OMMT Nanocomposites Research Articles

PPR/EPDM/POE-g-MA/OMMT nanocomposites with superior low-temperature toughness based on embedded OMMT within compound rubber dispersion phase

A new approach to produce polypropylene random copolymer/ethylene propylene diene monomer/polyolefin elastomers modified with maleic anhydride/organic modified nanomontmorillonite (PPR/EPDM/POE-g-MA/OMMT) nanocomposites with superior low-temperature toughness was conducted. The brittle-ductile transition temperature (Tbd) of PPR/EPDM/POE-g-MA/OMMT nanocomposites reduced from −20 °C to −40 °C. The incorporation of POE-g-MA results in the distribution of OMMT changing from the interfacial distribution into dispersed inside rubber phase and a compound rubber dispersed phase in PPR/EPDM/POE-g-MA/OMMT nanocomposites was comprised of EPDM, POE-g-MA and embedded OMMT. The synergistic effect of POE-g-MA and OMMT was considered to result from the special compound rubber dispersed phase consisting of EPDM and POE-g-MA as well embedded OMMT, which led to the reduction in space between rubber domains and the increase in internal friction and ultimately brought about the remarkable enhancement in mechanical properties.

Localization of different types of organoclay montmorillonite in the compatibilized polyamide 6/carboxylated acrylonitrile butadiene rubber nanocomposites: Morphology and rheological properties

AbstractIn this study, nanocomposites based on polyamide 6/carboxylated acrylonitrile butadiene rubber (PA6/XNBR) reinforced by the clay montmorillonite (OMMT) (Cloisite 20A and Cloisite 30B) were prepared by melt mixing. Glycidyl methacrylate‐grafted XNBR (XNBR‐g‐GMA) compatibilizer was used for immiscible blends of PA6/XNBR. The results illustrated that OMMT wanted to be selectively present in the more hydrophilic PA6 phase. Also, by adding the XNBR‐g‐GMA compatibilizer and increasing OMMT content, tensile strength, rheological and dynamic mechanical properties of the nanocomposites improved. According to transmission electron microscopy (TEM) images, a few layers of OMMT (Cloisite 20A) in the XNBR‐g‐GMA compatibilizer phase was observed. The results of X‐ray diffractometry and TEM analyses demonstrated that the formation of intercalated or exfoliated structures for both types of OMMT nanocomposites. In end of all analysis was found PA6/XNBR reinforced by the Cloisite 30B could be substantially improved by adding XNBR‐g‐GMA as a compatibilizer when compared to those reinforced by Cloisite 20A.

A Characteristic Study of Polylactic Acid/Organic Modified Montmorillonite (PLA/OMMT) Nanocomposite Materials after Hydrolyzing

In this study, the montmorillonite (MMT) clay was modified with NH4Cl, and then the structures were exfoliated or intercalated in a polylactic acid (PLA) matrix by a torque rheometer in the ratio of 0.5, 3.0, 5.0 and 8.0 wt%. X-ray diffraction (XRD) revealed that the organic modified-MMT(OMMT) was distributed successfully in the PLA matrix. After thermal pressing, the thermal stability of the mixed composites was measured by a TGA. The mixed composites were also blended with OMMT by a co-rotating twin screw extruder palletizing system, and then injected for the ASTM-D638 standard specimen by an injection machine for measuring the material strength by MTS. The experimental results showed that the mixture of organophilic clay and PLA would enhance the thermal stability. In the PLA mixed with 3 wt% OMMT nanocomposite, the TGA maximum decomposition temperature (Tmax) rose from 336.84 °C to 339.08 °C. In the PLA mixed with 5 wt% OMMT nanocomposite, the loss of temperature rose from 325.14 °C to 326.48 °C. In addition, the elongation rate increased from 4.46% to 10.19% with the maximum loading of 58 MPa. After the vibrating hydrolysis process, the PLA/OMMT nanocomposite was degraded through the measurement of differential scanning calorimetry (DSC) and its Tg, Tc, and Tm1 declined.

Nanomaterials and nanotechnology for composites: synthesis, structure, properties and new application opportunities

Nanomaterials and nanotechnology for composites: synthesis, structure, properties and new application opportunities

Organic Montmorillonite Intercalated Nano-composites Prevent Post-Surgical Associated Infections

In this study, organic montmorillonite (OMMT) is a modified form of montmorillonite (MMT) in which chitosan (CS) intercalated MMT by ion exchange of sodium ions from Na/MMT with –NH3 + of CS. The structural analysis confirmed intercalation of CS into MMT layers, indicating that CS molecular chains incorporated into the MMT layers. The interlayer distance of the MMT layered was 1.128nm and in the OMMT layers enlarged to 2.365 nm. Antibacterial activity analysis showed that unmodified MMT could not inhibit the growth of bacteria. Nevertheless, after addition of the CS molecules, an increase in the interlayer distance of MMT was observed. No difference was observed between the viability of the human dental pulp stem cells (hDPSCs) contacted to different concentrations (ranging from 0.5 to 2mg/ml) of MMT and OMMT in all time intervals, when compared with the control samples. Furthermore, neither MMT nor OMMT showed apoptosis and cytotoxicity effect on the cells. The strong antibacterial activity of the synthesized OMMT nanocomposite was also confirmed against E. coli, S. aureus, K. pneumonia and P. aeruginosa, suggesting its high potential for the prevention of post-surgical infections.

Morphology, mechanical property, and processing thermal stability of PVC/La‐OMMTs nanocomposites prepared viain situintercalative polymerization

Poly(vinyl chloride) (PVC) nanocomposites were prepared via anin situintercalative suspension polymerization of vinyl chloride with four organic carboxylic acid salts (montmorillonite [MMT] units) containing thermally stable lanthanum ions. The effects of different lanthanum organic montmorillonites (La‐OMMTs) on the particle features and molecular weight were investigated. The transmission electron microscopy data indicated the formation of partially exfoliated or intercalated PVC/La‐OMMTs nanocomposites. The effect of different functional groups on the mechanical properties and processing thermal stability of PVC/La‐OMMT nanocomposites were investigated. Tensile testing and two‐roll mill processing results showed that La‐OMMTs could enhance the dynamic thermal stability and mechanical properties versus PVC pure resin and PVC/I.30P nanocomposites (composed of PVC and I.30P). This suggested that the double bond and amidogen group in La‐OMMTs could promote the dispersion of La‐OMMTs in the PVC matrix and also improve the adhesion between the La‐OMMTs and PVC matrix. The results have potential value in the industrial development of PVC/La‐OMMTs nanocomposites. J. VINYL ADDIT. TECHNOL., 26:97–108, 2020. © 2019 Society of Plastics Engineers

Poly(acrylic acid-co-styrene)/clay nanocomposites: efficient adsorbent for methylene blue dye pollutant

In this contribution, polymer/clay (nano)composites, based on poly(acrylic acid) (PAA) and poly(acrylic acid-co-styrene) poly(AA-co-St), were synthesized by free radical polymerization, using 2,2′-azobis(isobutyronitrile) (AIBN), as initiator and organomodified clay (OMMT), as nanofillers. The structural and morphological characteristics of the obtained (nano)composites, PAA/OMMT (1, 3, 5 wt%), poly(AA75-co-St25)/OMMT (3 wt%) and poly(AA25-co-St75)/OMMT (3 wt%), were examined by X-ray diffraction and scanning electron microscopy, indicating the successful intercalation of polymer chains into the clay nanoplatelets. Thermal properties of obtained (nano)composites were evaluated according to thermogravimetric analysis and differential scanning calorimetry. Based on morphological and thermal results, poly(AA25-co-St75)/OMMT (3 wt%) (nano)composite was selected as an efficient adsorbent matrix for methylene blue dye, with about 74% of elimination obtained after only 80 min of swelling, under soft conditions.

Structure and Properties of a cis-1,4-Polybutadiene/Organic Montmorillonite Nanocomposite Prepared via In Situ Polymerization

ABSTRACTCis-1,4-polybutadiene (cis-1,4-PB) is one of the most important synthetic rubbers, having superior performances such as wear resistance, cold resistance and high elasticity. However, its mechanical properties, including low tensile strength, tear resistance and thermal stability, limit its application in comparison to natural rubber and butadiene-styrene rubber that have excellent overall performances. Thus, the reinforcing of cis-1,4-PB is a necessity. The dispersion of clay in rubbers on the nanoscale can improve the mechanical, gas permeability and thermal properties of the resulting composites. In this paper, organic montmorillonite (OMMT) clay was dispersed into the cis-1,4-PB matrix via an in-situ polymerization method and the chemical structure, phase morphology, mechanical properties and thermal stability of the composite were investigated. The properties of the composite were analyzed by such techniques as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA). In the in-situ polymerization, a Ni-based catalyst system with the presence of OMMT showed high efficiency and 1,4-selectivity for the polymerization of butadiene. The OMMT could be dispersed in the polymeric matrix on the nanoscale during the polymerization. The interfusion of OMMT had little influence on the thermal stability and the chemical micro-structure of the cis-1,4-PB when the content of cis-1,4 units was more than 95%. The loss tangent of the composite was higher than that of cis-1,4-PB from −110 to −55°C, the temperature range examined, and the mechanical properties of the cis-1,4-PB/OMMT nanocomposite (NC) were improved upon the addition of OMMT.

Optimization of High Stress Abrasive Wear of Polymer Blend Ethylene and Vinyl Acetate Copolymer/HDPE/MA-g-PE/OMMT Nanocomposites

High stress (two-body) abrasive wear behavior of maleic anhydride grafted polyethylene (MA-g-PE) compatibilized ethylene and vinyl acetate copolymer (EVA)/high-density polyethylene (HDPE) polymer blend added with organophilic montmorillonite nanoclay in increasing quantity (0, 1, 2, 3, and 4 phr) has been evaluated in this study. Comparative volume losses and specific wear rates of polymer nanocomposites (PNCs) using two-body abrasion tester are discussed. Specific abrasive wear rate is optimized under different loads and sliding distances with different abrasive grade papers as per Taguchi L18 orthogonal array. Analysis of variance (ANOVA) is employed to determine the significance of factors influencing wear. Confirmation experiments are performed to predict and verify the improvement in observed values with the optimal combination level of control factors. It is observed that maximum wear volume loss and specific wear rate occur at 10 N load and 8 m sliding distance in all polymer nanocomposites. Scanning electron microscopy (SEM) images are used to analyze wear mechanisms under different experimental conditions.

Effect of organoclay incorporation and blending protocol on performance of PA6/ABS nanocomposites compatibilized with SANMA

The effect of organoclay incorporation and four different blending protocols on morphological, rheological, thermal, thermomechanical, and mechanical properties of PA6/ABS/SANMA/OMMT (55.0/35.0/5.0/5.0 wt%) nanocomposites was evaluated. As expected, even only with minor amounts of clay loading, significant reinforcement effect on mechanical and thermomechanical properties was achieved. Despite the morphological and structural similarities between studied compositions, it was found that mixing sequence might have great influence in mechanical properties, particularly in toughness. It is supposed that compatibilizing process though in situ reactions is much more efficient when PA6, ABS and SANMA are blended in the same extrusion step. Otherwise, when such condition is not satisfied, PA6/OMMT interactions seems to hamper the compatibilizing effect of SANMA, leading to inferior impact strength. POLYM. ENG. SCI., 57:1147–1154, 2017. © 2017 Society of Plastics Engineers

Preparation of nanocomposite by adding of Tunisian nanoclay in unsaturated polyester matrix: mechanical and thermal study

Unsaturated Polyester (UP) resin is widely used for many applications such as reinforced plastic (FRP) and polymer composites. However, these materials suffer from their low mechanical and thermal properties. For enhancing their performance, researchers have used Tunisian montmorillonite (MMT) for manufacturing of unsaturated polyester-montmorillonite (UP-MMT) nanocomposite synthesized by dispersing the UP resin into the silicate layers of MMT. The MMT has been modified ammonium quaternary as organic cation (OMMT). Test results, supported by mechanical testing, X-ray diffraction, thermal analysis (DSC and TGA) and transmission electron microscopy, indicated that the mechanical properties and the thermal stability of unsaturated polyester with OMMT nanocomposite (UP/OMMT) are better than those of pure UP. The degradation temperature increased by 78 °C with the addition of organic modification, and SEM micrographs show good dispersion of modified montmorillonite in the polymer matrix. Tensile strength is increased by 81 % for the UP/OMMT nanocomposite.

Preparation and characterization of poly (phenylene sulfide) nanocomposites with both silica and clay fillers

Poly (phenylene sulfide) (PPS)/silica (SiO2)/organophilic montmorillonite OMMT(clay) nanocomposites are prepared and two kinds of nanofillers of different dimensions, the plate-like OMMT(clay) and globe-like SiO2, are dispersed through their “filler–filler” interaction in melt processing. In PPS/SiO2/clay system, strong filler–filler interaction is established by different responses to shear flow of inorganic clay and SiO2, thus the well dispersion of nanofillers is achieved successfully. However, the OMMT platelets are prone to be entangled by PPS molecular chains in PPS/SiO2/OMMT composites due to the extremely low interfacial tension between PPS and OMMT, which blocks the interaction between OMMT and SiO2. The result reveals two key points in realizing well dispersion of nanofillers in polymer by establishing filler–filler interaction in processing, namely, the distinct responses to shear flow of nanofillers provide an important condition for filler–filler interaction, while the direct collision between each other is another key point to successfully realize this interaction.

Preparation, characterization, and biodegradation of PS:PLA and PS:PLA:OMMT nanocomposites usingAspergillus niger

Poly(lactic acid) (PLA) was synthesized using l-lactic acid by condensation polymerization. Polystyrene (PS) and surface modified montmorillonite (OMMT) was used for the preparation of PS:PLA composites and PS:PLA:OMMT nanocomposites. The composite materials prepared had varying amount of PLA (10–30%) and OMMT (0.5–5 phr). These composites were subjected to degradation in minimal medium using the fungi Aspergillus niger (A. niger) under controlled conditions. Scanning electron microscopy (SEM) showed the growth of microorganism on the polymer surface and fracture within the polymer matrix as a result of degradation. Fourier transform infra red spectroscopy (FTIR) was further used to determine the mechanism leading to biodegradation. It was found that the biodegradation of both PS:PLA and PS:PLA:OMMT took place mainly via break down and utilization of ester group, as can be seen from disappearance of absorption peak of ester group and simultaneous appearance of a typical IR absorption of microbial mass at 1450 cm−1. The thermal stability of PS:PLA:OMMT nanocomposites was found to increase with increasing concentration of OMMT, as observed from thermo gravimetric analysis (TGA), while mechanical property was found to be decreased after degradation at 30% of PLA and 5 wt% of OMMT content. Change in extracellular protein content, biomass production and % degradation with respect to time (up to 28 days) were studied and correlated to evaluate the effectiveness of A. niger in biodegradation of the composites. POLYM. COMPOS., 35:263–272, 2014. © 2013 Society of Plastics Engineers

Researches on Flame Retardation and Hygrothermal Aging Properties of PP/PA6/APP/OMMT Composites

PP/PA6/APP/OMMT Nanocomposites were Prepared via One-Step and Two-Step Melt Intercalation. the Flame Retardation, Thermostability, Structure Characters and Hygrothermal Aging Properties of PP/PA6/APP/OMMT Nanocomposites were Studied by UL-94, OI, TG and TEM. the Results Show that Two-Step can Improve the Flame Retardation of PP/PA6/APP/OMMT Nanocomposites; when OMMT Content is 4% or 6%, the Flame Retardation Gets Tofv-0, and the Lois are 32.2% and 32.8% Respectively; OMMT Doesn’t Play an Obvious Role to Hygrothermal Aging of PP/PA6/APP/OMMT Nanocomposites.

Study on Organic Montmorillonite Modified Recycled Optical-Grade Polycarbonate Nanocomposite

Optical–grade polycarbonate (PC) was separated from optical disks by a chemical approach and used to prepare nanocomposite to make full use of the wasted polymers. A quaternary ammonium-modified montmorillonite (organic montmorillonite, OMMT) was chosen as a modifier and an auxiliary functional resin (CBT160) was utilized to exfoliate the layers of montmorillonite. The characterization results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) for PC/ OMMT (5wt %) revealed that an exfoliation structure of the nanocomposite was obtained. The mechanical measurements show a great increase in tensile strength and Izod impact strength of PC/ OMMT nanocomposite compared with the recycled optical–grade PC.

Radiation induced modification of NBR and SBR montmorillonite nanocomposites

Nanocomposites of two different kinds of rubber (acrylonitrile-butadiene rubber NBR and styrene butadiene rubber SBR)/organo-montmorillonite nanocomposites modified by hexadecyltrimethyl ammonium bromide were prepared by the reactive mixing intercalation method in the presence of trimethylolpropane trimethylmethacrylate (TMPTMA). The influence of gamma irradiation on the morphology and properties of the rubber nanocomposites was investigated. Intercalated polar or unsaturated matrices (e.g., NBR and SBR)/OMMT nanocomposites can be obtained, which was confirmed by X-ray diffraction (XRD). The clay layers could be uniformly dispersed in the rubber matrix on the nanometer level. Mechanical tests showed that the nanocomposites had good mechanical properties as compared to the neat composites. The results also showed that the irradiated NBR/OMMT nanocomposites had higher thermal stabilities than irradiated SBR/OMMT nanocomposites.

Crystallization behavior of poly(p‐dioxanone)‐PU/montmorillonite nanocomposites prepared by chain‐extending reaction

AbstractOrgano‐modified montmorillonites and poly(p‐dioxanone) (PPDO) diol prepolymers were used to prepare Poly(p‐dioxanone)‐PU/organic montmorillonite (PPDO‐PU/OMMT) nanocomposites by chain‐extending reaction. The crystallization behavior and spherulitic morphology of PPDO‐PU/OMMT nanocomposites were investigated by WXRD, differential scanning calorimetry, and polarized optical microscopy. The results show that the regularity of the chain structure plays a dominant role during the crystallization process rather than that of OMMT content and its dispersion status in PPDO matrix. With similar molecular weight and same OMMT content, PPDO‐PU/OMMT nanocomposite, which derived from lower molecular weight PPDO prepolymer, exhibits lower crystallization rate, melting point, and crystallinity. The influence of the clay content on the crystallization behavior highly depends on its dispersing state. The nucleating effect of OMMT can be only observed at high loading percentage. For the nanocomposites with low clay loading percentage, the retarding effect of exfoliated platelets on the chain‐ordering into crystal lamellae became the key factor. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Dielectric properties and structural dynamics of melt compounded hot-pressed poly(ethylene oxide)–organophilic montmorillonite clay nanocomposite films

The dielectric properties of melt compounded hot-pressed nanocomposite films consisting of a poly(ethylene oxide) (PEO) and organophilic montmorillonite (OMMT) clay surface modified with trimethyl stearyl ammonium as filler with increasing amount up to 20 wt.% OMMT were investigated in a frequency range of 20 Hz–1 MHz at 30 °C. The predominance of OMMT exfoliated structures in PEO–OMMT nanocomposites were recognized by a decrease of the real part of complex dielectric function. OMMT concentration dependent dielectric and electric modulus relaxation times have revealed that the interactions compatibility between PEO molecules and dispersed OMMT nano-platelets in PEO matrix governs the PEO segmental dynamics. A.C. conductivity of these nanocomposites increases by two orders of magnitude in the experimental frequency range.

Poly(methyl methacrylate)/montmorillonite nanocomposites prepared with a novel reactive phosphorus–nitrogen‐containing monomer of N‐(2‐(5,5‐dimethyl‐1,3,2‐dioxaphosphinyl‐2‐ylamino)ethyl)‐ acrylamide and its thermal and flame retardant properties

AbstractA novel reactive phosphorus–nitrogen‐containing monomer, N‐(2‐(5,5‐dimethyl‐1,3,2‐dioxaphosphinyl‐2‐ylamino)ethyl)‐acrylamide (DPEAA), was synthesize and characterized. Flame retardant poly(methyl methacrylate)/organic‐modified montmorillonite (PMMA‐DPEAA/OMMT) nanocomposites were prepared by in situ polymerization by incorporating methyl methacrylate, DPEAA, and OMMT. The results from X‐ray diffraction and transmission electron microscopy (TEM) showed that exfoliated PMMA‐DPEAA/OMMT nanocomposites were formed. Thermal stability and flammability properties were investigated by thermogravimetric analysis, cone calorimeter, and limiting oxygen index (LOI) tests. The synergistic effect of DPEAA and montmorillonite improved thermal stability and reduced significantly the flammability [including peak heat release rates (PHRR), total heat release, average mass loss rate, etc.]. The PHRR of PMMA‐DPEAA/OMMT was reduced by about 40% compared with pure PMMA. The LOI value of PMMA‐DPEAA/OMMT reached 27.3%. The morphology and composition of residues generated after cone calorimeter tests were investigated by scanning electronic microscopy (SEM), TEM, and energy dispersive X‐ray (EDX). The SEM and TEM images showed that a compact, dense, and uniform intumescent char was formed for PMMA‐DPEAA/OMMT nanocomposites after combustion. The results of EDX confirmed that the carbon content of the char for PMMA‐DPEAA/OMMT nanocomposites increased obviously by the synergistic effect of DPEAA and montmorillonite. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Influence of Nanoclay Concentration on the CO2Diffusion and Physical Properties of PMMA Montmorillonite Microcellular Foams

Microcellular foams of poly(methyl methacrylate) with variable concentrations of an organically modified montmorillonite, oMMT (2.5–10 wt %), were prepared using a supercritical CO2 dissolution physical foaming process. Particular importance was given to the analysis of the influence of the montmorillonite on the CO2 desorption behavior out of the several nanocomposites. The saturation concentration of CO2 was found to be two times higher in the nanocomposites when compared to the pure PMMA and a comparative analysis of the desorption curves showed that a higher concentration of CO2 remained in the nanocomposites for long times when compared to PMMA, except for the 10 wt % oMMT nanocomposite. Also, the incorporation of oMMT promoted the formation of submicrometric foams with much lower cell sizes and higher cell densities. With increasing the amount of oMMT, the glass transition temperature of PMMA decreased in both the solids and foams and important improvements were observed regarding the specific elastic moduli of the foams, demonstrating the mechanical reinforcement effect of oMMT.