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transcript
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2012 Bohn 1
© Fraunhofer ICT, Pfinztal, Germany
Characterization of ageing of NC based gun propellants by molar
mass degradation of nitrocellulose and its modelling by random
chain scission models
Dr. Manfred A. Bohn
Fraunhofer-Institut fuer Chemische Technologie, ICT
Pfinztal, Germany
Presentation on the
NDIA Insensitive Munitions and Energetic Materials Technology Symposium
Event # 2550 May 14-17, 2012
Las Vegas, Nevada, USA
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2012 Bohn 2
© Fraunhofer ICT, Pfinztal, Germany
Motivations and Objectives
Nitrocellulose (NC) is an important ingredient in gun and rocket propellants, also in recently
developed ones, having improved IM characteristics, as the DNDA-RDX-NC based GP from
Fraunhofer ICT /1, 2/ or the ECLTM series of Nitrochemie Wimmis.
This means NC has properties which are not reached by other energetic binders up today.
Nitrocellulose decomposes slowly intrinsically and after some induction time also
autocatalytically, because of low kinetic energy barriers
The autocatalytic decomposition can be supressed by stabilizers, but not the intrinsic one
The intrinsic decomposition of NC leads to scissioning of the NC chains, expressed as
decrease in mean molar masses with time-temperature load
Chain scissioning of NC is accomponied by NOx formation, which consumes stabilizers
The chain scissioning is very sensitive to decompostion: already decomposing of one chain
element leads to roughly half of the original chain length
With decrease of chain length the mechanical strength of NC products is reduced
Therefore: Determination of NC chain degradation is a sensitive monitoring for NC products
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2012 Bohn 3
© Fraunhofer ICT, Pfinztal, Germany
Determination of NC chain length degradation
NC STANAG: STANAG 4178 “Assessing the Quality of Nitrocellulose Deliveries from
one NATO Nation to Another”, Edition 2 /8/.
Generally the chain length degradation of a polymer is best determined by GPC (Gel Permeation
Chromatogrphy) also called SEC (Size Exclusion Chromatography)
This is the case also with NC.
At ICT this method was introduced in the early 1980s and several publications have been
published on the early results and on later work /3, 4, 5, 6/.
Also at Nitrochemie Wimmis (NCW) the GPC method was introduced at the same time and
some early RR on GPC have been performed between ICT and NCW. End of the 1990 AWE has
started a lot of GPC work on NC and HMX bonded by NC /7/.
With time the importance of this method was increasingly recognized and finally found its
expression in the implementation of the GPC method in the recently updated NC-STANAG.
For this an applicable method was worked out and especially adapted for analysing NC
by collaboration between: AWE, Univ. Cranfield-Shrivenham, Fraunhofer ICT, Nitrochemie
Wimmis, TNO-Rijswijk /9, 10, 11, 12/.
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2012 Bohn 4
© Fraunhofer ICT, Pfinztal, Germany
How to use GPC results on NC degradation
First, one gets the elugramme of the size-separated NC chains, means a frequency distribution
of chain length versus retention volume Ve.
This elugramme is tranformed to a molar mass distribution function (MMD), by use of a
calibration function between retention volume Ve and molar mass M of a calibration substance.
Then the characteristic quantities of this molar mass distribution (MMD) are calculated:
Mean molar masses Mn, Mw, Mz and polydisperity D = Mw/Mn
Mn: averageing done by polymer fractional mol number to weigh the fractions
Mw: averageing done by polymer fractional mass to weigh the fractions
Mz: averageing done by polymer fractional z-weight to weigh the fractions
Mp: molar mass at peak maximum of the MMD
These data can be established as function of ageing of NC or the NC in a propellant respectively.
Here the degradation of NC in the triple base gun propellant Q5560 (19 hole, 27mm maschine
gun) is presented.
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2012 Bohn 5
© Fraunhofer ICT, Pfinztal, Germany
Not only NC polymer chain degradation....
Random chain scissioning of polymer chains is widespread.
Hydrolysis of polymeric esters
Attack on thermoplastic elastomers by ‘aggressive’ substances as
ADN, HNF, nitric acid plasticizers as nitroglycerine, TMETN, BTTN, NENA,..
Attack on binders as GAP and HTPB by CL-20, RDX,...
Polyvinylnitrate (PVN)
...... M.A. Bohn, J. Aniol, M. Dörich, K. Hartlieb, H. Pontius
Stability, Ageing and Usetime Prediction of Polyvinylnitrate (PVN).
Paper 73, pages 73-1 to 73-18 in Proceedings of the 37th International Annual Conference of ICT 2006, June
27 to 30, 2006, Karlsruhe,Germany. Fraunhofer-Institut für Chemische Technologie (ICT), D-76318 Pfinztal.
Bohn M.A., Dörich M., Aniol J., Pontius H., Kempa P.B., Thome V.
Reactivity between -CL20 and GAP in Comparison to -HMX and GAP.
Paper 4, pages 4-1 to 4-30, in Proceedings of the 35th International Annual Conference of ICT, June 29 to July
2, 2004, Karlsruhe, Germany. Fraunhofer-Institut für Chemische Technologie (ICT), D-76318 Pfinztal-
Berghausen, Germany.
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2012 Bohn 6
© Fraunhofer ICT, Pfinztal, Germany
Mean molar masses Mn, Mw, Mz and MMD-peak Mp as function of ageing
degradation of NC in GP Q5560
ageing at 90°C
0
200000
400000
600000
800000
1000000
1200000
1400000
0 5 10 15 20 25 30 35 40
ageing time [d]
Mi [g/mol]
0
1
2
3
4
5
6
D [-]
Mn [g/mol]
Mw [g/mol]
Mz [g/mol]
Mp [g/mol]
D
Mw
Mz
D
Mp, M at peak
Results for the NC degradation in gun propellant Q5560, 27 mm, triple base
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2012 Bohn 7
© Fraunhofer ICT, Pfinztal, Germany
Relative mean molar masses and MMD-peak Mp as function of ageing
GP Q5560
aged at 90°C
relative degradation of mean molar masses, Mn, Mw, Mz
and of MMD peak molar mass Mp
0
0.2
0.4
0.6
0.8
1
1.2
0 3 6 9 12 15 18 21 24 27 30 33 36 39
ageing time [d]
Mx(t)/Mx(0) [-]
Mn(t)/Mn(0)
Mw(t)/Mw(0)
Mz(t)/Mz(0)
Mp(t)/Mp(0)
If the data are measured and evaluated well, all the mean molar masses nearly coincide in relative
representation /8, 9, 10, 11, 12/.
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2012 Bohn 8
© Fraunhofer ICT, Pfinztal, Germany
Use of GPC results
Determine NC degradation as function of time and temperature
90°C, 80°C, 70°C, 60°C,…
Which ageing times can be chosen – orientaion can be obtained from:
time temperature loads given in AOP 48, which are adapted for NC-based materials
generalized van’t Hoff extrapolation /15/
own ageing experience
ageing times chosen for basic investigations
literature data
Time-temperature data can be kinetically parameterized, with NC-based material by
Arrhenius
Generalized van‘t Hoff (GvH)
Necessary for this is the determination of rate constants
H GvH pre-factor
FT scaling factor with regard to chosen T
T temperature
T temperature scaling interval, mostly 10°C
Z expon. pre-factor
exp Euler number e
T temperature (absolute)
Ea activation energy
R general gas constant
T/T
TGvH FH)T(k
RT/EaexpZ)T(k Arrh
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2012 Bohn 9
© Fraunhofer ICT, Pfinztal, Germany
Description of two-step ageing of NC based material with GvH
This two step mechanism for NC-based materials is included in STANAG 4582 and AOP 48, Ed. 2 /13, 14/
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2012 Bohn 10
© Fraunhofer ICT, Pfinztal, Germany
Description of two step mechanism by two Arrhenius rate constants
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2012 Bohn 11
© Fraunhofer ICT, Pfinztal, Germany
Description of two step mechanism by generalized van’t Hoff (see /15/)
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2012 Bohn 12
© Fraunhofer ICT, Pfinztal, Germany
Choosing the type of temperature parameterization
The scission process is chemically based
Arrhenius behaviour can be expected for the rate constants.
If intrinsic dual mechanistic behaviour occurs, as it is assumed with NC-based materials
(see AOP 48 and STANAG 4582), then the generalized van’t Hoff parameterization is of
advantage /15/.
Manfred A. Bohn
Prediction of equivalent time-temperature loads for accelerated ageing to simulate preset in-storage ageing
and time-temperature profile loads.
Paper 78, pages 78-1 to 78-28 in Proceedings of the 40th International Annual Conference of ICT on
‘Energetic Materials – Characterization, Modelling, Validation’, June 23 to 26, 2009, Karlsruhe, Germany.
ISSN 0722-4087.
Fraunhofer-Institut für Chemische Technologie (ICT), D-76318 Pfinztal-Berghausen. Germany.
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2012 Bohn 13
© Fraunhofer ICT, Pfinztal, Germany
Kinetic models to describe NC chain scission and molar mass degradation
Model based on random chain scission (CS) by bond scission between chain elements (BS)
no material is lost, no mass loss; model CS-BS
Model based on random chain scission (CS) by chain element decomposition (ED)
material is lost, mass loss occurs; model CS-ED
Model based on random chain scission (CS) by bond scission between chain elements (BS)
and recombination of chains (CR)
no material is lost, no mass loss; model CS-BS with CR
Model based on random chain scission (CS) by chain element decomposition (ED)
and recombination of chains (CR)
material is lost, mass loss occurs; model CS-ED with CR
The model must be able to describe the whole course of Mx = f(t) as precise as possible
The model should have a true kinetic base, developed from the type of scission process of
NC chains
Only this ensures a correct extrapolation
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2012 Bohn 14
© Fraunhofer ICT, Pfinztal, Germany
Which molar mass is the right one for the kinetic description of chain
degradation in polymers
Kinetic processes in chemistry describe reaction of atoms or molecules and between them.
The adequate quantity followed is a concentration, means ‘particle’ number per any unit
(volume, mass,…)
Conclusion
The right mean molar mass is the one which ‘counts’ particles, means which is based on mol
numbers – this is Mn
So the models are formulated with Mn, which is the center of gravity molar mass of the
distribution function hn, the fractional mol number related MMD
Remark:
With RI and UV detectors the distribution function hm is determined, the fractional mass
related MMD;
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2012 Bohn 15
© Fraunhofer ICT, Pfinztal, Germany
Use of kinetic modelling to get rate constants
degradation of NC in GP Q5560 at 90°C
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
110000
120000
130000
0 5 10 15 20 25 30 35 40
ageing time [d]
Mn [g/mol]
0
1
2
3
4
5
6D [-]
Mn [g/mol]
D
The Mn data obtained from the MMD of NC in GP Q5560 are used for modelling
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2012 Bohn 16
© Fraunhofer ICT, Pfinztal, Germany
Elugrammes of the NC degradation of GP Q5560, obtained by RI detection
Concentration related elugrammes of the NC of GP Q5560, obtained by referactive index (RI) detection
to maximum normalized elugrams
NC of Q5560
ageing at 90°C
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
9.5 10 10.5 11 11.5 12 12.5 13 13.5 14 14.5 15 15.5 16 16.5
Ve [ml]
RI [aU]
unaged
2d-1
8d-1
16d-1
28d-1
35d-1
zero
unaged
2d
8d
16d28d
35d
Low molar mass
end, increase of
concentration by
ageing of the NC
in the GP
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2012 Bohn 17
© Fraunhofer ICT, Pfinztal, Germany
Area normalized molar mass distributions hm of NC degradation
Frequency
distribution of
the fractional
polymer parts
as function of
molar mass
molar mass distribution of NC of Q5560
polymer fraction mass related
ageing at 90°C
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07
M [g/mol]
hm(lgM)unaged
2d
5d
8d
12d
16d
22d
28d
35dunaged
2d
5d
12d
8d35d
28d
22d
16d
Low molar mass
end, increase of
frequency by
ageing of the NC
in the GP
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2012 Bohn 18
© Fraunhofer ICT, Pfinztal, Germany
Model with chain scission by bond splitting between chain elements
B(t): number of bonds between chain elements in polymer sample
Nm(t): number of chain elements in the polymer sample
nc(t) number of polymer chains in the sample, nc(t) = Nm(t) / (Mn(t)/m)
Mn(t) mol number averaged mean molar mass
m molar mass of one chain element of the polymer
t)T(kexp)0(B)T,t(B 1B )t(Bkdt
)t(dnc1B
Model set-up
Formation rate of new chains is proportional to the present number bonds B(t) between
chain elements Nm(t).
Splitting of one bond splits a chain. This process is of first order.
The number of bonds B(t) decreases to reaction of first order. The number of chain
elements stays constant. No mass loss.
1tkexp)0(Mn
m
tkexp
m
)t(Mn
1B
1B
Model CS-BS See also /18/
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2012 Bohn 19
© Fraunhofer ICT, Pfinztal, Germany
Model with chain splitting by chain element decomposition
B(t): number of bonds between chain elements in polymer sample
Nm(t): number of chain elements in the polymer sample
nc(t) number of polymer chains in the sample, nc(t) = Nm(t) / (Mn(t)/m)
Mn(t) mol number averaged mean molar mass
m molar mass of one chain element of the polymer
t)T(kexp)0(N)T,t(N 1M
Model set-up
Formation rate of new chains is proportional to the present number of chain elements Nm(t).
Destruction of one chain element splits a chain. This process is of first order. Number of
chain elements decrease steadily. Mass loss occurs.See also /7, 8/
)t(Nmkdt
)t(dnc1M
tkexp1)0(Mn
m
tkexp
m
)t(Mn
1M
1M
First derived by Norbert
Eisenreich at Fraunhofer ICT in
the 1980s
See also /16, 17, 18/
Model CS-ED
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2012 Bohn 20
© Fraunhofer ICT, Pfinztal, Germany
Results: model with chain element decomposition: Q5560 at 90°C
The description
with model CS-
ED (or CS-BS) is
not satisfying.
The description
must be done in
two steps, to get
adequate
modelling.
—————
2012 Bohn 21
© Fraunhofer ICT, Pfinztal, Germany
Results: model with chain element decomposition: Q5560 at 80°C
The description
with model CS-ED
(or CS-BS) is not
satisfying.
The description
must be done in
two steps, to get
adequate
modelling.
—————
2012 Bohn 22
© Fraunhofer ICT, Pfinztal, Germany
Model chain splitting by bond scission with chain recombination - kB2(n(t)-n(0))
Model set-up
1. Formation rate of new chains is proportional to the present number of bonds B(t) between
chain elements Nm(t).
Splitting of one bond splits a chain. This process is of first order.
The number of bonds B(t) decreases to reaction of first order. The number of chain
elements stays constant. No mass loss.
2. The loss rate of chains is proportional to the number of chains n(t)-n(0) already formed.
The active ends arising by splitting are radicals and attack the reservoir of chains.
The second reactant of this bimolecular reaction is nearly constant and is included in the
reaction rate constant kB2
)0(n)t(nck)t(Bkdt
)t(dnc2B1B
t)kk(exp1kk
)0(Mn
mkk
t)kk(exp)0(Mn
m
1
m
)t(Mn
2B1B2B1B
2B1B
2B1B
)0(Mn
mkk
kkm)te(Mn
2B1B
2B1B
Model CS-BS with CR
Mn(te) =plateau value in
Mn at t versus ; Note:
Mn(te,T) is T-dependent
via the kB1(T) and kB2(T)
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2012 Bohn 23
© Fraunhofer ICT, Pfinztal, Germany
Model chain splitting by element decomposition with chain recombination- kM2(n(t)-
n(0))
Model set-up
1. Formation rate of new chains is proportional to the present number of chain elements Nm(t).
Destruction of one chain element splits a chain. This process is of first order.
The number of chain elements decrease steadily. Mass loss occurs.
2. The loss rate of chains is proportional to the number of chains newly formed already, n(t)-n(0).
The active ends arising are radicals and attack the great reservoir of chains. The second
reactant of this bimolecular reaction is nearly constant (in initial conversion range) and is
included in the reaction rate constant kM2.
)0(n)t(nck)t(Nmkdt
)t(dnc2M1M
1)tkexp()0(Mn
mtkkexp1
kk
k
)0(Mn
m
tkkexp
m
)t(Mn
2M2M1M2M1M
1M
2M1M
t)T(kexp)0(N)T,t(N 1M
Model CS-ED with CR
Mn(te,T) = 0 at t versus at every T
Means all chain elements will be decomposed
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2012 Bohn 24
© Fraunhofer ICT, Pfinztal, Germany
Comparison of models: CS-BS versus CS-BS with CR
comparison
model CS-BS: chain splitting (CS) by bond scission (BS)
model CS-BS with CR-kB2*(n(t)-n(0)): CS with chain recombination
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160 180 200
time [d]
Mn(t)/Mn(0)
0
0.2
0.4
0.6
0.8
1
1.2
B(t)/B(0)
Mn(t)/Mn(0) kb1 kb2
Mn(t)/Mn(0) kb1
B(t)/B(0) kb1 kb2
B(t)/B(0) kb1
kB1 = 9.0 E-5 1/d
kB2 = 5.0 E-3 1/d
m = 279.96 g/mol
Mn(0) = 112548 g/mol
—————
2012 Bohn 25
© Fraunhofer ICT, Pfinztal, Germany
Comparison of models: CS-ED versus CS-ED with CR
comparison
model CS-ED: chain splitting (CS) by chain element decomposition (ED)
model CS-ED with CR-kM2*(n(t)-n(0)): CS with chain recombination
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160 180 200
time [d]
Mn(t)/Mn(0)
0
0.2
0.4
0.6
0.8
1
1.2
Nm(t)/Nm(0)
B(t)/B(0)
Mn(t)/Mn(0) km1 km2
Mn(t)/Mn(0) km1
B(t)/B(0) km1 km2
Nm(t)/Nm(0) km1
kM1 = 9.0 E-5 1/d
kM2 = 5.0 E-3 1/d
m = 279.96 g/mol
Mn(0) = 112548 g/mol
—————
2012 Bohn 26
© Fraunhofer ICT, Pfinztal, Germany
Comparison of models: CS-BS with CR versus CS-BS with CR
comparison
model CS-BS with CR-kB2*(n(t)-n(0)): CS by bond sicission and chain recombination
model CS-ED with CR-kM2*(n(t)-n(0)): CS by element decomposition and chain recombination
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160 180 200
time [d]
Mn(t)/Mn(0)
0.5
0.6
0.7
0.8
0.9
1
1.1
B(t)/B(0)
Nm(t)/Nm(0)
Mn(t)/Mn(0) kb1 kb2
Mn(t)/Mn(0) km1 km2
B(t)/B(0) kb1 kb2
B(t)/B(0) km1 km2
Nm(t)/Nm(0) km1kB1 = kM1= 9.0 E-5 1/d
kB2 = kM2 = 5.0 E-3 1/d
m = 279.96 g/mol
Mn(0) = 112548 g/mol
—————
2012 Bohn 27
© Fraunhofer ICT, Pfinztal, Germany
In T-scan: Comparison of models: CS-BS versus CS-BS with CR
comparison in T-scanning mode
model CS-BS
model CS-BS and CR with CR-kB2*(n(t)-n(0))
-0.15
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
20 50 80 110 140 170 200 230
T [°C]
Mn(t)/Mn(0)
Mn(te)/Mn)0)
-0.15
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
B(t)/B(0)
Mn(t)/Mn(0) kb1
Mn(t)/Mn(0) kb1 kb2
Mn(te)/Mn(0)
zero
B(t)/B(0) kb1
B(t)/B(0) kb1 kb2
m = 279.96 g/mol
Mn(0) = 112548 g/mol
kB1
ZB1 = 8.0 E+14 1/d
EaB1 = 133 kJ/mol
kB2
ZB2 = 8.0 E+10 1/d
EaB2 = 87 kJ/mol
T0 = 25°C
h = 0.6 °C/d
—————
2012 Bohn 28
© Fraunhofer ICT, Pfinztal, Germany
In T-scan: Comparison of models: CS-ED versus CS-ED with CR
comparison in T-scanning mode
model CS-ED
model CS-ED and CR with CR-kM2*(n(t)-n(0))
-0.15
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
20 50 80 110 140 170 200 230
T [°C]
Mn(t)/Mn(0)
-0.15
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
Nm(t)/Nm(0)
B(t)/B(0)
Mn(t)/Mn(0) km1
Mn(t)/Mn(0) km1 km2
zero
N(t)/N(0) km1
B(t)/B(0) km1 km2
m = 279.96 g/mol
Mn(0) = 112548 g/mol
kM1
ZM1 = 8.0 E+14 1/d
EaM1 = 133 kJ/mol
kM2
ZM2 = 8.0 E+10 1/d
EaM2 = 87 kJ/mol
T0 = 25°C
h =0.6 °C/d
—————
2012 Bohn 29
© Fraunhofer ICT, Pfinztal, Germany
In T-scan: Comparison of models: CS-BS with CR versus CS-BS with CR
comparison in T-scanning mode
model CS-ED
model CS-BS
model CS-ED and CR with CR-kM2*(n(t)-n(0))
model CS-BS and CR with CR-kB2*(n(t)-n(0))
-0.15
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
20 50 80 110 140 170 200 230
T [°C]
Mn(t)/Mn(0)
-0.15
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
Nm(t)/Nm(0)
B(t)/B(0)
Mn(t)/Mn(0) km1Mn(t)/Mn(0) kb1Mn(t)/Mn(0) km1 km2Mn(t)/Mn(0) kb1 kb2zeroN(t)/N(0) km1B(t)/B(0) km1 km2B(t)/B(0) kb1 kb2
m = 279.96 g/mol
Mn(0) = 112548 g/mol
kM1 / kB1
Z1 = 8.0 E+14 1/d
Ea1 = 133 kJ/mol
kM2 / kB2
Z2 = 8.0 E+10 1/d
Ea2 = 87 kJ/mol
T0 = 25°C
h =0.6 °C/d
—————
2012 Bohn 30
© Fraunhofer ICT, Pfinztal, Germany
Results: Description of data by model CS-ED with CR
The description
with model CS-
ED with CR is
now satisfying.
—————
2012 Bohn 31
© Fraunhofer ICT, Pfinztal, Germany
Results: Description of data by model CS-BS with CR
Also the
description with
model CS-BS
with CR is now
satisfying.
At isothermal
conversions not
to high both
models are nearly
equal in
descrption
quality.
But from
mechanistic point
of view model
CS-ED with CR is
the right one
—————
2012 Bohn 32
© Fraunhofer ICT, Pfinztal, Germany
Comparison: chain scission alone versus scission and recombination
GP Q5560
aged at 90°C
NC degradation
0
0.2
0.4
0.6
0.8
1
1.2
0 10 20 30 40 50 60 70 80 90 100 110 120
ageing time [d]
Mn(t)/Mn(0) [-]
0
0.2
0.4
0.6
0.8
1
1.2Nm(t)/Nm(0) [-]
Mn(t)/Mn(0)-1k
Mn(t)/Mn(0)-2k
Mn(t)/Mn(0)-exp
Mn(te)r
Nm(t)/Nm(0)
decrease of chain elements
Nm(t)/Nm(0)
decrease of Mn, one k
experimental data decrease of Mn, two k,
leveling to Mn(te)Mn(te)/Mn(0)
Correct description is achieved with model CS-ED with CR;
illustration here done with model CS-BS with CR in order to get the value for Mn(te) at t →
—————
2012 Bohn 33
© Fraunhofer ICT, Pfinztal, Germany
Summary and Conclusions
Decrease of NC chain length is a very sensitive probing of ageing of NC based materials
Decrease of chain length of polymers can be well determined by GPC (also named SEC)
The chain degradation of NC is expressed in decrease of the mean molar masses
To use the data, suitable modelling is applied to extract the rate constants of the
degradation process
Models using chain splitting by chain element decomposition are nearest to the reality of the
splitting process for NC
With NC it seems that besides chain splitting also recombination of chains occur.
Best model for NC: chain splitting by chain element decomposition with recombination of
chains
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2012 Bohn 34
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Acknowledgement
To my colleague Dr. Norbert Eisenreich
For the development of the model ‘chain splitting by chain element decomposition’
in the early 1980s.
For always helpful discussions in set-up and handling of kinetic models.
To my colleagues in the ‘stability group’ at ICT
providing me with measurement results of high quality:
Manuela Doerich, Heike Pontius
Kerstin Wimmer, Monika Raab, Juergen Hickmann
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References – part 1 of 3
1/ M.A. Bohn, D. Mueller Insensitivity aspects of NC bonded and DNDA plasticizer containing gun propellants
2006 Insensitive Munitions & Energetic Materials Technology Symposium, April 24-28, 2006, Bristol, UK. /2/ D. Mueller, M.A. Bohn, W. Langlotz
LTC propellants based on DNDA plasticizer.
Paper on the 33rd International Pyrotechnics Seminar July 16 to 21, 2006, Fort Collins, Colorado, USA. Organized and proceedings by International Pyrotechnics Seminar USA, Inc. and the International Pyrotechnics Society.
/3/ M. A. Bohn, F. Volk.
Aging Behavior of Propellants investigated by heat generation, stabilizer consumption, and molar mass degradation.
Propellants, Explosives, Pyrotechnics, 17, 4 (1992) 171 – 178. /4/ F. Volk, M.A. Bohn, G. Wunsch.
Determination of chemical and mechanical properties of double base propellants during aging.
Propellants, Explosives, Pyrotechnics, 12 (1987) 81 – 87.
/5/ M.A. Bohn The Use of Kinetic Equations to Evaluate the Ageing Behaviour of Energetic Materials – Possible Problems.
Proceed. 11th Symp. on ‘Chemical Problems Connected with the Stability of Explosives’ (held in Båstad, May 24 to 28, 1998),
pages 89-151. Editor: Jan Hansson, Ola Listh. 1999, Sundbyberg, Sweden. /6/ M.A. Bohn, J. Aniol, M. Dörich, K. Hartlieb, H. Pontius Stability, Ageing and Usetime Prediction of Polyvinylnitrate (PVN).
Paper 73, pages 73-1 to 73-18, in Proceedings of the 37th International Annual Conference of ICT, June 27 to 30, 2006, Karlsruhe,Germany. Fraunhofer-Institut für Chemische Technologie (Fraunhofer ICT), D76318 Pfinztal, Germany.
/7/ C. L. Bauer, P. R. Deacon, R. N. Garman, A. M. Emsley, J. R. Jones.
Low Temperature Non-Isothermal Aging of Nitrocellulose.
Propellants, Explosives, Pyrotechnics 30 (2005), No. 3.
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References – part 2 of 3 /8/ GPC method described in
STANAG 4178 “Assessing the Quality of Nitrocellulose Deliveries from one NATO Nation to Another”, Edition 2.
/9/ H. Pontius, M. Dörich, M.A. Bohn. Gel permeation chromatography of nitrocellulose (NC) and NC containing substances.- I. Parameter study for preparation of NC
solutions and chromatogram evaluation.
Paper 69, Pages 69-1 to 69-15, in Proceedings of the 39th International Annual Conference of ICT, ‘Energetic Materials – Processing and Product Design’, June 24 to 27, 2008, Karlsruhe, Germany. ISSN 0722-4087. Fraunhofer-Institut für Chemische
Technologie (ICT), D-76318 Pfinztal-Berghausen. Germany. /10/ Manfred A. Bohn.
Gel permeation chromatography of nitrocellulose (NC) and NC containing substances. - II. Remarks on calibration, molar mass distributions and mean molar masses.
Paper 70, pages 70-1 to 70-22, in Proceedings of the 39th International Annual Conference of ICT on ‘Energetic Materials –
Processing and Product Design’, June 24 to 27, 2008, Karlsruhe, Germany. Fraunhofer-Institut für Chemische Technologie (ICT), D-76318 Pfinztal-Berghausen, Germany.
/11/ Heike Pontius, Manuela Dörich, Manfred A. Bohn. Gel permeation chromatography of nitrocellulose (NC) and NC containing substances. - III. Recent results from a continued parameter study on the GPC of NC samples.
Paper 80, pages 80-1 to 80-12 in Proceedings of the 40th International Annual Conference of ICT on ‘Energetic Materials – Characterization, Modelling, Validation’, June 23 to 26, 2009, Karlsruhe, Germany. ISSN 0722-4087. Fraunhofer-Institut für Chemische Technologie (ICT), D-76318 Pfinztal-Berghausen. Germany.
/12/ P. Deacon, A. Macdonald, P. Gill, N. Mai, M.A. Bohn, H. Pontius, M. Van Hulst, W. de Klerk, C. Baker
An update on the Round Robin test to evaluate the nitrocellulose SEC method in STANAG 4178 (Ed.2).
Paper 81 in Proceedings of the International Annual Conference of ICT, 2009, Karlsruhe, Germany. /13/ NATO Standardization Agreement (NATO STANAG) 4582 ‘Explosives, Nitrocellulose Based Propellants, Stability Test
Procedure and Requirements Using Heat Flow Calorimetry’
Military Agency for Standardization, NATO Headquarters, Brussels, Belgium.
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References – part 3 of 3
/14/ NATO Allied Ordnance Publication (NATO AOP) 48, edition 2
Explosives, Nitrocellulose-based Propellants, Stability Test Procedures and Requirements Using Stabilizer Depletion.
Military Agency for Standardisation, NATO Headquarters, 1110 Brussels, Belgium.
/15/ Manfred A. Bohn Prediction of equivalent time-temperature loads for accelerated ageing to simulate preset in-storage ageing and time-temperature profile loads.
Paper 78, pages 78-1 to 78-28 in Proceedings of the 40th International Annual Conference of ICT on ‘Energetic Materials – Characterization, Modelling, Validation’, June 23 to 26, 2009, Karlsruhe, Germany. ISSN 0722-4087. Fraunhofer-Institut für Chemische Technologie (ICT), D-76318 Pfinztal-Berghausen. Germany.
/16/ A. Pfeil, H. H. Krause, N. Eisenreich.
The Consequences of Beginning Slow Thermal Decomposition of the Molecular Weight of Nitrated Cellulose.
Thermochim. Acta, 1985, 85, 395. /17/ N. Eisenreich and A. Pfeil.
Non-linear least-squares fit of non-isothermal thermoanalytical curves: Reinvestigation of the kinetics of the autocatalytic decomposition of nitrated cellulose.
Thermochim. Acta 61 (1983) 1 – 13.
/18/ Manfred A. Bohn und Norbert Eisenreich.
Kinetic modelling of the change of molar mass distribution function of nitrocellulose during ageing.
Paper 86, pages 86-1 to 86-24 in Proceed. of 41th International Annual Conference of ICT on ‘Energetic Materials – High Performance, Insensitive Munitions, Zero Pollution’, June 29 to July 2, 2010, Karlsruhe, Germany. ISSN 0722-4087. Fraunhofer-Institut für Chemische Technologie (ICT), D-76318 Pfinztal-Berghausen. Germany.
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Thank you for your attention
Questions ?