The effect of alkanolamide loading on properties of carbon black- lled natural rubber (SMR-L), epoxidised natural rubber fi (ENR), and styrene-butadiene rubber (SBR) compounds
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The effect of alkanolamide loading on properties of carbon black-filled natural rubber (SMR-L), epoxidised natural rub.pdf
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Date: 2017-12-06 08:26 UTC
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Polymer Testing 42 (2015) 208e2 Contents lists available at ScienceDirect
Polymer Testing
j o u h r o n m a w e l w p a w g . c e e o : l m s / e l v o i c e a r t . e / p o l y t e s t
Material properties The effect of alkanolamide loading on properties of carbon black- lled natural rubber (SMR-L), epoxidised natural rubber
fi (ENR), and styrene-butadiene rubber (SBR) compounds
a b b
- ,
Indra Surya , H. Ismail , A.R. Azura a
On study leave from Department of Chemical Engineering, Engineering Faculty, University of Sumatera Utara, Medan, 20155, Sumatera Utara, Indonesia
b
School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal, 14300, Penang, Malaysia
a e i r n t a f i b o c s l t r a c t
Article history: The effect of Alkanolamide (ALK) loading on properties on three different types of carbon
Received 14 November 2014 black (CB)- lled rubbers (SMR-L, ENR-25, and SBR) was investigated. The ALK loadings fi
Accepted 23 December 2014 were 1.0, 3.0, 5.0 and 7.0 phr. It was found that ALK gave cure enhancement, better ller fi
Available online 20 January 2015 dispersion and greater rubber ller interaction. ALK also enhanced modulus, hardness, efi resilience and tensile strength, especially up to 5.0 phr of loading in SMR-L and SBR
Keywords: compounds, and at 1.0 phr in ENR-25 compound. Scanning electron microscopy (SEM) Alkanolamide proved that each optimum ALK loading exhibited the greatest matrix tearing line and Carbon black surface roughness due to better rubber - ller interaction.
fi Filler dispersion
© 2015 Elsevier Ltd. All rights reserved. Rubber - ller Interaction
fi Plasticiser
1. Introduction modulus and hardness. The enhancement of these prop- erties was attributed to the improvement of silica disper- In the rubber industry, it is very common to utilise sion in the rubber compounds, and excellent crosslink reinforcing llers to achieve rubber end products with a density that stemmed from the incorporation of ALK. The
fi satisfactory level of strength or service life [1] . Carbon black results also indicated that ALK could function as an accel- (CB) and silica are the most popular reinforcing llers for erator and internal plasticiser.
fi rubbers, and have been widely utilised. CB is commonly A further study on the comparison of effect of ALK and utilised for producing black rubber products, while silica is APTES-silane coupling agents on the properties of silica- used in coloured products. Sometimes, they are also uti- [4] . Due to its
filled NR compounds was also reported lised in combination form (as hybrid ller) for the purpose combined and unique function as an accelerator and in- fi of achieving their synergistic effect in order to produce ternal plasticizer, at a similar loading, ALK produced a better overall mechanical properties [2] . higher reinforcing ef ciency than APTES.
fi In our previous work [3] , the preparation and applica- It is important to investigate further the effect of ALK tion of alkanolamide (ALK) in silica- lled natural rubber he properties of several types of rubbers lled with CB.
fi fi
[54]
(NR) compounds was reported. The ALK enhanced the Hence, this study reports the effect of ALK on properties of mechanical properties viz. tensile strength, tensile CB- lled NR, epoxidised natural rubber (ENR) and styrene-
fi [54] butadiene rubber (SBR) compounds . The study is focused on the effect of ALK loading on cure characteristics and mechanical properties of the CB- lled rubbers
Corresponding author. Tel.: þ 60 (0)4 5996113; fax: þ 60 (0)4 5941011. fi
- E-mail addresses: profhana @gmail.com ihana @usm.my , (H. Ismail). compounds.
fi fi http://dx.doi.org/10.1016/j.polymertesting.2014.12.009 © 0142-9418/ 2015 Elsevier Ltd. All rights reserved.
I. Surya et al. / Polymer Testing 42 (2015) 208e2
2. Experimental
fi vulcanisates, respectively ; z was the ratio by weight of ller
fi
[60]
according to ISO 1817. Test pieces with dimensions of
30 mm 5 m m 2 mm were prepared from the moulded ts . The initial weights were recorded prior to testing. The test pieces were then immersed in toluene and
[60] conditioned at room temperature in a dark environment for 72 hours. After the conditioning period, the weights of
[81]
the swollen test pieces were recorded. The swollen test
pieces were then dried in the oven at 70
C for 15 minutes and were allowed to cool at room temperature for another 15 minutes before the nal weights were recorded. The
fi
Lorenz and Park's equation [5e7] was applied and the swelling index was calculated according to Equation . (2)
Qf Qg ae = ¼ [78] z
þ b (2) where, the subscripts f and g referred to lled and gum
Fig. 1. Molecular structure of Alkanolamide.
fi to hydrocarbon rubber in the vulcanisate; while a and b were constants. The higher the Qf/Qg value, the weaker is the rubber ller interaction.
[13]
Table 1 Composition of the rubber compounds.
Ingredients Content (phr)
a
Rubber
b
100.0 Zinc oxide
5.0 Stearic acid
2.0 IPPD
2.0 MBTS
1.5 Sulphur
1.5 CB N330
30.0 ALK 0.0; 1.0; 3.0; 5.0; 7.0
a parts per hundred parts of rubber. b SMR-L, ENR-25, or SBR.
2.6. Measurement of rubber ller interaction efi The rubber ller interactions were determined by efi swelling the cured CB- lled rubber compounds ine,
2.1. Materials NR grade SMR-L was obtained from Guthrie (M) Sdn. Bhd., Seremban, Malaysia, epoxidised natural rubber with 25 mol% epoxidation (ENR-25) was supplied by the Rubber Research Institute Malaysia (RRIM), and styrene-butadiene rubber (SBR), Taipol 1502, was purchased from TSRC Cor- poration, Taiwan. N330-B was supplied by the Cabot
2.5. Scanning electron microscopy (SEM) The tensile fractured surfaces of the rubber compounds were examined using a Zeiss Supra-35VP scanning electron microscope (SEM) to obtain information regarding the ller
[13]
Corporation. Other compounding ingredients , such as
sulphur, zinc oxide, stearic acid , N-isopropyl-N'-phenyl-p- phenylenediamine (IPPD) and benzothiazolyl disul de fi (MBTS), were supplied by Bayer Co. (M) Sdn. Bhd., Petaling
Jaya, Selangor, Malaysia. The ALK was synthesised in our laboratory using Re ned Bleached Deodorized Palm Stearin fi
(RBDPS) and diethanolamine. The reaction procedures and molecular characterisations of the ALK were given in our previous report . The molecular structure of ALK is pre- [3] sented in Fig. 1.
2.2. Compounding A semi-ef cient vulcanisation system was used and
fi Table 1 displays the compound formulation of CB- lled
fi rubber compounds with and without ALK. The com- pounding procedure was performed on a two-roll mill (Model XK-160).
[ 13]
2.3. Cure characteristics
The cure characteristics of the CB- lled rubber com- fi pounds were obtained using a Monsanto Moving Die Rheometer (MDR 2000), which was employed to deter- mine the scorch time (ts
2 ), cure time (t
90 ) and torque dif- ference (M H dM L
[13] ) according to ISO 3417. Samples of respective rubber compounds were tested at 150
C. The
rubber compounds were subsequently compression- moulded using a stainless steel mould at 150
q 2 is the maximum rebound angle.
) and
q 1 is the initial angle of displacement (45
where
1 Þ 100 = (1)
q
2 Þ ð 1 cos
% Resilience ¼ ½ ð1 cos q
(TS), stress at 100% elongation (M100), stress at 300% elongation (M300), and elongation at break (EB) were determined. The hardness measurements of the samples were performed according to ISO 7691-I, using a Shore A type manual durometer. The resilience was studied by utilising a Wallace Dunlop Tripsometer, according to BS 903 Part A8. The rebound resilience was calculated according to Equation . (1)
speed of 500 mm/min using an Instron 3366 universal tensile machine, according to ISO 37. The tensile strength
sheets. The tensile tests were performed at a cross-head
[75]
Dumbbelled samples were cut from the moulded
C, with a pressure of 10 MPa, and applying a laboratory hot-press based on respective curing times.
fi dispersion, and to detect the possible presence of micro- defects. The fractured pieces were coated with a layer of gold to eliminate electrostatic charge build-up during extion.
2.4. Tensile, hardness, and resilience properties
I. Surya et al. / Polymer Testing 42 (2015) 208e214
The reduction of the torque difference beyond 1.0 phr can be attributed to the dilution effect of the excessive amounts of ALK, which not only reduced the total crosslink density (as happened with SMR-L and SBR systems), but also facilitated a signi cant formation of amine-epoxy
value, the higher the crosslink density . The addition of ALK
up to the optimum loading (5.0 phr) increased the torque difference of SMR-L and SBR. This was attributed to the additional function of ALK as an internal plasticizer agent, which plasticizd softened the lled compounds. This
fi resulted in reduced viscosity and improved processability of the CB dispersion and rubber-CB interaction. The rubber- CB interaction can be de ned as additional physical cross-
fi links [14,15] and, together with sulphide crosslinks, con- tributes to total crosslink density [16,17].
The reductions of the torque difference beyond 5.0 phr were most probably attributed to the dilution effect of the excessive amounts of ALK formed layers-which not only absorbed and attracted CB and some of cs inside the layers, but also reduced the total crosslink density.
In contrast to SMR-L and SBR, the torque difference of ENR-25 increased with the addition of ALK at a relatively lower loading, 1.0 phr, and then decreased with further increase in the loading. ENR-25 is a polar rubber due to the presence of some epoxy groups. Amine can utilize the epoxy groups as crosslinking sites [18,19]. Thus, increased torque difference due to the addition 1.0 phr of ALK was contributed to, not only by the formation of additional physical crosslinks, but also, presumably, by the formation of amine-epoxy crosslinks which were formed simulta- neously during the curing process. The amine-epoxy crosslinks can also be considered as another type of crosslink and, together with physical and sulphide cross- links, contribute to the total crosslink density of the CB- filled ENR-25 compound.
fi crosslinks which disrupted the stereo regular structure of ENR-25, making the compound less elastic.
Q ¼ ½ Swollen Dried weight =½Initial weight 100=Formula weight (3)
[ 55]
Fig. 2. Scorch times (ts
2 ) of the CB- lled rubber compounds at various ALK fi loadings .
Fig. 3. Cure times (t
90 ) of the CB- lled rubber compounds at various ALK
fi loadings.
10e1 3 ]; the greater the
In this study, the weight of the toluene uptake per gram of hydrocarbon rubber (Q) was calculated based on Equa- tion . (3)
3. Results and discussion
) of the three types of rubber compounds. The incorporation of 1.0 phr of ALK into the control compounds produced com- pounds with higher torque difference values. SMR-L and SBR have similar trends of torque difference which increased with the addition of ALK up to 5.0 phr, and ded beyond the loading.
According to Chouch and Chang [7,9] , the cure rate of a
3.1. Effects of ALK on cure characteristics of CB- lled rubber fi compounds The effects of ALK on the scorch and cure times of CB-
filled SMR-L, ENR-25, and SBR compounds are shown in Figs. 2 and 3, respectively. The addition of each 1.0 phr of ALK into the control compounds caused a decrease in the scorch and cure times. Cure enhancements were observed, which indicated that ALK can be considered a co-curing agent. Since amine is an ingredient of accelerator activa- tors , the amine part of ALK caused the cure [8] enhancement.
It was also seen that, the higher the ALK loading, the more pronounced the cure enhancement phenomenon became. This was simply attributed to the higher content of amine present in the CB- lled rubber compounds.
fi At a similar ALK loading, the scorch and cure times of both SMR-L and ENR-25 were shorter than those of SBR.
[13] rubber compound depends on the number of allylic hydrogen atoms in the statistical repeat unit, whereby a higher content of allylic hydrogen resulted in a lower overall apparent activation energy of curihus
L
[13] increasing the cure rate. Therefore, shorter scorch and cure times of SMR-L and ENR-25 were attributed to a higher allylic hydrogtent of these rubbers compared to that
[13] of SBR. Generally, a statistical repeated unit of natural rubber (SMR-L or ENR-25) and SBR have 7 and 3 . 3 allylic
[13] hydrogen atoms, respectively . [ 9]
The scorch and cure times of ENR-25 were lower than those of SMR-L, even although NR has the same reactivity as ENR-25. The lower scorch and cure time of ENR-25 was attributed to the presence of epoxide groups in the ENR-25 molecule, which activated the adjacent double bonds and made them more susceptible and ready for curing.
Table 2 shows the torque difference (M
H
dM
Torque difference indicates the degree of crosslink [13] [13] density of a rubber compound [
I. Surya et al. / Polymer Testing 42 (2015) 208e2
11.76
6.70
L , dN.m
0.17 M H dM
0.18
0.21
0.23
0.28
0.07
10.94 M L , dN.m
11.81
12.30
12.53
12.43
6.77
9.45 ENR-25 M H , dN.m
9.63
9.14
8.64
8.10
4.81
, dN.m
12.15
11.60
0.29 M
1.21
Fig. 5. The L values of CB in rubber phases. The Qf/Qg values of CB with and without ALK.
10.91 Fig. 4.
11.75
11.24
10.63
8.82
5.46
L , dN.m
1.08 M H dM
1.23
11.58
1.27
1.29
0.72
11.99 M L , dN.m
12.96
12.47
11.90
10.11
6.18
10.77 SBR M H , dN.m
H dM L
3.2. Effects of ALK on ller dispersion fi
The degree of CB dispersion in the three different types of rubber compounds due to the addition of ALK can be determined quantitatively by Equation (4) [3,4,20,21].
L ¼ h r m r (4)
Hf
The decreased trends of both minimum torque and L values are attributed to the function of ALK as an internal plasticizer, as mentioned earlier, which reduced the vis- cosity of the rubber compounds and, consequently, improved the CB dispersion.
fi weakened the ller ller interaction. fi efi
) i n Table 2. The minimum torque represents the ller ller inter agglom- fi efi eration , and the value is used to measure the relative [22] viscosity of a rubber compound . The lower the value, [23] the lower the viscosity of the compound - which not only results in easier processability of ller dispersion, but also
L
Based on data in Table 2, values of L for CB dispersion in the three different types of rubber phase are presented in Fig. 4. It can be seen that ALK reduced the value of L. The higher the ALK loading, the lower the value of L, which indicated better CB dispersion. The trends of L values were similar to those of minimum torque (M
are the minimum and maximum torques of the un lled/gum rubber compound. A fi lower value of L, at a particular loading, means a better degree of CB dispersion.
Hg
and M
Lg
are the minimum and maximum torques of the lled fi compounds; and M
and M
fi efi attachments/interactions. The rubber ller interaction efi due to the addition of ALK into the CB- lled rubber com-
Lf
]; where M
Hg
/M
r ¼ [M Hf
], and m
Lg
/M
h r ¼ [M Lf
where:
3.3. Effects of ALK on rubber ller interaction efi Better ller dispersion means stronger rubber ller
fi pounds, and based on the Lorenz and Park's equation, is presented in . Fig. 5
0.31
5.0
0.32
0.33
0.07
9.74 M L , dN.m
9.93
9.45
8.96
8.43
4.88
7.0 SMR-L M H , dN.m
3.0
It can be seen that, for both SMR-L and SBR systems, the Qf/Qg values decreased with increasing the ALK loading up to 5.0 phr, and ncreased with further increase in the
1.0
Rubber Compounds Gum ALK Loadings 0.0 (Control)
Table 2 Torque differences of rubber compounds at various ALK loadings.
For the ENR-25 system, Qf/Qg value decreased at 1.0 phr of ALK, and then increased with increasing ALK loading. The decreased Qf/Qg again indicated stronger rubber ller efi interaction due to the plasticizing effect of ALK, which increased the physical crosslinks. However, the increase of the Qf/Qg value at more than 1.0 phr of ALK weakened the rubber ller interaction due to the excessive amount of efi ALK, as occurred in SMR-L and SBR compounds.
fi was dispersed inside layers of excessive ALK and had no contribution to rubber ller interaction. efi
fi itive contribution to rubber ller interaction was not efi observed in this case. In all probability, only a part of the total ller was dispersed in the rubber phase, and the rest
The increased Qf/Qg beyond 5.0 phr is most likely due to the excessive loading of ALK, which reduced the viscosity continuously and further dispersed the ller. Further pos-
efiller interaction in the rubbers systems became stronger, which was attributed to the capability of ALK as a plasti- cizer which improved the dispersion of CB.
loading. The decreased Qf/Qg indicated that the rubber-
[88]
0.30
I. Surya et al. / Polymer Testing 42 (2015) 208e214
3.4. Effects of ALK on mechanical properties
0.5
59
0.8
57
0.9
54 0.8 ± ± ± ± ± Resilience, %
56.7
0.6
59.2
57.5
61
0.5
55.1
0.7
53.5 0.7 ± ± ± ± ± SBR M100, MPa
1.31
0.09
1.34
0.09
0.3
60
0.3
22.6 ± ± ± ± ±
0.15
6.49
0.15
5.62
0.18
5.19
0.20
4.75 0.22 ± ± ± ± ± EB, % 825.7 21.2 852.4 23.3 881.3 22.9 944.6 20.2 975.0
TS, MPa
0.12
30.5
0.9
31.1
0.8
30.7
0.9
30.3
1.1
29.7 1.1 ± ± ± ± ± Hardness, Shore A
1.39
1.43
1.33 0.24 ± ± ± ± ± M300, MPa
Resilience, %
56
0.2
57
0.3
58
0.3
56
0.3 ± ± ± ± ±
55.1
55
0.4
56.1
0.4
56.7
0.6
58.4
0.5
56.4 0.6 ± ± ± ± ±
0.2
18.1 0.8 ± ± ± ± ± Hardness, Shore A
0.10
0.08
1.35
0.09 ± ± ± ± ±
M300, MPa
3.18
0.06
3.89
0.07
4.47
4.73
0.6
0.08
3.58 0.09 ± ± ± ± ± EB, % 770.9 17.5 776.1 18.9 782.1 19.8 829.2 19.2 866.7 20.2 ± ± ± ± ± TS, MPa
18.2
0.5
18.8
0.5
19.1
0.6
19.8
5.82
Table 3 shows the effects of ALK on the tensile modulus (M100 and M300), hardness, and resilience of the CB- lled
fi SMR-L, ENR-25 and SBR compounds. The incorporation of ALK up to 5.0 phr for SMR-L and SBR, and at 1.0 phr for ENR- 25 enhanced those properties, but beyond those loadings these properties decreased.
5.0
[55]
Qf/Qg values were lowest at the optimum loadings. An
Table 3 The mechanical properties of CB- lled rubber compounds at various ALK loadings .
fi
CB- lled Rubber Compounds ALK Loadings fi
0.0 (Control)
1.0
3.0
7.0 SMR-L M100, MPa
crographs of the tensile fractured surfaces were in good agreement with the graphs in , which showed that the Fig.
1.28
0.20
1.30
0.21
1.33
0.21
1.36
0.23
1.25
5
tensile modulus, tensile strength and hardness. The mi-
M300, MPa
The enhancements in tensile strength up to the opti- mum loadings were attributed the capability of ALK to soften and plasticize the lled compounds in order to gain a
Tensile modulus and hardness of a rubber vulcanisate are only dependent on the degree of crosslinking . [24,25] Resilience is enhanced to some extent as the crosslink density rises . The enhancements of tensile [26,27] modulus, hardness and resilience up to the optimum loadings were attributed to a higher crosslink density, and the deteriorations of those properties beyond those opti- mum loadings were attributed to a lower crosslink density. This explanation is in line with the torque difference data in Table 2.
The effects of ALK on the elongation at break (EB) of the CB- lled SMR-L, ENR-25, and SBR compounds are pre-
fi sented in Table 3. It can be seen that ALK caused an increasing trend of EB for all the rubbers. The EB increased with increase of the ALK loadings. Again, this can be attributed to the function of ALK as an additional plasticizer which modi ed the exibility of vulcanisates of the CB-
fi fl filled rubbers. ALK provided a free volume which allowed more exibility for the rubber chains to move. The higher
fl the ALK loading, the greater was the free volume, and the more exible the rubber chains. Presumably, free volume
fl he layers of excessive ALK.
The effects of ALK on the tensile strength of the CB- lled fi [80] SMR-L, ENR-25 and SBR compounds are shown in Table 3.
The additions of ALK up to 5.0 phr for SMR-L and SBR, and 1.0 phr for ENR-25, enhanced the tensile strength, but beyond those loadings caused a decrease in tensile strength.
fi stronger rubber- ller interaction. This explanation is in line fi with the results in and the SEM micrographs of the Fig. 5
[80]
CB- lled rubbers vulcanisates in . The micrographs of fi
Fig. 6 the CB- lled rubber vulcanisates with the optimum ALK fi loadings (b, e, and h) exhibit homogeneous micro disper- sion of CB as a result of the incorporation of ALK.
The deterioration of tensile strength after the optimum loadings can be attributed to the excessive amount of ALK which caused a more pronounced softening effect, result- ing in weaker rubber ller attachments/interactions. An efi additional explanation for the ENR-25 system is that ALK also initiated a more dominant amine-epoxy interaction. This interaction promoted a signi cant amount of ring-
fi opened product, and disrupted the stereo regular struc- tures of the ENR-25 molecule. The disruption of stereo regular structures of the ENR molecule made it less elastic and reduced the strength [19].
3.5. Scanning electron microscopy (SEM) study Fig. 6 shows SEM micrographs of fractured surfaces of the vulcanisates of CB- lled SMR-L, ENR-25 and SBR, with
fi and without ALK, which were taken at magni cation 500X.
fi It can be clearly observed that the CB- lled rubber vulca-
fi nisates with optimum ALK loadings (micrographs of Fig. 6(b), (e) and (h)) exhibit signi cant matrix tearing lines
fi and surface roughness. They show greater matrix tearing lines and surface roughness compared to those of the control rubber vulcanisates ( (a), (d) and (g)). This in- Fig. 6 dicates greater rubber ller interaction which altered the efi crack paths, leading to increased resistance to crack prop- agation, thus causing an increase in properties such as
0.27 ± ± ± ± ±
4.92
1.44
65.5
0.6
49 0.7 ± ± ± ± ± Resilience, %
58.4
0.6
59.2
0.6
60.1
0.7
0.8
0.7
65.0
0.8 ± ± ± ± ±
ENR-25 M100, MPa
1.75
0.18
1.82
0.20
1.58
0.25
54
52
0.18
0.9
5.02
0.20
5.05
0.23
5.15
0.22
4.32 0.25 ± ± ± ± ± EB, % 835.8 20.2 885.8 23.7 932.8 22.8 966.3 23.0 1072.7 17.8 ± ± ± ± ± TS, MPa
25.3
27.5
0.4
1.4
28.6
1.0
29.2
1.2
28.3 0.7 ± ± ± ± ± Hardness, Shore A
50
0.4
51
0.22
I. Surya et al. / Polymer Testing 42 (2015) 208e2
Fig. 6. SEM micrographs of the failed fracture of CB- lled vulcanisate at a magni cation of 500X; (a) CB- lled SMR-L, (b) CB- lled SMR-L ALK5, (c) CB- lled d fi fi fi fi fi
SMR-L ALK7, (d) CB- lled ENR-25, (e) CB- lled ENR-25 ALK1, (f) CB- lled ENR-25 ALK3, (g) CB- lled SBR, (h) CB- lled SBR ALK5, and (i) CB- lled d fi fi d fi d fi fi d fi SBR ALK7. d enhancement in rupture energy, due to a greater rubber- loading of alkanolamide was the optimum loading in efiller interaction, was responsible for the roughness and epoxidised natural rubber compound. the matrix tearing line of the fractured surface. The mi-
3. The alkanolamide improved the tensile modulus, hard- crographs of the tensile fractured surfaces were in good ness, resilience and tensile strength of the carbon black- agreement with the results obtained by other researchers filled natural rubber, epoxidised natural rubber and [28,29] who reported that an increase in rupture energy styrene-butadiene rubber compounds, especially up to was responsible for the roughness and the matrix tearing the optimum loading.
4. Morphological studies of the tensile fractured surfaces line of the fractured surface. The matrix tearing lines and surface roughness of mi- of carbon black-fi lled rubbers vulcanisates, at the op- crographs of Fig. 6 (c), (f) and (i) were smoother than those timum alkanolamide loadings, indicated that the sur- of micrographs of Fig. 6 (b), (e) and (h), which indicated a faces exhibited the greatest matrix tearing line and lower crosslink density and a more pronounced plasticizing surface roug hnes s due to better rubberefiller or lubricating effect of the excessive ALK. interaction.
4. Conclusions
Acknowledgements From this study, the following conclusions can be
The authors woul d like to thank Universiti Sains drawn: Malaysia for providing the research facilities for carrying out the experiment and for making this research work
1. Alkanolamide can be utilised as a new curative additive possible. One of the authors (Indra Surya) is grateful to in carbon black- lled natural rubber, epoxidised natural
fi the Directorate Gene ral of Higher Education (DIKTI) , rubber and styrene-butadiene rubber compounds.
Ministry of Education and Culture (Kemdikbud) of the Alkanolamide increased cure rate, degree of ller
fi Republic of Indonesia, for the award of a scholar ship dispersion and rubber ller interaction. The cure rate efi under the fifth batch of the Overseas Postgraduate and degree of ller dispersion increased with increasing
fi Scholarship Program. the alkanolamide loading, while rubber- ller interaction
fi increased up to an optimum loading.
References
2. A 5.0 phr loading of alkanolamide was the optimum loading in carbon black- lled natural rubber and fi
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