Ngoc Minh Ho, Thi Thanh Van Tran, Thuy Chinh Nguyen, Hoang Thai, Ternary nanocomposites based on epoxy, modified silica, and tetrabutyl titanate: Morphology, characteristics, and kineti
Trang 1GRADUATE UNIVERSITY SCIENCE AND
TECHNOLOGY -
Ho Ngoc Minh
PROJECT NAME: MANUFACTURE, INVESTIGATE THE PROPERTIES AND MORPHOLOGY OF COMPOSITE MATERIAL BASED ON GLASS FIBER E AND NANOSILICA-REINFORCED EPOXYRESIN
Major: Theoretical Chemistry and Physical Chemistry
Code: 9 44 01 19
SUMMARY OF CHEMISTRY DOCTORAL THESIS
Ha Noi - 2019
Trang 2The thesis was completed in : Graduate University Science and Technology/ Vietnam Academy of Science and Technology
Supervisors:
1) Assist Prof PhD Tran Thi Thanh Van
2) Prof PhD Thai Hoang
The thesis can be found at:
- Library of Graduate University of Science and Technology
- Vietnam National Library
Trang 3LIST OF PUBLICATIONS
1 Ngoc Minh Ho, Thi Thanh Van Tran, Thuy Chinh Nguyen, Hoang
Thai "Characteristics and morphology of nanosilica modified with
isopropyl tri (dioctyl phosphate) titanate coupling agent", Journal of
Nanoscience and Nanotechnology Vol18, No 5, 2018, pp 3630(7) (ISI)
3624-2 Ngoc Minh Ho, Thi Thanh Van Tran, Thuy Chinh Nguyen, Hoang
Thai, Effect of surface-modified nanosilica on the characteristics,
poroperties and morphology of silica/epoxy nanocomposites, The 6th
Asian Symposium on Advanced Materials: Chemistry, Physics & Biomedicine of Functional and Novel Materials (ASAM6), pp 343-
348, 2017
3 Ngoc Minh Ho, Thi Thanh Van Tran, Thuy Chinh Nguyen, Hoang
Thai, Epoxy/titanate modified nanosilica composites: morphology,
mechanical properties and fracture toughness Tạp chí Khoa học
Công nghệ, 56 (2A),133-140, 2018
4 Hồ Ngọc Minh, Trần Thị Thanh Vân, Nguyễn Thúy Chinh, Thái
Hoàng, Chế tạo, nghiên cứu đặc trưng, tính chất của nhựa epoxy
đóng rắn bằng hợp chất cơ titan và một số hợp chất amin, Tạp chí
Hóa học, 56(3), 401-406 (2018)
5 Ngoc Minh Ho, Thi Thanh Van Tran, Thuy Chinh Nguyen, Hoang
Thai, Epoxy-silica nanocomposite: Creep resitance and toughening
mechanisms, Emerging Polymer Technologies Summit (EPTS) and
Emerging Material Technologies Summit 2018 (EPTS/EMTS'18) /
2018
6 Ngoc Minh Ho, Thi Thanh Van Tran, Thuy Chinh Nguyen, Hoang
Thai, Ternary nanocomposites based on epoxy, modified silica, and
tetrabutyl titanate: Morphology, characteristics, and kinetics of the curing process, Inc J Appl Polym Sci 2019, 136, 47412 (ISI)
Trang 4INTRODUCTION
1 Necessity of the thesis
Polymer composite based on glass fiber E-reinforced epoxy resin were commonly used in transportation, electronics, mechanical engineering, machine, building, and chemicals … However, the disadvantages and limitations affecting the application of this composite material are their brittleness and poor impact resistance Therefore, improving toughness / toughening for epoxy resins is very important Some nanoscale additives have been applied to manufacture epoxy-based composites as products for industries Among nano additives, surface modification of nanosilica with organic coupling agent is one of the most commonly used for polymers, rubbers, and plastics because it is easy to find, easy to use, relatively cheap
Titanium-based hardened epoxy resin can work long time at high temperature Research on composite materials based on epoxy / glass fiber combined with surface modification of nanosilica by titanate coupling and titanium curing agent is very new, promising to create material system with high mechanical, physical, thermal properties And good electrical Therefore, the PhD student chooses the thesis
topic "Manufacture, investigate the properties and morphology of
composite material based on glass fiber E and nanosilica-reinforced epoxy resin”.
2 Purpose of the thesis
Manufacture composite based on epoxy reinforced by glass fiber with organ – modified nanosilica using organotitanate curing agent that have good mechanical strength, thermal stability, flame restraint ability
Improve the toughness of epoxy resin by incorporating reinforcing agent such as organ – modified nanosilica and glass fiber with appropriate manufacturing condition and ratio
3 The main research content of the thesis
Study on grafting nanosilica surface with KR-12 titanate coupling agent to enhance their dispersion ability in epoxy resin
Trang 5Study on curing reaction of epoxy resin YD-128 by tetrabutyl titanate and properties of post-hardening products
Manufacture, investigate the properties and morphology of nanocomposite material based on epoxy, nanosilica and tetrabutyl titanate
Manufacture, investigate the properties and morphology of composite material based on glass fiber E and nanosilica-reinforced epoxy resin
4 New contributions of the thesis
Successfully grafted K200 nanosilica particle surface with
KR-12 titanate coupling agent Nanosilica nanoparticles after modified have good dispersion ability in epoxy resin
We studied the curing reaction of YD-128 epoxy resin with tetrabutyl titannate and clarified the advantages of this curing agent compared to conventional amine compounds
Explained the positive effect of KR-12/nanosilica to mechanical properties, dynamic mechanical properties, toughness, toughness, toughening mechanism of composite material based on epoxy/m-nanosilica/ tetrabutyltitanate and glass fiber
CHAPTER 1
OVERVIEW OF EPOXY RESIN, NANOCOMPOZIT AND COMPOZIT MATERIALS BASED ON EPOXY/ NANOSILICA / GLASS FIBER
This chapter present the following:
1 Epoxy resin: Classification, physical and chemical properties Curing agents, curing mechanisms and applications of epoxy in various fields
2 Nanosilica: introduction about composition, properties, structure, applications of nanosilica in industry and surface modification methods to increase their dispersion ability in plastic matrix
3 Introduction about polymer composites, epoxy resin, reinforcements and some parameters affected on the durability of materials
Trang 64 Domestic and foreign research situation and application of
composite materials based on epoxy / nanosilica / fiberglass
CHAPTER 2
EXPERIMENTAL
2.2 Methods
2.2.1 Determine coupling efficiency of KR-12 on nanosilica K200
Was determined by thermogravimetry:
H = (mbt.750 – mbd.750)/ mo
where: mbt.750 is the mass of SiO2 after modifying at 750 oC
mbd.750 is the mass of unmodified SiO2 at 750 oC
mo is the mass of initial SiO2
2.2.2 Determine particle size and Zeta potential
Particle size distribution and zeta potential of nanosilica before and after modifying was determined by Zetasizer Nano ZS (Malvern-UK) using laser scattering method
2.2.3 Determine gel content
Gel content of the samples after curing was determined by Soxhlet extraction and calculated using the following formulation:
GC = 100 (m1/m0) where: m0 is the mass of initial sample (g); m1 is the mass of the sample after extracting (g); GC: gel content (%)
2.2.4 Viscometry
The viscosity was determined on the viscometer Brookfield Model RVT- Series 93412 (American), at 25 oC following the standard DIN 53018
2.2.5 Transmitted Electronic Microscopy (TEM)
TEM image was recorded on JEM1010 of JEOL (Japan) The sample was cut into ultrathin layers having the size of 50÷60 nm by
specialized knife Leica Ultracut S microtome, then take TEM image
at acceleration voltage of 80 kV
2.2.6 Field Emission Scanning Electronic Microscopy
Was done on high resolution Model HITACHI S-4800, Japan,
acceleration voltage of 5 kV
Trang 72.2.7 Energy Dispersive X-rays
Was determined on Model HORIBA 7593H (England)
2.2.10 Dynamic Mechanical Analysis
Was done on DMA-8000 (Perkin Elmer, America) by single
bending method, with heating rate of 4 oC/min, temperature range 30-200 oC, vibration frequency 1 Hz
2.2.11 Determine toughness and destroying energy
Fracture toughness of the sample was determined following the standard ASTM D 5045-99 on LLoyd 500 N (England), the stress applied rate of 10 mm/min at room temperature
2.2.12 Determine bending strength
Was determined following ISO 178:2010 on Instron 5582-100 kN (England), bending rate of 5 mm/min
2.2.13 Determine tensile strength
Was determined on Zwick (Germany) following ISO 527-1:2012 with the dragging rate of 5 mm min
2.2.14 Determine impact resistance
Was determined following ASTM D6110 on Ray Ran (America) Each sample was measured six times and take the average
2.2.15 Determine Interlaminar Fracture Toughness
Was determined following ASTM D 5528-01 [85], on Lloyd 500
N (England) with the interlaminar pull off rate of 2 mm/min
2.2.16 Preparation of the samples
Trang 82.2.16.1 Modify nanosilica
Weigh nanosilica in the beaker, adding toluen and stir thoroughly
at the speed 21.000 round/min for 5 minutes, then sonicate the mixture for 10 minutes Adding slowly KR-12 with different contents (5; 10; 15; 30; 45 % compared to nanosilica) into the system, repeat the process of stirring and sonicating 3 times Then, the mixture was separated from the solvent by centrifuging with the speed of 7000 round/min, obtaining the gel then using toluen to wash KR-12 that does not react, the process was repeated 3 times then dry to remove toluen at 90 oC for 24 hours
2.2.16.2 Prepare nanocomposite based on epoxy and m-nanosilica
Mix thoroughly epoxy YD-128 and m-nanosilica with different contents by mechanical stirrer, adding curing agent TBuT with the studying ratio, then pour into the mold that has been cleaned and anti-stick Curing process was done at different temperatures and times then machined to determine mechanical properties (tensile strength, bending strength, impact resistance)
2.2.16.3 Prepare epoxy with different curing agents
Weigh epoxy resin and curing agents into beakers, with the composition given in Table 2.1, stir the mixture for 5 minutes then vacated to remove bubble The mixture was poured into the mold (clean, antistick) curing and determining mechanical stability
Table 2.1 Composition of epoxy resin and curing agents
Resin – curing
agent
Epoxy YD128, g
Curing agent, g Curing condition
oC); 10 hours (70 oC)
oC); 10 hours (70 oC)
oC); 10 hours (70 oC)
Trang 92.2.16.4 Manufacture composite epoxy/m-nanosilica/TBuT/glass fiber
m-nanosilica was dispersed in epoxy resin YD128 with the ratio 0÷7 % by weight, then add 15 fraction per weight (pkl) of curing agent TBuT Glass fiber was dried 100 oC for 3 hours to remove moisture Epoxy resin or epoxy-nanosilica were prepared as in 2.3.2 Glass fiber was cut into rectangle sheet having the size (150 x 200)
mm then put layer by layer in the mold and pour the resin with the different ratios of glass fiber/resin Distribute the resin to permeate into the fiber by roller and brushes The samples of composite was then cured at 120 for 3 hours in vacuum dryer
CHAPTER 3 RESULTS AND DISCUSSION
2.1 Determination of coupling efficiency of KR-12 onto nanosilica nanosilica
The reaction of KR-12 with the surface of nanosilica is described in Figure 3.1
Fig 1 Functionalization of silica nanoparticles with tiatanate agent
The result reveals that easy methodology for functionalization of SiO2 nanoparticles with titanate agent KR-12 in toluene solvent The surface reaction was found to be rapid, less energetic demanded thus
Carried out in Toluen
Trang 10less depends on reaction temperature and completes in a short
reaction period The loading amount of titanate was found to be
strongly depending in relative concentration of titanate agent
Grafting efficiency was determined via thermal analysis, the
appropriate content of KR-12 to modify nanosilica is 15 % in weight
After the period of 45 minutes , the efficiency of 13,16%
3.1.1 Size Distribution
Size distribution of nanosilica and modified nanosilica
was expressed in Figure 3.2, in which nanosilica modified
by 0–15 wt.% of KR-12 correspoding to U-SiO2, SiO2-KR.12 (5),
SiO2-KR.12 (10) and SiO2-KR.12 (15), respectively Before being
modified, the size distribution of silica (U-SiO2) was not
homogeneous with large particles (the average particle size was
found at 656.7 nm (72.7%) and5078 nm (27.3%)) due to the
aggregation of nanosilicaparticles during storage When using
titanate coupling agent to modify nanosilica, the size distribution
after stirring and sonicating indicated the much smaller size than in
the case of unmodified nanosilica The particle size of nanosilica has
a tendency of reduction symmetrical arcording to the amount of
titanate coupling agent KR-12 grafted onto nanosilica surface For
nanosilica modified by 5 wt.% of KR-12 (SiO2-KR.12 (5)), the
average particle size was 408.8 nm(99.7%) and 4962 nm (0.3%),
nanosilica-KR-12 (10), the particle size was decreased to 149.5 nm,
and for nanosilica modified by 15 wt.% of KR-12 (SiO2-KR.12 (15)),
there was only 1 peak corresponding to size distribution by intensity
peaks at 84.58 nm This demonstrated that the use of titanate
coupling agent KR-12 plays important role in increasing the
dispersiveness of nanosilica by reacting with hydroxyl groups on the
surface to form a polymer layer preventing aggregation of nanosilica
Surface modification followed by stirring and sonicating helps to
decrease the size of the particles to the nano scale
(b)
Trang 11of 600–1000 nm as determined by laser scattering.2 It is the aggregation during storage that limits the application of nanosilica After being modified by titanate coupling agent KR-12, incorporated with stirring and sonicating, silica nanoparticles had much more smaller size than 100 nm (Fig 3.3) The agglomeration
of nanosilica modified by KR-12 decreases remarkably due to the physical interactions between the nanoparticles is instead of chemical interactions between nanosilica and KR-12 This can be explained due to the surface of nanosilica had been covered by a layer of organic titanate that increased the hydrophobicity as well as decreased the surface energy of nanosilica Here may be the KR-12 layer thickness on the surface of modified silica is too thin, thus, this
can not see morphology of KR-12 on these TEM images
Figure 3.2 TEM image of unmodified nanosilica
Trang 12
Figure 3.3 TEM image of modified nanosilica
3.2 Influence of Silica Nanoparticles on Changes in the Physical State and Viscosity of the Epoxy/m-Nanosilica Systems
The content of silica nanoparticles had a strong effect on their dispersion in the epoxy matrix, characteristics, and properties of the cured epoxy–nanosilica–TBuT nanocomposites Table I presents the weights of the components in the epoxy–nanosilica systems and the changes in the physical state and viscosity (at 25 oC) of the epoxy with and without silica nanoparticles
Table 3.1 Viscosities of the Epoxy/nanosilica systems
Samples Epoxy, g Nanosilica, g Physical
Trang 13The viscosity of the epoxy–m-nanosilica systems increased rapidly with increasing mnanosilica content and reached a maximum value of 803.823 cP at 5 wt % m-nanosilica This could be explained
by the organic layer grafted onto the surface of the silica nanoparticles, which led to the reduction of interactions between the hydroxyl groups (Si─OH) on the surface of m-nanosilica and hydroxyl and glycidyl groups in the epoxy;
3.3 Study factors affecting on the curing process of YD-128 epoxy resins by TBuT
The effect of temperature, time, and curing agent on curing process is assessed through variations in the glass transition temperature and mechanical strength of the sample The results were shown in Figure 3.4, which has determined the appropriate curing conditions for YD-128 epoxy resins by TBuT curing agent as follows: Curing temperature: 150 oC; time: 180 minutes; Curing content: 15 phr After solidification, the glass transition temperature of 123.6 oC; flexural strength 88.7 MPa; impact resistance of 19.71 J/m2
Trang 14
Figure 3.4 Influence of temperature (a), time (b), content of curing
agent (c) on mechanical strength and glass transition temperature of epoxy-TBuT system
Temperature, o C Time, min