scholarly journals Photoinduced Metal-Free Surface Initiated ATRP from Hollow Spheres Surface

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 599 ◽  
Author(s):  
Chun-Na Yan ◽  
Qian Liu ◽  
Lin Xu ◽  
Li-Ping Bai ◽  
Li-Ping Wang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Free Surface ◽  
Methyl Methacrylate ◽  
Hybrid Materials ◽  
Hollow Spheres ◽  
Polymerization Process ◽  
Resonance Spectroscopy ◽  
Hydroxyl Groups ◽  
Metal Free ◽  
Thermal Stability Of

Well-defined amphiphilic diblock copolymer poly (methyl methacrylate)-b-poly (N-isopropylacrylamide) grafted hollow spheres (HS-g-PMMA-b-PNIPAM) hybrid materials were synthesized via metal-free surface-initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiators α-Bromoisobutyryl bromide (BIBB) were attached onto hollow sphere surfaces through esterification of acyl bromide groups and hydroxyl groups. The synthetic ATRP initiators (HS-Br) were further used for the metal-free SI-ATRP of methyl methacrylate (MMA) and N-isopropyl acrylamide (NIPAM) using 10-phenylphenothiazine (PTH) as the photocatalyst. The molecular weight of the polymers, structure, morphology, and thermal stability of the hybrid materials were characterized via gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), 1H-nuclear magnetic resonance spectroscopy (1H NMR), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA), respectively. The results indicated that the ATRP initiator had been immobilized onto HS surfaces successfully followed by metal-free SI-ATRP of MMA and NIPAM, the Br atom had located at the end of the main PMMA polymer chain, and the polymerization process possessed the characteristic of controlled/“living” polymerization. The thermal stability of the hybrid materials was increased significantly compared to the pure PMMA and PNIPAM.

scholarly journals Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2254
Author(s):  
Adeleke A. Oyekanmi ◽  
N. I. Saharudin ◽  
Che Mohamad Hazwan ◽  
Abdul Khalil H. P. S. ◽  
Niyi G. Olaiya ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Cellulose Nanofibrils ◽  
Hydroxyl Groups ◽  
Water Contact ◽  
Silane Coupling ◽  
Cnf Films ◽  
Kenaf Bast ◽  
Thermal Stability Of

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.

Enhanced Thermal Stability of Esterified Lignin in Different Solvent Mediums

2018 ◽  
Vol 9 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Sharifah Nurul Ain Syed Hashim ◽  
Sarani Zakaria ◽  
Chin Hua Chia ◽  
Sharifah Nabihah Syed Jaafar
Keyword(s):  
Thermal Stability ◽  
Alkaline Solution ◽  
Room Temperature ◽  
Hydroxyl Groups ◽  
Aqueous Alkaline Solution ◽  
Alkali Lignin ◽  
Weight Percentage ◽  
H Nmr ◽  
Ft Ir ◽  
Thermal Stability Of

In this study, soda alkali lignin from oil palm empty fruit bunch (EFB-AL) and kenaf core (KC-AL) are esterified with maleic anhydride under two different conditions, namely i) pyridine at temperature of 120°C for 3h and ii) aqueous alkaline solution at room temperature for 4h. As a result, the weight percentage gain (WPG) of the esterified EFB-AL (EFB-EL) and esterified KC-AL (KC-EL) in pyridine demonstrated a higher compared to aqueous alkaline solution. The FT-IR results of EFB-EL and KC-EL in both solvents exhibited some changes at the carbonyl and hydroxyl groups. Furthermore, the esterification process induced the carboxylic peak to appear in both alkali lignin samples. The outcome is confirmed by conducting H-NMR analysis, which demonstrated ester and carboxylic acid peaks within the spectral analysis. Finally, the TGA results showed both EFB-EL and KC-EL that are exposed to aqueous alkaline actually possessed better thermal stability and higher activation energy (Ea) compared to the esterified samples in pyridine.

PP/Wasted PET Fabric Composites Compatibilized by two Different Methods: Mechanical Properties, Morphology and Thermal Stability

2012 ◽  
Vol 476-478 ◽  
pp. 730-733
Author(s):  
Zhi Dan Lin ◽  
Zi Xian Guan ◽  
Neng Sheng Liu ◽  
Zheng Jun Li
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Maleic Anhydride ◽  
Injection Molding ◽  
Methyl Methacrylate ◽  
Pet Fabric ◽  
Fabric Composites ◽  
Different Types ◽  
Thermal Stability Of

The composites of polypropylene (PP) and wasted PET fabric (WF) were prepared by extrusion blending and injection molding, and then, the interface of the composites was modified by two different types of compatibilizers, i.e., maleic anhydride grafted PP (PP-g-MA) and the mixture of methyl methacrylate (MMA) and styrene (St). The mechanical properties, morphology and thermal stability of these composites were studied.

The influence of β-FeOOH nanorods on the thermal stability of poly(methyl methacrylate)

2007 ◽  
Vol 92 (1) ◽  
pp. 70-74 ◽  
Author(s):  
Milena Marinović-Cincović ◽  
Maja Č. Popović ◽  
Mirjana M. Novaković ◽  
Jovan M. Nedeljković
Keyword(s):  
Thermal Stability ◽  
Methyl Methacrylate ◽  
Poly Methyl Methacrylate ◽  
Thermal Stability Of

scholarly journals The effects of certain glycols, substituted glycols and related organic solvents on the thermal stability of soluble collagen

1971 ◽  
Vol 125 (2) ◽  
pp. 599-604 ◽  
Author(s):  
G. J. Hart ◽  
A. E. Russell ◽  
D. R. Cooper
Keyword(s):  
Thermal Stability ◽  
Optical Rotation ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Thermal Transition ◽  
Denaturation Temperature ◽  
Rotation Measurement ◽  
Skin Collagen ◽  
Positional Isomerism ◽  
Thermal Stability Of

The effects of a number of related diols, substituted diols and glycerol on the thermal stability of acid-soluble calf skin collagen were investigated. Thermal transition temperatures were determined by optical rotation measurement. Short-chain diols with terminal hydroxyl groups, i.e. ethylene glycol and propane-1,3-diol, stabilized the protein at all accessible concentrations. Stabilization was also observed with glycerol and diethylene glycol. Higher homologues in the diol series produced various effects, as did hydroxyl-group positional isomerism. Monoalkyl substitution of diols progressively lowered the denaturation temperature of collagen. Results are discussed in relation to possible mechanisms of perturbant action.

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