Surface Modification Of Nanofillers Research Articles

Effect of alkylated surface modified silica nanoparticles on degradation products of PP during photooxidation aging: A Py-GC-MS analysis

Introducing nano-fillers to PP matrix improves its mechanical performance, but impairs the stability and changes its aging behavior. Surface modification of nano-fillers may have further influence. To investigate the effect of alkylated surface modified silica nanoparticles on PP degradation during photooxidation aging, Py-GC-MS flash evaporation technique was applied to qualitatively analyze the degradation products and quantitatively analyze their accumulation during photooxidation aging. Thermal processing of PP composites led to thermal decomposition and oxidation before aging. During photooxidation aging, both silica nanoparticles and the alkylated surface modification promoted the oxidative degradation of PP. Oxidation products accumulated, while the aging mechanism did not change. Nine typical oxidation products with different carbon numbers were selected and their accumulation during photooxidation aging were analyzed. For C1-C6 total oxidation products, there exhibits an induction period and subsequent linear accumulation during photooxidation aging. The induction period was used to show the effect of nano-silica and its surface modification. It was shortened by introducing nano-silica and further shortened by alkylated surface modification of nano-silica.

Dynamic tensile mechanical behavior of polyurethane films incorporated with functionalized graphene oxide

Since high-speed collisions often give rise to catastrophic damage, investigating the enhancement and dynamic behavior of composites is essential. Herein, graphene oxide (GO) and its surface-modified derivative were separately incorporated into the polyurethane matrix and their dynamic mechanical properties were examined and compared. A drop-weight dynamic tension device was used to characterize the mechanical properties of composites. The collected results show significant improvement in failure strength while incorporating GO as the nanofiller. And, the slightly reduced graphene oxide (SRGO) grafted with polyethyleneimine (SRGO-PEI) is beneficial in improving the plastic stress. The high-speed deformation process reveals severe strain localization before the break. The morphology of fracture surfaces indicates the SRGO-PEI plays a vital role in hindering crack propagation. Then the constitutive equation was derived to describe the stress-strain curves of modified polyurethane films. This work involves the synergistic effect between surface modification of nanofillers and the dynamic behavior of polymer-based composites, which could be regarded as a guideline for designing the composites under high-velocity impact environments.

Effect of Nanofillers on Tribological Properties of Polymer Nanocomposites: A Review on Recent Development.

Polymer nanocomposites with enhanced performances are becoming a trend in the current research field, overcoming the limitations of bulk polymer and meeting the demands of market and society in tribological applications. Polytetrafluoroethylene, poly(ether ether ketone) and ultrahigh molecular weight polyethylene are the most popular polymers in recent research on tribology. Current work comprehensively reviews recent advancements of polymer nanocomposites in tribology. The influence of different types of nanofiller, such as carbon-based nanofiller, silicon-based nanofiller, metal oxide nanofiller and hybrid nanofiller, on the tribological performance of thermoplastic and thermoset nanocomposites is discussed. Since the tribological properties of polymer nanocomposites are not intrinsic but are dependent on sliding conditions, direct comparison between different types of nanofiller or the same nanofiller of different morphologies and structures is not feasible. Friction and wear rate are normalized to indicate relative improvement by different fillers. Emphasis is given to the effect of nanofiller content and surface modification of nanofillers on friction, wear resistance, wear mechanism and transfer film formation of its nanocomposites. Limitations from the previous works are addressed and future research on tribology of polymer nanocomposites is proposed.

Surface Modifications of Nanofillers for Carbon Dioxide Separation Nanocomposite Membrane

CO2 separation is an important process for a wide spectrum of industries including petrochemical, refinery and coal-fired power plant industries. The membrane-based process is a promising operation for CO2 separation owing to its fundamental engineering and economic benefits over the conventionally used separation processes. Asymmetric polymer–inorganic nanocomposite membranes are endowed with interesting properties for gas separation processes. The presence of nanosized inorganic nanofiller has offered unprecedented opportunities to address the issues of conventionally used polymeric membranes. Surface modification of nanofillers has become an important strategy to address the shortcomings of nanocomposite membranes in terms of nanofiller agglomeration and poor dispersion and polymer–nanofiller incompatibility. In the context of CO2 gas separation, surface modification of nanofiller is also accomplished to render additional CO2 sorption capacity and facilitated transport properties. This article focuses on the current strategies employed for the surface modification of nanofillers used in the development of CO2 separation nanocomposite membranes. A review based on the recent progresses made in physical and chemical modifications of nanofiller using various techniques and modifying agents is presented. The effectiveness of each strategy and the correlation between the surface modified nanofiller and the CO2 separation performance of the resultant nanocomposite membranes are thoroughly discussed.

Enhancing Permeability of Thin Film Nanocomposite Membranes via Covalent Linking of Polyamide with the Incorporated Metal–Organic Frameworks

Thin film nanocomposite (TFN) membranes were invented in 2007 to enhance the permeability of thin film composite (TFC) membranes. Surface modification of nanofillers was a common method to improve ...

Assessment of nanoscopic dynamic mechanical properties and B-C-N triad effect on MWCNT/h-BNNP nanofillers reinforced HDPE hybrid composite using oscillatory nanoindentation: An insight into medical applications.

A thrust on improvement of different properties of polymer has taken a contemporary route with advent of nanofillers. Although several nanofillers are existent; MultiWalled Carbon Nanotubes- (MWCNTs) and h-Boron Nitride nanoplatelets-(h-BNNPs) unique combination of 1D and 2D dimensional geometry aids an advantage of B-C-N triad elemental effects on properties of tested samples. The current study aims to investigate the effects of MWCNT and h-BNNP reinforcement in High Density Polyethylene (HDPE) for high load bearing areas of medical applications requiring both elastic and viscous behavior. The results were analyzed keeping a view of its application in areas like HDPE based fracture fixation plates, acetabular cups and others. The composite and hybrid samples with different loadings were prepared after surface modification of nanofillers by mechanical mixing and molding technique. The dynamic nano-mechanical properties like storage modulus, loss modulus and tan delta were assessed for each sample during frequency swept from 10 to 220 Hz. The viscoelastic properties like hc/hm, H/E, elastic-plastic deformation were investigated and evaluated. At a frequency of 10 Hz, the storage and loss modulus of 0.1 CNT increased by 37.56% and decreased by 23.52% respectively on comparison with pure HDPE. This infers a good elastic as well as viscous behavior. Overall elastic behavior of 0.1 CNT was confirmed from tan delta evaluation. The interaction between B-C-N elemental triad had significant effect on creep strength, visco-damping property (hc/hm and H/E), elastic plastic displacement and pile-up and sink-in behavior. Highest creep strength and visco-damping property was exhibited by 0.25 CNT/0.15 BNNP hybrid. The elastic-plastic displacement of hybrid composite was noted as least, which decreased by 30% on comparison with pure HDPE. It can be inferred that presence of 1D-MWCNT and 2D-h-BNNP had significant effect on important dynamic viscoelastic and creep properties of HDPE based hybrid composites.

Application of Surface Modified XLPE Nanocomposites for Electrical Insulation of High Voltage Cables- Partial Discharge Study

This paper presents the experimental results of PD test using IEC 60270 standard for 0-27.5 kV range with the PD characteristics of XLPE nanocomposites for un-modified, agglomerated and Octylsilane modified silica nanofillers using nano 1, 2, 3, 4, 5, 10 wt %. The unmodified and agglomerated nanocomposites show the lowest PD activity at nano 5 wt %. The surface modification of nanofiller helps to reduce the PD formation marginally due to improved nanofiller dispersion. Octylsilane surface modified XLPE/silica nano 3 wt % exhibits the lowest PD activity. To prove the further suitability of Octylsilane surface modified nanocomposites over unmodified and agglomerated nanocomposites, the discharge inception voltage (DIV) and breakdown voltage (BDV) have also been measured using IEC 60270 standard. The hypothetical theory has been proposed to explain the role of nanofillers in reducing PD activity and increasing DIV as well as BDV.

Application of surface-modified XLPE nanocomposites for electrical insulation- partial discharge and morphological study

This paper investigates partial discharge (PD) characteristics of crosslinked polyethylene (XLPE) nanocomposites for unmodified, agglomerated, and Octylsilane-modified silica nanofillers (nano 1, 2, 3, 4, 5, 10 wt %) case. The surface modification of nanofiller helps to reduce the PD formation marginally. Octylsilane surface-modified XLPE/silica nano 3 wt % exhibits the lowest PD activity with highest discharge inception voltage and breakdown voltage. Also, the issue of change in the polymer structure due to the addition of nanofillers is reported here. The differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), fourier transform infrared (FTIR), and contact angle measurement study conducted suggests that the addition of nanosilica leads to the change in the melting point, thermal degradation temperature, heat of fusion, bonding structure and the contact angle of the polymer, respectively. These structural changes are explained with the supporting theory.

Bio-Based Coatings for Paper Applications

The barrier resistance and wettability of papers are commonly controlled by the application of petroleum-based derivatives such as polyethylene, waxes and/or fluor- derivatives as coating. While surface hydrophobicity is improved by employing these polymers, they have become disfavored due to limitations in fossil-oil resources, poor recyclability, and environmental concerns on generated waste with lack of biodegradation. Alternatively, biopolymers including polysaccharides, proteins, lipids and polyesters can be used to formulate new pathways for fully bio-based paper coatings. However, difficulties in processing of most biopolymers may arise due to hydrophilicity, crystallization behavior, brittleness or melt instabilities that hinder a full exploitation at industrial scale. Therefore, blending with other biopolymers, plasticizers and compatibilizers is advantageous to improve the coating performance. In this paper, an overview of barrier properties and processing of bio-based polymers and their composites as paper coating will be discussed. In particular, recent technical advances in nanotechnological routes for bio-based nano- composite coatings will be summarized, including the use of biopolymer nanoparticles, or nanofillers such as nanoclay and nanocellulose. The combination of biopolymers along with surface modification of nanofillers can be used to create hierarchical structures that enhance hydrophobicity, complete barrier protection and functionalities of coated papers.

Polymer nanocomposites for energy applications

energy production, energy transportation, and storage, has grown rapidly in recent years due to the increase in fossil fuel consumption, environmental issue and global warming. Nanomaterials with different morphologies, properties and structures (e.g. barium titanate nanoparticles, carbon nanotubes, ZnO nanowires) offer superior chemical, mechanical or physical properties compared to their micro meter-scale counterparts. Accordingly, they are potential candidate materials for clean energy applications such as the energy storage, fuel cells, and solar cells (ISBN: 978-0-12-407796-6). The nanomaterials can be incorporated into polymers at low loading levels to form nanocomposites with greater mechanical flexibility, tailored properties and functionalities. These include bipolar plates of fuel cells (DOI: 10.1039/c0ee00689k), high-energy density capacitors, solid polymer electrolytes, and hybrid polymer/nanoparticle solar cells (DOI: 10.1016/ j.jcis.2011.12.016). Nanofillers offer larger interfacial area that allows better interaction with the polymer matrix. Polymers provide structural support and protection for nanomaterials during their industrial service lives. A wide variety of polymers can be selected for making nanocomposites for various fields of energy applications depending on the designed chemical, physical and mechanical properties. The major challenges of achieving high-performance polymer nanocomposites are the attainment of uniform dispersion of nanofillers in the polymer matrix and the manipulation of nanofiller/polymer interfaces. Typical approaches include surface modification of nanofillers via covalent and noncovalent functionalization. Significant research efforts have been devoted by chemists and materials scientist for developing polymer nanocomposites with novel functionalities using improved fabrication techniques recently. For instance, polymeric materials with high dielectric constant (k) and low loss find useful application for making supercapacitors. The !-phase of polyvinylidene fluoride is known to exhibit excellent ferroelectric and piezoelectric effects. This phase can be increased to ~46% by adding 0.5 wt% carbon nanotubes and processed through electrospinning. The process stretches polymer solution uniaxially under an electric potential. It can be further increased over 90% by mechanical drawing (DOI: 10.1021/jp4011026). To reduce dielectric loss, core-shell nanoparticle strategy emerges as a powerful method for preparing high-k nanocomposites especially filled with conducting nanomaterials (DOI: 10.1002/adma.201401310). To fully realize widespread commercial applications of polymer nanocomposites, it is necessary to develop cost-effective processes for the mass production of these materials in large quantities.

Development of Fabrication Methods of Filler/Polymer Nanocomposites: With Focus on Simple Melt-Compounding-Based Approach without Surface Modification of Nanofillers

Many attempts have been made to fabricate various types of inorganic nanoparticle-filled polymers (filler/polymer nanocomposites) by a mechanical or chemical approach. However, these approaches require modification of the nanofiller surfaces and/or complicated polymerization reactions, making them unsuitable for industrial-scale production of the nanocomposites. The author and coworkers have proposed a simple melt-compounding method for the fabrication of silica/polymer nanocomposites, wherein silica nanoparticles without surface modification were dispersed through the breakdown of loose agglomerates of colloidal nano-silica spheres in a kneaded polymer melt. This review aims to discuss experimental techniques of the proposed method and its advantages over other developed methods.

Compounding and processing of polymer nanocomposites: from scientific challenges to industrial stakes

materials showing promising industrial application potential and have been the focus of an ever-growing interest in the past few years due to their quite exceptional properties at low filler contents (around 5 wt% or less). Compared to neat polymers and depending on the nanofiller used (nanofibres such as carbon nanotubes or cellulose whiskers, nanoplatelets such as layered silicate/clay or layered double hydroxides; nanosized isotropic particles such as silica or titanium dioxide), nanocomposites may offer: – better mechanical properties (e.g. strength and modulus) and dimensional stability (reduced shrinkage and warpage) – reduced permeability to gases and improved chemical resistance – better thermal stability and heat deflection temperature – flame retardancy and reduced smoke emissions. However only well-dispersed and well-exfoliated nanoparticles can lead to the expected improvement of properties. Raw material producers, converters and end-users have therefore to tackle both compounding and processing issues. Surface modification of nanofillers with organic surfactant and adaptation of compounding conditions (high shear, high residence time, special screw profile design in case of melt compounding for example) may help to get rid of most of compounding issues. Research groups have made significant progress in that field. The development of masterbatches has reduced the health and safety hazards. The final injectionor extrusion-moulded part may be easily obtained by mixing/diluting the masterbatch with the appropriate polymer matrix. The nanoparticle dispersion (and exfoliation where applicable) is usually assumed to be achieved during the masterbatch compounding. Experience unfortunately often shows that the industrial reality is quite different. More research efforts are still required to identify the processing conditions that allow maintaining the dispersion and avoiding nanoparticle to aggregate again in the manufactured products. In conclusion the high potential of nanocomposites has already been demonstrated at the lab scale. There is now time to bridge the gap between scientific challenges and industrial stakes. The key issue is currently to maintain nanoparticle dispersion during the industrial scale processing of nanocomposites on machines and equipments that are used to manufacture polymer composites parts on a regular basis. Efforts have to be oriented in this direction.