Properties Of Polyurethane Nanocomposites Research Articles

Hybrid polyurethane nanocomposites reinforced with clay and multiwalled carbon nanotubes: Synthesis and characterization

Polyurethane (PU) nanocomposites were fabricated using renewable castor oil and 4,4′-diphenylmethane diisocyanate. The modified Multiwalled Carbon Nanotubes (MWCNTs), as well as Clay (Closite 30B), was used as fillers for hybridizing the nanocomposites. The clay percentage was varied from (1–5) wt % and MWCNTs was varied from (0.05–0.2) wt % for the PU nanocomposite. The prepared nanocomposites were characterized using Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), wide angle X-ray diffraction (WAXD), and field emission scanning electron microscopy (FESEM). FTIR analysis confirmed the formation of polyurethane linkages as well as the presence of peaks corresponding to clay and MWCNTs, which indicates the good dispersion of hybridizing filler content. Also, the results obtained further confirmed the presence of detangled nanotubes in TEM images for nanocomposites. The addition of filler content will lead to enhancement in the properties of polyurethane nanocomposites.

Thermal and Mechanical Characterizations of Nanoclay/Palm Oil Polyol Based Polyurethane Composites

Effect of organically modified nanoclay on thermal and mechanical properties of palm oil polyol (POP) based polyurethane (PU) were investigated. Thermoplastic PU elastomer was synthesized utilizing polycaprolactonediol (PCL), POP, 4,4’-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) as chain extender via two-step prepolymer process in bulk. The amount of clay added is between 1 to 5 wt%. The produced nanocomposites were subjected to thermal and mechanical characterization which includes thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and tensile test. The results obtained showed improved thermal stability and tensile properties of PU nanocomposites upon addition of clay content.

Structure–property correlation of polyurethane nanocomposites: Influence of loading and nature of nanosilica and microstructure of hyperbranched polyol

AbstractNew generation polyurethane nanocomposites based on toluene diisocyanate, poly(propylene glycol), hyperbranched polymers (HBPs), and nanosilica were synthesized with the aim of determining the effect of the loading and nature of nanosilica and the functionality of HBP on the structure and properties of polyurethane nanocomposites. Good dispersion of nanosilica at 4 wt % loading in the polymer was confirmed from atomic force microscopy. The properties of the polyurethane nanocomposites were a function of content and nature of the nanosilica in the matrix. The optimum silica loading was 4 wt %. At this loading, tensile strength and storage modulus at 25°C of the nanocomposites increased by 52 and 40%, respectively over the pristine polyurethane. Organo‐treated nanosilica exhibited higher physico‐mechanical properties than the untreated one. With the increase of functionality in the hyperbranched polyol, the tensile strength, thermal stability, and dynamic mechanical properties of the nanocomposites improved. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Preparation and Properties of Polyurethane Nanocomposites with Organoclay or Nanosilica

Polyurethane nanocomposites reinforced with organoclay or nanosilica were prepared by dispersing the filler during polymerization. The modulus and thermal stability of polyurethane were enhanced with the addition of fillers and the effect was more pronounced with organoclay than with nanosilica. The crystallization and damping behaviors showed that the mobility of polyurethane chain is restricted by the filler, and the effect was more evident with organoclay.

Influence of a Reactive Organoclay on Polymerization and Properties of Polyurethane Nanocomposites

In this study, segmented polyurethane/clay nanocomposites were prepared via in situ intercalative polymerization of polyether polyol mixed nanoclay with toluene diisocyanate, followed by chain extending with 1,4-butanediol. The reactive prepolymer tended to gel by increasing the clay content from 0.4 to 1.5 wt.%. This unusual phenomenon was found to be caused by a catalytic effect of quaternary ammonium intercalant on the organoclay. The procedure used for intercalated nanocomposites, is confirmed by wide angle X-ray diffraction studies. Thermogravimetric analysis results demonstrated a very good increase in onset degradation temperature by adding only 0.8 wt.% of organoclay.

Effect of the Microstructure of a Hyperbranched Polymer and Nanoclay Loading on the Morphology and Properties of Novel Polyurethane Nanocomposites

Novel polyurethane nanocomposites based on toluene diisocyanate, poly(propylene glycol), various hyperbranched polymers (HBPs), and layered silicate were synthesized with the aim of determining the effect of the layered silicate loading and the functionality of HBP on the structure and properties of polyurethane nanocomposites. The microstructure of the nanocomposites was investigated by X-ray diffraction analysis and high-resolution transmission electron microscopy. It was found that exfoliated morphology and good dispersion were obtained up to 8 phr clay loading for all of the nanocomposites. approximately 100% increment in tensile strength, approximately 2-fold increase in the lap shear strength, approximately 200% increment in the peel strength, and 120% increment in the storage modulus along with a dramatic improvement in thermal stability were observed with the addition of 8 phr clay, over the pristine polyurethane. The higher the level of functionality of the HBP, the higher is the property enhancement. These properties were correlated with the state of dispersion of the clay platelets in the polyurethane matrix, the structure of the matrix, and clay-polymer interaction.

Selection of Nanofiller Dispersion Method and Properties Evaluation of Polyurethane/ZrO<sub>2</sub>:Eu Composites for Optoelectronic Applications

In the present study the distribution of nanofillers in the polyurethane matrix and the composite properties were investigated. As a nanofiller, zirconium oxide doped with 10% Eu3+ was used. The nanofiller was added at 0.1 wt%. Different ways of nanofiller incorporation were investigated. The microstructure of the obtained materials was examined by atomic force microscopy in force modulation. The size analysis of the nanofiller was investigated with HRSEM. The thermal (DSC, TGA) properties of polyurethane nanocomposites were also investigated in addition to the analysis of transmittance and luminescence of obtained materials. The results obtained indicate a possibility of fabrication of polymeric nanocomposites for optoelectronic applications via a relatively inexpensive processing route.

Influence of Surface Functionalized Carbon Nanotubes on the Properties of Polyurethane Nanocomposites

Thermoplastic polyurethane elastomer/carbon nanotubes nanocomposites were prepared by melt mixing process and the influence of surface functionalization of carbon nanotubes on the properties of the nanocomposites was investigated. Improvement of tensile modulus was observed by the addition of functionalized carbon nanotubes compared to pristine carbon nanotubes. Dynamic mechanical analysis showed that glass transition temperature (Tg) of polyurethane decreased slightly with increasing carbon nanotubes content. Functionalized carbon nanotubes resulted in better dispersion and it was attributed to the improved interaction between functionalized carbon nanotubes and polyurethane. Functionalization of carbon nanotubes also improved the thermal stability of polyurethane/carbon nanotubes nanocomposites.

Structure and properties of polyurethane nanocomposites with zirconium oxide including Eu

In order to receive new properties of transparent polymers, nanofillers with luminescence properties are introduced into the polyurethane matrix, this enables us to obtain polymer nanocomposites that are widely used in optoelectronics. Additionally, introduction of rare-earth elements to nanofillers gives us high luminescence properties in obtained nanocomposites. The aim of this study was to evaluate the influence of zirconium oxide including Eu3+ elements on polyurethane nanocomposites structure and properties, manufactured by “in situ” polymerisation method. Microscopic observations of the section structure of obtained materials were performed using Scanning Electron Microscope and Atomic Force Microscopy. Grain size analysis of nanofillers was performed with HRSEM and TEM. Physical properties of nanofillers (specific surface and density) as well as physical and mechanical properties of obtained composites were studied. Also an analysis of transmittance and luminescence of obtained materials was performed.

Applications of Quantitative Image Analysis to the Description of the Morphology of Boehmite and their Polyurethane Nanocomposites

This paper presents the application of stereology methods to the description of morphological properties of nanoboehmite and its nanocomposites. Images of boemithe, fracture and cut surface of composites were obtained using high-resolution electron microscopy technique and atomic force microscopy. Quantitative analysis of the fracture structure images obtained with HRSEM technique, allowed us to explain the mechanism of changes of mechanical and thermal properties of polyurethane nanocomposites, as well as allowed to determine relationships between structure characteristics and properties of examined materials. Quantitative image analysis was also found to be useful in comparative analysis of polyurethane nanocomposites structure and structure of boehmite and products of its modification.

Polyurethane/clay nanocomposites foams: processing, structure and properties

Polyurethane (PU)/montmorillonite (MMT) nanocomposites were synthesized with organically modified layered silicates (organoclays) by in situ polymerization and foams were prepared by a batch process. Clay dispersion of polyurethane nanocomposites was investigated by X-ray diffraction and transmission electron microscopy. The morphology and properties of PU nanocomposites and foams greatly depend on the functional groups of the organic modifiers, synthesis procedure, and molecular weight of polyols because of the chemical reactions and physical interactions involved. Silicate layers of organoclay can be exfoliated in the PU matrix by adding hydroxyl and organotin functional groups on the clay surface. The presence of clay results in an increase in cell density and a reduction of cell size compared to pure PU foam. In the polyurethane with high molecular weight polyol, a 6°C increase in Tg, 650% increase in reduced compressive strength, and 780% increase in reduced modulus were observed with the addition of 5% organically treated clays. Opposite effects were observed in PU nanocomposite foams with highly crosslinked structure. The interference of the H-bond in the presence of clay is probably the reason.