Tóm tắt Luận án Study on enhancement of technical characteristics for some composite rubbers with nano additive

The above results show that the thermal conductivity of materials

increases when there are CB and CNT. At a temperature of 30oC, with 40pkl

CB, the thermal conductivity of the material increased slightly from 0.509 to

0.574 W/mK, while only 1 pkl of combined CNT replaced the thermal

conductivity CB of the material increased sharply (to 0.691 W/mK).

When raising the temperature, the thermal conductivity of rubber

blend samples increased. For blends that do not contain reinforcement fillers,

the thermal conductivity does not increase significantly. Meanwhile, blends

contained 39CB/1CNT with the highest thermal conductivity. It is the ability

to increase high thermal conductivity when increasing the temperature so

blended rubber products based on NBR/PVC with CB and CNT can reduce

endogenous heat during operation.

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hapter 3: RESULTS AND DISCUSSION 3.1.1. Modified carbon nanotubes additive 3.1.1.1. CNT denaturation by polyvinylcloride Dispersion results in organic solvents: Figure 3.2: Dispersion of CNT (a) and CNT-g-PVC (b) in THF After alkylation, on the infrared spectrum (IR) of CNT-g-PVC (figure 3.3b) compare to the IR spectrum of CNT (figure 3.3a), the absorption peaks appear at 3048cm-1, 2914cm-1 corresponding to the valence oscillation of the - CH, -CH2 group and absorption peak at 1437cm-1 corresponding to the strain variation of the -CH2 group in the -CH-CH2- group. In addition, an absorption peak at 618cm-1 is found with the valence oscillation of the C-Cl bond. Figure morphological structure of materials: The morphological figure structure of CNT not denatured and CNT-g-PVC is studied by FE- SEM method, results are shown in figure 3.5 below: 7 Figure 3.5: FE-SEM image of the surface of CNT (a) and CNT-g-PVC (b) After oxidation, the structure is quite uniform with less shrinkage, diameter of CNT-g-PVC increase significantly up to 23.6 - 29.1nm (CNT diameter before joining PVC chain only 9.26 to 15.1nm). 3.1.1.2. Modifying CNT surface with PEG CNT surface modification diagram by PEG is described in Figure 3.9: Figure 3.9: Diagram of denatured CNT surface by Fischer esterification reaction On the spectrum of CNT-(CO)-PEG (Figure 3.10), there is a peak of 3264cm-1 characteristic for oscillation of OH group at the end of circuit CNT- COO-(CH2-CH2)n-OH, pic 3624cm-1 and 1668cm-1 denotes the signal of the NH group, the peak 1716cm-1 is the strong signal of the group (C = O) ester. The IR spectrum of CNT-(CO)-PEG also appears 1038cm-1 pic assigned to the CO group in PEG, the two peaks 2836 cm-1 and 3019cm-1 characterize the symmetric oscillation and antisymmetry of the joint C-H link in PEG. + Content group -(CO)-PEG and group -(CO)-TESPT paired on CNT: Content group -(CO)-PEG and group -(CO)-TESPT grafted onto CNT surface is also determined by the method of distribution Heat buildup (TGA). Results analysis is obtained, shown in Table 3.4. Table 3.4: Results of TGA analysis of CNT-(CO)-PEG and CNT-(CO)-TESPT Sample Starting decomposition temperature Strong decomposition temperature most 1, oC Strong decomposition temperature most 2, oC Mass loss to 750oC, (%) CNT 4900C 629.77 0C - 13.50% CNT-(CO)-PEG 4050C 449.150C 619.110C 36.63% The thermal decomposition of CNT-(CO)-PEG starts at about 4050C and reaches a peak at 449.150C, extending until 619.110C, then the speed decreases until it reaches 7500C no longer losing weight, at this level of mass loss is about 36.63%, it is possible to roughly calculate the content of CO- PEG functional group attached to the surface of CNT corresponding to 8 23.13%. From the results of thermal analysis of the weight of CNT-(CO)- TESPT sample, this material began to decompose at about 3990C and occurred strongly at 446.63oC lasting until 684.26oC. Starting decomposition temperature low as well as maximum first decomposition is low of organic groups attached to the surface of CNT as well as the poorly structured components of CNT begin to decay. The corresponding decomposition of the amino group and separation of sulfur atoms according to the reaction [8]: (CNT-COO)3Si(CH2)3S4(CH2)3Si(OH)3  Ct 0 (CNT-COO)3Si(CH2)3S-H Next is the decomposition process of CNT and its heat-stable components. The process lasts until about 750oC, the volume does not change anymore, at this temperature the volume loss of the whole sample is 23.31%, so that can calculate the content of the preliminary group -(CO)- TESPT grafting on CNT surface is 9.81%. Comment: From the research results obtained shows that: - By alkyl reaction Fridel Craft has assembled PVC on the surface CNT with content PVC composite is about 23.0%. - By the surface reaction of Fischer esterification CNT (oxidized) by TESPT or PEG, 23.13% of group (-CO)-PEG and 9.81% -(CO)-TESPT on CNT surface. 3.1.2. Denatured nano additivesilica 3.1.2.1. Determine the optimal concentration of silane The infrared spectrum of Bis- (3-trietoxysilylpropyl) tetrasulphite (TESPT) is shown in figure 3.2. Figure 3.11: FT-IR of Bis-(3-trietoxysilylpropyl) tetrasulphite (TESPT) From figure 3.11, it was found that, in the range of 4000 - 400cm-1, TESPT has a number of characteristic absorption bands, namely: in the wave number of 3000 - 2800cm-1, there is a fluctuation of the etoxy group, the number of waves from 1200-1000cm-1 asymmetrical stretching oscillations of C-O-Si, 1000 - 600cm-1 with stretching oscillation of C - C and oscillating symmetry of C - O - Si, under 500cm-1 with knives Dynamic deformation of C - O - Si. The oscillations of TESPT at 2990cm-1 and 1395cm-1 are asymmetric and symmetrical strain fluctuations of the methyl group (-CH3) in ethoxy. Pic 2883cm-1 is the asymmetric oscillation of C-H in CH3. Pic 1445 and 1395cm-1 are respectively asymmetric deformations of C - H in methylene (CH2) and methyl groups. 9 Figure 3.12: FT-IR spectrum of nanosilica Figure 3.13: FT-IR spectrum of nanosilica denatured TESPT at different concentrations - In the survey concentration range, the optimal concentration of silane in order to denatured nanosilica is 2%. - Continuing to rely on infrared spectra, comparing the intensity of peaks at 2930cm-1 and 2860cm-1, specific for C-H, the reaction time is 4 hours; reaction temperature 300C; - Size of silica particles after denatured: Table 3.5: Particle size distribution of nanosilica has been denatured % < 5 25 50 75 95 Size (  m) 0,05 0,11 0,15 0,28 0,88 Figure 3.21: Particle size distribution of nanosilica after denatured The surface morphology of nanosilica particles before and after denatured is described in figure 3.22. a) Nanosilica b) Nanosilica denatured TESPT Figure 3.22: TEM images of nanosilica particles and denatured by TESPT 10 The TEM image in Figure 3.22 can be seen, after denaturing the nanosilica particles less agglomeration, leading to the reduction of particle aggregation size. The results are consistent with the results of particle size analysis in the above section. 3.1.3. Denatured nanoclay The Nanoclay modified with HH1 (DTAB:BTAB:CTAB molar ratio of 30:5:65) is the most effective. There are basic distance characteristics d=18.6nm, highest organic matter content (21.3%), high degree of solids in solvents. 3.2. Research and manufacture rubber nanocomposite materials based on rubber, reinforced rubber blend with nano additives 3.2.1. Effect of nano content on the mechanical properties of materials 3.2.1.1. Effect of unmodified nano content on the tensile strength of the material Nano (nanosilica (NS); carbon nanotubes (CNT); nanoclay (NC) are reinforced for the NR and rubber blend in different survey content from 1 to 10 pkl. Figure 3.24: Tensile strength of materials using non-denatured nano Figure 3.25: Length of elongation of nanomaterials not yet denatured From the results in the table and the figures above, the content of nano additives is suitable for each specific material background as follows: - For NR substrate, the suitable reinforcement nanosilica content (NS) is 3pkl, resulting in maximum tensile strength and elongation when breaking. - For rubber base blend NR/NBR nanosilica content reinforced at 7pkl, resulting in tensile strength and elongation at maximum breaking. - For rubber base blend NR/CR content of nanosilica with appropriate reinforcement at 5pkl, resulting in tensile strength and elongation at maximum breaking. - For rubber base blend NR/NBR content of CNT reinforced at 4pkl, resulting in tensile strength and elongation at maximum breaking. - For rubber base blending NR/CR with appropriate reinforcement nanoclay content at 5pkl, resulting in maximum tensile strength and elongation when breaking 3.2.1.2. The effect of nano additive denatured on the mechanical properties of materials Samples of materials are compared accordingly on the charts below: 11 Figure 3.26: Comparison of tensile strength of materials using denatured and non-denatured nano Figure 3.27: Comparison of elongation at breakage of materials using denatured and non-denatured nano From figure 3.26 and figure 3.27 charts, the drag properties of superior denatured nano-materials compare to when not denatured 3.2.2. The influence of content nano on the figure structure of material 3.2.2.1. Figure structure of Thai NR material using nanosilica denatured and not denatured: The NR of 3 pkl and 7 pkl nanosilica has not been and has been denatured by TESPT as shown in figure 3.30 and figure 3.31. a. NR/3pkl nanosilica b. NR/3pkl nanosilica modified TESPT Figure 3.30: Cutting surface FESEM image NR / NS 3pkl nanosilica a. NR/7pkl nanosilica b. NR/7pkl nanosilica modified TESPT Figure 3.31: Cutting surface FESEM image NR / 7 pkl nanosilica From figure 3.30 and figure 3.31, it was found that, in all samples, nanosilica particles dispersed in the NR substrate were mostly in sizes larger than 100nm. In materials reinforced with non-denatured nanosilica (Figure 3.30a) nanosilica particles are dispersed more steadily, even with particles up b a a b 12 to 1 m in diameter. Meanwhile, in reinforced materials 3pkl nanosilica denatured by TESPT, nanosilica particles are more evenly dispersed and have particles below 100nm (Figure 3.30b). In denatured material samples of 7pkl of non-denatured and denatured nanosilica, nanosilica particles are poorly dispersed and there appear to be quite a large set of particles in both cases (m-Figure 3.31). 3.2.2.5. Structure of figure thai model rubber blend materials NR/CR to strengthen organic nanoclay: On Figure 3.35 is a snapshot of the cut surface of some material samples from them. From the FESEM image, when the low content nanoclay (5pkl) dispersed nanoclay particles in rubber blend are quite uniform, the particle size is quite small only from a few hundred nanometers. Figure 3.35: FESEM photo cut surface of rubber materials NR/CR/nanoclay (a) 5 pkl nanoclay; (b) 10 pkl nanoclay The figures below are X-ray diffraction diagram of nanoclay and denatured HH1 nanoclay material HH1. Figure 3.37: X-ray diffraction scheme of NR/CR containing 5pkl nanoclay HH1 Figure 3.38: Sample TEM image of NR / CR containing 5pkl nanoclay From the X-ray diffraction scheme in Figure 3.37, the reflection peak (d001) of nanoclay after being dispersed into rubber blend NR/CR, the distance of nanoclay increased strongly, approximately 4.08 nm (initial base distance d001 = 1.86nm) with 2 angle = 2,2o. This result shows that the structure of nanoclay layers has been changed and transformed into an interlayer structure in rubber blends. This is also evidenced by TEM image in Figure 3.38. a b 13 3.2.3. Effect of nano additive on thermal properties of materials 3.2.3.1. Effect of nanosilica on the thermal properties of NR material 50 100 150 200 250 300 350 400 450 500 550 600 650 700 0 20 40 60 80 100 Nhieät ñoä( o C) TG/% DTG/(%/phuùt) Toån hao khoái löôïng:93,80% 358.18 0 C, -11,15%/phuùt -12 -10 -8 -6 -4 -2 0 100 200 300 400 500 600 700 0 20 40 60 80 100 Nhieät ñoä ( o C) TG/% 363.45 0 C , -11.23%/phuùt Toån hao khoái löôïng: -92.84% -12 -10 -8 -6 -4 -2 0 DTG(%/phuùt) Figure 3.40.a: TGA schema of NR/3pkl nanosilica samples Figure 3.40b: TGA schema of NR / 3 pkl nanosilica denatured sample by TESPT The mechanism of linking between nanosilica denatured by TESPT and rubber substrate can be described as follows (figure 3.42): Figure 3.41: Illustration of the reaction between NR and nanosilica denatured TESPT This bonding makes the material structure more rigid than the temperature and the highest decomposition temperature is higher than the larger compare model using non-denatured nanosilica (up to 2,850C and 5,270C respectively). This is also the reason for the mechanical properties of materials increasecao. 3.2.3.2. Effect of nanosilica on the thermal properties of rubber blend materials * Thermal properties of rubber blend NR/NBR reinforced nanosilica * Thermal properties of rubber blend NR/CR system to strengthen nanosilica * Thermal properties of rubber blend NR/CR system for nanoclay reinforcement: * Thermal properties of rubber blend NR/NBR reinforced CNT. In general, when using nano additive denatured for natural rubber and rubber blend substrates, the thermal properties of the fabric are positively affected. When there is a nano additive surface in the rubber base material that shields the impact of heat for rubber elements, it has increased the stability and thermal durability for materials. 3.3 Research, manufacturing nanocomposite rubber materials based on rubber blend carbon black reinforcement combined with nano additive Silica Silica 14 3.3.1. Combine nano silica and carbon black to reinforce natural rubber 3.3.1.1. The effect of content on black carbon on the mechanical properties of materials When the carbon black content increases: tensile strength of the material increase fast, the abrasion resistance resistance increases such as only a certain limit of 25pkl and then begins to decrease again. The choice of content carbon black is 25pkl used in order to conduct further surveys. 3.3.1.2. Effect of nanosilica on the physical properties of materials The results of examining the effect of content nanosilica on the mechanical properties of 25pkl carbon black NR materials are presented in Table 3.16 below: Table 3.16: Effect of content nanosilica on the mechanical properties of NR material containing 25pkl carbon black Property Content nanosilica (pkl) Tensile strength (MPa) Elongation tensile at break (%) Abrasion level (cm3/1,61 km) Stiffness (Shore A) 0 21.40 643 0.985 56.0 3 22.94 663 0.948 57.1 5 23.72 655 0.944 58.3 7 19.81 632 0.973 58.8 Notice that the tensile strength, abrasion resistance, elongation and elongation of the material peaked at optimal nanosilica content when combined with carbon black for NR material is 5pkl. 3.3.1.3. Figure structure of the material In order to evaluate the morphological structure of materials, we use scanning electron microscopy (SEM) in order to capture fracture surfaces of some typical material samples. Results are presented in figures 3.44, and figure 3.45 below: Figure 3.44: Surface SEM image fracturing NR/25pkl carbon black material sample Figure 3.45: Surface SEM image of fractured material NR/25pkl carbon black/5pkl nanosilica Realizing that, in the natural rubber model, there are 25pkl carbon black, carbon black filler is distributed relatively evenly on the surface of the NR platform, but there is a convex surface. When 5pkl nanosilica is added to the sample, the sample surface retains the regular distribution of such NR 15 fillers as 25pkl carbon black reinforcement, but the surface is less convex. This proves that with small content nanosilica still maintains the uniform distribution of the components in the material block, the components in the combination are better connected. Thus, the fractured surface of the material is less convex, concave, indicating the figure structure of the tight material. 3.3.1.4. Effect of denatured process on thermal stability of materials Table 3.17: Starting decomposition temperature and mass loss of quantitative materials Sample Starting decomposition temperature [oC] The strongest decomposition temperature 1 [oC] Weight loss to 440 0C [%] NR/25pkl carbon black 302.2 374.05 66,359 NR/25pkl carbon black/5pkl nanosilica 303.6 374.07 65.829 NR/25pkl carbon black/10pkl nanosilica 299.0 375.06 62.625 Realizing that the material's durability is a little bit higher when the content of nanosilica denatured is 5pkl (starting decomposition temperature increase of 1.4oC). When the nanosilica content is too high (10pkl) starting decomposition temperature of the material falls sharply (4oC reduction). This can be explained by the fact that the nanosilica content in the rubber component is too large, which leads to the formation of separate phases (such as the figure state structure indicated), reducing the tight structure of the material leading to The thermal stability of the material decreases. 3.3.1.5. Environmental stability of materials The aging coefficient of the material is determined according to TCVN 2229-77 after testing in the air and salt water 10% at 70oC after 96h is shown in Table 3.18. Table 3.18: Aging coefficient of the material after testing at 70oC after 96 hours of testing in air and 10% saline Aging factor Samples In the air (%) 10% salt water (%) NR/25pkl carbon black 0.80 0.80 NR/25pkl carbon black/5pkl nanosilica 0.86 0.85 Realizing that, when denatured with the NR reinforcement of 25pkl carbon black with content nanosilica is appropriate (5pkl compare to NR) has made the increase of environment for materials (aging coefficient in air and salt water 10% both increases significantly). This can be explained by the presence of nanosilica which makes the material more structured, preventing the effect of oxygen in the air as well as other aggressive elements, making the increase environmental durability for the material. 3.3.2. Combine nano additive silica, nanoclay and carbon black to enhance the blend of natural rubber and rubber cloropren 16 In rubber processing technology, people use many types of reinforcing fillers such as black carbon, silica, clay, dolomite, ... However, in each specific rubber and additive system, the fillers have influence and content Different optimizations. In this study, the nano additive used includes: nanosilica (NS), carbon black (CB) and nanoclay (NC) as reinforcement for the rubber blend system NR/CR (70/30). 3.3.2.1. The effect of content on black carbon on the mechanical properties of materials Results of the survey are presented in figures 3.47 and 3.48 below. Figure 3.47: Effect of CB content on breaking strength and elongation at breaking of materials Figure 3.48: Effect of content of CB on hardness and abrasion of materials Notice that, when content carbon black (CB) increasen, tensile strength of increaseand material reaches maximum value at content carbon black is 30pkl. Own stiffness of increasing material gradually with the increasecontent carbon black The change of these values is because when the CB content is within the optimal limit of CB particles forming its network, it also separates the large rubber molecules in all directions to form a hydrocarbon network. Two interwoven networks, hooked together to form a rubber structure - the filler continuously enhances the mechanical properties of the material. From the above results, the combined carbon black content is 30pkl selected to order in order to continue research. 3.3.2.2. The effect of nanoclay content replaces nanosilica to the mechanical properties of the material Table 3.19: The effect of nanoclay content replaces nanosilica to the mechanical properties of the material Sample (silica/clay) Tensile strength (MPa) Elongation tensile at break (%) Stiffness (Shore A) Residual extension (%) SC0 (5/0) 22.79 608 61.4 14.0 SC1 (4/1) 23.14 632 61.8 13.8 SC2 (3/2) 24.56 653 62.0 13.2 SC5 (0/5) 22.85 607 63.2 12.0 Symbols of samples: SC0: NR/CR/5NS-30CB; SC1: NR/CR/4NS-30CB-1NC; SC2: NR/CR/3NS-30CB-2NC; SC5: NR/CR/30CB-5NC 17 Results on table 3.19 show that tensile strength and elongation when the material's breakage reaches the maximum value when nanosilica content is replaced with 2% nanoclay. Then, further increasecontent nanoclay replacement, these properties of the material again reduced. Particularly stiffness of materials increases and the residual extension is slow when the replacement content nanoclay increases. This change in properties can be explained: on the one hand, nanoclay has better reinforcement effect than compare to nanosilica. On the other hand, with content 2% nanoclay in the material block can create nano additive resonance effects and thus, tensile strength and elongation when breaking of the material is improved. 3.3.2.3. Effect of denatured process on thermal stability of materials Thermal durability of materials is evaluated by thermal thermal analysis (TGA) method. Results thermal analysis of models based on rubber blend NR/CR are shown in figures and tables below: Figure 3.50: TGA chart of material sample NR/CR/5NS-30CB Figure 3.51: TGA sample material chart NR/CR/3NS-30CB-2NC Realizing that the thermal stability of rubber blend material was significantly improved when there was 30pkl of black coal through the decomposition start temperature of the material increased sharply, from 280oC to 300oC. When combining 2% nanosilica replacement with nanoclay, the thermal stability of the material is also improved (the decomposition start temperature increases by 6oC, the highest decomposition temperature increases by more than 3oC, percentage of mass loss to 600oC of materials also decreased from 92.34% to 90.41%) Table 3.20. Table 3.20: Analysis results of TGA sample rubber blend NR/CR with nano additives Samples Starting decomposition temperature [oC] The strongest decomposition temperature 1 [oC] The strongest decomposition temperature 2 [oC] Weight loss to 6000C [%] NR/CR/5NS 280.0 347.3 443.1 91.92 NR/CR/5NS-30CB 300.0 347.4 447.8 92.34 NR/CR/3NS-30CB-2NC 306.0 350.7 446.5 90.41 3.3.2.5. Research Morphological structure of materials Morphological structure of rubber blend material NR/CR/3NS-CB-2NC nanocomposite is determined by methods such as emission field scanning 18 electron microscope (FESEM) and X-ray diffraction. Figure 3.53 below is a cut surface FESEM image of the material sample. Figure 3.52 Material cut surface FESEM image NR/CR/3NS-30CB-2NC nanocompozit From FESEM images, nano-additives were dispersed in the rubber substrate quite evenly with a relatively small particle size below 100nm. Results of X-ray diffraction analysis of modified nanoclay samples by mixture and sample NR/CR/3NS-30CB-2NC: VNU-HN-SIEMENS D5005 - Mau Clay Na+ 38 File: Huynh-Toan-Giap-DHBK-Clay Na+ 38.raw - Type: 2Th/Th locked - Start: 0.400 ° - End: 10.000 ° - Step: 0.020 ° - Step time: 1.5 s - Temp.: 25.0 °C (Room) - Anode: Cu - Creation: 04/22/08 20:32:28 L i n ( C p s ) 0 1000 2000 3000 4000 5000 2-Theta - Scale 0.5 1 2 3 4 5 6 7 8 9 10 d = 1 8 . 6 3 1 Figure 3.53: X-ray diffraction diagram of nanoclay HH1 Figure 3.54: X-ray diffraction diagram of NR / CR / 3NS-30CB-2NC From the X-ray diffraction diagrams, the reflection peak (001) of nanoclay appears at angle 2 = 5.2o with the base distance d = 1.86 nm (Figure 3.53). With this base distance, the layers of the original nanoclay remain in order. After being dispersed into rubber blend NR/CR, the base distance of nanoclay increased to approximately 4.14 nm with the angle of 2 = 2.1o (Figure 3.54). This result shows that the structure the layers of nanoclay have been changed and changed into interlayer structures in the rubber base. Therefore, the physical and mechanical properties of the material improved markedly. 3.3.3. Combined study of enhanced nano silica and black coal for blends of natural rubber and nitrile butadiene rubber (NR/NBR) 3.3.3.1. Effect of black coal content on the mechanical properties of materials The used black coal content surveyed in the range of 20pkl-35pkl according to the result of the rubber content at 25pkl ratio is more advantageous in terms of elongation when breaking and abrasion resistance. 19 Based on these results, the content of black coal of 25pkl is used to carry out the next survey. 3.3.3.2. Effect of nanosilica on the physical properties of materials The survey results of the effect of nanosilica content on the mechanical properties of materials from NR with 25pkl of black coal are presented in Table 3.23 below. Table 3.23: Effect of nanosilica content on mechanical properties of NR material containing 25pkl of black coal Property Content nanosilica (pkl) Tensile strength (MPa) Elongation tensile at break (%) Abrasion level (cm3/1,61 km) Stiffness (Shore A) 3 23,12 670 0,925 60,2 5 24,82 668

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