design and study of ricinoleates as processing aids and activators in rubbers…
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Design and Study of Ricinoleates as processing aids and activators in rubbers…
What is RPA Any material used at relatively low dosage
levels, will improve processing characteristics without significantly affecting physical properties.
They also improve the physical properties such as,
Elasticity, Flex life, Low temp performance and, Aid in incorporation & dispersion of
pigments
RPA – main appc’s
RPA & its effects-
What is an Activator
- Increase the efficiency of cross-linking
- Help in dispersing the sulphur and accelerator
Driving- FACTOR
Conventional Processing aid, petroleum based Polycyclic Aromatic Hydrocarbons (PAH) has been banned in European countries at 2009.
Stearic acid (present as activator), is a saturated fatty acid obtained from animal fat.
Driving- FACTOR
Zn can be released into the environment from rubber during production, use, and recycling of rubber goods, particularly tyres.
Harmful effect of soluble Zn-compounds to aquatic organisms.
ZnO causes a mammalian reproductive toxinExposure to zinc oxide in the air, result in a nervous
malady called metal fume fever.ZnS deposited on the wall of the mold, causes mold
fouling.
Car photo
ZnO Reduction
AS FUTURE TECHNOLOGISTS, WE
OFFER YOU SOLUTIONS…
EXPERIMENT We have tried to reduce the ZnO by
using a combination of metal oxide (MgO & Ca(OH)2) of varying ratios, is mixed with CASTOR OIL under microwave heating at a set frequency (1.32GHz).
Composition of Castor OilAcid Name Average percentage Range
Ricinoleic acid 85 to 95%
Oleic acid 2 to 6%
Linoleic acid 1 to 5%
Linolenic acid 0.5 to 1%
Stearic acid 0.5 to 1%
Palmitic acid 0.5 to 1%
Dihydroxystearic acid 0.3 to 0.5%
Others 0.2 to 0.5%
Structure of Castor oilMono-unsaturated,
18 carbon fatty acid (esters of 12-
hydroxy-9-octadecenoicacid)
Contains Functional groups:
1.carboxylic group
2.unsaturation 3.hydroxy group
Why Castor Oil
Naturally obtained non-toxic Vegetable oilVegetable oil offers LubricityOther seed oils lack the HYDROXY GroupDue to this Hydroxy group- 1. Reactive 2. Offers xtra stability 3. High viscosity
Metal Oxide Varying ratiosCOMPOUND ZnO MgO Ca(OH)2
1 1 1 1
2 2 1 1
3 1 1 2
4 1 2 1
5 1 0 0
6 0 1 0
7 0 0 1
Blank Preparation
NRZnOstearic acidSulphurCBS
MATERIALS Parts by Weight
Natural Rubber 100
Zinc Oxide 3
Stearic Acid 2
Sulphur 2.5
Acc (CBS) 1
RX formulationMATERIALS Parts by Weight
Natural Rubber 100
Activator System 5
Sulphur 2.5
Acc (CBS) 1
Natural RubberActivatorSulphurAcc (CBS)
03.
756.
258.
75
11.2
5
13.7
50
102030405060708090
RHEOGRAPH
rxrx1rx2
Torq
ue
1600C for 20mins
1.75
5.25
8.75
12.2
5
15.7
5
19.2
50
1020304050607080
RHEOGRAPH
rx3rx4rx5
Torq
ue
1600C for 20mins
01.
755.
258.
75
12.2
5
15.7
5
19.2
50
5
10
15
20
25
30
35
RHEOGRAPH
rx6rx7
Torq
ue
Both RX6 and RX7 haven’t cured, so we neglected both the samples.
INFERENCE :
1600C for 20mins
COMPOUNDS Ts2 mins Tc90 mins
RX 1.04 4.15
RX1 1.27 2.45
RX2 1.44 2.70
RX3 2.06 3.11
RX4 1.52 2.58
RX5 1.54 2.69
RX6 0.00 0.00
RX7 0.47 0.47
Rheological Props (GUM cmpds)
INFERENCE : Scorch time is INCREASED, While Cure time is very much DECREASED
Tests for Gum cmpds :Hardness (ASTM D2240)Tensile Properties (ASTM D412)Tear Strength (ASTM D624)Aging properties (ASTM D573)
Hardness
0
10
20
30
40
50
60
Hardness
RX
RX1
RX2
RX3
RX4
RX5
COMPOUNDS HARDNESS (Shore A)
RX 58
RX1 18
RX2 25
RX3 16
RX4 16
RX5 32
INFERENCE : Hardness values found to decrease with our Activator compounds
COMPOUNDS TENSILE STRENGTH
MPa
RX 22.65
RX1 1.44
RX2 4.65
RX3 2.99
RX4 2.83
RX5 4.5
TENSILE STRENGTH
INFERENCE : T.S is very much lower
RXRX2
RX4
0
5
10
15
20
25
Column1
MAX Strain %
0
100
200
300
400
500
600
700
EB%
RX
RX1
RX2
RX3
RX4
RX5
COMPOUNDS Max Strain%
RX 436.5
RX1 558
RX2 587
RX3 573
RX4 615
RX5 489
INFERENCE : profound increase in STRAIN %
All our Activator Compounds exceeded above 600% elongation
COMPOUND 100% MOD 200% MOD 300% MOD
RX 1.97 3.71 15.97
RX1 0.84 1.24 3.24
RX2 0.44 0.74 1.04
RX3 0.57 0.76 1.14
RX4 0.58 0.78 1.07
RX5 1.53 2.38 5.12
MODULUS
MODULUS = Resistance to extension or stiffness
INFERENCE : Modulus was found to be low
Aging PropertiesCOMPOUND Tensile Strength MPa
R 15.4
RX1 0.3
RX2 2.8
RX3 1.1
RX4 1.02
RX5 2.6
Aging Condition- 700C for 7 days
Tear Strength (GUM cmpds)
COMPOUNDS TEAR STRENGTH (Kgf/mm)
RX 0.264
RX1 0.731
RX2 1.839
RX3 0.701
RX4 1.051
RX5 2.076
INFERENCE : Tear Strength usually higher for our Activator Cmpds
PC FormulationMATERIALS Parts by Weight
Nitrile Rubber, NBR
100
C-Black 50
Activator system 5
Sulphur 1.5
TMTD 1.5
CBS 1.5
Benchmarked with usual mixture,
ZnO - 3 phrSt Acid – 2 phr
Rheograph
1.75 3.5 5.25 7 8.75 10.50
20
40
60
80
100
120
140
PPC1PC2
Time (mins)
Torq
ue (
)lb
-in
)
1600C for 20mins
Rheograph
1.75 3.5 5.25 7 8.75 10.50
20
40
60
80
100
120
140
PC3PC4PC5
Time (mins)
Torq
ue (
)lb
-in
)1600C for 20mins
Rheological PropsCOMPOUNDS Ts2 mins Tc90 mins
P 1.03 11.00
PC1 1.15 1.54
PC2 1.21 2.33
PC3 3.07 6.05
PC4 1.13 3.13
PC5 1.37 3.34
INFERENCE : Scorch time is INCREASED, While Cure time is very much DECREASED
1600C for 20mins
Tests for C-B filled cmpds
HardnessTensile StrengthTear StrengthSwelling IndexCompression SetFlex Cracking Resistance
HardnessCOMPOUND HARDNESS (Shore A)
P 76
PC1 72
PC2 70
PC3 68
PC4 71
PC5 69
INFERENCE : Not much change in Hardness
Tensile StrengthCOMPOUND Tensile Strength
(Before aging) MPaTensile Strength (After aging) MPa
P 25.57 19.61
PC1 22.45 18.20
PC2 20.72 16.97
PC3 15.37 9.57
PC4 17.25 11.23
PC5 19.50 12.60
Aging Condition – 1000C for 22hr
INFERENCE : Tensile Strength is low But % retention of our activator cmpds is high
Tear StrengthCOMPOUND Tear Strength
(Before aging) N/mmTear Strength
(After aging) N/mm
P 7.07 3.61
PC1 15.78 9.11
PC2 18.83 15.62
PC3 9.48 4.54
PC4 11.25 8.05
PC5 14.14 10.15
Aging Condition – 1000C for 22hr
INFERENCE : Tear Strength and % Retention is HIGH for our activator compounds
Swelling IndexCOMPOUND SWELLING INDEX %
P 69
PC1 87
PC2 80
PC3 76
PC4 80
PC5 77
Swelling Index α 1 / Crosslink Density
Immersed in toluene for 7 days
SWELLING INDEX = (Ws – Wi)/Wi
Compression SetCOMPOUND Compression Set %
P 32
PC1 58
PC2 49
PC3 43
PC4 51
PC5 46
SET % = (t0 – tr) / (to - ts) × 100
INFERENCE : Set found to be lower as cross-link density is less
Flex Cracking resistanceSAMPLE No of cycles for Pin-Prick to
appear
P 1777
PC1 >1,00,000
PC2 15,796
PC3 2481
PC4 7596
PC5 5319
INFERENCE : profound increase in Flex-Cracking resistance
SummaryWith reduced viscosity, thereby reducing mix duration
with less mech generation of heat & energy consumption reqd to breakdown rubber.
Ease of handling as processing aids is in the form of pellets.
With increased scorch time(Ts2), better Processing safety.
With shorter curing cycles, we get faster productivity.The physical props of C-B filled cmpds was similar to the
control, but this was not the case in GUM cmpds.
Coupling action of Veg. oil
Interacts with Rubber molecules
Interacts with C-Black asits surface contains Phenol,Carboxyl, Quinone & Lactones
Why MgO & Ca(OH)2
These were the acid acceptors playing a dual role :
1. Neutralization of acid-byproducts of vulcanization and;
2. Act as cross-linking agents forming weak ionic bonds.
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