Effect of dimensional factors of a disperse filler on the strength of epoxy composites

In this review the wide spectrum of properties of filled polymer systems is generalized. Classical and modern conceptions dealing with the influence of the boundary layer and filler on melting and crystallization of the polymer matrix. Polymer properties in the melted and condensed state are considered, attention being given to the influence of the filler particle size and shape, the nature of its surface, its structure, and agglomeration on the theological and mechanical characteristics of composites.Data on structure and properties of filled thermoplastic composites are summarized for the first time. Special attention is paid to the peculiarities of composites with modified polymerized filler behavior during rheological and mechanical testing and processing of such composites. IntroductionPolymeric composite materials (PCM) belong to one of the most important classes of structural materials attracting ever growing interest, as manifested by the huge flow of published scientific and technical information dealing with the problems of developing, preparing, processing and using PCM [1]. Whereas the oil and gas fuel crisis has receded recently, the problem of their restrained use still remains an urgent one if only because the oil and gas reserves are not unlimited and practically non-reproducible. Estimates by specialists have shown [2,3] that the development of PCM with a view to cut the consumption of polymeric materials can only be economically feasible if not less than 15% by volume of the filler are added.Waste products from a number of commercial processes can be used as cheap and readily available fillers for PCM. For example, lightweight structural materials may be obtained by filling various low-viscous resins with waste materials [4,5]. Also by adding fillers to reprocessed polymers it is possible to improve their properties considerably and thus return them to service [6]. This method of waste utilization is not only economically feasible but also serves an ecological purpose, since it will help to protect the environment from contamination. The maximum percentage of the filler should in these cases be such as to assure reliable service of the article made from the PCM under specified conditions for a specified period of time.However, the chief purpose of introduction of fillers into PCM is to make possible the modification of polymers and thereby create materials with a prescribed set of physico-mechanical properties, and, obviously, the properties of filled materials may be controlled by, for example, varying the type of the base polymer (the "matrix") and filler, its particle size distribution and shape. It may not require a large quantity of filler [7]. Thanks to considerable advances in PCM research, their use in a broad range of industries -machine building, construction, aerospace technology, etc. -has become extensive [8][9][10][11].Development of an assortment of polymeric composite materials, decSsions concerning their possible scope of applicability and service conditions involve research in...

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“…Solomatov et al [131] derived an equation for strength at the polymer --spherical particle interface:…”

Section: Effect Of Filler Particle Size and Shape Upon The Physico-mementioning

confidence: 99%

Filled polymers: Mechanical properties and processability

Enikolopyan

Fridman

Stal'nova

et al. 1990

Filled Polymers I Science and Technology

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“…The clusters occur at all levels of the material’s structural heterogeneity and are subjected to the process of the self-assembly. Their main feature is the fractal nature, which allows observation of them at each of the structure’s level [ 1 , 19 , 20 , 21 , 22 , 23 , 24 ]. The key elements in this description are the separation surfaces between clusters that appear in the form of technological cracks, created at the initial stage of formation of the cement matrix structure.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Metakaolinite on the Development of Thermal Cracks in a Cement Matrix

Szeląg

2018

Materials

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In the paper the cluster cracks of cement paste that has been modified with metakaolinite was analyzed. The samples were loaded with an elevated temperature based on a thermal shock. To describe the crack structure, three stereological parameters were proposed to measure: (i) the cluster average area (A¯); (ii) the cluster average perimeter (L¯); and (iii) the crack average width (I¯). The computer image analysis was implemented in the study, and 4 series of samples were subjected to the examination. In two series, metakaolinite was used as a substitute for 10% of a cement’s mass. An assessment of the basic physico-mechanical characteristics of the cement matrix was also carried out. The structure of the cement paste was considered as a highly concentrated dispersion system, in which the interactions between the cement’s grains at the initial stage of the structure self-assembly affect the crack characteristics. The study has been supplemented with microstructural investigations using a scanning electron microscope and an X-ray microanalyzer. The conducted research indicated the direction of changes in the geometrical characteristics of thermal cracks if the technological variables of the material are subjected to modification. It was also confirmed that the cluster structures have fractal character and can be analyzed and observed on many levels of a structural heterogeneity.

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“…The nature of the separation surface between the clusters and its parameters, such as length or shape, depend on the quantitative and qualitative composition of the dispersed phase particles and on the intermolecular forces between them, including adhesion and cohesion forces. The exact determination of places where cracks would be created and propagated in the micro- and macrostructure of a material is associated with the formation of separation surfaces between the clusters, at various levels of a structural heterogeneity [ 5 , 43 , 51 ].…”

Section: Resultsmentioning

confidence: 99%

“…A result of this process is a creation of the binding units. Depending on the size of the particles, binding units of different sizes are formed, which can be defined as the clusters [ 4 , 43 , 49 , 50 , 51 ]. The cluster-forming process in cement paste has a fractal character, which results in clusters occurring at all levels of material heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

Development of Cracking Patterns in Modified Cement Matrix with Microsilica

Szeląg

2018

Materials

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The paper evaluates the cracking patterns created on the surface of a microsilica-modified cement matrix, which has been subjected to exposure at elevated temperatures. To do this, image analysis techniques were used, and the structure of the cracks was described by the stereological parameters. Four series of specimens were tested and in two of them, microsilica was used as a 10% replacement for the cement content. Using the theory of dispersion systems, the factors affecting the cracks’ characteristics were identified. Additionally, the development process of cracking patterns due to the thermal interaction was schematically modeled. In addition, the analysis of the local microstructure of the cement matrix was performed by means of a scanning electron microscope and energy dispersive x-ray spectroscopy.

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Effect of dimensional factors of a disperse filler on the strength of epoxy composites

Cited by 10 publications

References 2 publications

Filled polymers: Mechanical properties and processability

Filled polymers: Mechanical properties and processability

The Influence of Metakaolinite on the Development of Thermal Cracks in a Cement Matrix

Development of Cracking Patterns in Modified Cement Matrix with Microsilica

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