Modified Clay Nanocomposites Research Articles

Preparation of Polypropylene Organically Modified Clay Nanocomposites with Enhanced Physico-Chemical Properties

Preparation of Polypropylene Organically Modified Clay Nanocomposites with Enhanced Physico-Chemical Properties

Mechanical and Thermal Properties of Natural Rubber/Poly Lactic Acid /dioctadecyldimethylammonium bromide Modified Clay Nanocomposites

This paper tackles a me1t blend of po1y(lactic acid)/ natura1 rubber with dioctadecyldimethylammonium bromide(DODAB) modified clay. The study investigated mechanical, therma1 and morpho1ogical properties of poly(lactic acid)/ natural rubber and nanocomposites. The paper also examined Montmori1lonite clay with alky1 ammonium ion of (DODAB). the studied parameters, PLA/ NR nanocomposites revealed 1arger enhancements in mechanical properties in comparison to PLA/ NR blend because of high polymer blend matrix shear forces exerted on clay aggregated during mixing po1ymer-clay. The original MMT with Na+ action leads to weak improvements in mechanica1 properties in comparison to organoclays. It is noted that the strength of tensile, modulus, and the nanocomposite samples can be improved with 4% of clay loading. The optimum samp1e morphology and chemical structure were tested by X-ray diffraction and FT-IR spectroscopy respectively. This paper denotes that poly(lactic acid)/ natural rubber-toughened nanocomposites with a higher modulus and in this way, thermal stability could be made.

Novel Hydrogel-Advanced Modified Clay Nanocomposites as Possible Vehicles for Drug Delivery and Controlled Release.

Present study refers to the synthesis of new advanced materials based on poly(methacrylic acid) (PMAA) with previously reported own advanced modified clays by edge covalent bonding. This will create the premises to obtain nanocomposite hydrogels with combined hydrophilic-hydrophobic behavior absolutely necessary for co-delivery of polar/nonpolar substances. For the synthesis, N,N’-methylenebisacrylamide was used as cross-linker and ammonium persulphate as initiator. As a consequence of the inclusion of clay into the polymer matrix and the intercalation of PMAA between the layers as well as the presence of hydrophobic interactions occurred between partners, the final hydrogel nanocomposites possessed greater swelling degrees, slower de-swelling process and enhanced mechanical properties depending on the clay type in comparison with pure hydrogel. In vitro MTS ([3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt]) colorimetric assay showed that direct exposure with PMMA-clay-based constructs did not affect cell viability and proliferation in time (24 and 48 h) on either normal or adenocarcinoma cell lines.

PVDF-ionic liquid modified clay nanocomposites: Phase changes and shish-kebab structure

Crystalline behaviour of PVDF nanocomposite with 1-alkyl-3-methylimidazolium modified montmorillonite clay was analyzed. The phase change from α to β increased with alkyl chain length of the organic modifier in the filler; 1-alkyl-3-methylimidazolium clay and maximum conversion (99%) was observed for PVDF-1-hexadecyl-3-methylimidazolium modified clay composite with 2% loading. The phase conversion was evident from X-ray diffraction, DSC analysis and improved electrical properties. AFM analysis of PVDF-1-butyl-3-methylimidazolium montmorillonite clay composite (PVDF-C4) showed a shish-kebab structure while pristine PVDF and all other composites showed spherulite structures. Computational studies revealed that the extended chain α-phase forms the 'shish', the back bone and folded chain β-phase forms the 'kebab'. This was further supported by the superior mechanical properties for PVDF-C4 composite. Present work shows that introducing ionic liquid modified MMT-clay within the PVDF matrix enables nucleation of electroactive β phase and the presence of equal content of α and β phases can lead to the formation of self reinforced shish-kebab structures in PVDF.

Hydrophilic Modified Clay Nanocomposites: Effect of Clay on Thermal and Vibrational Properties

Epoxy (LY-556/HY-951) system filled with modified clay (MC) was synthesized by using mechanical shear mixing with the addition of hardener as tri-ethylene-tetra-amine (TETA). The effect of the fumed silica can be negated by the application of a shear force (e.g. mixing, brushing, spraying etc), allowing the liquid to flow, level out and permit the escape of entrapped air. The reinforcement effects of MC in the epoxy polymer on thermal, mechanical and vibration properties were studied. Curing study shows that the addition MC does not show any effect in the curing behavior of epoxy polymer. Thermogravimetry analysis (TGA) shows enhanced thermal stability for epoxy with MC fillers. The epoxy with MC fillers shows considerable improvement on tensile and impact properties over pure epoxy polymer. SEM studies shows that addition of clay significantly turns the epoxy system from brittle to ductile nature was played instrumental in scaling performance. The improvement in tensile and impact properties of nanocomposites is supported with the fracture surface studies. Epoxy with MC fillers shows enhanced vibration characteristics than that of the pure epoxy polymer. FTIR studies indicated the formation of C-H bonds on the surface of the nanocomposites.

Mechanical and thermal properties of toughened PA6/HDPE/SEBS‐g‐MA/Clay nanocomposite

Preparation and morphology of Polyamide 6 (PA6)/high density polyethylene (HDPE)/Styrene/Ethylene–Butylene/Styrene grafted with maleic anhydride (SEBS‐g‐MA)/Modified clay nanocomposites were studied. Mixing was performed using melting process in an extruder co‐rotating twin screw. After etching the materials with boiling toluene and THF at room temperature, the morphology of sample checked by scanning electron microscopy (SEM) analyses. X‐ray diffraction (XRD) used for evaluation of the effects of organo‐clay addition in the structure of nanocomposites. XRD traces showed that the characteristic (001) peak of the nanocomposites shifted to the lower degree region. XRD and SEM results showed more uniformly distribution and dispersion of HDPE in the PA6 matrix. Better sample morphology obtained, regarding less distance, and more uniformity between nanoparticles. The mechanical properties like tensile strength, impact strength, hardness and thermal properties of these toughened nanocomposites are discussed in terms of the nanoclay, SEBS‐g‐MA contents and morphology. Adding nanoclay improved hardness of nanocomposites product but reduced toughness and thermal properties. Meanwhile the presence of SEBS‐g‐MA as a compatibilizer improved toughness, thermal properties, hardness property, and the balance properties are achieved. POLYM. ENG. SCI., 55:29–33, 2015. © 2014 Society of Plastics Engineers

Hydrophilic Modified Clay Nanocomposites: Effect of Clay on Thermal and Vibrational Properties

Epoxy (LY-556/HY-951) system filled with modified clay (MC) was synthesized by using mechanical shear mixing with the addition of hardener as tri-ethylene-tetra-amine (TETA). The effect of the fumed silica can be negated by the application of a shear force (e.g. mixing, brushing, spraying etc), allowing the liquid to flow, level out and permit the escape of entrapped air. The reinforcement effects of MC in the epoxy polymer on thermal, mechanical and vibration properties were studied. Curing study shows that the addition MC does not show any effect in the curing behavior of epoxy polymer. Thermogravimetry analysis (TGA) shows enhanced thermal stability for epoxy with MC fillers. The epoxy with MC fillers shows considerable improvement on tensile and impact properties over pure epoxy polymer. SEM studies shows that addition of clay significantly turns the epoxy system from brittle to ductile nature was played instrumental in scaling performance. The improvement in tensile and impact properties of nanocomposites is supported with the fracture surface studies. Epoxy with MC fillers shows enhanced vibration characteristics than that of the pure epoxy polymer. FTIR studies indicated the formation of C-H bonds on the surface of the nanocomposites.

Maleic Anhydride Grafted Atactic Polypropylene As Exciting New Compatibilizer for poly(Ethylene-co-Octene) Organically Modified Clay Nanocomposites: Investigations on Mechanical and Rheological Properties

This is probably the first report on maleic anhydride (MA) grafted atactic polypropylene (aPP) acting as a typical compatibilizer for synthesis of poly(ethylene-co-octene) (POE) organically modified montmorillonite (OMMT) nanocomposites. The maximally grafted aPP (93.67% with 3 wt % MA) was used for compatibilization. OMMT concentrations were varied as 1, 3, and 5 wt % with respect to POE. Only moderate improvements in mechanical and rheological properties were recorded in both uncompatibilized (POE–OMMT) and compatibilized (POE–OMMT–1 wt % compatibilizer) nanocomposites due to predominant aggregation of OMMT layers. However, at higher compatibilizer content, e.g. 3 and 5 wt %, similar properties were hugely improved (92% rise in tensile strength, 55% rise in net elongation, etc.) due to partial delamination of OMMT galleries. Better processability including reduced die swell and flow activation energy and smoother extrudate profiles were also obtained as additional benefits at those compositions due to o...

Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O2 gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites.

Degradation Behavior of Polypropylene–Organically Modified Clay Nanocomposites

The degradation mechanism of polypropylene (PP)–clay nanocomposites is investigated in the present study. The PP–clay nanocomposites are prepared through a solution process with 4 and 8 wt % incorporation of nanoclay in a polymer matrix. Nanoclay with two types of organic modifications (25–30 wt % methyl dihydroxyethyl hydrogenated tallow ammonium (TA) and 25–30 wt % octadecylamine (OA)) is used with isotactic PP, atactic PP, and ethylene propylene copolymer with ∼20 wt % rubber. Characterization of nanocomposites is done through X-ray diffraction (XRD) analysis while melting and crystallization behavior is studied through differential scanning calorimetry (DSC). XRD and DSC analysis shows formation of intercalated type nanocomposites with improved barrier properties. Degradation behavior of nanocomposites is studied through thermogravimetric analysis (TGA). Weight loss curves are further analyzed through the Friedman technique to find the rate of degradation. Nanoclay incorporation increases the lifetime...

Crystallization Kinetics of Ethylene Vinyl Acetate with Modified Clay Nanocomposites

The interaction of nanoclays with polar polymers is receiving greater interest because the nanoclay significantly improves the thermal stability of the composites; however, since most polar polymers are bio-based, their mechanical properties and processing are of relatively lower standard than the oil-based polymers. We investigated a commercially relevant polymer with varying degree of polarity (poly(ethylene vinyl acetate) copolymer (EVA) with varying polarity due to varying vinyl acetate content (9, 18 and 28%)) and its interaction with organo-modified nanoclay filler (CloisiteR C15A and C30B). Specifically, we studied the crystallization kinetics and the relative dispersion of the nanoclays within the composites using modulated differential scanning calorimetry (DSC) and X-ray Diffraction techniques. Transmission Electron Microscopy results show that clay platelets have increasing tendency to be dispersed as the polarity of the matrix is increased; however, the overall matrix crystallinity remains largely unmodified due to nanoclays but the overall morphology was significantly modified in a way that there was an increase in the ‘rigid-amorphous’ phase. Using Avrami kinetics, we demonstrate that nanoclays play a significant role in the mechanism of growth of crystals and crystalline distribution for EVA polymer and the analysis could be used to compare processing of composites for optimizing mechanical properties for a range of applications in the flexible packaging industry. [DOI: 10.1380/ejssnt.2012.79]

Epoxidized Palm Oil Plasticized Polylactic Acid/Fatty Nitrogen Compound Modified Clay Nanocomposites: Preparation and Characterization

Fatty nitrogen compounds (FNCs); fatty amides (FAs), fatty hydroxamic acids (FHAs), and N,N′-carbonyl difatty amides (CDFAs), which were synthesized from palm oil, have been used as organic compounds to modify a natural clay (sodium montmorillonite). The clay modification was carried out by stirring the clay particles in an aqueous solution of FAs, FHAs, or CDFAs by which the clay layer distance increased from 1.23 to 2.69, 2.89 and 3.21 nm, respectively. The modified clay was then used in the preparation of the epoxidized palm oil (EPO) plasticized polylactic acid (PLA) nanocomposites. The interaction of the modifier in the clay layer was characterized by X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). Elemental analysis was used to estimate the presence of these FNCs in the clay. The nanocomposites were synthesized by solution casting of the modified clay and a PLA/EPO blend at the weight ratio of 80/20, which has the highest elongation at break. The nanocomposites were then characterized using XRD, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and tensile properties measurements. The XRD and TEM results confirmed the production of nanocomposites. PLA/EPO modified clay nanocomposites show higher thermal stability and significant improvement of mechanical properties in comparison with those of the PLA/EPO blend.

Preparation and properties of isobutylene–isoprene rubber (IIR)/clay nanocomposites

Isobutylene–isoprene rubber/organic modified clay nanocomposites (IIRCN) were prepared by solution or melt intercalation (S-IIRCN or M-IIRCN), and the dispersion states of clay layers in these nanocomposites were investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM images demonstrate that both exfoliated and intercalated nanoscale clay layers co-exist in these nanocomposites, and the aspect ratio of clay layers in S-IIRCN is larger than that in M-IIRCN. XRD patterns reveal that the basal spacing of clay increases from 2.2 nm for the original organically modified silicates to 4.2 nm for those dispersed in the composites, indicating intercalation of some rubber macromolecules into the galleries of clay layers. Compared with corresponding micro-composites and pure IIR vulcanizate, the prepared nanocomposites exhibit outstanding mechanical performances and improved gas barrier properties, which are likely attributed to the nanometer scale dispersion and high aspect ratio of clay layers. In addition, the properties of nanocomposites prepared by solution intercalation are somewhat superior to those of nanocomposites by melt intercalation.

Study on the thermal stability of polystyryl surfactants and their modified clay nanocomposites

Five oligomeric styrene surfactants, N,N,N-trimethylpolystyrylammonium, N,N-dimethyl-N-benzylpolystyrylammonium, N,N-dimethyl-N-hexadecylpolystyrylammonium, 1,2-dimethyl-3-polystyrylimidazolium, and triphenylpolystyrylphosphonium chlorides were synthesized and used to prepare organically modified clays. Both styrene and methyl methacrylate nanocomposites were prepared by melt blending and the type of nanocomposite was evaluated by X-ray diffraction and transmission electron microscopy. The thermal stability of the organically modified clays and the nanocomposites were studied by thermogravimetric analysis; these systems do give clays which have good thermal stability and may be useful for melt blending with polymers that must be processed at higher temperatures.

Study on the thermal stability of polystyryl surfactants and their modified clay nanocomposites

Five oligomeric styrene surfactants, N, N, N-trimethylpolystyrylammonium, N, N-dimethyl- N-benzylpolystyrylammonium, N, N-dimethyl- N-hexadecylpolystyrylammonium, 1,2-dimethyl-3-polystyrylimidazolium, and triphenylpolystyrylphosphonium chlorides were synthesized and used to prepare organically modified clays. Both styrene and methyl methacrylate nanocomposites were prepared by melt blending and the type of nanocomposite was evaluated by X-ray diffraction and transmission electron microscopy. The thermal stability of the organically modified clays and the nanocomposites were studied by thermogravimetric analysis; these systems do give clays which have good thermal stability and may be useful for melt blending with polymers that must be processed at higher temperatures.