Carboxyl‐terminated butadiene acrylonitrile CTBN liquid rubber is also used to manufacture advanced composite materials, make binder, fillings, environmentally resistant paint systems …
Trang 1MINISTRY OF EDUCATION AND TRAINING MINISTRY OF NATIONAL DEFENSE ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY
DANG TRAN THIEM
RESEARCHING TO MANUFACTURE CARBOXYL TERMINATED BUTADIENE ACRYLONITRILE RUBBER
IN THE APPLICATION OF MAKING BINDERS AND ADHESIVES
Specialization: Organic Chemistry Code: 9 44 01 14
SUMMARY OF PhD THESIS IN CHEMISTRY
Hanoi - 2019
Trang 2The work has been completed at:
Academy of Military Science and Technology
Scientific Supervisors:
1 Associate Prof PhD Chu Chien Huu
2 Prof PhD Do Quang Khang
Reviewer 1: Prof Dr Nguyen Dinh Thanh
University of Science, Vietnam National University, Hanoi
Reviewer 2: Assoc Prof Dr Dang Viet Hung
Ha Noi University of Science and Technology
Reviewer 3: Assoc Prof Dr Ninh Duc Ha
Academy of Military Science and Technology
The thesis was defended in front of the Doctoral Evaluating Council at Academy level held at Academy of Military Science and Technology at 8:30 AM, date … mon … , 2019
The thesis can be found at:
- Academy of Military Science and Technology Library
- National Library of Vietnam
Trang 31INTRODUCTION
1 Necessity of the thesis
Carboxyl‐terminated butadiene acrylonitrile (CTBN) liquid rubber is researched and developed to serve military sectors as materials for making adhesives for mixed propellant of various types of rocket engines Carboxyl‐terminated butadiene acrylonitrile (CTBN) liquid rubber is also used to manufacture advanced composite materials, make binder, fillings, environmentally resistant paint systems …
Carboxyl‐terminated butadiene acrylonitrile (CTBN) liquid rubber has many precious properties but not exist in other polymers, especially in the application of making binder and adhesives for mixed rocket fuel The import of Carboxyl‐terminated butadiene acrylonitrile (CTBN) liquid rubber meeting technical requirements to make binder and adhesives is very difficult Currently, there are not any unit investing in researching and producing this type of rubber Therefore, the research to synthetize Carboxyl ‐ acrylonitrile (CTBN) liquid rubber is considered to be a scientific and practical research to satisfy urgent requirements of national defense and people’s life
2 Objective of the thesis
The topic: “Researching to manufacture Carboxyl‐terminated butadiene acrylonitrile in the application of making binder and adhesives”
is execute for the objective of: Building up general conditions and processes and manufacturing Carboxyl‐terminated butadiene acrylonitrile, capable of applying to make binder and adhesives
3 Research content of the thesis
- Researching to select suitable materials and methods to synthesize Carboxyl‐terminated butadiene acrylonitrile
- Researching to determine conditions to synthesize nitrile-butadiene rubber with carboxyl head terminal group
- Determining conditions for refining and preserving liquid rubber products
- Applying nitrile-butadiene rubber with carboxyl head terminal group to make binder and adhesives
4 Scientific and practical significance and new contribution
to the thesis:
Research results of the thesis has opened a new research direction in the field of synthesizing polymer materials, making binder and adhesives with practical applications to proactively manufacture high-quality materials for assuring of technical equipment weapons in the army and people’s life
Trang 4* The research method
In order to implement aforementioned contents, the thesis has used the method of polymers compound processing, the method of synthesizing polymers compound (original copolymer) and modern chemical and physical analysis methods (FTIR, NMR, GPC), methods of analysis and measurement of appropriate technical features to survey the technical specifications of the product
* The layout of the thesis
In addition to the introduction and conclusion, the thesis consists of three chapters, references and appendices
Chapter I: Overview: Analyzing and evaluating domestic and overseas research situation
Chapter II: Research method and experiment: Presenting synthetic process, methods of surveying and measuring features and quality indicators of the product
Chapter III: Research results and discussion: This chapter focuses on presenting research results as obtained during the implementation of thesis
CONTENT OF THE THESIS Chapter I: OVERVIEW
The domestic and foreign research situation, related issues as well as contents to be addressed in the thesis have been analyzed and evaluated Chapter II: RESEARCH METHOD AND EXPERIMENT
2.1 Materials and chemicals
Chemicals of Merck-Germany: acrylonitril, ≥ 98%, the initiator
4,4’-Azobis(4-cyanovaleric axit), ≥ 98%, reactive solvent tert-butanol,
PbO, 99,2% Russian chemicals: nitrile-butadiene rubber containing carboxyl group in the head CKH-10 KTP, epoxy resin ЭД -20 Korean chemicals: epoxy resin YD-128, polyetheramine Chinese chemicals: toluen
AR, etanol AR, metanol AR, axeton AR, terahydrofuran AR, metyletylketon AR, acid HCl 35,5%, KOH AR, H2O2 30%, NaNO2 98% Other chemicals: rubber CKH-18, Lanxess, 1,3-butadien, 99%, BHD England, the chemicals for analysis, N-phenyl-2-naphhtylamin
2.2 Equipment and devices
- High pressure equipment system to synthetize Carboxyl‐terminated butadiene acrylonitrile (CTBN) liquid rubber by monomer copolymer method
- Reactive cutout system by agent including: 3-neck glass flask 1000 ml; drip funnel 200 ml; stirrer 1200 revolutions/minute generating reflux; water stove
- Other experimental devices: electronic scale, argon gas tank 99.9%,
Trang 53oil-ring vacuum machine, acrylonitril distillation equipment, planetary crushing and mixing equipment with the scale of 200g/batch
2 3 Experimental method
2.3.1 Method of making liquid rubber using cutout agent
Dissolving 25 g rubber NBR and 0,25g surfactant in 250ml Toluen in 3-neck glass flask with capacity of 1000ml Synchronous installation with stirrer, water stove Raising the reactive system to 60 ºC, dropping solution NaNO2 40% in the reactive system, then dropping solution H2O2 30% at a rate of 30 drops/minute Maintain reaction time for 72 hours, cool down and disassemble the product Precipitate and wash the product in large quantities of distilled water Dry the product for 24 hours in a vacuum cabinet to a constant volume
2.3.2 Method of synthetizing Carboxyl‐terminated butadiene acrylonitrile (CTBN) liquid rubber by copolymer method
Step 1: Cooling system: Initially lower the flask temperature and chemicals included 1,3 butadien, acrylonitril, tert-butanol to -5 ºC
Step 2: Removing oxygen in the flask by vacuum aspiration
Step 3: Saturating the system with argon, loading argon inert gas into the flask to pressure 1,2atm
Step 4: Feeding
Loading liquid butadiene, acrylonitril, initiator solution into the quantitative bottle and then put it into the reactor with the connecting funnel in valve 3, the process of filling argon gas to prevent air from diffusing into the bottle
Step 5: Executing the reaction
Checking the valves of the reactor system, stir and raise the heat, maintain the temperature of the reaction system at the required temperature with the EG circulating pump as heated in flask 8
When the reaction reaches the temperature as observed at the thermometer, gradually add amount of mixed catalyst above so that the speed of adding the size of 10ml catalyst solution/hour The catalytic supplementation process is conducted as follows:
For the catalyst into the flash 3, open valve 3, valve 5 and valve 6 to adjust the opening of the valve 6 so that the drip speed as calculated During the initial reaction the pressure will increase then stabilize due to polymerization, the determination time of molecular mass reaches 3,000-5,000 dvc as the required time to stop the reaction
Step 6: Stop the reaction: Removing non-reaction monomer, cooling the reaction and disassemble the product
Trang 642.3.3 Refining method:
The copolymer product is precipitated in pure methanol The product part of obtained polymer insoluble in methanol will separate the layer, the tert-butanol and the initiator azobis solvent shall dissolve in methanol and separate the upper layer The product is separated by repeated washing and continue to wash methanol The solvent mixed in the product
is chased by vacuum deposition method and the product is finally put into a vacuum drying cabinet incorporating heating at 50ºC with a pressure of -1 atm from 24 hours to 48 hours Obtained product is a colorless, moderate viscosity liquid
2.3.4 Application of CTBN rubber to use as binder and adhesives
2.3.4.1 Application of CTBN rubber to be the binder
a) Method of making binder
b) Processing metal rubber paste
2.3.4.2 Application of CTBN rubber to be the adhesives for the mixed solid propellant fuel
a) Method to determine the solidification ability of materials
b) Method to research rubber application as adhesives
2.4 Research Methodology
- Survey method: Including modern analytical methods such as: Infrared spectrum, TGA thermal analysis, nuclear magnetic resonance method 1
H NMR, 13C NMR, photography of Scanning Electron Microscope (SEM)
- Evaluation method: Determining kinematic viscosity according to TCVN 3171-1995; determining molecular mass by Gel permeation chromatography (GPC); determining iodine index by titration method; method of “determining total nitrogen by method Kjeldahl”; content of total carboxyl group of of rubber sample as determined according to TCVN 6127-2010; tensile strength, elongation to break and residual extension determined
by TCVN 4509:2006; sliding tensile strength determined according to US federal standards: ASTM-D-816-55 or GOST: 14759 – 69; balance pull force determined according to TCVN - 1596 - 74; gel content is determined using the soxhlet kit;
Chapter III: RESULTS AND DISCUSSION
3.1 Results of inspection and refining of raw materials
3.1.1 Results of raw material research and inspection 1,3 - butadien The butadiene gas tanks are tested for purity by mass spectrometry before conducting liquid rubber synthesis reaction
According to the chromatographic results analyzing material sample containing only one component at retention time of 1,759 minutes, but no
Trang 75other pic were detected on the gas chromatography spectrum Combining with the mass spectrometry results to receive signal M+ by 55 and molecular fragments different from m/z = 36; 37; 38; 39; 40; 50; 51;52; 53; 54;55 to enably confirm to be 1,3-butadien
3.1.2 Research and inspection resuls of initiator 4,4’-Azobis cyanovaleric axit)
(4-Results of analyzing proton nucleus magnetic resonance spectroscopy 1
H NMR, 13C-NMR samples of 4,4’-Azobis (4-cyanovaleric acid) are shown in Figure 3.2 and Figure 3.3 1H NMR spectrum with peak 1,645 (3H of CH3); 2.33 ÷ 2.19 (2H, H-2); 2,39 ÷ 2,359 (2H, H-3); 12,378 (H, COOH) 13C-NMR spectrum has pic 22.86 of CH3; 28.69 of C-2; 32.47 of C-3; 71.73 of C-4; 118.05 of C-5; 172,61 of C-1 Attributing resonance signals with protons and carbon allows us to confirm that the sample is 4,4’-Azobis (4-cyanovaleric acid) has the molecular structure as follows:
3.1.3 Results of acrylonitril purification research
After refining acrylonitrile, testing some specific characteristics of the materials Results are presented in Table 3.1:
Table 3.1: Physical and chemical properties of acrylonitrile after refining
1 Appearance: Colorless liquid, no mechanical impurities
3.2.1 Determining molecular mass of CKH-10KTP
The result determining molecular weight showed that: analytical polymers have the number average molecular mass Mn = 2948 and the weight average molecular mass Mw = 3436, the multi-dispersion Mw/Mn = 1,165 is quite small, showing that the rubber distributed molecular mass relatively equal This means that solid polymerization shall give good mechanical strength
Trang 863.2.2 Determining molecular structure of CKH-10KTP rubber
In the IR spectrum (Figure 3.5), the results of analyzing
characteristic vibrations are observed that CKH-10KTP rubber has the structural characteristics of nitrile-butadiene rubbere with cacboxyl group such as: acrylonitril group with characteristic vibration frequency
at 2238 cm-1, double bond C=C of butadien with characteristic vibration frequency at 1639 cm-1 Bond of C=O of cacboxyl group with characteristic vibration frequency at 1713 cm-1, -OH group with characteristic vibration frequency at 3431 cm-1 Characteristic vibration frequency at 913-968 cm-1, of cis, tran butadien
Figure 3.5: Infrared spectrum CKH-10KTP rubber
Results of spectrum analysis 1H NMR, 13C-NMR: The results showed that the chemical shift proton H on the spectrum 1H NMR, 13C-NMR of CKH-10KTP rubber has characteristics of molecular chain copolyme butadien acrylonitril: acrylonitril group, olefin group, vinyl
Thus, through the research determing molecular mass, 1H NMR, 13
C-NMR spectrum possibly affirm that, CKH-10KTP liquid rubber is oligomer with the number average molecular mass Mn=2948; the weight average molecular mass Mw= 3436 and has the main molecular structure as follows:
3.3 Results of research generalizing CTBN rubber by cutout chain in solution using agent H2O2/NaNO2
The thesis has conducted cutting rubber chain NBR-18 by the agent
H2O2/NaNO2 toluene solvent medium, using an assay solvent of tetrahydrofuran, reaction temperature 60 ºC, time of 72 hours Results
Trang 97determining molecular weight showed that: Polymer analysis has the number average molecular mass Mn = 9804, the weight average molecular mass Mw = 13.858
Infrared absorption spectrum of cutout product with redox agent
H2O2/NaNO2 (Figure 3.10), with characteristic vibration of new groups at
3440 cm-1, 1721 cm-1 showing the appearance of new groups –OH, C-O-C, C=O Increasing in absorption intensity in the zone 3440 cm-1 showed that, hydroxyl groups are newly formed Spectral lines in the zone 1590-1609
cm-1 appears with very weak strength, proving that the circularisation process occurs lower than when cutting with pyrolysis
Figure 3.10: Sample infrared spectrum NBR cutout chain by H 2 O 2 /NaNO 2
Results of analyzing proton nucleus magnetic resonance spectroscopy (Table 3.6) showed that the proton-specific signals of chain oxidized NBR rubber molecule showed olefin and acrylonitril chains
Table 3.6: Signal matching 1 H NMR and Combined signal 13 C-NMR and
bonding characteristics of oxidized rubber
No Proton characteristics of the bond δH (ppm)
Trang 10Table 3.7: Signal matching 13 C NMR and Combined
and bonding characteristics of oxidized rubber
No Carbon characteristics of the bond δc (ppm)
The thesis used H2O2/NaNO2 agent to oxidize for rubber cutout NBR
18 with molecular mass average several hundred thousand, elastic solid state The obtained product has a mass molecular average Mn = 9804; Mw
= 13.858, viscous liquid state The cutout process by H2O2/NaNO2 agent does not change the main chain of the original NBR 18 rubber The appearance of a new hydroxyl functional group at the two ends of the chain, a relatively small average molecular mass is an important result to expand the metabolism and subsequent application
3.4 Research generalizing CTBN rubber according to copolymer method The process of synthetizing butadien rubber with carboxyl head terminal group is executed with the original copolymer monome butadien and acrylonitril in tert-butanol solvent, the initiator is 4,4’-azobis(4-cyanovaleric axit)
3.4.1 Effect of the initiator content
The molar ratio of initial materials is agreed with butadien:acrylonitril: tert-butanol = 5,56:0,57:4,58, change of mol 4,4’-azobis(4-cyanovaleric axit) reacting as in Table 3.8
1,3-Table 3.8: Reaction to content 4,4’-bis azo valeric axit different
Sam
ple
Butadien Acrylonitril
cyanovaleric axit) Ter-
4,4-azobis(4-butanol Weight
Trang 113.4.2 Effect of temperature
In order to survey the effect of temperature, the rate of reactants was selected according to the sample M1 in Table 3.8, the temperature range varies from 50 to 90ºC (Table 3.10) At a temperature of 50ºC, the reaction
is slow, the efficiency is low due to the low temperature of initiation reaction At about 70-80 ºC the reaction is stable At 80ºC, the reaction efficiency reached the highest of 19.5% When continuing to raise the temperature to 90ºC, the reaction occurred quickly with a large amount of heat generated but the reaction efficiency decreased to only 10.5%
Table 3.10: Effect of temperature on reaction efficiency
3.4.3 Effect of reaction time
Table 3.11: Gather results of sample GPC analysis according toreaction time
Trang 1210Within about 20 hours of reaction, the polymer was obtained in a bright yellow liquid When extending the reaction time, the weight average molecular mass Mw increases gradually from 3088 to 9040, the number average molecular mass Mn increases from 2645 to 8403 (Table 3.11), and the multi-dispersion of the system also decreases from 1,176
to 1,075 proving that the reaction occurs in accordance with the rule: at the beginning of the chain development phase, the molecular mass continuously increases, when the system reaches a stable state, the active free radicals are about 15 hours, the molecular mass does not increase but increases its uniformity in molecular mass distribution When the reaction stops at the time of 5 hours, the polymer is obtained with a molecular mass of about 3088 suitable for the product required
by Russia (Mn = 2700-3000)
3.4.4 Effect of the substance ratio involved in the reaction
In the research of adjusting acrylonitril content, fixing the reaction temperature parameters of 80ºC, reaction time by 5 hours (Table 3.12) Results in Table 3.13 showed that the input acrylonitrile increased leading to the increased acrylonitril group and molecular mass Viscosity of the reaction product increased strongly due to the increase in the content of the –CN group in polymer chain, leading to an increase in the density of the polarization interaction groups
Table 3.12: Ratio of reactants when changing acrylonitril content
Sample Butadien Acrylonitril
4,4-azobis(4-cyanovaleric axit)
Ter- butanol Weight
Trang 1350oC, Pa.s
Observation
Reaction performance,
3.4.5.1 Results of infrared spectrum analysis:
The results showed that most of the characteristic spectral lines in synthetic acrylonitrile butadiene rubber product is coincided with specific spectral line in Russian product (Figure 3.21)
Figure 3.21: Infrared spectrum of sample CTBN synthetized,
Federal Republic of Russia