Preparation and characterization of super-strong natural rubber latex film

doi:10.21203/rs.3.rs-4006313/v1

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Preparation and characterization of super-strong natural rubber latex film

https://doi.org/10.21203/rs.3.rs-4006313/v1

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Natural latex materials with excellent elongation, widely used in impregnated products and foam products. However, the lack of performance of traditional products has limited their application in high-end aspects, such as condoms and medical gloves. In this study, orthogonal test was used to determine the basic formula, and then silica and silane coupling agents were used to further improve the properties of natural latex film. The purpose of reinforcing natural latex film was realized, and super reinforced natural latex film was prepared. The results showed that the primary and secondary order of the optimized formula of natural rubber latex was sulfur > accelerator PX > zinc carbonate > Accelerator M with the tensile strength and tear strength as the indexes. With the increase of silica content, the tensile strength and tear strength of the obtained natural rubber latex vulcanized film reached 27.59 MPa and 50.73 kN/m, respectively. With the increase of the amount of silane coupling agent, the tensile strength of the obtained natural rubber latex vulcanized film was further increased to 29.01 MPa, while the tear strength tended to decrease. Including infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and other instrument analysis to further reveal the mechanism of silica reinforced natural rubber latex.

natural rubber latex(NRL)

orthogonal test

mechanical properties

silica

silane coupling agent

Natural rubber latex(NRL) is a kind of pure natural polymer raw material extracted from Brazilian clover rubber tree. Because of its excellent comprehensive performance and convenient processing and production, it is widely used in impregnated products, pressed products, sponge products and mold casting products[1–3]. Polyisoprene, the main component of NRL, is a non-polar molecule, which is easy to interact with hydrocarbon organic solvents, so its oil resistance and organic solvent resistance are poor. In addition, it contains a certain amount of unsaturated double bonds, so its thermal oxygen aging resistance, ozone resistance and ultraviolet resistance are poor, which limits its application in some special occasions[4–8].

In the natural rubber industry, the research on the composite of carbon black, clay, silica, carbon nanotubes and other reinforced particles has been widely carried out, and the modified composite materials with excellent performance have been developed. Zhan, Y. H. et al.[9] Carbon black / carbon nanotubes / natural rubber composites with high elastic modulus were prepared by ultrasonic assisted emulsion mixing method. Hou, Z. F. et al.[10] A clay mineral sepiolite was pretreated by ultrasonic dispersion and oxalic acid activation to achieve good dispersion in NRL. The introduction of sepiolite improved the mechanical properties of rubber materials. Zhang, C. F. et al.[11] used PMHS to modify the surface of silica to prepare natural rubber composites, and their mechanical properties and dynamic properties have been greatly improved.

However, when these nanoparticles are added to latex system, they are prone to agglomeration. If they are not fully dispersed, they will have a bad effect on the latex [12, 13].Xiao, Y. et al. [14] loaded the accelerator DPG on the surface of silica, induced latex to achieve self-flocculation, promoted the dispersion of silica in rubber system, and realized a more complete filler-rubber network and three-dimensional cross-linking network. Wang, J.et al. [15] prepared silica / graphene oxide / natural rubber composites by wet mixing process using a new interfacial modifier CDHC. Compared with the conventional mechanical mixing method, the dispersion of silica and graphene oxide in the composites prepared by wet method was improved. Sun, Y. et al. [16] prepared composite natural rubber materials with excellent properties by ball milling and dispersing precipitated silica and adding modifier Si747. Therefore, controlling nano-particle size, improving surface activity and uniform dispersion are still the key factors for nano-enhancement of NRL film[17–19].

In this paper, the ' high-speed stirring, grinding, ultrasonic dispersion ' three-step treatment process was used to prepare the aqueous dispersion of the complexing agent. The orthogonal experimental design was used to optimize NRL formulation system, and silica and its modification were used to reinforce, in order to obtain super-strong NRL film, which provides a technical basis for the application of high-quality NRL products.

2.1 Materials

Concentrated natural latex was provided by Hainan Jinlian Rubber Processing Branch(Danzhou,China). Sulfur was purchased from Shanghai Longli Chemical Co., Ltd(Shanghai China). Bis(ethylphenylcarbamodithioato-S,S′)-, (T-4)-Zinc (Accelerator PX) was purchased from Shanghai Myrill Biochemical Technology Co., Ltd. Zinc carbonate was purchased from Suzhou Ketong Biomedical Technology Co., Ltd(Suzhou China). 2,6-Ditert-butyl-4-methyl phenol(Antioxidant 264) was purchased from Shanghai Bohr Chemical Reagent Co., Ltd(Shanghai China). 2-Mercaptobenzothiazole(Accelerator M) was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd(Shanghai China). The silica was produced by precipitation method from Tonghua Shuanglong Chemical Co., Ltd(Shanghai China). Silane coupling agent KH560 was purchased from Nantong Feiyu Biotechnology Co., Ltd(Shanghai China). Sodium salt of polynaphthalene sulphonic acid (Dispersing agent NNO) was purchased from Shanghai Bohr Chemical Reagent Co., Ltd(Shanghai China). Casein was purchased from Xilong Chemical Co., Ltd(Guangzhou China). Potassium hydroxide was purchased from Guangzhou Chemical Reagent Factory(Guangzhou China). Aqua ammonia was purchased from the Shanghai McLean Biochemical Technology Co., Ltd. (Shanghai, China).. Pure water was made by the laboratory.

2.2 Experimental design

In order to optimize the compound formulation, we used L₉(4³) orthogonal design, sulfur, accelerator PX, Accelerator M and zinc carbonate were selected to design the compound formula at three levels, as shown in Table 1.

Table 1

Compound formula design (Dry-base ratio)
Test number	Sulfur( phr )	Accelerator PX( phr )	Accelerator M( phr )	Zinc carbonate( phr )
1	0.8	0.4	0.3	0.3
2	0.8	0.5	0.4	0.4
3	0.8	0.6	0.5	0.5
4	1.0	0.6	0.4	0.3
5	1.0	0.4	0.5	0.4
6	1.0	0.5	0.3	0.5
7	1.2	0.5	0.5	0.3
8	1.2	0.6	0.3	0.4
9	1.2	0.4	0.4	0.5

On the basis of optimizing the formula of the rubber compound, the reinforcing experiment of NRL was carried out by adding the three-level treated silica, and the ingredient design was shown in Table 2.

Table 2

Formula of silica reinforced latex (dry basis meter)
Sample number	SN0	SN1	SN2	SN3	SN4	SN5
NRL( phr )	100.00	100.00	100.00	100.00	100.00	100.00
Silica( phr )	0.00	0.25	0.50	0.75	1.00	1.25

On the basis of silica reinforced natural latex, the silane coupling agent was added to modify the silica, and then the NRL was reinforced. The ingredient design is shown in Table 3.

Table 3

Silane coupling agent modified silica reinforced NRL formula (dry basis meter)
Sample number	KSN0	KSN1	KSN2	KSN3	KSN4	KSN5
NRL( phr )	100.00	100.00	100.00	100.00	100.00	100.00
Silica( phr )	1.00	1.00	1.00	1.00	1.00	1.00
KH560/Silica	0.00	0.50	1.00	1.50	2.00	2.50

2.3 Sample preparation

2.3.1 Three-stage treatment

A variety of complexing agents such as sulfur, accelerator PX, accelerator M, zinc carbonate and silica were placed in a stirred tank for high-speed stirring with aqueous solution as the dispersion medium to obtain a pre-dispersed suspension. Then the KNB-S-1L horizontal sand mill of Dongguan Kangbo Intelligent Equipment Co., Ltd. was used for high-speed grinding. Finally, the ultra-fine water dispersion was obtained by ultrasonic dispersion treatment. We recorded the particle size changes of different materials during refining treatment.

2.3.2 Preparation of vulcanized latex

According to the experimental formula in Table 1, a variety of complexing agent aqueous dispersions were added to the NRL in turn, and a small amount of ammonia was added. After slow stirring, a uniform complexing latex was obtained, and then transferred to a water bath pot. Continue to stir slowly, the water bath pot is set at 60°C, starting from 25°C, the time to reach the set temperature is started, the pre-vulcanization time is controlled to 1.5 h, and then stand for 1 d.

According to the experimental formula in Table 2, different proportions of silicon dioxide were added to the optimized formula of natural latex, and then mixed evenly to prepare vulcanized latex according to the same experimental operation.

According to the experimental formula in Table 3, after determining the appropriate amount of silica, different proportions of silane coupling agent were added to the silica grinding solution, and the natural latex optimization formula was added. The vulcanized latex was prepared according to the same experimental operation.

2.3.3 Preparation of vulcanized film

After standing, the vulcanized latex was obtained in a stable state, and the film was spread on the glass plate. The thickness of each sample was controlled at 0.5–0.6 mm. After being dried naturally, it was transferred to the oven for vulcanization. The vulcanization temperature was 80 ° C and the time was 2 h. After that, the film was placed for 24 h and tested.

2.4 Characterization

The HL2020-c laser particle size analyzer of Beijing Haixinrui Technology Co., Ltd. was used to test the particle size of the dispersion under the shading ( optical concentration ) of about 15% and the wet test standard.

According to the national standards GB / T528-2009 and GBT529-2008, the tensile strength and tear strength of the vulcanized rubber film were measured by using the AI-7000-SU2 type tensile machine of High-speed Railway Technology Co., Ltd., cutting the vulcanized rubber film into dumbbell-shaped and right-angled with a specific cutter, and setting the speed of the tensile machine at 500 mm / min. The cyclic tensile tests of the specimens at 200%, 400% and 600% elongation were carried out at a strain rate of 100 mm / min.

The T27 Fourier transform infrared spectrometer of German BRUKER company was used. The test wave number range of the sample was 4000 ~ 450 cm^− 1, and the infrared spectral data of the film were collected.

The microstructure of the film section was observed by Phenom ProX scanning electron microscope of Phenom-World BV company in the Netherlands, and the film section was sprayed with gold before observation.

Thermogravimetric analysis experiments were carried out using the TL9000 type thermogravimetric-infrared image-gas chromatography-mass spectrometry in-situ reaction system of PE company in the temperature range of 25°C ~ 800°C, the heating rate of 10°C / min, and the protection of N₂ gas.

3.1 Dispersion refine grinding particle size test results

Using pure water as the dispersing medium, all kinds of compounding agents and silica were treated with three levels of refinement. The HL2020-c laser particle size analyzer was used for detection and analysis, and the particle size changes of the dispersion during the refining process were recorded, as shown in Figure S1 and Figure S2. Finally, fully refined dispersions are obtained, and the particle size is shown in Table 4 and Figure S3.

Table 4 Particle size test results of wet grinding dispersion

Ingredient	D₁₀ ( μm )	D₅₀ ( μm )	D₉₀ ( μm )
Sulfur	0.31	0.70	1.42
Silica	0.38	1.11	2.97
Accelerator PX	0.38	0.81	1.66
Accelerator M	0.51	1.19	2.63
zinc carbonate	0.56	1.42	3.18
Antioxidant 264	0.67	1.48	3.17

Taking the three-stage treatment of sulfur as an example, as shown in Figure 1, ( a ) and ( b ) record the particle size change of sulfur during fine grinding and ultrasonic treatment, ( c ) and ( d ) represent the particle size distribution of the final sulfur and NRL, respectively. The comparison results show that after three-stage treatment, the obtained sulfur dispersion basically reaches the particle size equivalent to that of NRL.

3.2 Optimization and analysis of NRL formula

The rubber compound was prepared according to table 1, and the mechanical properties of the vulcanized film were tested. The test results are shown in Table 5.

Table 5 Mechanical properties of vulcanized rubber film

Test number	300% stretching strength	500% stretching strength	700% stretching strength	Elongation at break	Tensile strength	Tear strength
Test number	( MPa )	( MPa )	( MPa )	( % )	( MPa )	( kN/m )
1	0.72	1.10	4.59	960	22.39±1.33	34.01±0.78
2	0.76	1.23	5.94	922	22.51±0.47	32.48±2.90
3	0.72	1.11	4.67	987	24.47±1.02	37.57±3.10
4	0.66	0.95	3.64	1012	23.68±0.86	37.98±2.33
5	0.80	1.25	5.96	928	24.08±0.60	33.20±1.34
6	0.81	1.18	4.86	967	24.94±0.77	41.47±2.03
7	0.71	1.09	4.96	959	23.44±1.67	38.86±2.00
8	0.67	1.04	4.49	987	24.91±0.88	38.63±1.53
9	0.85	1.26	4.90	959	25.01±0.41	37.69±1.27

At the same time, the tensile strength and tear strength were taken as the investigation indexes, and the weight of both was assumed to be 50 %. The range analysis was carried out by the index membership weighted scoring method [20]. The calculation results of the comprehensive score are shown in Table 6, and the range analysis process is shown in Table 7.

Table 6 Comprehensive score calculation

	1	2	3	4	5	6	7	8	9
Tensile strength( MPa )	22.39	22.51	24.47	23.68	24.08	24.94	23.44	24.91	25.01
Tear strength( kN/m )	34.01	32.48	37.57	37.98	33.20	41.47	38.86	38.63	37.69
Tensile strength membership	0.00	0.05	0.79	0.49	0.65	0.97	0.40	0.96	1.00
Tear strength membership	0.17	0.00	0.57	0.61	0.08	1.00	0.71	0.68	0.58
Comprehensive score	0.09	0.02	0.68	0.55	0.36	0.99	0.56	0.82	0.79

Table 7 Results of range analysis

Index	Sulfur	Accelerator PX	Accelerator M	Zinc carbonate
K_g1	0.790	1.200	1.900	1.240
K_g2	1.900	1.200	1.360	1.570
K_g3	2.170	2.460	1.600	2.050
k_g1	0.263	0.400	0.633	0.413
k_g2	0.633	0.400	0.453	0.523
k_g3	0.723	0.820	0.533	0.683
R_g	0.460	0.420	0.180	0.270

In sulfur-based vulcanization system, different compounds play different roles. The main function of sulfur is to promote the vulcanization reaction, and disulfide bonds are formed between the rubber molecular chains inside the film[21, 22]. However, the original vulcanization rate is slow, the accelerator can accelerate the vulcanization reaction, the use of different types of accelerators, can achieve complementary and mutual activation. Zinc carbonate can increase the activity of the accelerator. Under the action of different compounding agents, faster vulcanization speed is achieved and better application value is achieved[23, 24].

The results showed that the primary and secondary order of factors was sulfur, accelerator PX, zinc carbonate, accelerator M ; the optimization scheme is sulfur 1.20 phr, accelerator PX 0.60 phr, zinc carbonate 0.50 phr, accelerator M 0.30 phr. Taking the selected optimization scheme as an example, the prediction is carried out according to the experimental design method [20], and the comprehensive prediction value is 1.240.

The verification experiment is carried out for the selected optimization scheme, and the results are shown in Table 8.

Table 8 verifies the experimental results

testing contents	predicted value	authentication value	standard deviation	standard error
Tensile strength (MPa)	25.88	25.65	0.65	0.89%
Tear strength (kN/m)	42.77	42.49	3.32	0.65%

Similarly, the comprehensive score of 1.179 can be calculated, which is very close to the predicted comprehensive score of 1.240. Therefore, the optimized formula of NRL was determined as sulfur 1.20 phr, accelerator PX 0.60 phr, accelerator M 0.30 phr, zinc carbonate 0.50 phr, antioxidant 264 0.5 phr and NRL 100 phr.

3.3 The influence and analysis of different materials on the mechanical properties of rubber

3.3.1 Effect of silica on properties of vulcanized NRL film

On the basis of optimizing the formula by orthogonal test, the three-stage treated silica was added to carry out the NRL reinforcement experiment, and the mechanical properties of the vulcanized film were tested. The cyclic tensile test was carried out at 200 %, 400 % and 600 % elongation. The results are shown in Figure 2.

The results show that when the silica is 0.75 phr, the tear strength increases from 42.49 kN / m to 50.73 kN / m, while the tensile strength increases from 25.65 MPa to 27.59 MPa when the silica is 1.00 phr. However, with the further increase of the amount of silica, both tensile strength and tear strength began to decrease. In addition, from the cyclic tensile curve Figure 2 ( b ), it can be seen that compared with the blank group, the cyclic tensile curve of the vulcanized rubber film added with silica shifted upward. From the results of stress-strain curves Figure 2 ( c ) ( d ), it can be seen that the stress-strain curve moved to the upper left with the increase of the amount of silica.

Therefore, the introduction of silica into the latex system can effectively improve the strength of the film. At the same elongation, the film bears greater strength due to resistance to stretching. This is also consistent with the current popular view[25, 26]. The introduction of fillers increases the performance at the expense of breaking elongation. The introduction of silica hinders the movement of the polymer chain and forms a filled rubber crosslinking network, thus resulting in improved mechanical properties[27]. When the amount of silicon dioxide exceeds the optimal value, the performance tends to decrease instead. It may be that with the increase of the amount of silicon dioxide, the agglomeration structure of silicon dioxide will be formed, and defects will be generated inside the film, which will affect the continuity of the rubber composition, and then damage the mechanical properties of the film[28].

3.3.2 Effect of silane coupling agent modified silica on properties of NRL vulcanized film

Silica has improved the performance of NRL vulcanized film to a certain extent, and then silane coupling agent is used to further change the distribution state of silica and its combination with NRL, looking forward to generating new bonds and promoting the further improvement of the mechanical properties of the film. According to the experimental scheme of table 3, the mechanical properties of the obtained vulcanized film were tested, and the cyclic tensile test was carried out at 200 %, 400 % and 600 % elongation lengths, and the results were shown in Table S1 and Figure 3.

The results showed that the introduction of silane coupling agent could promote the further improvement of the tensile strength of the obtained NRL vulcanized film, from 27.37 MPa to 29.01 MPa, while it seemed to be unfavorable for the tear strength, and the test results generally showed a decrease. In the stage of less amount of silane coupling agent, the tensile strength is still improved. When the tensile strength reaches the peak, it tends to decrease, and the tear strength tends to decrease with the increase of the amount of silane coupling agent. From Figure 3 ( b ), compared with the silica-reinforced film, the cyclic tensile curve of the film after silane coupling agent modified silica shifted downward. From Figure 3 ( c ) ( d ), the stress-strain curve moved to the lower right with the increase of the amount of silane coupling agent, and then moved to the original position after reaching the optimal result.

The addition of silane coupling agent can change the distribution of silica in rubber and make silica dispersed more evenly[29, 30]. The uniform dispersion of the reinforcing particles can produce a good reinforcing effect on the film. At the same time, the silane coupling agent promotes the formation of chemical bonds between the silica and the rubber molecular chains, making the chemical structure between the silica and the polymer chains closer[31, 32]. When the silane coupling agent is further increased, a chemical bond may be formed between the silicon dioxide, which causes the agglomeration of the silicon dioxide and affects the dispersion of the silicon dioxide. Therefore, it has a bad effect on the mechanical properties[33-35]. It shows a decrease in tensile strength and tear strength.

3.3.3 Comparison and analysis of mechanical properties of natural latex film

Table 9 Test results of mechanical properties of different natural latex film

Sample	300% Tensile strength	500% Tensile strength	700% Tensile strength	Elongation at break	Tensile strength	Tear strength
Sample	(MPa)	(MPa)	(MPa)	(%)	(MPa)	(kN/m)
SN0	1.01	1.63	7.54	897	25.65±0.65	42.49±3.33
SN4	0.95	1.85	9.31	870	27.59±0.45	49.51±3.04
KSN2	0.86	1.57	7.71	909	29.01±0.90	40.28±3.72

Note: SN0 is the sample after optimization of orthogonal test, SN4 is the sample after comparison of different amounts of silica, KSN2 is the sample after comparison of different amounts of silane coupling agent.

Compared with SN0, the mechanical properties were improved by introducing silica into the rubber system. The tensile strength of the film was increased from 25.65MPa to 27.59MPa, and the tear strength was increased from 42.49kN /m to 49.51kN /m. The modified silica was modified by silane coupling agent, and the mechanical properties of the film were changed. The tensile strength of the film was increased from 27.59 MPa to 29.01 MPa, and the tear strength was reduced from 49.51 kN/m to 40.28 kN/m.

Silica is added to the rubber system, and the silica is mixed between the rubber molecular chains. When the film is stretched, the rubber molecular chains slide relative, and silica prevents the rubber molecular chains from moving with each other. Therefore, when the film is stretched and torn, it needs to receive greater force, which is reflected in the improvement of mechanical properties[36, 37].

3.4 Infrared spectrum analysis

In order to further reveal the reinforcing properties of silica on NRL vulcanized film, the infrared spectra of silica, silane coupling agent modified silica and three different films were tested respectively, and the results were shown in Figure 4.

The test results show that, as shown in Figure 4 ( a ), the absorption peaks of Si-OH, Si-O-Si and Si-O bonds are near 3440cm^-1,1100cm^-1 and 808cm^-1, respectively, which are exclusive to SiO₂ absorption peaks. The absorption peaks of silane coupling agent KH560 appeared near 2940cm ^{− 1} and 2870cm ^{− 1}, which were the absorption peaks of -CH₃ and -CH₂-, respectively, indicating that the silane coupling agent had a cross-linking reaction with silica, and a mixed absorption peak appeared[28, 38, 39].

As shown in Figure 4 ( b ), after the introduction of silica in the NRL system, the absorption peak near 1100cm^-1 is enhanced, indicating the presence of silica in the latex system[40]. This result proves that silica is incorporated into the latex system.

3.5 Scanning electron microscopy analysis

In order to further reveal the reinforcing effect of silica on the vulcanized film of NRL, three different vulcanized films were analyzed by SEM, as shown in Figure 5.

After the film was broken by tensile test, the fracture surface was observed by scanning electron microscopy. The cross section of the film presents a layered structure. After adding silica, the distribution of rubber components in the rubber compound is changed, and the cross section becomes more neat. It may be that the introduction of silica will hinder the movement of the latex molecular chain and affect the tensile crystallization[26, 31]. The cross-linked substance in the cross-section of the sample using silane coupling agent may be the reason for the change of performance[41-43].

3.6 Thermogravimetric analysis

In order to further reveal the thermal effect of silica on the NRL vulcanized film, TG analysis was performed on three different vulcanized films, as shown in Figure 6.

From Figure 6 ( a ) ( b ), it can be seen that after the addition of silica, the thermogravimetric curve moves to the left, the thermal decomposition temperature of the film is advanced, and the decomposition temperature of the film modified with silane coupling agent is further moved forward.

From Figure 6 ( c ) ( d ), it can be seen that after the addition of silica, the peak of the derivative thermogravimetric curve moved to the upper left. After the silica was modified by silane coupling agent, the peak of the derivative thermogravimetric curve of the film continued to move to the upper left.

The reason may be that the introduction of silica accelerates the transfer of heat between the rubber molecular chains, making the rubber begin to crack earlier[44-48]. The introduction of silane coupling agent may promote the formation of new cross-linked structure, so that the heat transfer inside the film is faster, and the polymer chain in the film is more likely to decompose due to heat absorption[49, 50].

( 1 ) Under the experimental conditions, the optimized formula of NRL was sulfur 1.20 phr, accelerator PX 0.60 phr, accelerator M 0.30 phr, zinc carbonate 0.50 phr, antioxidant 264 0.5 phr, NRL 100 phr.

(2) Silica promoted the mechanical properties of natural latex film, the tensile strength of the film was increased from 25.65MPa to 27.59MPa, and the tear strength was increased from 42.49kN /m to 49.51kN /m. The modified silica also changed the mechanical properties of the film, and the tensile strength of the film increased from 27.59 MPa to 29.01 MPa, but the tear strength decreased.

( 3 ) Infrared results showed that silica was modified by silane coupling agent and acted on the latex system. Scanning electron microscopy showed that the introduction of silica and silane coupling agent may change the distribution of polymer chains inside the film and thus bring about the difference in the cross-section of the film. The results of thermogravimetric curve and derivative thermogravimetric curve showed that the introduction of silica promoted the heat transfer inside the film. The silane coupling agent may cause a new cross-linked structure inside the film, so the thermal cracking temperature of the film moves forward.

Funding information

Natural Science Foundation of Hainan Province (ZDYF2023SHFZ110), Natural Science Foundation of Hainan Province (521RC1037), and the Graduate Students Innovation Research Project of Hainan Province (Qhys2022-146).

Conflict interests

The authors declare no conflicts of interest.

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Preparation and characterization of super-strong natural rubber latex film

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Version 1

Abstract

Figures

1 Introduction

2 Experimental

2.1 Materials

2.2 Experimental design

2.3 Sample preparation

2.3.1 Three-stage treatment

2.3.2 Preparation of vulcanized latex

2.3.3 Preparation of vulcanized film

2.4 Characterization

3 Results and discussion

4 Conclusions

Declarations

References

Supplementary Files

Status:

Version 1

Test number	Sulfur( phr )	Accelerator PX( phr )	Accelerator M( phr )	Zinc carbonate( phr )
1	0.8	0.4	0.3	0.3
2	0.8	0.5	0.4	0.4
3	0.8	0.6	0.5	0.5
4	1.0	0.6	0.4	0.3
5	1.0	0.4	0.5	0.4
6	1.0	0.5	0.3	0.5
7	1.2	0.5	0.5	0.3
8	1.2	0.6	0.3	0.4
9	1.2	0.4	0.4	0.5

Test number	Sulfur( phr )	Accelerator PX( phr )	Accelerator M( phr )	Zinc carbonate( phr )
1	0.8	0.4	0.3	0.3
2	0.8	0.5	0.4	0.4
3	0.8	0.6	0.5	0.5
4	1.0	0.6	0.4	0.3
5	1.0	0.4	0.5	0.4
6	1.0	0.5	0.3	0.5
7	1.2	0.5	0.5	0.3
8	1.2	0.6	0.3	0.4
9	1.2	0.4	0.4	0.5

Test number	Sulfur( phr )	Accelerator PX( phr )	Accelerator M( phr )	Zinc carbonate( phr )
1	0.8	0.4	0.3	0.3
2	0.8	0.5	0.4	0.4
3	0.8	0.6	0.5	0.5
4	1.0	0.6	0.4	0.3
5	1.0	0.4	0.5	0.4
6	1.0	0.5	0.3	0.5
7	1.2	0.5	0.5	0.3
8	1.2	0.6	0.3	0.4
9	1.2	0.4	0.4	0.5