There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.

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Effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate–polymer composites

Effect of core–shell rubber (CSR) nano-particles on mechanical properties and fracture toughness of an epoxy polymer

Experimental Study of Cement-Asphalt Emulsion Composite

A study on PTFE reinforced with SiO2 was described. It included the manufacturing process of SiO2-reinforced PTFE and the effects of the SiO2 content and size on the properties of the composite material, such as thermal, dielectric, tensile strength and morphology, etc. PTFE/SiO2 composites loaded with two sizes (5 µm or 25 µm SiO2) of filler contents varied from 0–60 wt% were mixed by a high-speed dispersion mixer and made via a two-roll milling machine. Our results showed that the composite filled with 25 µm SiO2 at 60 wt% filler content had the highest modulus, lowest CTE
 z
 and acceptable dielectric properties. Composites with different sizes of filler showed a similar trend of decreasing tensile strength and coefficient of thermal expansion (CTE
 z
 ), and increasing tensile modulus, water absorption and dielectric properties as the filler content increased. Furthermore, the composites filled with small-size filler showed higher water absorption and dielectric loss properties due to the presence of higher SiO2 surface area. Poor adhesion between filler and matrix is a primary cause of low tensile properties and lack of increase in thermal stability. Such phenomenon was also confirmed by fracture surface analysis of scanning electron microscope (SEM). Experimental data were compared with theoretical models from the literatures, which are used to predict the properties of two component mixtures. The results revealed that experimental values of dielectric constant and CTE
 z
 agreed with the theoretical calculated values. It was also found that the modified Nicolais-Narkis equation provided a good estimation for the tensile strength of composite.

The Effects of Filler Content and Size on the Properties of PTFE/SiO2 Composites

This paper studies flexural properties of vinyl ester–glass hollow-particle filled composites, which are used in marine applications. Sixteen compositions of composite materials are studied under three-point bending conditions to assess the effect of wall thickness and volume fraction of hollow inclusions. The results show that the flexural modulus of several composites is higher as compared to the neat resin. Moreover, the specific modulus of all composites is higher than the neat resin providing the possibility of appreciable weight saving in marine structures. Nevertheless, the flexural strength of the composites is lower than that of the neat resin. In addition, it is found that the flexural strength decreases as the inclusion volume fraction increases and is independent of the inclusion wall thickness. An analytical framework is presented to interpret the experimental findings and generate predictive capabilities for hollow-particle filled composites. Tractable formulas are used for computing the flexural modulus and strength from the mechanical and geometrical properties of the constituents. Analytical and experimental results are found to be in close agreement.

Analysis of flexural properties of hollow-particle filled composites

The damage mechanism in tensile testing of glass bead-filled high-density polyethylene was studied byin situ scanning electron microscopy observation, acoustic emission monitoring and volume dilatation tests. The critical damage stress was measured by micromechanical tests. When the stress field of a multiparticle model has been calculated via Eshelby's method, the interfacial bonding strength can be determined.

Microdamage and interfacial adhesion in glass bead-filled high-density polyethylene

The effect of filled-in rigid particles on the strength, modulus and toughness of polymers has been investigated previously, as has creep damage in short fibre reinforced polyprolylene [1-5]. Rigid filler produces a large turbulence of stress field in matrix, and induces microdamage. It therefore significantly affects the mechanical properties of filled materials. In this letter, the influences of bead fraction and interfacial adhesion on creep behaviour are reported. The testing results show that creep damage plays an important role in the high stress level tests. Commercial high density polyethylene (HDPE), J3, supplied by Beijing Second Chemical Factory was used as the matrix material. The neat HDPE has a melting flow index (MFI) of 1.5 g 10 min -1 for series A and 1.9 g 10 rain -1 for series B. The diameter of the glass beads was 30-40 pro. In the manufacturing process, the glass beads and coupling agents were mixed in the chamber of a high speed mixer, then HDPE powder and treated glass beads were blended in a twin-screw extruder, and the pelleted extmdate was injection moulded into tensile bars. Annealing was carried out to relieve the residual stress in the specimens. The materials of series A are the filled HDPE with different volume fractions of glass beads (Table I). For material series B, glass beads were treated by three kinds of coupling agent to make filled HDPE with different interfacial adhesion. Details of these materials are shown in Table II. It has been indicated previously that excellent interfacial adhesion was obtained in Js [1]. J6 has weak bonding and J4 is intermediate in its bond strength. The geometry of the creep specimens refers to ASTM 638 type A. The dimensions of the gauge length area were 50 m m × 10 mm × 3 mm. Creep tests were carried out on a specially designed creep test machine. Linear voltage differential transformer (LVDT) was used to measure the extension of

The role of creep damage in glass bead filled high density polyethylene

Kinds of glass bead filled HDPE in different interfacial adhesion were manufactured. Damage mechanism in the loading material was studied by in–situ SEM observation, acoustic emission monitoring and volume dilatation measurement. Experimental results show that the interfacial adhesion between matrix and rigid particle affects the process of damage initiation and evolution, and thereby significantly influences on the macro-mechanical properties. It is concluded that the addition of suitable coupling agent enhances the interfacial adhesion. It result in an improvement of Young's modulus, yield strength and creep resistance, and a fairly good toughness. Thus the excellent adhesion material would have good complehensive mechanical properties.

Lu Sinien

Papers

Microdamage and interfacial adhesion in glass bead-filled high-density polyethylene

The role of creep damage in glass bead filled high density polyethylene

The effect of interfacial adhesion on the mechanical properties and damage mechanism of glass bead filled hdpe