Lecture - 17 B - Identification_of_Plastics

8/10/2019 Lecture - 17 B - Identification_of_Plastics

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IDENTIFICATION OF PLASTICSIDENTIFICATION OF PLASTICSBY

SIMPLE METHODS

BY

SIMPLE METHODS



IDENTIFICATION TECHNIQUESSIMPLE INSTRUMENTAL

1. APPEARANCE 1. THERMAL ANALYZER

2. METHOD OF 2. GPC

FABRICATION

3. PENETRATION TO 3. X RAY DIFRACTIOMETER

HOT ROD AND

CUTTING WITH A 4. I. R. SPECTROSCOPY

KNIFE

5. NMR SPECTROSCOPY

4. FLOTATION TEST

5. SCRATCH RESISTANCE

6. COLOUR

7. ODOUR

8. TEAR

.

10. BURNING

CHARACTERISTICS

11. PYROLYSIS

12. MELTING POINT

13. CONFIRMATION TEST

.



HOW TO IDENTIFY A

Look at the sample. Is it transparent, translucent or opaque?

.

like?

Cut the sample with a sharp knife. Does it cut easily: Are the edge smooth or

jagged? Does it crumble or flake?

Subject the sample to a float test. Does it float or sink? (the test is invalid if

plastic foam. Wash with detergent solution initially to stop air bubbles adhering to

surface.)

Try to burn a small piece of sample. What is the size and colour of flame? Is

sample self-extinguishing? Is there any odour when flame has been extinguished?

SAFETY : Use only a small sample held with tongs or pliers. Hold sample over a

me a ray. cau ous y an no w en s gn e .



BENDING TEST ( WITH MOULDED BAR)

1. Polyethylene Bends, tends to remain

2. Polypropylene Unbends most of the way

3. Polystyrene Cracks but retains bend

4. ABS Bend tends to remain

.

back quickly

6. Cellulose acetate Bend tends to remain

7. PMMA Cracks and splinters

8. N lon Difficult to bend s rin s back

9. Polycarbonate Tough to bend



THERMOPLASTICS

VISUAL OBSERVATION TEST Low gloss easily be scratched by nail - LDPE OR LLDPE

High gloss can be scratched by nail - HDPE

-

DROPPING TEST

When a moulded component is dropped on hard surface

Metallic sound Dull sound

PS, HIPS Cellulosics

,PC, PP S PTFE,PMMA

PPO Polyacetal

Polysulphone PVC ,

Polyolefins



TEST TO DIFFERENTIATE

THERMOPLASTICS AND THERMOSETSCUTTING TESTS

a) If a shaving can be pared off with knife, it may be a

ermop as c.

Note:PMMA and Polystyrene are brittle and difficult to pare

b) If the material is rigid and will not pare off instead

flakes of powders, it may probably a thermoset plastic.

Heat an electronic soldering iron to red hot and press against

the unknown sample.

a e p as c ma er a so ens, an e ro pene ra esthe sample is thermoplastic.

b) If the plastic material does not soften and the rod does

not penetrate, the sample is thermoset plastic.



FLOTATION TESTWhen the material is dropped in water

loats Sinks

Polyolefins Other thanPolyolefins

o e: e po yo e ns an ce u ar oams are

exceptional for this test.

. .

Talk filled PP PVC , PU

Glass filled PP and PS foams



PYROLYSIS TESTHEAT THE SAMPLE IN AN IGNITION TUBE AND TEST THE PYROLYTIC VAPOUR WITH A MOISTENED INDICATOR PAPER.

ACID : TURNS BLUE LITMUS TO RED

: .

ACID VAPOURS

MAY COME FROM CARBOHYDRATE POLYMERS & THEIR DERIVATIVES . [E.G.,

CELLULOSE ACETATE]

OFTEN INDICATES THE PRESENCE OF CHLORINE . [E.G., PVC OR RUBBER NEUTRAL

VAPORS]

EVOLVED FROM HYDRO CARBON POLYMERS, SILICONES AND SOME POLYESTERS

HYDROCHLORIDE.

ALKALINE VAPOURS

INDICATE THE PRESENCE OF N2 . E.G., POLYAMIDE, PUs, PROTEINS & AMINO

FORMALDEHYDE RESINS.



BURNING CHARECTERISTICS OF

THERMOPLASTICS

S. No. Plastic Flame Kind of Melt Odour

Material Characteristics smoke behaviour

1. PE Blue base yellow tip No smoke Drips Waxysmell

2. PP Blue base and No smoke Dri s Lubricatin

yellow tip oil smell

3. PS Orange yellow Black soot No Merry gold

flame (Heavy smoke) dripping smell

4. HIPS -do -do -do- Burning rubber

smell

. - - - - - -

Note: ABS & HIPS can be differentiated by detection of Nitrogen by elemental analysis.

6. SAN -do- -do- -do- Merry gold

smell

Note: SAN & PS can be differentiated by detection of present of extra element Nitrogen.



S. No. Plastic Flame Kind of Melt Odour

Material Characteristics smoke behaviour

7. PVC Green edged flame emitting white burnt pungent

self extinguishing fume after edges smell

put off the charing of chlorine

flame

Note: A copper wire is heated to redness and the material is taken by the wire and ignited.

Bright green flame confirms presence of chlorine - PVC

8. Polyamides:

Nylon-6 Blue base yellow No smoke Burned face Burned

tip, spurting self bubbles and hair

extinguishing drips smell

Nylon-6,6 -do- -do- -do -do-

Nylon-6,10 -do- -do- -do- -do-

Nylon-11&12 -do- -do- -do- -do-

Note: The individual type of polyamides can be differentiated by melting temperature and

solubility.

Nylon 11 & 12 will not dissolve in formic acid at room temperature. But Nylon 11 will

dissolve in formic acid at elevated temperature.



S.No. Plastic Flame Kind of Melt Odour

Material Characteristics smoke behaviour9. Cellulose -do- -do- -do- Rancid

Butyrate or charred

milk smell

Cellulose Burns vi orousl Black Sublimation Cam er

Nitrate with bright yellow smoke like camper smell

10. Polyester (thermoplastics)

PBT & PET Orange yellow flame Sooty Drips Fruity

spurting, self flame smell of

extinguishing ester

.

11. PMMA Blue base yellow tip No smoke No driping Fruity

burns continuously but bubbling smell

on the burnt

surface

12. PC Orange yellow flame Black Burnt edge Phenolic

self extinguishing smoke chars smell

(Ink

13. POM Pale blue flame No smoke Driping Pungent burns continuously smell of

formaldehyde



14. PPS Orange yellow Black No Dripping H2S gas

flame self smoke but charring smell

extinguishing

15. PPO -do- -do- -do- Phenolic

Smell

Note: It can be differentiated with polycarbonate by pyroloising PPO, which emits brown gas

acidic in nature.

16. TPU

MDI based Blue base yellow No smoke Drips like Faint

smell

TDI based Yellow flame self Black Drips very -do-

resin extin uishin smoke fast

17. PTFE Does not burn No smoke No dripping Pungent

smell of HF

ote: en eate strong y ecomes transparent.



BURNING CHARECTERISTICS OF

S. No. Plastics Flame Kind of Odour

Material Characteristics smoke

1. PF Self extinguishing No Charcoal smell

2. UF -do- No Fishy smell

. - o- o - o-

Note: When the moulded component of all the three materials burn in the flame, the burnt surface

slightly swells and cracks.

4. Polyester Burns with orange Black Ester smell

(unsaturated) yellow flame burns smoke

continuously

. poxy - o- - o- arre our sme



BURNING CHARACTERISTICS OF

ELASTOMERS

S.No TYPE OF POLYMER COLOUR OF FLAME ODOUR OTHER NOTABLE

& KIND OF SMOKE CHARACTERISTICS

1 POLY BUTYLENE YELLOW, BLUE BASE DISAGREEABLE , CHARS READILY

SMOKY SWEET2 STYRENE - BUTADIENE BURNS CONTINUOUSLY PUNGENT SMELL OF CHARS , DRY

YELLOW SOOTY STYRENE POWDERY

3 EPDM NO SMOKE ,BLUE BASE WAXY SMELL DRY

YELLOW TIP POWDERY

4 N BR YELLOW SOOTY UNPLEASANT TACKY

5 BUTILE RUBBER (IIR) SMOKE FREE , CANDLE HYDROCARBON MELT &

LIKE SMELL TACKY

6 POLYISOPRENE (NR) YELLOW SOOTY PUNGENT LIKE CHARS &

7 POLYCHLOROPRENE (CR) SELF EXTINGUISHING PUNGENT SMELL STRONGLY

YELLOW & SMOKY OF CHLORIN ACIDIC

8 SILICONE RUBBER BURNS CONTINUOUSLY NO ODOUR DRY WHITE

9 EBONITE SMOKE FREE SULPHUR ODOUR CHARS

READILY



IDENTIFICATION BY PYROLYSIS TEST

• This scheme is useful for identification of CR , NBR , SBR , NR / IR , IIR

type of rubbers

• Test Procedure : Heat strongly 0.5gm of sample in a test tube until sample

begins to decompose and pass the fume in solution I and II and observe

change in colour initially and after heating.(Refer the following table)

SOLUTION - I : Dissolve one gram of p - dimethyl amino benzaldehyde in

5ml of HCl and add 10ml of ethylene glycol. Adjust the density to 0.851

gm /cc. By addition of methanol.

SOLUTION - II : Dissolve 2gm sodium citrate , 200mg of citric acid , 300mg

of bromocresol green and 300mg of metanil yellow in 500ml of water.



COLOUR REACTION WITH SOLUTION - I & II

RUBBER SOLUTION - I SOLUTION II

INITIAL AFTER HEATING

BLANK SOLUTION PALE YELLOW PALE YELLOW GREEN

GREEN

NBR ORANGE RED RED GREEN

SBR YELLOW GREEN GREEN GREEN

NR / IR BROWN VIOLET BLUE GREEN

I I R YELLOW PALE BLUE GREEN GREEN

DROPLET FLOATS



DETERMINATION OF SPECIFIC GRAVITY

PROCEDURE:

Weight of empty specific gravity bottle : a gm

+

Weight of the material + S. G. bottle + liquid: c gm

Weight of the S. G. Bottle + Liquid : d gm

Weight of the material (b-a) : e gm

Specific Gravity of the material : e x D

(e + d) - c

Where D - specific gravity of the liquid taken for testing

specific gravity of the material x 0.999 (gm/cc)



DENSITY & MELTING POINT OF PLASTICSS. NO. POLYMER ABBREVATION DENSITY MELTING

gm/cc POINT Deg. C

.

1. Low density Polyethylene LDPE 0.91 - 0.92 110

2. High density Polyethylene HDPE 0.94 - 0.96 130

3. Linear low density polyethylene LLDPE 0.91 - 0.93 125

4. High Molecule HDPE HMHDPE 0.94 - 0.97 135

5. Ultra High Molecular HDPE UHMHDPE 0.97 130

6. Polypropylene PP 0.89 - 0.91 160

.

1. Poly vinyl chloride PVC 1.38 - 1.41 160 - 220

2. Poly vinyledene chloride PVDC 1.65 - 1.75 190 - 200

3. Chlorinated PVC PVCC 1.44 - 1.47 200 - 210

4. Co-polymer of vinyl chloride & PVC Co VA 1.16 - 1.36 130

5. Poly vinyl Alcohol PVAI 1.21 - 1.32 218

6. Poly vinyl Acetate PVAc 1.17 - 1.26 175



III. FLUORINATED POLYMERS

1. Polyvinyl fluoride PVF 1.44 200

2. Poly vinyledene Fluoride PVDF 1.76 - 1.771 172

3. Poly chloro tri fluoro ethylene PCTFE 2.10 - 2.20 210

4. Poly Tetra Fluoro ethylene PTFE 2.10 - 2.30 320

IV. POLY STYRENE & CO-POLYMERS

1. Acrylonitrile-Butadiene styrene ABS 1.07 - 1.10 200 - 210

2. Styrene Acrylo nitrile SAN 1.06 200

3. Po ystyrene PS 1.04 - 1.07 190

V. POLYAMIDES

1. Nylon 6 PA 6 1.10 - 1.16 215

2. Nylon 66 PA66 1.09 - 1.14 265

. y on . - .

4. Nylon 12 PA12 1.01 - 1.02 180

5. N lon 6,10 PA6,10 1.07 - 1.09 210



VI. ACRYLIC POLYMERS

1. Polymethamethacrylate PMMA 1.17 - 1.20 190

2. Polyacrylonitrile PAN 1.16 - 1.19 -

.

1. Polyoxym,ethylene(homo) POM 1.43 175

2. Polyoxymethylene (Co) POM 1.41 163

VIII. ESTERS

. .

2. Poly ethylene terepthalate PET 1.37 255

3. Poly butylene terepthalate PBT 1.32 225

IX. POLYURETHANES

. . - . -



X. CELLULOSIC POLYMERS

1. Cellulose acetate CA 1.25 - 1.35 230

2. Cellulose acetate butyrate CAB 1.15 - 1.25 180

3. Cellulose noitrate CN 1.58 - 1.66 -

4. Cellulose propinate CP 1.20 - 1.24 -

XI. HEAT RESISTANCE POLYMERS

1. Poly phenylene oxide PPO 1.06 262

2. Poly phenylene sulphide PPS 1.35 290

3. Poly sulphone PSU 1.24 260

4. Poly imide PI 1.42 -

5. Poly ether ether ketone PEEK 1.27 335



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Lecture - 17 B - Identification_of_Plastics