Nghiên cứu gia cường màng phủ nhựa epoxy bằng ống nanocacbon biến tính và graphen oxit tt t

1 PREFACE Introduction Nowadays the polymer coatings is considered that the advanced method of anticorrosion protection and decoration for materials surfaces, which were used in life and industry [21] There are many industrial areas, that have been required to protect for corrosion such as manufacturing of automobiles, motorbikes, machines, equipments, construction, transport, air, electronic etc The paint films are necessary and importance so that high the demand for research and development Because of the diversity of technical performances and applicability of industrial products so coatings production have been become a high-priority approach Hence the search and orientation play a part in films creation with properties that have been improved more than the traditional ones According to there 1D and 2D structure Nanocarbon materials have used as a reinforcement agent in the Epoxy resin for protective coatings application for metal surfaces in this thesis The polymer coatings are established by nanostructure materials and binders, which are named as nannocomposite coatings or nanocoatings They have been predicted that provide great features (fire resistance, heat resistance, microbial resistance, anti-fouling, self-cleaning, bactericidal etc.) in addition to the usual features corrosion protection or bonded aesthetic of conventional coatings [26] The addition in polymer binders as a pigment or a filler in order to improve physico-mechanical performances and corrosion protection for paint coatings is crucial in the paint coating technology Therefore, this work presents the use of nanocarbon materials to fill in epoxy binder for application as anticorrosion coatings for metal surfaces The doctoral thesis’s name is "Study on reinfortment of the modified carbon nanotubes and graphene oxide for epoxy coatings” The objects and research area The thesis’s objects are nanocarbon materials including: 1D strucrure of nanotubes and 2D structure of nanoplates of graphene They have used to reinforce for epoxy resin coatings for metals surfaces corrosion protection The objectives The objectives of this study have been investigating the reinforcement of nanostructure materials of CNTs and GO so that can support high mechanical performances and thermal durability, good corrosion resistance properties for epoxy resin coatings This may be orientated to prepare for the thermal resistance and functional nanopaint films production for corrosion protection of metals surfaces The contents + Investigating the characteristics of modified CNTs products by oxidative method + Investigating the characteristics of GO that were received by synthesi processing from the original material is Graphite + Investigating the ultrasonic conditions for dispersion of NC into Epoxy resin so that the good dispertion state have been obtained + Measuring the curing conditions of NC/Epoxy nanocomposite coatings + Investigating the reinforcement ability for thermal properties and anticorrosion protection performances of NC/Epoxy nanocomposite coatings + Measuring the weight ratio of 1D structure of CNTs and 1D structure of Graphene that the reinforcement ability have been the best Scientific and practicality The scientific of this doctoral thesis has been great that has been showed by modern characteristic methods such as FTIR, XPS, XRD, SEM, HR-TEM, TGA-DTA, DSC and tests of thermal and mechanical properties, corrosion resistace of coatings according to international standards Also it has high applicale ability for with the traditional functions of anticorrosive protection for metals enhanced with thermal-mechanical performances to meet the applications in the harsh conditions, high technique, orientation to fabricate functional nanopaints such as heat resistance and corrosion resistance Outline of the thesis The layout of the thesis is as follows: - Opening: is presented content such as the urgency, the reasons for choosing objectives, contents, scientific and practicality of the thesis - Chapter - Overview: nanocomposite paint coatings, nanocarbon materials (1D structure of CNTs and 2D structure of Graphene) A liture overview of publishcasion of studies on nanocarbon materials related to this thesis This supported a base for option of structure type of nanocarbon that good ability for reinforcement to improve and enhance technicality performances of epoxy resin coatings - Chapter - Experimental methods: Presentation of materials, chemicals and equipments were used in research; Experimental process, characterize methods and technical properties measurements of nanocomposite films - Chapter - Results and discussion: Presenting the results and discussion including: Characteristics of modified CNTs by oxidation with HNO3/HCl mixture and synthesized GO by improved Tour’s method from graphite materials; Investigating the effect on the properties of epoxy coatings of oxidtived CNTs and GO The results showed that thermal mechanical and anticorrosive properties of nanocomposite NC/Epoxy coatings were increased significantly In there the effect of 1D and 2D hybrid structure of nanocarbon have been better than or 1D structure of carbon nanotubes (CNTs) or 2D structure of graphene oxide (GO); Determining dispersion of nanocarbon in Epoxy resin; Investigation of curing conditions for NC/Epoxy nanocomposit coatings - General conclusions: Summary of achievements, new contributions of the thesis, also some recommendations were suggested for next researches - List of published articles of the thesis - References CHAPTER 1: OVERVIEW 1.1 Overview of nanocomposite coatings Introducing concepts, classifications, properties, needs and use of nano-coating films worldwide 1.2 Overview of epoxy resin based coatings Epoxy coatings have been used common for anti-corrosion protection of sea constructions, industrial constructions such as chemicals, steel structures, aircraft, tanks, and primer in internal equipment cars, household appliances etc Epoxy resin types usually have been applied for surfaces protection coatings preparation plastics which have performance on molecular weight of 450-500 (such as Epikote 828, DER 337); 850 - 1000 (such as Epikote 1001, DER 671); 1750 -2025 (Epikote 1007, DER 664) Epoxy coating film with many preeminent features as follows: - Good adhesion thanks to many polar groups in epoxy resin structure - High hardness, flexural strength, good impact resistance - The curing process does not release any auxiliary substances; - Great corrosion resistance, water resistance, acid resistance, alkali resistance, excellent a lot of organic solvents resistance Beside the above advantages, epoxy paint has some disadvantages such as: - High solvents selectivity - Used hardening agents for curing reaction of epoxy resin have been quite toxic, specially amino curing agents [22, 28] 1.3 Overview of nanocarbon reinforcement materials Presenting an overview of the chemical structure, crystal structure, classification and physicomechanical properties of nanocarbon materials They are research objects of the thesis Also an overview of modified methods of NC materials and a review on the literature of published studies on NC modification 1.4 Overview of the researches on nanocarbon material for nanocomposite coatings application In this section, a review on published reports of NC includes: oxidation of CNTs and GO synthesis from graphite material Modification methods of NC were selected in this work that supporting application as a reinforcement for epoxy coating CHAPTER 2: EXPERIMENTAL METHODS 2.1 Materials and chemicals 2.1.1 Materials - Multiwalled carbon nanotubes (MWCNTs) material was producted by Bao Lam Khoa company (Da Nang, Vietnam): purity 96.7%, tube diameters from 20 - 30 nm - Graphite powder was procured from General Pencil Company (USA) - Epotec YD 011X-75 is a solution of unmodified low molecular weight solid diglycidyl ether of bisphenol-A resin in xylene The dissolution of Epotec YD 011 in xylene facilitates handling Epotec TH 7515 is a high viscosity reactive polyamide used as a curing agent for liquid or solution grade epoxy resins such as Epotec YD 515 or Epotec YD 011X75 to produce thermoset adhesives and coatings They are received by Aditya Birla Chemicals Ltd, Rolling 2.1.2 Chemicals - Solvent: Xylene, n-Butanol of Merch - The chemicals include: H2SO4 98%; H3PO4 63%, 36.5% HCl, KMnO4 were produced by Xilong Chemical Factory and Guangdong Guanghua Sci - Tech Co They are pure chemicals for experiments These materials and chemicals are used directly as received N008-N pristine graphene powder was supported by Angstron Materials company (USA); 2.2 Equipments and instruments The used experimental devices and instruments are in the laboratories of the faculty of Chemistry, the University of Danang – University of Science and Technology and University of Education The characterization techniques and the physico-mechanical properties test of NC/epoxy nanocomposite coatings were operated in laboratories of centers, institutes, universities, companies inside and outside campus of Danang of University 2.3 Experimental process and research contents This study was carried out according to the general experimental process is described in Figure 2.1 Figure Diagram of the experimental process 2.4 Experimental methods 2.4.1 Modification method of CNTs CNTs material was modified by HNO3/HCl aqua regia mixture 2.4.2 Synthetic method of GO The modified Tour’s method [3] was used for synthesis of graphene oxide from natural graphite materials 2.4.3 Dispertion method of NC materials in the epoxy resin NC materials were used to produce nanocomposite coatings with a content of 0,1wt% on epoxy resin At first, measured Graphite/GO was dispersed in n-butanol solvent with 1mg/1ml rate using sonication bar for 1h After that, they were mixed in the epoxy binder by a stirrer bar until becoming a homogeneous mixture 2.4.4 Preparation of the coating samples on the steel surface for tests Before applying paint on the surface, NC/epoxy resin mixture were mixed with the curing agent (calculated weight ratio of 10:1 on the epoxy binder) and xylene solvent until becoming a homogeneous mixture After that the resin solution was sprayed on the substrate surfaces by a gun The finally, the promotion was carried for fully curing the epoxy binder to creating the paint films The samples were formed for examination of physicomechanical and anti-corrosion properties Dry paint film thickness of the samples was about 20 - 30 µm 2.5 Research methods 2.5.1 Characterization methods of the nanocarbon materials Fourier Transform Infrared spectroscopy (FTIR) was used to evaluate results of created NC products The crystal structure characterization of them was analyzed by X-ray diffraction (XRD) and performed using a Siemens D5005 X-ray diffractometer Also SEM was employed to analyze morphology of the materials in this work 2.5.2 Thermal analysis methods of NC/epoxy films The used thermal analysis techniques including: Differential scanning calorimetry (DSC), Thermal gravimetric analysis techniques (TGA) and Thermal conductivity coefficient measurement 2.5.3 Characterization methods of the coatings Using physicochemical analysis methods to determine chemical structure (FTIR); Morphological structure (SEM) 2.5.4 Physico-mechanical properties test methods of the coating samples To evaluate the strength of NC/epoxy-based films, the physicomechanical performances of the coating were measured such as follows: - Adhesion: The cross-cut test is a simple and easily practicable method for evaluating the adhesion of single- or multi-coat systems The standard ASTM D 3359-97 test is used; a numerical rating system from 1-mark for total failure to 5-marks scale may be used to evaluate tape adhesion test results [20] The test is operated using aslicer’s instrument of Sheen (England) - Hardness: Performed according to ASTM D3363 via a pencil method and using a Wolff-Wilborn Pencil Tester which includes 20 pens corresponding from 9B to 9H scale It is usually used to measure resistance to indentation by a series of increasingly hard pencils that have been sharpened to a chisel point [20] - Bending strength: Determined according to ASTM D522, the data was collected using Sheen's 809 device - Impact resistance: A way to measure impact resistance is ASTM D2794-93 was used, a standard weight is dropped from a height on a coated panel The indentation is inspected to detect if the coating has cracked The weight can be dropped from different heights, and the results are then measured in kG.cm unit [20] 2.5.5 Determination of chemical stability and anti-corrosive ability of NC/epoxy coatings Using two methods to check the corrosion protective property of the samples The one of them is measurement the change of the weight of the film before and after soaking in some another solutions, including: water, sea water, HCl 5% and NaOH 5% This item is employed according to ASTM G 31-72 and ASTM Gl-90 [20] The other is the salt spray method, which is related to ASTM B117 using the Q-FOG salt spray test machine CHAPTER 3: RESULTS AND DISCUSSION 3.1 Investigating of modified CNTs product characteristics This study the characteristics of the modified CNTs product (O-CNTs) were characterized by physic-chemical analysis methods including: FTIR, XRD, SEM, HR-TEM The results are summarized in the following sections 3.1.1 The results of FTIR analysis FTIR spectra was used to determine the chemical structure of before and after modified CNTs The results is showed in Table 3.1 Table 3.1 FTIR spectra data of CNTs and O-CNTs Wavenumber (cm-1) CNTs O-CNTs - 2360 2918 Peak assignment C-O-C stretching vibration of epoxide group C-O stretching vibration of carboxyl 1162 group (-COOH) O-H stretching vibration of hydroxyl 1383 group 1567 C-O of 1634, 2355 C-C of crystals structure of NC C=O of cacboxylic group or cacbonyl 1727 group 1018 2917 C=C of crystals structure of NC 3429 O-H of cacboxylic group or of moisture This results are indicated the presence of functional groups on the modified CNTs structure 3.1.2 The results of XRD analysis The crystal structure of CNTs and O-CNTs was determined by XRD pattern in Figure 3.3 The XRD analysis shows the spectrum of a typical CNTs In there both pristine CNTs and modified CNTs were expected that chemical modification of CNTs material, which only decorated functional groups on CNTs surfaces that still unchanged the crystal structure of pristine CNTs Figure 3.2 XRD patterns of pristine CNTs and modified CNTs 3.1.3 The resuls of SEM and HR-TEM The morphology of nanocarbon materials was analyzed by the scanning electron microscope and high resolution transmission electron microscopy methods The results are showed on the Figure 3.3, Figure 3.4 Figure 3.3 SEM image of pristine CNTs and modified CNTs (b) SEM image showed that O-CNTs remained stable in morphological structure compared to the original CNTs However, surface and inside of the tubes of CNTs was smoother and sharper The diameter of the tube is lower than that of the original CNTs This may be considered that impurities and amorphous carbon were removed in this reaction condition This is indicated in HR-TEM image in Fig 3.4 10 Figure 3.4 HR-TEM image of CNTs (a1 a2) and OCNTs (b1 b2) 3.1.4 Study on improvement of pristine CNTs and modified CNTs dispersion in polar environments The homogeneous dispersion samples of NC in the polar environments (water and n-butanol) were poured in glass vitros and looked over respectively in different time periods: 1h and 24h The results determinated that after hour, CNTs were completely deposited under bottom of the vitro, in there dispersion of O-CNTs was stable evenly after 24 hours This demonstrates that dispersal ability and dispersal stability of OCNTs in the polar were improved better than pristine CNTs 3.2 Study on characterization of prepared GO by graphite oxidation method This study investigated the characteristics of the product of Graphite oxidation by the modified Tour’s method The results may be considered to appreciate effectiveness of the synthesis The characteristics including chemical structure, crystal structure, geometric morphology of prepared product were determinated by physicochemical analysis methods such as FTIR, XRD, XPS and SEM The obtained results are showed in the following sections 16 3.5.1 Study on curing conditions of the neat epoxy resin coating To investigate the influence of NC on curing of the epoxy coating, the first of all it is necessary to measure cure condition of pure epoxy coatings The used content of curing agent is constant for all samples Here the DSC method was employed for curing degree evaluation of the samples The results showed in Figure 3.14 that correspond to the first heating and the analytical data are summarized in Table 3.9 Thus, it can be seen that curing degree increased with the curing conditions as follows: (1)