Next Article in Journal
Mechanical and Structural Properties of Nanocomposite CrAlSiN–AlSiN Coating with Periodically Modulated Composition
Next Article in Special Issue
Graphene Oxide Reinforcing Genipin Crosslinked Chitosan-Gelatin Blend Films
Previous Article in Journal
Nonlinear Dynamic Characteristic Analysis of a Coated Gear Transmission System
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Coatings
Volume 10
Issue 1
10.3390/coatings10010040
coatings-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Mechanical and Thermal Properties of Waterborne Polyurethane Coating Modified through One-Step Cellulose Nanocrystals/Graphene Materials Sols Method

by
Feng Yang
1,2,
Yan Wu
3,*,
Shuqin Zhang
2,
Haiming Zhang
1,
Suilang Zhao
1,
Jilei Zhang
4 and
Benhua Fei
2,*
1
Fashion Accessory Art and Engineering College, Beijing Institute of Fashion Technology, Beijing 100029, China
2
Key Laboratory of Bamboo and Rattan Science and Technology of the State Forestry Administration, Department of Bio-materials, International Centre for Bamboo and Rattan, Futong Dong Dajie, Chaoyang District, Beijing 100102, China
3
College of Furnishings and Industrial Design, Nanjing Forestry University, Nanjing 210037, China
4
Department of Sustainable Bioproducts, Mississippi State University, Mississippi State, MS 39762, USA
*
Authors to whom correspondence should be addressed.
Coatings 2020, 10(1), 40; https://doi.org/10.3390/coatings10010040
Submission received: 29 November 2019 / Revised: 21 December 2019 / Accepted: 26 December 2019 / Published: 2 January 2020
(This article belongs to the Special Issue Advances in Graphene Based Composite for Bio-Applications)
Browse Figures
Review Reports Versions Notes

Abstract

:
Developing multifunctional coatings with excellent mechanical and thermal properties is highly desirable for wood-based composite application. The recent development of waterborne coatings for wood products suggests that a promising thermosetting material needs to also have properties like low volatile organic contents (VOCs), hardness, and fast curing. The cellulose nanocrystals/graphene materials (CNC/GM) sols were prepared through the one-step method as the thermally conductive and reinforced modifier for preparing waterborne polyurethane (WPU) coatings. The influence of this modifier on the thermal and mechanical properties such as thermal conductivity, abrasion resistance, and adhesion of WPU coatings was investigated. The results indicated that adding CNC/GM sols increased the hardness, abrasion resistance, and thermal conductivity of the WPU coatings, and meanwhile maintained the coating adhesion at the highest grade (level 1). The highest abrasion resistance value of 0.023 g/100 r was obtained for the modified WPU coating when the addition of GM was 3%.

Graphical Abstract

1. Introduction

Waterborne coatings recently have been increasingly used in the worldwide wood industry because of low health and environmental impact [1,2]. These environmentally friendly coatings have low or no emissions of volatile organic contents (VOCs) and good mechanical properties and durability [3,4]. Currently inorganic nano-additives (fillers) such as Al2O3 [5,6], SiO2 [7,8], TiO2 [9], ZnO [10,11], CaCO3 [12], Cr2O3 [13,14], etc. are used to improve the durability and functionality of waterborne coatings. However, these inorganic nano-fillers encounter the dispersion issues in waterborne coatings of organic polymer matrixes, like incomplete dispersion of nanoparticles in the polymer matrix and poor adhesion between cured coatings and wood substrates [7,8]. Directly incorporating organic nanoparticle materials into aqueous media is one of the most promising strategies [15]. Cellulose nanocrystals (CNCs) have received tremendous attention in sustainable biomaterial-based society [16,17,18] because of their remarkable physical and chemical properties.
CNCs, a new renewable nontoxic nanoscale materials isolated from native cellulose sources like wood [19,20], bamboo [21,22,23,24], cotton [25,26], hemp [27], bacteria [28], green algae [29], tobacco stalk [30], etc. have excellent properties such as a high specific surface area of 300 m2/g, a Young’s modulus of 150 GPa, and a tensile strength of 10 GPa [31]. CNCs are proven to be an excellent mechanical reinforcement filler when mixed with aqueous polymer matrixes. Pei et al. [32] prepared a nanocomposite film of poly(l-lactide) (PLLA) reinforced with CNCs or silylated cellulose nanocrystals (SCNC) using the solution casting method. Rao et al. [33] investigated the rheological behavior of composite polymer-CNC gels in dimethylformamide because the behavior of CNC-polymer gels in organic solvents can affect the processable ability of the polymer mixture. Kargarzadeh et al. [34] reviewed the studies related to CNC- and cellulose nanofibril (CNF)-reinforced rubbers or thermoset polymers, including preparation methods, morphology, mechanical behavior, thermal properties, and barrier action.
Current waterborne coatings used in wood products started its application mainly in building industries [1,5]. The limitation of waterborne coatings in wood products is mainly because of their poor water resistance, hardness, wear resistance, and stability in some applications [35]. For fibrous wooden materials, conduction, convection, and radiation are the three main routes to processing heat transfer, among which the most significant way is conduction [12,24]. Therefore, their thermal conductivity needs to be improved if used in heating floor applications [2,8]. In the previous literature, various conductive materials, such as iron [35], steel, copper [36], and carbon materials [37,38], have been utilized to coat heating composite materials for making energy-saving wooden products. Among these modified materials, graphene (Gr) has emerged as a revolutionary functional material because of its superior thermal conductivity property (above 3000 W·m·K−1) [33]. Tang et al. [39] observed that adding graphene materials into epoxy resin increased the resin thermal conductivity enhancement factor up to 1900% with a significantly improved stability at a high temperature. However, the large specific surface area of graphene-based carbon nanomaterials tends to agglomerate together when dispersed into other materials as property enhancement agents, thereby causing lower performance of these nanomaterials as property-enhancement agents. Carrasco et al. [40] reported that CNCs as stabilizer are very efficient for graphite exfoliation through tip sonication and stabilization, resulting in graphene flakes dispersed in aqueous media at a high concentration up to 1 mg/mL.
In our previous study, impregnating graphene materials/phenol-formaldehyde resin into wood floor products was successfully completed [41,42]. This work investigated the influence of CNC/GM sols as a modifier on the thermal and mechanical properties such as thermal conductivity, abrasion resistance, and adhesion of WPU coatings.

2. Experimental

2.1. Materials

Microcrystalline cellulose (MCC) powder was provided by Shanghai Jinsui Biological Inc. (Changzhou, China). The multilayer graphene-based carbon nano-materials were provided by the Department of Sustainable Bioproducts, Mississippi State University (Starkville, MS, USA), which had an average particle size of 842 nm and an average dispersion degree of 0.451 [37]. Sulfuric acid (analytical reagent, mass fraction 98%) was provided by Nanjing Chemical Reagents Co. (Nanjing, China). Basswood (Tilia) pieces measured by 100 mm long × 100 mm wide × 10 mm thick were obtained from Dehua New Material Co., Ltd., Weifang, China. These wood samples had three groups in terms of their length directions, longitudinal, tangential, and radial. Two-component waterborne polyurethane coating (2K-WPU) was supplied by the Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry (CAF, Beijing, China). The ratio of hardener to resin of the 2K-WPU was 3.5:10 [43]. Deionized-distilled water (DDW) was used exclusively.

2.2. Preparation of CNC/GMsol Mixture through One-Step Method

The three mixtures of microcrystalline cellulose (MCC) powder and graphene materials (GM) (Table 1) were hydrolyzed first by sulfuric acid (analytical reagent, mass fraction 64%) in water baths at 45 °C for 1 h. The supernatant, produced by centrifuging the acid-treated solution at 4000 r/min for 5 min, was replaced with distilled water. The mixed solution was then centrifuged again. The process was repeated until a white emulsion solution was obtained after 5–6 circulations. The white emulsion solution was dialyzed under flowing water for 3 days until pH 6 value was reached, and then the dialyzed solution was sonicated for 20 min; the black thick CNC/GM sols were finally obtained.

2.3. Preparation of CNC/GM/2K-WPU Coating Samples

The modified 2K-WPU coating using CNC/GM sol, CNC/GM/2K-WPU, was prepared through magnetic stirring the mixture of 2K-WPU coating and CNC/GM sol at 25 °C for 20 min. The weight ratio of 2K-WPU coating to CNC/GM sol was 100:3. For conductive property test, the modified coatings were coated onto tin plates (120 mm long × 50 mm wide × 2 mm thick) using a paint film fabricator, followed by drying the coated tin plates under controlled conditions (25 °C and 50% of relative humidity) for one week according to GB/T1727-1992 [44]. The control samples without CNC/GM sols coated were also prepared. For adhesion, hardness, and abrasion resistance properties tests, the control and modified coatings were applied on the Basswood surface along the tangential direction. After coating, samples were put in an oven for 20 min at 60 °C and then air-dried in a fume hood for 7 days. The targeted coating thickness was 60 μm.

2.4. Characterizations

2.4.1. CNC/GM Sols

The absorbance values of CNC/GM sol mixture were measured on a Lambda 950 ultraviolet spectrophotometer (PE Co., Melville, NY, USA). The wavelength scanning range of absorbance was 200–800 nm. The FT-IR spectra were recorded on a VERTEX 80V spectrometer (Bruker, Berlin, Germany) over the scan range of 400–4000 cm−1. The dried CNC/GM sol mixtures (1 part in weight) were mixed to potassium bromide (KBr) (100 parts in weight). The transmission mode was selected. The Raman spectra were collected from 50 to 3300 cm−1 using an NRS 300 laser Raman spectrometer (Themor DXR532, Waltham, MA, USA) with an excitation wavelength of 532 and 780 nm at room temperature. The X-ray diffraction (XRD) was performed using Cu kα radiation source (step size 0.02°, scanning speed 5°/min, voltage 40 kV, current 100 mA) in an Ultima IV XRD instrument (Rigaku, Tokyo, Japan). The morphology and structure of the CNC/GM sol mixtures were characterized by transmission electron microscopes (TEM, Hitachi JEM-140, Tokyo, Japan).

2.4.2. CNC/GM/2K-WPU Coating

The hardness of the coated wood samples was determined with the pencil hardness according to the GB/T 6739-2006 standard [45], and abrasion resistance and adhesion tests were measured in accordance with the GB/T1768-2006 and GB/T4893.4-1985 standards [46,47], respectively. The thermostability was determined with a TG209F3 thermogravimetric analyzer (Netzsch, Germany) with the heat ramping temperature set from 25 to 800 °C at 40 mL/min under nitrogen atmosphere.
A heat conduction coefficient tester (ISOMET 2104, Shanghai, China) was employed to record heating temperatures according to GB/T 11048-2018 standard [48]. An improved test method is used here. A standard sample and a test sample are placed in the middle of two heating plates with a constant temperature gradient to measure and obtain the thermal conductivity of the target material [49]. The thermal conductivity ( λ ) was calculated by using the following formula; the measurement accuracy to 0.001.
λ = m c Δ T Δ t | T = T 2 ⋅ h T 1 − T 2 ⋅ 1 π R 2
where λ is the thermal coefficient (W/m·k), m is the quality of copper cooling plate (kg), c is the specific heat capacity of copper cooling plate, 385 J/(kg·K), Δ T Δ t | T = T 2 is the heat dissipation rate of copper cooling plate at T2 (mV/s), h is the thickness of tested sample (m), T 1 − T 2 is the temperature difference between upper and lower sample surfaces (K), and π R 2 is the area of copper cooling plate (m2).

3. Results and Discussion

3.1. Properties of CNC/GM Sols

3.1.1. Absorbance Analysis

According to Lambert Beer’s law, the absorbance at 660 nm of CNC/GM sols was taken for comparison and analysis. Figure 1 indicates that increasing the amount of GM from 1% to 2% can increase the absorbance value of GM dispersion, but continuing the increase of GM to 3% could decrease the absorbance value. These indicate that the dispersion of GM had its optimum dispersion when 2% GM was added. Adding 1% of GM can weaken its dispersion stability.

3.1.2. FT-IR Spectra Analysis

The infrared spectrum of CNC/GM sol mixtures (Figure 2) indicates that there was a broad and strong absorption peak near 3432 cm−1, which belongs to the stretching vibration peak of –OH [50]. There was an obvious C–O stretching vibration peak at 1720 cm−1 and an obvious C–OH stretching vibration peak at 1380 cm−1. There was a C–H tensile vibration peak near 2903 cm−1. The C–O stretching vibration peak at 1052 cm−1 was also relatively strong, indicating the presence of GM in the dispersion [51,52]. However, the FT-IR spectra alone will not be able to tell whether or not the GM could be successfully grafted to the surface of CNC to form chemical bonds.

3.1.3. Raman Spectrum Analysis

The Raman spectrum of graphene is composed of many characteristic peaks, such as G peak, D peak, G’ peak, etc. G peak appearing near 1580 cm−1 is the main characteristic of graphene materials, which can effectively reflect the number of layers of graphene but be affected by stress [53]. D peak near 1350 cm−1 is the disordered vibration peak of GM. G’ peak near 2700 cm−1, also known as 2D peak, is used to characterize the inter-layer stacking mode of carbon atoms in GM [54]. Figure 3 indicates that G, D, and G’ peak signals observed in the CNC/GM sol mixtures were all stronger, indicating that the graphene flakes were evenly dispersed in CNC sols. The ID/IG ratios were 0.853 and 1.001 for GM and CNC/GM sol mixtures, respectively. The value of ID/IG ratios increased from 0.853 to 1.001, and the peak strength was significantly increased, and 2D peak occurred at 2700 cm−1 in the Raman spectrum of the CNC/GM sol mixtures, which was caused by coupling between graphene sheets. These experimental results indicated that the graphene materials were deposited on the surface of cellulose nanocrystals, implying a good dispersion of graphene materials in the CNC sols.

3.1.4. XRD Analysis

The XRD pattern of CNC/GM sol mixtures (Figure 4) indicates that a very sharp diffraction peak appears near 22° that is close to the diffraction peak of graphene materials, indicating the presence of graphene materials in CNC/GM sol mixtures [55]. There is also a wide diffraction peak near 15°, indicating that GM was successfully mixed with CNC sols and the CNC sol was evenly dispersed.

3.1.5. TEM Analysis

The TEM images of CNC/GM sol mixtures (Figure 5) show that graphene materials could be evenly dispersed in CNC sols through depositing in the network of CNC structures.

3.2. Mechanical Properties of CNC/GM/2K-WPU Coatings

3.2.1. Adhesion and Hardness

Adhesion and hardness were important properties of coatings, which were related to the durability and long-term performance [56]. In particular, it was required that the addition of CNC or GM did not worsen the adhesion characteristics of coatings for the actual using reason. Any particle or nanoparticle added to the coating would be expected to impact these properties and the system should behave as a true composite [57]. This experiment revealed that the adhesion strength of coatings with or without the addition of CNC/GM being practically at the same high level. Figure 6 indicates that the adhesion strengths of all coated samples being in the level 1, and the hardness of coatings with and without CNC/GM modifier added all meet the critical values outlined in standards, respectively. The higher GM loading yielded a harder coating (6H) than the control one (5H). This test revealed no significant difference of hardness between coatings with different GM additions, which was because GM was simply dispersed but not covalently bonded to or within the continuous phase, resulting in no increase of hardness [58].

3.2.2. Abrasion Resistances

The coatings can be cured to a hard finish and are known for their outstanding wear properties. It is important that an additive (modifier) does not worsen the wear characteristics of coating [59]. Figure 7 shows that CNC/GM modified coatings had significantly lower abrasion loss than the control one. Specifically, the addition of GM improved the mechanical resistance of coatings to 540%, 1180%, and 1500% if compared to the control one for GM loading 1%, 2%, and 3%, respectively. This improvement in abrasion resistance could be mainly because of the super-stiffness of graphene and CNC/GM higher dispersion state in modified coatings [58,60]. Adding CNC/GM and their proper dispersion within the coatings introduced the right hydrophobic/hydrophilic balance, creating suitable interfaces between the filler and matrix [54]. In addition, CNCs’ intrinsic features, like high aspect ratio and Young’s modulus, could also result in coating strengthening [61,62]. Furthermore, the geometrical characteristics of CNC and GM system might reinforce the binder matrix(coating) that is similar to the frameworks in the modern reinforced concrete-steel buildings at the nano-level [58].

3.3. Thermal Properties of CNC/GM/2K-WPU Coatings

3.3.1. Thermal Stability

The TG curves of the 2K-WPU and CNC/GM/2K-WPU coatings (Figure 8) indicate that the decomposition temperatures (Td) of 2K-WPU coatings at 10%, 50%, and 80% mass losses were 51, 322, and 453 °C, respectively. The decomposition temperatures of CNC/GM/2K-WPU coatings at 10%, 50%, and 80% mass losses were 251, 322, and 681 °C, respectively. The results showed that the CNC/GM/2K-WPU coatings had better thermal properties than 2K-WPU coatings, indicating that the addition of graphene materials could further improve the thermal resistance property of 2K-WPU coatings. This is because graphene materials have their initial decomposition temperature over 2800 °C under vacuum [63,64]. Meanwhile, the reaction between oxygen-containing functional groups such as hydroxyl in the composite system can improve thermal stability [60]. When the decomposition temperature increased from 300 to 430 °C, the mass losses values of CNC/GM/2K-WPU coatings were higher than the ones of 2K-WPU coatings, indicating that partial modifiers (CNCs) in coatings had begun to degrade. Particularly, the initial decomposition temperatures (Td) of CNCs are about 360–600 °C [65].

3.3.2. Thermal Conductivity

Figure 9 shows that the thermal conductivities of CNC/GM/2K-WPU coated samples ranged from 1.33 to 1.39 W/m·K, specifically, the maximum thermal conductivity of CNC/GM/2K-WPU coated samples was 4.5% higher than 2K-WPU coated ones, indicating better conductive behavior than 2K-WPU coated ones. The coated samples gained a thermal conductive functional ability because of the addition of GM in the coatings [66]. The statistical analysis indicated that there was no significant difference among GM loadings of coated wood samples. The lamellar structure of graphene materials can be maintained by van der Waals or restoration π-π stacking between adjacent Gr layers [67] if graphene materials were dispersed in CNC suspension uniformly. In addition, the addition of GM did not significantly improve the thermal conductivity, which may be due to the fact that GM is a multilayer material and the thermal conductivity improvement effect is limited compared with single-layer graphene [37,66].

4. Conclusions

A one-step preparation process of CNC/GM sol mixtures as a modifier for the improvement of waterborne coating properties was proposed, performed, and evaluated. Experimental results showed that the thermal conductivity of the waterborne coating evaluated in this study can be improved up to its highest of 1.39 W/m·K when a 2% loading of graphene materials evaluated in this study was added. Moreover, the pencil hardness and abrasion resistance of CNC/GM sol modified waterborne coatings were also improved significantly. The abrasion resistance of modified coatings can reach 0.0213 g that was up to 59.2% if compared to unmodified ones. The pencil hardness was increased from 5H to 6H and adhesion did not change significantly. It is believed that the findings of this study can provide data support for the research and development of wooden heating products and promote their products with better energy-saving features.

Author Contributions

Contributed to Synthesis, Testing, Data Analysis, and Writing the Manuscript: F.Y. and Y.W.; Suggested and Supervised the Work: B.F. and J.Z.; Contributed to Revising the Language of the Manuscript: H.Z.; Contributed to the Investigation: S.Z. and S.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Project of Science and Technology Plan of Beijing Municipal Education Commission (KM202010012001), the Special Scientific Research Fund of Construction of High-level teachers Project of Beijing Institute of Fashion Technology (BIFTQG201805), the National Natural Science Foundation of China (31770599), the Special Scientific Research Fund of Construction of High-level teachers Project of Beijing Municipal University (IDHT20180511), and the specially invited Professor Support Program of Beijing Municipal University (IDHT20190217).

Acknowledgments

The authors gratefully acknowledge financial support from P.R. China.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Aqdas, N.; Khalid, M.Z.; Mohammad, Z. Recent trends in environmentally friendly water-borne polyurethane coatings: A review. Korean J. Chem. Eng. 2015, 33, 1–13. [Google Scholar] [CrossRef]
  2. Dai, J.Y.; Ma, S.Q.; Liu, X.Q. Synthesis of bio-based unsaturated polyester resins and their application in waterborne UV-curable coatings. Prog. Org. Coat. 2015, 78, 49–54. [Google Scholar] [CrossRef]
  3. Wu, Y.; Sun, Y.C.; Yang, F.; Zhang, H.Q.; Wang, Y.J. The implication of benzene-ethanol extractive on mechanical properties of waterborne coating and wood cell wall by nanoindentation. Coatings 2019, 9, 449. [Google Scholar] [CrossRef] [Green Version]
  4. Wu, Y.; Wu, J.M.; Wang, S.Q.; Feng, X.H.; Chen, H.; Tang, Q.W.; Zhang, H.Q. Measurement of mechanical properties of multilayer waterborne coatings on wood by nanoindentation. Holzforschung 2019, 73, 1–7. [Google Scholar] [CrossRef]
  5. Palomares, E.; Clifford, J.N.; Haque, S.A.; Lutz, T.; Durrant, J.R. Control of charge recombination dynamics in dye sensitized solar cells by the use of conformably deposited metal oxide blocking layers. J. Am. Chem. Soc. 2016, 125, 475–482. [Google Scholar] [CrossRef] [PubMed]
  6. Sangermano, M.; Naguib, M.; Messori, M. Fracture toughness enhancement of UV-cured epoxy coatings containing Al. Macromol. Mater. Eng. 2013, 298. [Google Scholar] [CrossRef]
  7. Qiu, F.; Xu, H.; Wang, Y.; Yang, D. Preparation, characterization and properties of UV-curable waterborne polyurethane acrylate/SiO2 coating. J. Coat. Technol. Res. 2012, 9, 503–514. [Google Scholar] [CrossRef]
  8. Zhang, F.; Yang, W.; Pang, A.; Wu, Z.; Qi, H.; Yao, J.; Fan, Z.; Shao, J. Annealing effects on the optical and structural properties of Al2O3/SiO2 films as uv antireflection coatings on 4H-SiC substrates. Appl. Surf. Sci. 2008, 254, 6410–6415. [Google Scholar] [CrossRef]
  9. Samyn, P.; Stanssens, D.; Paredes, A.; Becker, G. Performance of organic nanoparticle coatings for hydrophobization of hardwood surfaces. J. Coat. Technol. Res. 2014, 11, 461–471. [Google Scholar] [CrossRef]
  10. Li, S.C.; Wang, L.W.; Wang, J.Y. Study on Properties of modified nano-ZnO/WPU hybrid material. Adv. Mater. Res. 2012, 510, 742–746. [Google Scholar] [CrossRef]
  11. Crespo-Soler, A.; Lardies-Miaza, N. Effect of nanosilica and ZnO nanoparticles on abrasion and uv resistance of waterborne polyurethane coating. Farby I Lakiery 2014, 5, 3–10. [Google Scholar]
  12. Sanderson, P.; Delgadosaborit, J.M.; Harrison, R.M. A review of chemical and physical characterisation of atmospheric metallic nanoparticles. Atmos. Environ. 2014, 94, 353–365. [Google Scholar] [CrossRef] [Green Version]
  13. Palimi, M.J.; Rostami, M.; Mahdavian, M.; Ramezanzadeh, B. Studying the effects of surface modification of Cr2O3 nanoparticles by 3-aminopropyltrimethoxysilane (APTMS) on its corrosion inhibitive performance. J. Sol-Gel Sci. Technol. 2015, 73, 141–153. [Google Scholar] [CrossRef]
  14. Chang, T.; Cao, X.; Li, N.; Long, S.; Jin, P. Facile and low-temperature fabrication of thermochromic Cr2O3/VO2 smart coatings: Enhanced solar modulation ability, high luminous transmittance and uv-shielding function. ACS Appl. Mater. Interfaces 2017, 9, 26029–26037. [Google Scholar] [CrossRef]
  15. Qian, B.; Song, Z.W.; Hao, L.; Fan, H.Q. Entrapment of polyaspartic acid on silica nanoparticle for self-healing coatings. Mater. Corros. 2017, 68, 717–724. [Google Scholar] [CrossRef]
  16. Habibi, Y.; Lucia, L.A.; Rojas, O.J. Cellulose nanocrystals: Chemistry, self-assembly, and applications. Chem. Rev. 2010, 110, 3479–3500. [Google Scholar] [CrossRef]
  17. Favier, V.; Chanzy, H.; Cavaille, J.Y. Polymer nanocomposites reinforced by cellulose whiskers. Macromolecules 1995, 28, 6365–6367. [Google Scholar] [CrossRef]
  18. Buffa, J.M.; Casado, U.; Mucci, V.; Aranguren, M.I. Cellulose nanocrystals in aqueous suspensions: Rheology of lyotropic chiral liquid crystals. Cellulose 2019, 26, 2317–2332. [Google Scholar] [CrossRef]
  19. Lemaster, R.L.; Lu, L.; Jackson, S. The use of process monitoring techniques on a CNC wood router. part 1. sensor selection. For. Prod. J. 2000, 50, 31. [Google Scholar]
  20. Huang, C.; Su, Y.; Shi, J.; Yuang, C.; Zhai, S.; Yong, Q. Revealing the effects of centuries ageing on the chemically structural features of lignin in archaeological fir woods. New J. Chem. 2019, 43, 3520–3528. [Google Scholar] [CrossRef]
  21. Lu, Q.; Lin, W.; Tang, L.; Wang, S.; Chen, X.; Huang, B. A mechanochemical approach to manufacturing bamboo cellulose nanocrystals. J. Mater. Sci. 2015, 50, 611–619. [Google Scholar] [CrossRef]
  22. Lin, W.; Chen, D.; Yong, Q.; Huang, C.; Huang, S. Improving enzymatic hydrolysis of acid-pretreated bamboo residues using amphiphilic surfactant derived from dehydroabietic acid. Bioresour. Technol. 2019, 293, 122055. [Google Scholar] [CrossRef] [PubMed]
  23. Huang, C.; Wang, X.; Liang, C.; Jiang, X.; Yang, G.; Xu, J.; Yong, Q. A sustainable process for procuring biologically active fractions of high-purity xylooligosaccharides and water-soluble lignin from Moso bamboo prehydrolyzate. Biotechnol. Biofuels 2019, 12, 189. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  24. Wang, X.; Song, L.; Cheng, D.; Liang, X.; Xu, B. Effects of saturated steam pretreatment on the drying quality of moso bamboo culms. Eur. J. Wood Wood Prod. 2019, 77, 949–951. [Google Scholar] [CrossRef]
  25. Csiszár, E.; Nagy, S. A comparative study on cellulose nanocrystals extracted from bleached cotton and flax and used for casting films with glycerol and sorbitol plasticisers. Carbohydr. Polym. 2017, 174, 740–749. [Google Scholar] [CrossRef]
  26. Gao, T.; Yang, Z.; Chen, C.; Li, Y.; Fu, K.; Dai, J.; Hitz, E.M.; Xie, H.; Liu, B.; Song, J. Three-dimensional printed thermal regulation textiles. ACS Nano 2017, 11, 11513–11520. [Google Scholar] [CrossRef]
  27. Luzi, F.; Fortunati, E.; Jiménez, A.; Puglia, D.; Pezzolla, D.; Gigliotti, G.; Kenny, J.M.; Chiralt, A.; Torre, L. Production and characterization of PLA_PBS biodegradable blends reinforced with cellulose nanocrystals extracted from hemp fibres. Ind. Crop. Prod. 2016, 93, 276–289. [Google Scholar] [CrossRef]
  28. Zhu, Y.P.; Wang, M.; Xiang, Y.; Qiu, L.; Hu, S.; Zhang, Z.; Mattjus, P.; Zhu, X.; Zhang, Y. Nach is a novel subgroup at an early evolutionary stage of the CNC-BZIP subfamily transcription factors from the marine bacteria to humans. Int. J. Mol. Sci. 2018, 19, 2927. [Google Scholar] [CrossRef] [Green Version]
  29. Leston, S.; Nebot, C.; Nunes, M.; Cepeda, A.; Ramos, F. Sulfathiazole: Analytical methods for quantification in seawater and macroalgae. Environ. Toxicol. Pharmacol. 2015, 39, 77–84. [Google Scholar] [CrossRef]
  30. Huang, C.; Sun, R.; Chang, H.M.; Yong, Q.; Jameel, H.; Phillips, R. Production of dissolving grade pulp from tobacco stalk through SO2-ethanol-water fractionation, alkaline extraction, and bleaching processes. BioResources 2019, 14, 5544–5558. [Google Scholar]
  31. Wu, Y.; Tang, Q.W.; Yang, F.; Xu, L.; Wang, X.H.; Zhang, J.L. Mechanical and thermal properties of rice straw cellulose nanofibrils-enhanced polyvinyl alcohol films using freezing and-thawing cycle method. Cellulose 2019, 26, 3193–3204. [Google Scholar] [CrossRef]
  32. Pei, A.; Qi, Z.; Berglund, L.A. Functionalized cellulose nanocrystals as biobased nucleation agents in poly(l-lactide) (PLLA)-Crystallization and mechanical property effects. Compos. Sci. Technol. 2010, 70, 815–821. [Google Scholar] [CrossRef]
  33. Rao, A.; Divoux, T.; Mckinley, G.H.; Hart, A.J. Shear melting and recovery of crosslinkable cellulose nanocrystal-polymer gels. Soft Matter 2019, 15, 4401–4412. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  34. Kargarzadeh, H.; Mariano, M.; Huang, J.; Ling, N.; Ahmad, I.; Dufresne, A.; Thomas, S. Recent developments on nanocellulose reinforced polymer nanocomposites: A review. Polymer 2017, 132, 368–393. [Google Scholar] [CrossRef]
  35. Yue, P.; Wang, S.; Li, X.; Ge, M. Preparation of polyaniline/Ag composite conductive fabric via one-step oxidation-reduction reaction. J. Text. Res. 2014, 60, 33–42. [Google Scholar]
  36. Yu, S.; Park, B.I.; Park, C.; Hong, S.M.; Han, T.H.; Koo, C.M. RTA-treated carbon fiber/copper core/shell hybrid for thermally conductive composites. ACS Appl. Mater. Interfaces 2014, 6, 7498–7503. [Google Scholar] [CrossRef]
  37. Mengal, N.; Sahito, I.A.; Arbab, A.A.; Sun, K.C.; Qadir, M.B.; Memon, A.A. Fabrication of a flexible and conductive lyocell fabric decorated with graphene nanosheets as a stable electrode material. Carbohydr. Polym. 2016, 152, 19–25. [Google Scholar] [CrossRef]
  38. Gan, L.; Shang, S.; Yuen, C.W.M.; Jiang, S.X. Graphene nanoribbon coated flexible and conductive cotton fabric. Compos. Sci. Technol. 2015, 117, 208–214. [Google Scholar] [CrossRef]
  39. Tang, B.H.G.; Gao, H.; Hai, L. Application of graphene as filler to improve thermal transport property of epoxy resin for thermal interface materials. Int. J. Heat Mass Transf. 2015, 85, 420–429. [Google Scholar] [CrossRef]
  40. Carrasco, P.M.; Montes, S.; García, I.; Borghei, M.; Jiang, H.; Odriozola, I.; Cabañero, G.; Ruiz, V. High-concentration aqueous dispersions of graphene produced by exfoliation of graphite using cellulose nanocrystals. Carbon 2014, 70, 157–163. [Google Scholar] [CrossRef]
  41. Tao, X.; Wu, Y.; Xu, W.; Zan, X.; Zhang, J. Preparation and characterization of multi-layer wood composite impregnated by graphene/phenol-formaldehyde resin for heating floor. J. For. Eng. 2019, 4, 1–7. (In Chinese) [Google Scholar] [CrossRef]
  42. Yang, F.; Lan, C.; Zhang, H.; Guan, J.; Zhang, F.; Fei, B.; Zhang, J. Study on graphene/CNC-coated bamboo pulp fabric preparation of fabrics with thermal conductivity. Polymers 2019, 11, 1265. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  43. Wu, G.; Kong, Z.; Chen, C.; Chen, J.; Huo, S.; Jiang, J. Crosslinking Reaction and Properties of Two-Component Waterborne Polyurethane from Terpene-Maleic Ester Type Epoxy Resin. J. Appl. Polym. Sci. 2013, 128, 132–138. [Google Scholar] [CrossRef]
  44. Krišťák, Ľ.; Igaz, R.; Ružiak, I. Applying the EDPS Method to the Research into Thermophysical Properties of Solid Wood of Coniferous Trees. Adv. Mater. Sci. Eng. 2019, 2019. [Google Scholar] [CrossRef] [Green Version]
  45. GB/T1727-92 General Preparation of Paint Film; Standardization Administration of the People’s Republic of China: Beijing, China, 1992; pp. 318–326. (In Chinese)
  46. GB/T 6739-2006 Paints and Varnishes-Determination of Film Hardness by Pencil Test; Standardization Administration of the People’s Republic of China: Beijing, China, 2006; pp. 425–428. (In Chinese)
  47. GB/T1768-2006 Paints and Varnishes-Determination of Abrasion Resistance by Rotary Rubber Grinding Wheel Method; Standardization Administration of the People’s Republic of China: Beijing, China, 2006; pp. 429–433. (In Chinese)
  48. GB/T4893.4-2013 Test of Surface Coatings of Furniture-Part 4: Determination of Adhesion-Cross Cut; Standardization Administration of the People’s Republic of China: Beijing, China, 2013; pp. 1–9. (In Chinese)
  49. GB/T 11048-2018 Textiles-Physiological Effects-Measurement of Thermal and Wate-Vapour Resistance under Steady-State Conditions (Sweating Guarded-Hotplate Test); Standardization Administration of the People’s Republic of China: Beijing, China, 2018; pp. 1–16. (In Chinese)
  50. Sahlin, K.; Forsgren, L.; Moberg, T.; Bernin, D.; Rigdahl, M.; Westman, G. Surface treatment of cellulose nanocrystals (CNC): Effects on dispersion rheology. Cellulose 2018, 25, 331–345. [Google Scholar] [CrossRef] [Green Version]
  51. Wang, X.; Wang, W.; Liu, Y.; Ren, M.; Xiao, H.; Liu, X. Characterization of conformation and locations of C–F bonds in graphene derivative by polarized ATR-FTIR. Anal. Chem. 2016, 88, 3926–3934. [Google Scholar] [CrossRef]
  52. Montes, S.; Carrasco, P.M.; Ruiz, V.; Germán, C.; Odriozola, I. Synergistic reinforcement of poly(vinyl alcohol) nanocomposites with cellulose nanocrystal-stabilized graphene. Compos. Sci. Technol. 2015, 117, 26–31. [Google Scholar] [CrossRef]
  53. Calizo, I.; Bao, W.; Miao, F.; Lau, C.N.; Balandin, A.A. The effect of substrates on the raman spectrum of graphene: Graphene-on-sapphire and graphene-on-glass. Appl. Phys. Lett. 2017, 91, 201904. [Google Scholar] [CrossRef]
  54. Claramunt, S.; Varea, A.; López-Díaz, D.; Velázquez, M.; Mercedes, C.A.; Cirera, A. The importance of interbands on the interpretation of the raman spectrum of graphene oxide. J. Phys. Chem. C 2015, 119, 10123–10129. [Google Scholar] [CrossRef]
  55. Sharma, P.; Saikia, B.K.; Das, M.R. Removal of methyl green dye molecule from aqueous system using reduced graphene oxide as an efficient adsorbent: Kinetics, isotherm and thermodynamic parameters. Colloids Surf. A Physicochem. Eng. Asp. 2014, 457, 125–133. [Google Scholar] [CrossRef]
  56. Toonder, J.D.; Malzbender, J.; De With, G.; Balkenende, R. Fracture toughness and adhesion energy of sol–gel coatings on glass. J. Mater. Res. 2002, 17, 224–233. [Google Scholar] [CrossRef]
  57. Shiue, J.; Matthewson, M.J.; Stupak, P.R.; Rondinella, V.V. Effects of silica nanoparticle addition to the secondary coating of dual-coated optical fibers. Acta Mater. 2006, 54, 2631–2636. [Google Scholar] [CrossRef]
  58. Vardanyan, V.; Poaty, B.; Chauve, G.; Landry, V.; Galstian, T.; Riedl, B. Mechanical properties of UV-waterborne varnishes reinforced by cellulose nanocrystals. J. Coat. Technol. Res. 2014, 11, 841–852. [Google Scholar] [CrossRef]
  59. Wang, H.; Song, X.; Wei, C.; Gao, Y.; Guo, G. Abrasion resistance enhancement of ultrafine-structured WC–Co coating fabricated by using in situ synthesized composite powder. J. Mater. Sci. Technol. 2013, 29, 1067–1073. [Google Scholar] [CrossRef]
  60. Dai, Y.T.; Qiu, F.X.; Xu, J.C.; Yum, Z.P.; Yang, P.F.; Xu, B.B.; Jiang, Y.; Yang, D.Y. Preparation and properties of UV-curable waterborne graphene oxide/polyurethane-acrylate composites. Plast. Rubber Compos. 2014, 43, 54–62. [Google Scholar] [CrossRef]
  61. Chen, Q.; Liu, P.; Sheng, C.; Zhou, L.; Duan, Y.; Zhang, J. Tunable self-assembly structure of graphene oxide/cellulose nanocrystal hybrid films fabricated by vacuum filtration technique. RSC Adv. 2014, 4, 39301–39304. [Google Scholar] [CrossRef]
  62. Veigel, S.; Grüll, G.; Pinkl, S.; Obersriebnig, M.; Müller, U.; Gindl-Altmutter, W. Improving the mechanical resistance of waterborne wood coatings by adding cellulose nanofibres. React. Funct. Polym. 2014, 85, 214–220. [Google Scholar] [CrossRef]
  63. Lei, Y.; He, J.; Zhao, Q.; Liu, T. A nitrile functionalized graphene filled ethylene propylene diene terpolymer rubber composites with improved heat resistance. Compos. Part B Eng. 2018, 134, 81–90. [Google Scholar] [CrossRef]
  64. Wei, D.; Liu, Y.; Wang, Y.; Zhang, H.; Huang, L.; Yu, G. Synthesis of N-doped graphene by chemical vapor deposition and its electrical properties. Nano Lett. 2009, 9, 1752. [Google Scholar] [CrossRef]
  65. Eyley, S.; Thielemans, W. Surface modification of cellulose nanocrystals. Front. Chem. Eng. China 2007, 1, 228–232. [Google Scholar] [CrossRef] [Green Version]
  66. Fugallo, G.; Cepellotti, A.; Paulatto, L.; Lazzeri, M.; Marzari, N.; Mauri, F. Thermal conductivity of graphene and graphite: Collective excitations and mean free paths. Nano Lett. 2014, 14, 6109–6114. [Google Scholar] [CrossRef] [PubMed]
  67. Wang, Y.; Zhang, H.; Lin, X.; Chen, S.; Jiang, Z.; Wang, J.; Huang, J.; Zhang, F.; Li, H. Naked Au nanoparticles monodispersed onto multifunctional cellulose nanocrystals-graphene hybrid sheets: Towards efficient and sustainable heterogeneous catalysts. New J. Chem. 2018, 42, 2197–2203. [Google Scholar] [CrossRef]
Coatings 10 00040 g001 550
Figure 1. Absorbance of CNC/GM sol mixture at 660 nm.
Figure 1. Absorbance of CNC/GM sol mixture at 660 nm.
Coatings 10 00040 g001
Coatings 10 00040 g002 550
Figure 2. FT-IR spectra of CNC/GM sol mixtures containing 2 wt % of GM.
Figure 2. FT-IR spectra of CNC/GM sol mixtures containing 2 wt % of GM.
Coatings 10 00040 g002
Coatings 10 00040 g003 550
Figure 3. Raman spectrum of graphene materials and CNC/GM sol mixtures containing 2 wt % of GM.
Figure 3. Raman spectrum of graphene materials and CNC/GM sol mixtures containing 2 wt % of GM.
Coatings 10 00040 g003
Coatings 10 00040 g004 550
Figure 4. XRD of graphene materials and CNC/GM sol mixtures containing 2 wt % of GM.
Figure 4. XRD of graphene materials and CNC/GM sol mixtures containing 2 wt % of GM.
Coatings 10 00040 g004
Coatings 10 00040 g005 550
Figure 5. TEM images of GM and CNC/GM sol mixtures containing 2 wt % of GM.
Figure 5. TEM images of GM and CNC/GM sol mixtures containing 2 wt % of GM.
Coatings 10 00040 g005
Coatings 10 00040 g006 550
Figure 6. Adhesion and hardness values of CNC/GM/ two-component waterborne polyurethane coatings (2K-WPU).
Figure 6. Adhesion and hardness values of CNC/GM/ two-component waterborne polyurethane coatings (2K-WPU).
Coatings 10 00040 g006
Coatings 10 00040 g007 550
Figure 7. Abrasion resistance of coatings as a function of GM loading.
Figure 7. Abrasion resistance of coatings as a function of GM loading.
Coatings 10 00040 g007
Coatings 10 00040 g008 550
Figure 8. Curves of 2K-WPU and CNC/GM/2K-WPU coatings containing 2 wt % of GM.
Figure 8. Curves of 2K-WPU and CNC/GM/2K-WPU coatings containing 2 wt % of GM.
Coatings 10 00040 g008
Coatings 10 00040 g009 550
Figure 9. Thermal conductivity of CNC/GM coated wood samples as a function of GM loading.
Figure 9. Thermal conductivity of CNC/GM coated wood samples as a function of GM loading.
Coatings 10 00040 g009
Table
Table 1. Weight ratios of microcrystalline cellulose (MCC) and graphene materials (GM) for making cellulose nanocrystals (CNC)/GM sol mixtures through one-step method.
Table 1. Weight ratios of microcrystalline cellulose (MCC) and graphene materials (GM) for making cellulose nanocrystals (CNC)/GM sol mixtures through one-step method.
H2SO4 (g)MCC (g)GM (g)
98100.1
98100.2
98100.3

Share and Cite

MDPI and ACS Style

Yang, F.; Wu, Y.; Zhang, S.; Zhang, H.; Zhao, S.; Zhang, J.; Fei, B. Mechanical and Thermal Properties of Waterborne Polyurethane Coating Modified through One-Step Cellulose Nanocrystals/Graphene Materials Sols Method. Coatings 2020, 10, 40. https://doi.org/10.3390/coatings10010040

AMA Style

Yang F, Wu Y, Zhang S, Zhang H, Zhao S, Zhang J, Fei B. Mechanical and Thermal Properties of Waterborne Polyurethane Coating Modified through One-Step Cellulose Nanocrystals/Graphene Materials Sols Method. Coatings. 2020; 10(1):40. https://doi.org/10.3390/coatings10010040

Chicago/Turabian Style

Yang, Feng, Yan Wu, Shuqin Zhang, Haiming Zhang, Suilang Zhao, Jilei Zhang, and Benhua Fei. 2020. "Mechanical and Thermal Properties of Waterborne Polyurethane Coating Modified through One-Step Cellulose Nanocrystals/Graphene Materials Sols Method" Coatings 10, no. 1: 40. https://doi.org/10.3390/coatings10010040

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop