Hydrophobic Modification of Nanocellulose via a Two-Step Silanation Method

Dodecyltrimethoxysilane (DTMOS), which is a silanation modifier, was grafted onto nanocellulose crystals (NCC) through a two-step method using KH560 (ɤ-(2,3-epoxyproxy)propytrimethoxysilane) as a linker to improve the hydrophobicity of NCC. The reaction mechanism of NCC with KH560 and DTMOS and its surface chemical characteristics were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and HCl–acetone titration. These analyses confirmed that KH560 was grafted onto the surface of NCC through the ring-opening reaction, before DTMOS was covalently grafted onto the surface of NCC using KH560 as a linker. The grafting of NCC with DTMOS resulted in an improvement in its hydrophobicity due to an increase in its water contact angle from 0° to about 140°. In addition, the modified NCC also possessed enhanced thermal stability.

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An Effective, Economical and Ultra-Fast Method for Hydrophobic Modification of NCC Using Poly(Methylhydrogen)Siloxane

Polymers ◽

10.3390/polym11060963 ◽

2019 ◽

Vol 11 (6) ◽

pp. 963

Author(s):

Xueqing You ◽

Qingjian Hu ◽

Xiaoyong Hu ◽

Hanxian Chen ◽

Wenbin Yang ◽

...

Keyword(s):

Thermal Stability ◽

Weight Ratio ◽

Hydroxyl Groups ◽

Fast Method ◽

Hydrophobic Modification ◽

X Ray Diffraction ◽

Water Contact ◽

X Ray ◽

Low Surface Energy ◽

Thermal Stability Of

Poor compatibility between nanocellulose crystals (NCCs) and major polymers has limited the application of NCC as bio-reinforcements. In this work, an effective and ultra-fast method was investigated to significantly improve the hydrophobicity of NCC by using poly(methylhydrogen)siloxane (PMHS) as modifier. PMHS possessed amounts of reactive –Si–H groups and hydrophobic –CH3 groups. The former groups were reactive with the hydroxyl groups of NCC, while the latter groups afforded NCC very low surface energy. As the weight ratio of PMHS to NCC was only 0.0005%, the hydrophobicity of NCC was significantly improved by increasing the water contact angle of NCC from 0° to 134°. The effect of weight ratio of PMHS to NCC and the hydrogen content of –Si–H in PMHS on the hydrophobicity and thermal stability was investigated in detail by Fourier transform infrared spectroscopy (FTIR), (X-ray Diffraction) XRD and (thermogravimetric analysis) TGA. The results indicated that PMHS chains were covalently grafted onto NCC and PMHS modification improved the thermal stability of NCC.

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Fabrication of Hydrophobic ZnO/PMHS Coatings on Bamboo Surfaces: The Synergistic Effect of ZnO and PMHS on Anti-Mildew Properties

Coatings ◽

10.3390/coatings9010015 ◽

2018 ◽

Vol 9 (1) ◽

pp. 15 ◽

Cited By ~ 2

Author(s):

Jingbing Chen ◽

Yunyun Ma ◽

Huiping Lin ◽

Qingzhu Zheng ◽

Xinxiang Zhang ◽

...

Keyword(s):

Synergistic Effect ◽

Trichoderma Viride ◽

Synthesis Method ◽

Penicillium Citrinum ◽

Surface Chemical ◽

Hydrophobic Modification ◽

X Ray Diffraction ◽

Water Contact ◽

X Ray ◽

Before And After

Poor mildew resistance has limited the application of bamboo materials. In this work, ZnO/PMHS coatings were fabricated on bamboo timber surfaces by hydrothermal synthesis method and hydrophobic modification with poly(methylhydrogen)siloxane (PMHS). The surface chemical characteristics and microstructure of the bamboo before and after modification were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and water contact angle (WCA). The morphology results indicated that ZnO on the surface of bamboo forms flower-like aggregations. The WCA of ZnO/bamboo increased from 65° to 142° after PMHS hydrophobic modification, indicating that the hydrophobicity of bamboo was significantly improved. The original bamboo had poor anti-mildew properties when exposed to Trichoderma viride, Aspergillus niger, and Penicillium citrinum. After depositing ZnO onto the surface of the bamboo, the anti-mildew properties were significantly improved. Furthermore, it was found that after PMHS hydrophobic modification, ZnO/bamboo had excellent anti-mildew properties when exposed to the three mold hyphae, which indicated that PMHS hydrophobic modification had a synergistic effect on the anti-mildew properties of bamboo with a ZnO coating.

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Study of Almond Shell Characteristics

Materials ◽

10.3390/ma11091782 ◽

2018 ◽

Vol 11 (9) ◽

pp. 1782 ◽

Cited By ~ 17

Author(s):

Xuemin Li ◽

Yinan Liu ◽

Jianxiu Hao ◽

Weihong Wang

Keyword(s):

Thermal Stability ◽

Electron Microscope ◽

Stability Analysis ◽

Photoelectron Spectroscopy ◽

Chemical Constituents ◽

Chemical Characteristics ◽

Almond Shell ◽

X Ray ◽

Alkaline Extract ◽

Extract Content

A large amount of almond shells are disposed of every year. The anatomical and chemical characteristics of almond shells are investigated in this paper in order to contribute to better utilization of these shells. The micromorphology, surface elements, thermal stability, crystallization, chemical composition, and relative properties of almond shells are analyzed. Under observation by microscope and electron microscope, the diameter of almond shells is 300–500 μm for large holes, and 40–60 μm for small holes present in the shell. X-ray photoelectron spectroscopy shows the elements of almond shells include C (72.27%), O (22.88%), N (3.87%), and Si (0.87%). The main chemical constituents of cellulose, hemicellulose and lignin in almond shells account for 38.48%, 28.82% and 29.54%, respectively. The alkaline extract content of almond shells is 14.03%, and benzene alcohol extraction is 8.00%. The benzene alcohol extractives of almond shells mainly contain 17 types of organic compound, including benzene ring, ethylene, carbon three bond, and other mufti-functional groups. Thermal stability analysis shows almond shells mainly lose weight at 260 °C and 335 °C. These characteristics indicate that almond shells have the capacity to be used in composites and absorption materials.

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