Cloisite 20A Research Articles

Effect of Nanoclay Hydrophilicity on the Poly(lactic acid)/Clay Nanocomposites Properties

In order to improve poly(lactic acid) (PLA) mechanical, thermal, and barrier properties, different layered silicate nanoclays are added. This work deals with the study of the effect of the type of nanoclays with different hydrophilicity on the preparation procedure and properties of PLA nanocomposites. Six kinds of clays have been loaded in PLA whose hydrophilicity varies in the following order of increased hydrophilicity: modified Dellite 67G (67G) < Cloisite 15A (C15A) < C20A < C93A < C30B < hydrophilic smectite clay (HPS). Resultant nanocomposites have been characterized both with respect to bulk and surface properties by mechanical, rheological, thermal analyses, X-ray diffraction study, Fourier transform infrared spectroscopy, gas permeability tests, contact angle measurements, scanning electron microscopy, and atomic force microscopy. Antimicrobial properties have been also tested. Evidenced was the dependence of most properties on the hydrophilicity/hydrophobicity of the clays. The nanocomposites containing the most hydrophilic clays such as Cloisite 93A, Cloisite 30B, and HPS show satisfactory antimicrobial activity against both Gram-positive and Gram-negative bacteria, excepting fungus Candida albicans.

Properties of Bio-nanocomposite Films from Tilapia Skin Gelatin as Affected by Different Nanoclays and Homogenising Conditions

Fish gelatin films incorporated with hydrophilic and hydrophobic montmorillonite (mmt) nanoclays with the aid of homogenisation using different pressure levels (1,000 to 4,000 lb/in2) and passes (two and four) were characterised. Young’s Modulus, tensile strength and elongation at break of films decreased with increasing pressure levels and number of passes. High pressure homogenisation generally lowered the mechanical properties of nanocomposite films. Additionally, water vapour barrier property became poorer, when high pressure homogenisation was implemented. Films incorporated with hydrophobic nanoclay (Cloisite 20A) exhibited the lower water vapour permeability (WVP) than those with hydrophilic nanoclay (Cloisite Na+). Colour parameters (L*, a*, b* and ∆E*) of nanocomposite films were affected to some degrees by homogenisation conditions. Transparency of films increased when homogenisation pressure and number of passes increased. As revealed by wide angle X-ray diffraction (WAXD) analysis, nanocomposite films prepared using homogenisation had exfoliated nanostructure, whilst those prepared without homogenisation exhibited intercalated nanostructure. Thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses indicated that thermal stability of nanocomposite films varied with homogenisation condition, being higher in these films than in those without nanoclay. Thus, homogenisation condition and hydrophobicity of nanoclay directly affected the properties of nanocomposite films from fish skin gelatin.

Effect of Amino alcohol functionalized polyethylene as compatibilizer for LDPE/EVA/clay/flame-retardant nanocomposites

The synergistic effect of organo-modified montmorillonite (Nanomer I28E and Cloisite 20A) and metal hydroxides (magnesium hydroxide MH and alumina trihydrate ATH) as flame retardants in LDPE/EVA nanocomposites compatibilized with amino alcohol grafted polyethylene (PEgDMAE) was studied. Morphological characterization of nanocomposites was carried out by means of X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). Flame-retardant properties of nanocomposites were evaluated by the UL-94 horizontal burning and cone calorimeter tests and limiting oxygen index (LOI). Thermal degradation behavior was analyzed with a Fourier transform infrared coupled with the thermogravimetric analyzer (TG-FTIR). The XRD analysis showed a displacement of the d001 plane characteristic peak of clay to lower angles, which indicates an intercalated–exfoliated morphology. From STEM images it was observed a good dispersion of flame retardants (MH and ATH) throughout the polymer matrix which was reflected in flame-retardant properties. TG-FTIR showed a better thermal stability of nanocomposites and the gases evolved during combustion showed an important reduction. Based on thermal stability and thermal degradation results, the flame-retardant mechanism of LDPE/PEgDMAE/EVA/Clay/MH nanocomposites was proposed.

Influence of the processing parameters and composition on the thermal stability of PLA/nanoclay bio‐nanocomposites

ABSTRACTPoly(lactic acid) (PLA) is one the most promising bio‐based and biodegradable polymer. However, its low thermal stability limits the range of applications and complicates its transformation via the most industrial common processes. The novelty of this work is studying the thermal stability of PLA and PLA/clay nanocomposites during use, as a function of the composition and using a wide range of extrusion and injection moulding processing parameters. To improve the thermal stability of the PLA, laminar silicates containing different organomodifications have been added (Cloisite 20A and Cloisite 30B). The results show that the processing conditions and composition define the morphology of the bio‐nanocomposites, which plays key role in defining final thermal properties of the material. In general, clays improve the thermal stability of the processed material, increasing the degradation temperature and decreasing the degradation rate under a wide range of processing conditions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40747.

Preparation and properties of hydrophobic layered silicate-reinforced UV-curable poly(urethane acrylate) nanocomposite films for packaging applications

Abstract A series of poly(urethane acrylate)/Cloisite 15A (PUA/C15A) nanocomposite films were successfully prepared via a UV-curing system, and their physical and barrier properties were investigated as a function of clay content. The physical properties were strongly dependent upon the chemical and morphological structures originating from differences in Cloisite 15A content. With high clay content, the PUA/C15A nanocomposite films displayed an intercalation/exfoliation combined structure. However, no strong interfacial interactions occurred between the PUA and clay, possibly leading to poor dispersion with relatively high clay content. The thermal stability displayed some enhancement with the introduction of clay into PUA, while the gas and moisture barrier properties showed significant enhancement. The oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) decreased with increasing contents of Cloisite 15A, and varied within the range of 714.0–71.1 cm3/m2 day and 29.9–13.9 g/m2 day, respectively. Thus the enhanced gas and moisture barrier properties of PUA/C15A nanocomposite films make them promising candidates for food and pharmaceutical packaging applications. However, further studies will be performed to increase the compatibility and dispersion of clay particles in the PUA polymer matrix.

Effects of nanoclay and short nylon fiber on morphology and mechanical properties of nanocomposites based on NR/SBR

Natural rubber and styrene butadiene rubber (NR/SBR) reinforced with both short nylon fibers and nanoclay (Cloisite 15A) nanocomposites were prepared in an internal and a two roll-mill mixer by a three-step mixing process. The effects of fiber loading and different loading of nanoclay (1, 3 and 5 wt. %) were studied on the microstructure and mechanical properties of the nanocomposites. The adhesion between the fiber and the matrix was improved by the addition of a dry bonding system consisting of resorcinol, hexamethylene tetramine and hydrated silica (HRH). This silicate clay layers was used in place of hydrated silica in a HRH bonding system for SBR/NR-short nylon fiber composite. Nanoclay was also used as a reinforcing filler in the matrix-short fiber hybrid composite. The cure and scorch times of the composites decreased while cure rate increased when the short fiber and nanoclay were added. The mechanical properties of the composites showed improvement in both longitudinal and transverse directions with increasing short fiber and nanoclay content. The structure of the nanocomposites was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM). X-ray diffraction results of nanocomposites indicated that the interlayer distance of silicate layers increased. The mechanical properties of nanocomposites (tensile, hardness and tear strength) are examined and the outcome of these results is discussed in this paper.

Effects of nano‐clay type and content on the physical properties of sesame seed meal protein composite films

SummarySesame seed meal protein (SSMP)/nano‐clay composite films were prepared, and the physical properties of the films were determined. The SSMP film was prepared with 5 g of SSMP and 2 g of glycerol in 100 mL of film‐forming solution, and the tensile strength (TS), elongation (E) and water vapour permeability (WVP) of the SSMP film were 2.51 MP, 21.84% and 3.23 × 10−9 g m m−2s−1 Pa−1, respectively. Two types of nano‐clays were incorporated to enhance the physical properties of the SSMP film. The TSs of the SSMP film with 5% Cloisite Na+ and 7% Cloisite 10A were 6.32 and 5.76 MPa, respectively, and the WVPs of the SSMP nanocomposite films were 2.04 × 10−9 g m m−2s−1 Pa−1 compared with the SSMP film without nano‐clay, which was 3.23 × 10−9 g m m−2s−1 Pa−1. Therefore, these results indicate that the SSMP nanocomposite film can be applied in food packaging.

Effect of OMMTs on flame retardancy and thermal stability of poly(ethylene‐co‐vinyl acetate)/LDPE/magnesium hydroxide composites

ABSTRACTThe aim of this study was to prepare poly (ethylene‐co‐vinyl acetate) (EVA)/ low density polyethylene (LDPE)/magnesium hydroxide (MH) composites applicable in cable industry with required flame retardancy. For this reason, two types of organo‐modified montmorillonites (OMMT) with different surface polarites (Cloisite 15A and Cloisite 30B) at various concentrations, and also combination of these two OMMTs with overall loadings of 2 wt % and 5 wt % were used. The samples were compounded using a twin screw extruder with total (MH + OMMT) feeding of 55 wt % and 60 wt %. Limiting oxygen index (LOI) of the samples containing 2 wt % of OMMTs increased about 16% and dripping was suppressed according to vertical burning test (UL‐94V). Thermogravimetric results of EVA/LDPE/MH samples containing OMMT showed that the beginning of second step degradation was shifted about 50°C to higher temperatures. The composite tensile strength results showed enhancement by incorporating some amount of nanoclays with EVA/LDPE/MH composites. Scanning electron microscopy images confirmed that MH particles had better wetting by EVA matrix in presence of nanoclays. Oxidative induction time of the EVA/LDPE/MH/OMMT nanocomposites was 140 min, which was more than that of the samples without OMMT (20 min). Employing the equal weight ratios of the two OMMTs demonstrated a synergistic effect on flame retardancy of the samples according to the both tests results (LOI, UL‐94V). X‐ray diffraction analysis of the samples confirmed the intercalation/semiexfoliation structure of nanosilicate layers in the bulk of EVA/LDPE matrix. This led to longer elongation at break and thermal stability of Cloisite 15A based nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40452.

Thermal Performance of Polyamide 6/Cloisite 20A Composite Hybrid by Adiabatic Extrusion: A Study on the Influence of Difference Approach of Compounding

In this paper, the possibility of thermal stability enhancement for PA6/Cloisite 20A through the application of adiabatic extrusion was inspected. Samples at 1 wt. %, 3 wt. % and 5 wt. % of clay loading Cloisite 20A were prepared by using adiabatic and conventional compounding with consistent screw speed of 200 RPM. The thermal properties of PA6/C20A nanocomposite were characterized from thermal gravimetric analysis. It has been found that adiabatic extrusion managed to increase the resistant of PA6 against heat degradation for PA6-1wt. % as PA6-3wt. % and PA6-5wt. % did not shown any distinctive in value of Tmin. as adiabatic extrusion does only have a minor effect on the increased content of clay C20A in PA6 based on thermal gravimetric characterization. The combination effect of adiabatic system and clay C20A presence is proposed as the main influence in the enhancement mechanism of thermal characteristic of PA6/C20A nanocomposite.

Effect of organoclay structure characteristics on properties of ternary PP‐EP/EVA/nanoclay blend systems

In this study, the effect on the degree of organoclay exfoliation in polypropylene‐ethylene (PP‐EP)/Ethylene vinyl acetate (EVA)/organoclay blend system was studied while varying organoclay structural characteristics. Cloisite 6A, Cloisite 15A, Cloisite 20A, Cloisite 25A, Cloisite 30B, Cloisite 93A, and Cloisite 10A were used because they have different type of modifier. Ternary PP‐EP/EVA/organoclay system was obtained with each type of clay and results were organized to analyze the effect of type of clay chemical modification (C20A, C15A, and C6A), steric effect caused by surfactant structure (C15A and C10A), length of substitute groups on the surfactant (C20 and C25A), and surfactant polarity (C30B and C93A). Samples were characterized by: wide angle X‐ray diffraction, scanning transmission electron microscopy (STEM), dynamic mechanical analysis, and capillary rheometry. Results showed that clay galleries can be saturated with chemical modifier complicating the polymer chain intercalation into the clay galleries. Some clay modifier substituent groups could cause certain steric effect promoting less exfoliated platelets structures. Finally, longer chains in the modifier substituent group can promote a better intercalated–exfoliated structure. Among all the studied organoclays, best results were obtained in the ternary system when using C20A, which modifier has two hydrogenated tallows. In this case, interlayer spacing was increased more noticeable after ternary system was formed. This was corroborated with the obtained increase in viscosity and the intercalated–exfoliated structure observed by STEM. POLYM. COMPOS., 35:2241–2250, 2014. © 2014 Society of Plastics Engineers

Preparation and characterisation of vinylsilane crosslinked low-density polyethylene composites filled with nano clays

The effects of dicumyl peroxide/vinyltriethoxysilane treatment and nanoclay content were investigated for low-density polyethylene (LDPE)/clay nanocomposites. LDPE was treated with 0.1 phr of DCP with, respectively, 1 phr and 3 phr VTES (System A), and with 0.2 phr of DCP with the same amounts of VTES (System B), and then mixed with different contents (1, 3, and 5 wt%) of modified clay (Cloisite 15A). The morphology and extent of crosslinking, as well as the thermal, mechanical, and thermomechanical properties were studied. X-ray diffraction results of all the VTES-treated LDPE/clay nanocomposites showed an increase in interlayer spacing, which indicates that the polymer chains were intercalated between the clay layers. Transmission electron microscopy micrographs of System B showed some evidence of exfoliated clay layers, indicating that the system exhibited a mixed morphology. The clay-containing samples had better thermal stability than LDPE, but the thermal stability did not differ much for the two systems. VTES observably decreased the melting enthalpy of LDPE, while the presence of clay had little influence on this value. This is somewhat contrary to the gel content results that showed a decrease in the extent of crosslinking in the presence of and with increasing clay content. VTES/DCP treatment and the presence of clay observably changed the dynamic mechanical and tensile behaviour of the LDPE.

Preparation of poly(acrylamide)/nanoclay organic-inorganic hybrid nanoparticles with average size of ∼250 nm via inverse Pickering emulsion polymerization

In this study, the preparation of poly(acrylamide)/nanoclay organic-inorganic hybrid nanoparticles via surfactant-free inverse emulsion polymerization by using organically modified clay platelets as stabilizers was discussed. Colloidally stable inverse Pickering emulsions of aqueous acrylamide solution in cyclohexane (solvent) stabilized by hydrophobic Cloisite 20A (MMT20) were prepared. Polymerization was carried out via 2,2′-azobis(isobutyronitrile) and composite particles with an average size of ∼250 nm were obtained. The effect of initiator and solvent type on the stability, size, size distribution, and morphology of the produced composite particles was examined. It was observed that in the presence of xylene as solvent, particles with bigger sizes and broader size distribution were obtained. Furthermore, using an ionic initiator resulted in a slight coagulation during polymerization and smaller particles. Moreover, the effect of various polymerization conditions such as temperature, initiator, and crosslinking agent concentration and clay content on the polymerization rate was evaluated. The experimental results showed that polymerization rate increases with an increase in polymerization temperature, crosslinking agent concentration, and initiator content. However, increasing in clay content results in a lower polymerization rate.

Cooperative rearrangement region in nanoclay‐reinforced unsaturated polyester resin

The effect of nanoclay on structural relaxation of unsaturated polyester (UP) resin containing 3 wt% Cloisite 10A (UP/10A), 3 wt% Cloisite 30B (UP/30B), and the neat resin was investigated by differential scanning calorimetry (DSC) and temperature modulated differential scanning calorimetry (TMDSC). X‐ray diffraction and transmission electron microscopy were used to evaluate the morphology of UP/10A and UP/30B nanocomposites. According to the strong‐fragile concept proposed by Angel, the values of the fragility index m were determined. The average size of a cooperative rearranging region (CRR) at the glass transition temperature (Tg) was then calculated. Considering the significant increase in δT (the mean temperature fluctuation) of UP/10A, it was concluded that UP/10A system was more heterogeneous than the neat UP and UP/30B specimen. Significant drop in Tg accompanied by an increase in δT and a decrease in characteristic length of cooperativity at glass transition temperature (ξTg) might be a sign of existence of smaller average CRR sizes in UP/10A nanocomposites. Results showed that the increase in the concentration of styrene between galleries of Cloisite 10A caused a decrease in styrene content outside the nanoclay layers leading to diminishing of crosslink density and as a consequence the decrease of ξTg. POLYM. ENG. SCI., 54:2859–2865, 2014. © 2014 Society of Plastics Engineers

Properties and characterization of biodegradable poly(lactic acid) (PLA)/poly(ethylene glycol) (PEG) and PLA/PEG/organoclay

Poly(ethylene glycol) (PEG) was mixed at various weight percentage with biodegradable poly(lactic acid) (PLA) via direct melt compounding method. Nanocomposites of PLA/PEG, with two types of organoclay namely, cloisite 93A (C93A) and cloisite 30B (C30B) were also prepared by melt blending method. The crystallization behaviors of PLA/PEG and PLA/PEG/organoclay were studied using differential scanning calorimetry (DSC). The isothermal crystallization kinetics has been investigated using the Avrami’s equation. In PLA/PEG, the PLA crystallized first followed by crystallization of PEG during the cooling. The viscoelastic behavior of the PLA/PEG and PLA/PEG/organoclay were investigated by dynamic mechanical analysis where the nanocomposites showed higher magnitude of storage modulus. The plasticizing effect of PEG acts predominantly in the mechanical performance of PLA/PEG, which shows increased percentage elongation and impact strength in the blend. The sample with 20 wt% PEG showed optimum impact strength. Again, the nanocomposite with 3 wt% C30B exhibited better tensile strength and modulus than the sample with C93A. The characterization of fractured surface of the matrix polymer and the blend were compared through scanning electron microscopy. The rheological and compostability study of the system were further investigated.

Mechanical properties of acrylonitrile–butadiene–styrene copolymer/poly(l‐lactic acid) blends and their composites

ABSTRACTAs the material properties of acrylonitrile–butadiene–styrene copolymer (ABS) have an excessively wide margin for applications in automobile console boxes, ABS partly replaced with poly(l‐lactic acid) (PLA) may be used for the same purpose with improved ecofriendliness if the corresponding deterioration of the material properties is acceptable through the choice of appropriate additives. ABS composites with 30 wt % renewable components (PLA and cellulose pulp) were prepared by melt compounding, and the material properties were examined as a function of the additive content. The changes in the mechanical properties of the ABS/PLA blends were examined after the addition of cellulose pulp and two clays [Cloisite 25A (C25A) and sodium montmorillonite] as well as these two clays treated with bis(3‐triethoxysilylpropyl)tetrasulfide (TESPT). The heat distortion temperatures of the composites were measured as a function of the content of the TESPT‐treated C25A. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40329.

Mechanical Properties of PA6/MMT Polymer Nanocomposites and Prediction Based on Content of Nanofiller

The possibility of creating new polymers with desired properties is now harder, so there is great place for modification of known thermoplastic with addition of fillers. At conventionally used fillers such as talc, calcium carbonate or glass fibers is normal degree of filling up to 40%. New nanocomposite fillers can improve all kinds of properties with small degree of filling. This study is aimed on improvement of basic mechanical properties of well-known polyamide 6 (PA6) thermoplastic with addition of three different types of nanofillers based on montmorillonite clay. Two fillers–Cloisite 30B and Cloisite 93A were organically modified, while filler Cloisite Na+ was in its pure form.

Inflamabilidade de Nanocompósitos de Polipropileno/Argila Organofílica

A inflamabilidade de nanocompositos com tres tipos de polipropileno (homo e copolimeros) contendo 5% de argila montmorilonita organofilica (Cloisite 20A), 5 e 15% de polipropileno enxertado com anidrido maleico como agente compatibilizante e 0, 0,5 e 1% de cis-13-docosenamida (Erucamida) como agente co-intercalante foi estudada atraves do teste de queima horizontal UL94HB. Concentrados foram preparados em misturador interno e diluidos com a matriz de polipropileno em extrusora de dupla rosca corrotacional com diferentes configuracoes de rosca e velocidades rotacao de 240 e 480 rpm. Os resultados indicaram aumento da velocidade de queima dos compositos quando comparados as das matrizes e que a velocidade de queima nao foi afetada pelas condicoes de processamento. Em todos os casos, foi observado durante o ensaio uma reducao da emissao de fumaca, ausencia de gotejamento de material e a formacao de uma camada carbonacea, levando a preservacao da estrutura interna da amostra.

Efeito do SBS Epoxidado como um Agente Compatibilizante para Obtenção de Nanocompósitos de SBS/Argila Cloisite 10A

Atualmente, cargas nanometricas sao utilizadas para desenvolver novos materiais polimericos com melhor desempenho mecânico. Neste trabalho, foi empregada uma mistura de borracha termoplastica de poli(estireno-b-butadieno-b-estireno) (SBS) e de argila Montmorilonita (Cloisite 10A) via intercalacao por fusao. Uma suspensao de Cloisite 10A em ciclohexano foi adicionada a SBS em solucao. Para maior compatibilidade entre a argila e a borracha termoplastica utilizou-se uma borracha termoplastica epoxidada como agente compatibilizante. Neste estudo, a proporcao argila compatibilizante foi de 0,6 ate 3,0 para verificar a influencia desta proporcao nas propriedades mecânicas dos nanocompositos. As propriedades morfologicas e mecânicas dos nanocompositos foram avaliadas atraves da difracao de raios X, microscopia eletronica de transmissao, ensaio de tracao, analise dinâmico-mecânica (DMA) e avaliacao do torque final da mistura. A combinacao de argila/conpatibilizante favoreceu a formacao de estruturas mais alongadas de argila que promoveram o ganho de modulo e tensao com pequena reducao de alongamento.

Influence of clay organic modifier on the thermal-stability of PLA based nanocomposites

Poly(lactic acid) (PLA) is a biodegradable aliphatic thermoplastic polyester well known for being a promising alternative to petroleum-based materials since it can be produced from renewable resources. Although this polymer has good properties when compared to other biodegradable polymers, it presents some limitations like poor thermal, mechanical resistance and gas barrier. The incorporation of clay minerals has been used as a way to overcome this problem. The present work aims to investigate the influence of clay organic modifier (Cloisite 30B, Cloisite 15A and Dellite 43B) and amount (3 and 5%) on PLA thermal stability. PLA and PLA nanocomposites were submitted to thermo-oxidative degradation at 140°C during 120h. Samples removed along the time were characterized by gel permeation chromatography (GPC), scanning electron microscopy (SEM), X-ray diffraction (XRD), nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). After degradation, even though all samples exhibited a significant decrease of molecular weight, it was smaller for nanocomposites. As a consequence of chain scission an increase in the crystallinity degree was observed for all nanocomposites. Results showed that clay mineral incorporation, mainly D43B enhanced the polymer thermal stability.

Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin

Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite.