. Dev. 0.189 0.127 0.241 0.153 0.242

PP Avg. 0.479 0.541 0.558 0.479 0.591

Std. Dev. 0.145 0.133 0.201 0.143 0.199

Fiber diameter

distribution

0

1

2

3

4

5

6

7

8

0.18 0.25 0.26 0.3 0.33 0.35 0.4 0.42 0.46 0.5 0.55 0.6 0.7 0.88 0.9 0.95 1.36

Sample 1

Fiber distribution PLA sample 1

Fiber Diameter (microns)

Freq

uenc

y of

Fib

er C

ount

0

1

2

3

4

5

6

7

0.18 0.2 0.28 0.33 0.4 0.45 0.5 0.52 0.55 0.6 0.66 0.75 0.8 0.99 1.2 1.28 1.36

Fiber distribution PLA sample 3 Sample 3

Fiber Diameter (microns)

Freq

uenc

y of

Fib

er C

ount

Fiber diameter

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

5 9 14 Fibe

r di

amet

er (m

icro

ns)

Air pressure (psi)

Fiber diameter vs. Air pressure at 200 mm

PLA PP

Air permeability

Samples 1 2 3 4 5

Air permeability

(cfm)

PLA 29.05 30.98 31.49 29.55 36.5

PP 15.14 16.74 21.26 25.52 17.7

Thickness

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

100 150 200

Thi

ckne

ss (m

m)

DCD (mm)

Thickness vs. DCD at 9 psi

PLA PP

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

5 9 14 T

hick

ness

(mm

) Air pressure (psi)

Thickness vs. Air pressure at 200 mm

PLA PP

Pore size

0

1

2

3

4

5

6

7

100 150 200

Pore

size

(mic

rons

)

DCD (mm)

Pore size vs. DCD at 9 psi

PLA PP

0

1

2

3

4

5

6

7

5 9 14

Pore

size

(mic

rons

)

Air pressure (psi)

Pore size vs. Air pressure at 200 mm

PLA PP

DSC Scans of Melt Blown PLA Nanofiber Webs

DSC cooling

Degree of crystallinity

Samples % Crystallinity

heating % Crystallinity

cooling

Pellets 64.04 9.10

1 51.53 4.57

2 63.67 7.04

3 53.93 4.80

4 55.85 4.34

5 55.34 4.60

DSC Scans of Typical Melt Blown PLA Webs

27

Summary • PLA can be melt blown to produce fine

fiber webs • Good mechanical and performance

properties • Better structure development during

nanofiber formation • A Greener alternative material for

disposable filtration related applications

28

Current Work

• Understanding the Process • Velocity and Temperature Profile • Equipment Modifications

29

Acknowledgements

• Nature works • UT-OR

30