scholarly journals Nano-Brushes of Alcohols Grafted onto Cellulose Nanocrystals for Reinforcing Poly(Butylene Succinate): Impact of Alcohol Chain Length on Interfacial Adhesion

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 95 ◽  
Author(s):  
Hatem Abushammala
Keyword(s):  
Surface Properties ◽  
Chain Length ◽  
Cellulose Nanocrystals ◽  
Interfacial Adhesion ◽  
Mechanical Analysis ◽  
Toluene Diisocyanate ◽  
Hydroxyl Groups ◽  
Water Contact ◽  
Butylene Succinate ◽  
Degradation Temperature

Despite the many interesting properties of cellulose nanocrystals (CNCs), their hydrophilicity is one of the main challenges for their processing with hydrophobic polymers and matrices. To overcome this challenge, this paper describes the preparation of brush-like CNCs with tailored surface properties by grafting alcohols of different chain lengths onto their surfaces. Ethanol, 1-butanol, 1-hexanol, and 1-octanol were grafted on the CNC surface using 2,4-toluene diisocyanate (TDI) as a linker. The CNCs were characterized for their structural, morphological, surface, and thermal properties. Because of the grafting, the water contact angle of the CNCs significantly increased from 32° to up to 120°, which was dependent on the chain length of the grafted alcohol. The thermal stability of the CNCs was also improved, mainly as a result of the reaction of TDI with the CNC hydroxyl groups. Later, the CNCs were used to reinforce films of poly(butylene succinate) (PBS), which were then characterized using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). An increase of up to two-fold in the storage modulus was observed using DMA, which was dependent on the chain length of the grafted alcohol. However, no change in the glass transition temperature or degradation temperature of PBS was detected. This approach is proved efficient for tailoring the surface properties of CNCs towards excellent interfacial adhesion in their composites.

scholarly journals Impact of the Surface Properties of Cellulose Nanocrystals on the Crystallization Kinetics of Poly(Butylene Succinate)

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 196 ◽  
Author(s):  
Hatem Abushammala ◽  
Jia Mao
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Cellulose Nanocrystals ◽  
Toluene Diisocyanate ◽  
Scanning Calorimetry ◽  
Water Contact ◽  
Butylene Succinate ◽  
Avrami Model ◽  
Nucleation Activity ◽  
The Impact

The hydrophilicity of cellulose nanocrystals (CNCs) is a major challenge for their processing with hydrophobic polymers and matrices. As a result, many surface modifications have been proposed to hydrophobize CNCs. The authors showed in an earlier study that grafting alcohols of different chain lengths onto the surface of CNCs using toluene diisocyanate (TDI) as a linker can systematically hydrophobize CNCs to a water contact angle of up to 120° depending on the alcohol chain length. Then, the hydrophobized CNCs were used to mechanically reinforce poly(butylene succinate) (PBS), which is a hydrophobic polymer. As a result of hydrophobization, PBS/CNCs interfacial adhesion and the composite mechanical properties significantly improved with the increasing CNC contact angle. Continuing on these results, this paper investigates the impact of CNC surface properties on the crystallization behavior of PBS using differential scanning calorimetry (DSC). The results showed that the crystallization temperature of PBS increased from 74.7 °C to up to 86.6 °C as a result of CNC nucleation activity, and its value was proportionally dependent on the contact angle of the CNCs. In agreement, the nucleation activity factor (φ) estimated using Dobreva and Gutzow’s method decreased with the increasing CNC contact angle. Despite the nucleation action of CNCs, the rate constant of PBS crystallization as estimated using the Avrami model decreased in general as a result of a prevailing impeding effect. This decrease was minimized with increasing the contact angle of the CNCs. The impeding effect also increased the average activation energy of crystallization, which was estimated using the Kissinger method. Moreover, the Avrami exponent (n) decreased because of CNC addition, implying a heterogeneous crystallization, which was also apparent in the crystallization thermograms. Overall, the CNC addition facilitated PBS nucleation but retarded its crystallization, and both processes were significantly affected by the surface properties of the CNCs.

Improving the Mechanical Properties of Ramie-Polylactic Acid Green Composites by Surface Modification using Single Bath Alkaline and Silane Treatment

2021 ◽  
Author(s):  
Swati Sharma ◽  
Abhijit Majumdar ◽  
Bhupendra Singh Butola
Keyword(s):  
Polylactic Acid ◽  
Interfacial Adhesion ◽  
Research Work ◽  
Mechanical Analysis ◽  
Silane Treatment ◽  
Compression Moulding ◽  
Water Contact ◽  
Impact Performance ◽  
Single Bath ◽  
Surface Modified

Abstract This research work emphasises on improving the interfacial adhesion of ramie/ polylactic acid (PLA) composites. For this purpose, ramie fabric was modified using vinyl trimethoxy silane with two different hydrolysing agents, i.e. sodium hydroxide and ammonia. The surface modified ramie fabric was characterised by static water contact angle, elemental dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). FTIR and EDX analysis confirmed the presence of silica. The tensile strength of fabric showed a decrease after the silane treatment. The composites were prepared by compression moulding using untreated and treated ramie fabrics with PLA. The treatment improved tensile and impact performance of ramie/PLA composites due to enhanced interfacial adhesion between fibre and matrix. Dynamic mechanical analysis (DMA) results revealed that treated ramie/PLA composites have higher storage modulus and lower tangent delta than untreated composites.

scholarly journals On the Para/Ortho Reactivity of Isocyanate Groups during the Carbamation of Cellulose Nanocrystals Using 2,4-Toluene Diisocyanate

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1164 ◽  
Author(s):  
Hatem Abushammala
Keyword(s):  
Cellulose Nanocrystals ◽  
Negative Impact ◽  
Toluene Diisocyanate ◽  
Molar Ratio ◽  
Hydroxyl Groups ◽  
Reaction Conditions ◽  
Surface Hydroxyl ◽  
Molar Ratios ◽  
Hydrolysis Method ◽  
Surface Hydroxyl Groups

2,4-toluene diisocyanate (TDI) has been commonly used to bind molecules and polymers onto the surface of cellulose nanocrystals (CNCs). Such a process usually involves two steps: (1) the more reactive para-isocyanates (p-NCOs) of TDI are reacted with the surface hydroxyl groups of CNCs then (2) the ortho-isocyanates (o-NCOs) are reacted with certain desired molecules. During the first reaction, an ideal para/ortho selectivity could be impossible to achieve, as o-NCOs are not fully unreactive. Therefore, there is a need to better understand the reaction between CNCs and TDI towards a maximum para/ortho selectivity. For that goal, CNCs were reacted with TDI under varying temperatures (35–75 °C) and TDI/CNCs molar ratios (1–5). The amount of the reacted TDI was estimated using elemental analysis while the free o-NCO groups were quantified following the hydrolysis method of Abushammala. The results showed that temperature had a negative impact on para/ortho selectivity while TDI/CNCs molar ratio improved it. A maximum selectivity of 93% was achieved using a temperature of 35 °C and a molar ratio of 3. This is a three-fold improvement to that using the traditional reaction conditions (75 °C and molar ratio of 1).

Investigation of Surface Properties of Titanium Treated with Combined Alkali and Sodium Removal Treatments

2016 ◽  
Vol 840 ◽  
pp. 225-230 ◽  
Author(s):  
Kwok Joon Tan ◽  
Maizlinda Izwana Idris ◽  
Hasan Zuhudi Abdullah
Keyword(s):  
Surface Properties ◽  
High Purity ◽  
Alkali Treatment ◽  
Heat Treatments ◽  
Hydroxyl Groups ◽  
Water Contact ◽  
X Ray ◽  
Sodium Removal ◽  
Titanium Foils ◽  
Purity Titanium

Recent studies revealed the incorporation of sodium removal treatment in between alkali and heat treatments to prepare a sodium-free bioactive surface on titanium. This method has been reported to be more effective than conventional alkali and heat treatments to promote titanium osteointegration. This study aims to investigate the surface properties of high purity titanium after subjected to alkali treatment and subsequent sodium removal treatment. High purity titanium foils were immersed in 5 M NaOH at 60 °C for 24 hours followed by immersion in diluted HCl acid and/or distilled water at 40 °C for a period of time. The surface morphology and composition were examined using Field Emission Scanning Electron Microscope/Energy-Dispersive X-Ray Spectroscopy (FESEM/EDS). The surface wettability was evaluated by water contact angle. The surface functional groups were analysed using Fourier Transform Infrared Spectroscopy (FTIR). It was revealed that alkali and subsequent sodium removal treatments have rendered these samples high wettability and surface energy with the introduction of hydroxyl groups. Furthermore, diluted HCl treatment, water treatment and combination of both treatments removed sodium from the surfaces of alkali-treated titanium effectively (<5wt% Na) without altering existing hydroxyl groups.

scholarly journals Bio-Based Poly(butylene succinate)/Microcrystalline Cellulose/Nanofibrillated Cellulose-Based Sustainable Polymer Composites: Thermo-Mechanical and Biodegradation Studies

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1472 ◽  
Author(s):  
Oskars Platnieks ◽  
Sergejs Gaidukovs ◽  
Anda Barkane ◽  
Aleksandrs Sereda ◽  
Gerda Gaidukova ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Microcrystalline Cellulose ◽  
Nanofibrillated Cellulose ◽  
Mechanical Analysis ◽  
Sem Analysis ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Crystallinity Degree ◽  
Sustainable Housing ◽  
Degradation Temperature

Biodegradable polymer composites from renewable resources are the next-generation of wood-like materials and are crucial for the development of various industries to meet sustainability goals. Functional applications like packaging, medicine, automotive, construction and sustainable housing are just some that would greatly benefit. Some of the existing industries, like wood plastic composites, already encompass given examples but are dominated by fossil-based polymers that are unsustainable. Thus, there is a background to bring a new perspective approach for the combination of microcrystalline cellulose (MCC) and nanofibrillated cellulose (NFC) fillers in bio-based poly (butylene succinate) matrix (PBS). MCC, NFC and MCC/NFC filler total loading at 40 wt % was used to obtain more insights for wood-like composite applications. The ability to tailor the biodegradable characteristics and the mechanical properties of PBS composites is indispensable for extended applications. Five compositions have been prepared with MCC and NFC fillers using melt blending approach. Young’s modulus in tensile test mode and storage modulus at 20 °C in thermo-mechanical analysis have increased about two-fold. Thermal degradation temperature was increased by approximately 60 °C compared to MCC and NFC. Additionally, to estimate the compatibility of the components and morphology of the composite’s SEM analysis was performed for fractured surfaces. The contact angle measurements testified the developed matrix interphase. Differential scanning calorimetry evidenced the trans-crystallization of the polymer after filler incorporation; the crystallization temperature shifted to the higher temperature region. The MCC has a stronger effect on the crystallinity degree than NFC filler. PBS disintegrated under composting conditions in a period of 75 days. The NFC/MCC addition facilitated the specimens’ decomposition rate up to 60 days

Production and characterization of cellulose nanocrystals/ acrylonitrile butadiene styrene nanocomposites

2020 ◽  
Vol 54 (27) ◽  
pp. 4207-4214
Author(s):  
Rosineide M Leão ◽  
Luiz CC Jesus ◽  
Paula T Bertuoli ◽  
Ademir J Zattera ◽  
João MLL Maia ◽  
...  
Keyword(s):  
Cellulose Nanocrystals ◽  
Chemical Interaction ◽  
Acrylonitrile Butadiene Styrene ◽  
Mechanical Analysis ◽  
Hydroxyl Groups ◽  
The Matrix ◽  
General Improvement ◽  
Injection Molded ◽  
Butadiene Styrene

The use of cellulose nanocrystals as reinforcement in polymers brings challenges mainly related to the dry thermal processing, and their adhesion and dispersion in the matrix. In this work, cellulose nanocrystals from sugarcane bagasse was used as reinforcement in nanocomposites of acrylonitrile-butadiene-styrene. Thus, the main objective of this work is to evaluate the mechanical and thermal performance of cellulose nanocrystals/acrylonitrile-butadiene-styrene (CNC/ABS) nanocomposites as a function of cellulose nanocrystals type and content. More specifically, to study the effects of the chemical interaction between acrylonitrile groups from ABS and hydroxyl groups from cellulose. The ABS and the nanocomposites, reinforced with 0.5, 1.0 and 1.5 wt% nanocrystals, were obtained by extrusion and then injection molded to obtain specimens for testing. Mechanical testing, dynamic mechanical analysis, rheology and thermogravimetric analysis were used for characterization. The main results are related to increased impact strength, elastic modulus, storage modulus and viscosity of the nanocomposite compared to ABS. However, tensile strength and thermal stability decreased. Therefore, if higher tensile properties are needed, the CNC220/ABS nanocomposites should be preferred whereas, for impact, CNC150/ABS. Thus, there is a general improvement in properties up to 0.5% cellulose nanocrystals content, which is followed by a loss in properties for higher content.

scholarly journals On the Effectiveness of Oxygen Plasma and Alkali Surface Treatments to Modify the Properties of Polylactic Acid Scaffolds

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1643
Author(s):  
Ricardo Donate ◽  
María Elena Alemán-Domínguez ◽  
Mario Monzón
Keyword(s):  
Surface Properties ◽  
Enzymatic Degradation ◽  
Oxygen Plasma ◽  
Physicochemical Characterization ◽  
Surface Treatments ◽  
Carboxyl Groups ◽  
Scanning Calorimetry ◽  
Water Contact ◽  
Angle Measurements ◽  
3D Printed

Surface modification of 3D-printed PLA structures is a major issue in terms of increasing the biofunctionality and expanding the tissue engineering applications of these parts. In this paper, different exposure times were used for low-pressure oxygen plasma applied to PLA 3D-printed scaffolds. Alkali surface treatments were also evaluated, aiming to compare the modifications introduced on the surface properties by each strategy. Surface-treated samples were characterized through the quantification of carboxyl groups, energy-dispersive X-ray spectroscopy, water contact angle measurements, and differential scanning calorimetry analysis. The change in the surface properties was studied over a two-week period. In addition, an enzymatic degradation analysis was carried out to evaluate the effect of the surface treatments on the degradation profile of the 3D structures. The physicochemical characterization results suggest different mechanism pathways for each type of treatment. Alkali-treated scaffolds showed a higher concentration of carboxyl groups on their surface, which enhanced the enzymatic degradation rate, but were also proven to be more aggressive towards 3D-printed structures. In contrast, the application of the plasma treatments led to an increased hydrophilicity of the PLA surface without affecting the bulk properties. However, the changes on the properties were less steady over time.

Effect of surface properties and polymer chain length on polymer adsorption in solution

2021 ◽  
Vol 155 (3) ◽  
pp. 034701
Author(s):  
Emily Y. Lin ◽  
Amalie L. Frischknecht ◽  
Karen I. Winey ◽  
Robert A. Riggleman
Keyword(s):  
Surface Properties ◽  
Chain Length ◽  
Polymer Chain ◽  
Polymer Adsorption ◽  
Effect Of Surface

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.

scholarly journals Tunable Crystalline Phases in UV-Curable PEG-Grafted Ladder-Structured Silsesquioxane/Polyimide Composites

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2295 ◽  
Author(s):  
Ryung Il Kim ◽  
Ju Ho Shin ◽  
Jong Suk Lee ◽  
Jung-Hyun Lee ◽  
Albert S. Lee ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Surface Properties ◽  
Weight Ratio ◽  
Hybrid Polymer ◽  
Water Contact ◽  
Uv Curable ◽  
Wide Range ◽  
Drastic Increase ◽  
Polyimide Composites ◽  
Crystalline Polyethylene

A series of UV-curable hybrid composite blends containing a carboxylic acid functionalized polyimidewith varying amounts of high molecular weight (~1 K) PEG-grafted ladder-structured polysilsesquioxanes copolymerized with methacryl groups were fabricated and their structural, thermal, mechanical, and surface properties characterized. At a composite weight ratio of polyimide above 50 wt.%, a stark shift from amorphous to crystalline polyethylene glycol (PEG) phases were observed, accompanied by a drastic increase in both surface moduli and brittleness index. Moreover, fabricated composites were shown to have a wide range water contact angle, 9.8°–73.8°, attesting to the tunable surface properties of these amphiphilic hybrid polymer composites. The enhanced mechanical properties, combined with the utility of tunable surface hydrophilicity allows for the possible use of these hybrid polymer composites to be utilized as photosensitive polyimide negative photoresists for a myriad of semiconductor patterning processes.

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