Melt compounding of syndiotactic polypropylene nanocomposites containing organophilic layered silicates and in situ formed core/shell nanoparticles

Kaempfer, Dirk; Thomann, Ralf; Mülhaupt, Rolf

doi:10.1016/s0032-3861(02)00113-1

Cited by 168 publications

(122 citation statements)

References 8 publications

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“…Exfoliation was very limited in the absence of MAPP indeed, as shown in the previous section. In the next series of experiments we added a small molecular weight MAPP compatibilizer with large functionality [27,28] to the composites. The effect of the compatibilizer on the gallery structure of the composites is shown in Figure 9.…”

Section: Pp/ommt/mapp Compositesmentioning

confidence: 99%

Kinetics of structure formation in PP/layered silicate nanocomposites

Hári¹,

Dominkovics²,

Fekete³

et al. 2009

Express Polym. Lett.

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Abstract. Polypropylene (PP)/organophilized montmorillonite (OMMT) and polypropylene/organophilized montmorillonite/maleic anhydride grafted polypropylene (MAPP) composites were prepared in an internal mixer under a wide range of processing conditions to study the kinetics of structure formation. Structure and properties were characterized by a variety of techniques. The gallery structure of the organophilic silicate changed in spite of the fact that no compatibilizer was added to PP/OMMT composites. Silicate reflection shifted towards smaller 2θ angles, broadened and its intensity decreased indicating intercalation. Transmission electron microscopy (TEM) micrographs even showed individual platelets at long mixing times. However, the extent and direction of changes in the gallery structure of the silicate did not justify those observed in properties. The analysis of the results and additional experiments proved that the degradation of the polymer also takes place during processing leading to the formation of carbonyl and/or carboxyl groups, as well as to the decrease of molecular weight. The modification of the chain structure of the polymer influences interfacial interactions and the intercalation process. Some properties are directly determined by molecular weight (rheological properties, elongation). Both the clay and the MAPP seem to accelerate degradation. Thermooxidative degradation must have disadvantageous effect during the application of PP nanocomposites and needs further study. : nanocomposites, layered silicate, polypropylene, gallery structure, thermal degradation eXPRESS Polymer Letters Vol.3, No.11 (2009) [692][693][694][695][696][697][698][699][700][701][702] Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2009.87 complicated systems containing several components like the polymer, the silicate, the surfactant, and quite often also swelling and coupling agents or other additives to help exfoliation [7][8][9][10][11][12][13][14]. The competitive interactions acting among the various groups of the components are very difficult to estimate and control, which results in a wide range of structures often with inferior properties. Similarly to the uncertainties related to the role and effect of interactions on the structure and properties of nanocomposites, the effect of kinetics, i.e. processing conditions, on structure development is also quite unclear. Some groups claim that processing conditions, or even preparation conditions do not influence the structure of the composites [15,16], while others found a strong effect of processing [17,18]. For example Yilmazer and Ozden [16] compared the effect of three preparation conditions, i.e. in situ polymerization, melt compounding and a masterbatch method, and did not find any significant difference in structure and properties of polystyrene (PS) nanocomposites. On the other hand, Paul and co-workers [19][20][21] carried out a detailed study on polyamide 6 (PA6) nanocomposites using a single and three twin-screw extruders...

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Section: Pp/ommt/mapp Compositesmentioning

confidence: 99%

Kinetics of structure formation in PP/layered silicate nanocomposites

Hári¹,

Dominkovics²,

Fekete³

et al. 2009

Express Polym. Lett.

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“…Because of its high resolution TEM does not supply information about larger structural entities, like larger stacks and especially particles. XRD is used to supply information on intercalation or exfoliation and the disappearance of the silicate reflection from the XRD pattern is falsely interpreted as a sign of complete exfoliation [19][20][21][22][23]. Usually subtle changes in gallery structure are not analyzed sufficiently thoroughly and reflection intensity indicating the amount of non-exfoliated silicates is not evaluated quantitatively practically at all [24].…”

Section: Introductionmentioning

confidence: 99%

Competitive interactions, structure and properties in polymer/layered silicate nanocomposites

Hári¹,

Horváth²,

Móczó³

et al. 2017

Express Polym. Lett.

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Abstract. Thermoplastic polymer/layered silicate composites were prepared from the same organophilized montmorillonite (OMMT) and four different matrices, polypropylene (PP), the blend of PP and a maleated polymer (MAPP), poly(lactic acid) (PLA) and polyamide (PA) in order to study the effect of their chemical structure and interactions on composite structure and properties. The components were homogenized by extrusion and then specimens were injection molded, which were then characterized by a variety of methods. The results showed that competitive interactions among silicate layers and between the silicate and the polymer determine the extent of exfoliation, and structure. The morphology of the composites is complicated, exfoliation is never complete, besides individual silicate layers, the composite can contain a silicate network, stacks of silicate platelets and larger particles in various amounts. Several local deformation processes can take place around the structural entities as well as in the matrix. Fracture and debonding are the main particle related processes, while cavitation takes place in the polymer, at least in PA and PLA. The macroscopic properties of layered silicate composites are determined by the extent of exfoliation and interfacial adhesion that decreases upon organophilization. Increased reinforcement and improved composite properties can be achieved only by the proper control of all interactions prevailing in the composite.

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“…Por utilizar equipamentos e procedimentos usuais no processamento de termoplásticos, resultando em baixos custos de preparação, o método mais comum para a obtenção de nanocompósitos de matriz poliolefinica é a intercalação no estado fundido [6] . Poliolefinas encontram várias aplicações no mercado de embalagens, inclusive na área de filmes poliméricos para aplicações alimentícias ou não.…”

Section: Introductionunclassified

Influência da concentração e purificação da argila na estrutura e permeação ao vapor de água de nanocompósitos PEBDL/bentonita

et al. 2012

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IntroduçãoA preparação e adequação do desempenho materiais a aplicações específicas é um dos principais objetivos da engenharia de materiais. Uma forma de se atingir estes objetivos é através da incorporação e dispersão de cargas inorgânicas, particuladas ou fibrosas, em matrizes poliméricas. Dessa forma, obtêm-se materiais compósitos (sistemas híbridos) com propriedades superiores e distintas dos seus componentes individuais. Recentemente, observou-se que a utilização de cargas minerais dispersas em escala nanométrica na matriz polimérica resultam em produtos com propriedades semelhantes às de compósitos convencionais, porém em níveis de carregamento muito inferiores. Em outras palavras, nanocompósitos com teores de carga de 1 a 5% podem apresentar propriedades equivalentes a de compósitos convencionais ou microcompósitos com 20 a 40% de carga em escala micrométrica. O uso de baixos níveis de carga de tamanho muito diminuto resulta tanto em ganhos no processamento (menor viscosidade, menor desgaste dos equipamentos, menor consumo de energia) quanto em produtos mais leves (importante para a indústria de transportes) e mais transparentes ou translúcidos (importante para embalagens de alimentos) [1] .Os silicatos em camadas estão entre as cargas mais utilizadas para a preparação de nanocompósitos poliméricos e a argila bentonita, formada por silicatos em camadas, vem sendo muito empregada para este fim. O estado de Paraíba apresenta-se como o principal produtor de bentonitas no Brasil. Atualmente, nove empresas de mineração atuam no estado, concentradas no município de Boa Vista; dentre elas, a principal empresa produtora de bentonita no país, a Bentonit União Nordeste (BUN).Bentonitas são argilas constituídas pelo argilomineral montmorilonita (seu principal -80% -componente) e impurezas minerais (quartzo, caulinita, etc.) e orgânicas (ácidos húmicos) que representam cerca de 20% de sua massa. A montmorilonita é um mineral do grupo das esmectitas, ou seja, um aluminosilicato hidratado com estrutura cristalina formada por camadas compostas de uma de folha octaédrica (alumina) entre duas folhas tetraédricas (sílica), unidas entre si por oxigênios comuns. As camadas triplas estão unidas por ligações fracas, o que permite sua separação com relativa facilidade em condições apropriadas [2] .Substituições isomórficas do Si +4 por Al +3 na folha tetraédrica e de Al +3 por Mg +2 na folha octaédrica resultam em uma carga negativa líquida nas camadas cristalinas, que é compensada pela incorporação de cátions inorgânicos hidratados (Na + e Ca +2 predominante nas bentonitas sódicas ou cálcicas, respectivamente) no espaço entre camadas (ou espaço interlamelar) da montmorilonita. Os cátions do espaço interlamelar podem ser facilmente trocados por cátions orgânicos. Sais de amônio ou fosfônio quaternários, com volumosos grupos apolares são comumente utilizados na troca catiônica durante o processo de organofilização do argilomineral. Resumo: Este trabalho tem por objetivo a preparação, caracterização e avaliação da permeabilidade...

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Melt compounding of syndiotactic polypropylene nanocomposites containing organophilic layered silicates and in situ formed core/shell nanoparticles

Cited by 168 publications

References 8 publications

Kinetics of structure formation in PP/layered silicate nanocomposites

Kinetics of structure formation in PP/layered silicate nanocomposites

Competitive interactions, structure and properties in polymer/layered silicate nanocomposites

Influência da concentração e purificação da argila na estrutura e permeação ao vapor de água de nanocompósitos PEBDL/bentonita

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