Robust Bicontinuous Elastomer–Metal Foam Composites with Highly Tunable Stiffness

New models for effective Young's modulus of particulate composites

In this paper, the effects of shape and arrangement of inclusions on the effective Young's modulus of materials are considered by the application of the finite element method through examining a model, which has two groups of periodically arranged inclusions in a matrix. Here, two groups of inclusions A and B are considered, both having equally shaped equally arranged inclusions, which have the same elastic constants but different from the ones of the matrix. This model includes square and hexagonal arrays of inclusions as its special cases. First, the effect of shape of inclusions on the Young's modulus of composite materials is considered from the comparison between the results of rectangular and elliptical inclusions. Next, when the position of group A is fixed, the effect of location of group B is considered. Then. the effective elastic Young's modulus is almost independent of the location of group B if the projected areas of groups A and B are not overlapped. In conclusion, the volume fraction of inclusion and projected area fraction of inclusions are found to be two major parameters controlling the effective Young's modulus of composites.

ABSTRACTIn this study, the factors affecting the Young's modulus of inorganic fibrous particulate‐reinforced polymer composites were analyzed, and a new expression of the Young's modulus was derived and was based on a simplified mechanical model. This equation was used to estimate the composite Young's modulus. The estimated relative Young's modulus increased nonlinearly with increasing filler volume fraction. Finally, we verified the equation preliminarily by quoting the measured Young's modulus values of poly(butylene terephthalate)/wollastonite, polypropylene/wollastonite, and nylon 6/wollastonite composites reported in the literature. Good agreement was shown between the predictions and the experimental data of the relative Young's modulus values for these three composite systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2957–2961, 2013

Maximizing Young's modulus of aminated nanodiamond-epoxy composites measured in compression

Multiple correlations of material parameters of light-cured dental composites

The influence of interfacial adhesion, particle size and size distribution on the predicted mechanical properties of particulate thermoplastic composites

Porosity effect on the thermal and mechanical properties of U-50Zr alloy: A molecular dynamics study

The structure/property relationships and morphology of glass bead–reinforced syndiotactic and isotactic polypropylene composites containing 0 to 20 vol% thermoplastic elastomer (TPE) were studied. Polystyrene‐block‐poly(ethylene‐co‐butylene)‐block‐polystyrene (SEBS) and the corresponding block copolymer grafted with maleic anhydride (SEBS‐g‐MA) were used as the TPEs. The Young's modulus of hybrid composites based on s‐PP showed no dependence on the type of TPE used, whereas i‐PP hybrid composites containing SEBS had a higher Young's modulus than composites containing SEBS‐g‐MA. A comparison of the data with theoretical predictions of Young's modulus and tensile yield stress gave strong evidence of two different morphologies for the hybrid composites. The increasing tensile yield stress of s‐PP hybrid composites and i‐PP hybrid composites containing SEBS‐g‐MA was attributed to an interlayer formation and in‐situ encapsulation of glass beads, which resulted in core‐shell particles with improved interfacial interactions. In contrast, SEBS in hybrid composites based on i‐PP formed a separate dispersed phase. Crystallization and scanning electron microscopy studies also provided evidence of a core‐shell morphology for hybrid composites based on s‐PP. Results of lap‐shear and peel tests confirmed strong interfacial interaction between glass and SEBS‐g‐MA and between SEBS and s‐PP as well as i‐PP. Only above a critical volume fraction did the TPE provide significant improvement of the notched Izod impact strength of hybrid composites based on s‐PP or i‐PP.

Theoretical prediction method of Young's modulus and yield strength of micron particle reinforced metal matrix composites at different temperatures

It is impossible to design structures without Young's modulus value. Structures in space is put under low temperature condition around ・70 -C. And when a spaceship returns back to the earth, outer material of the ship is exposed to very high temperature near 1400 -C. Then a design for structures in space needs Young's modulus value over wide range of temperature. We have proposed a method to measure Young's modulus value employing impact sound. The method needs small rectangular specimen, 4x5x50. Putting a specimen into atmosphere filled with liquid nitrogen vapour or heated up by furnace, Young's modulus values on steel, pure cupper and aluminium alloy were measured with ease employing the method over -190-C to room temperature and over room temperature near to melting point temperature of the materials.

Misinterpretation of ISO 4049 standard recommendations: Impact on Young's modulus and conversion degree of dental composites

Polydimethylsiloxane (PDMS) has been the pivotal materials for microfluidic technologies with tremendous amount of lab-on-a-chip devices made of PDMS microchannels. While molding-based soft-lithography approach has been extremely successful in preparing various PDMS constructs, some complex features have to been achieved through more complicated microfabrication techniques that involve dry etching of PDMS. Several recipes have been reported for reactive ion etching (RIE) of PDMS; however, the etch rates present large variations, even for the same etching recipe, which poses challenges in adopting this process for device fabrication. Through systematic characterization of the Young's modulus of PDMS films and RIE etch rate, we show that the etch rate is closely related to the polymer cross-link density in the PDMS with a higher etch rate for a lower PDMS Young's modulus. Our results could provide guidance to the fabrication of microfluidic devices involving dry etching of PDMS.

This paper discusses epoxy-based conducting adhesives for z-axis interconnections. Recent work on adhesives formulated using controlled-sized particles to fill small diameter holes is highlighted, particularly with respect to their integration in laminate chip carrier substrates, and the reliability of the electrically conductive joints formed between the adhesive and metal surfaces. A variety of conductive adhesives with particle sizes ranging from 80 nm to 15 /spl mu/m were laminated into printed wiring board substrates. SEM and optical microscopy were used to investigate the micro-structures, conducting mechanism and path. Volume resistivity of Cu, Ag and low melting point (LMP) alloy based paste were 5 /spl times/ 10/sup -4/ ohm-cm, 5 /spl times/ 10/sup -5/ ohm-cm, and 2 /spl times/ 10/sup -5/ ohm-cm, respectively. Volume resistivity decreased with increasing curing temperature. The mechanical strength of the various adhesives was characterized by 90 degree peel test and measurement of tensile strength. Adhesives exhibited peel strength with Gould's JTC-treated Cu as high as 2.75 lbs/inch for silver, and as low as 1.00 lb/inch for LMP alloy. Similarly, tensile strength for silver, Cu and LMP alloy was 3370, 2056 and 600 psi, respectively. Reliability of the adhesives was ascertained by IR-reflow, thermal cycling, pressure cooker test (PCT), and solder shock. Change in tensile strength of adhesives was within 10 % after 1000 cycles of deep thermal cycling (DTC) between -55 /spl deg/C and 125 /spl deg/C. There was no delamination for silver, copper and LMP alloy samples after 3X IR-reflow, PCT, and solder shock. Among all, silver-based adhesives showed the lowest volume resistivity and highest mechanical strength. It was found that with increasing curing temperature, the volume resistivity of the silver-tilled paste decreased due to sintering of metal particles. Sinterability of silver adhesive was further evaluated using high temperature/pressure lamination, and shows a continuous metallic network when laminated at 365 /spl deg/C. As a case study, an example of silver-filled conductive adhesives as a z-axis interconnect construction for a flip-chip plastic ball grid array package with a 150 /spl mu/m die pad pitch is given. This effort is an integrated approach centering on three interrelated fronts: (1) materials development and characterization; (2) fabrication, and (3) integration at the device level.

Influence of process parameters on the structure and the properties of ZrO 2 coatings deposited by reactive pulsed magnetron sputtering (PMS)

ABSTRACTOrgano‐modified nanoclay (Cloisite 30B) was added via direct melt mixing to the acrylonitrile butadiene rubber/poly(vinyl chloride) (PVC/NBR) to fabricate polymer blend/clay nanocomposites. The states of nano‐fillers dispersion were investigated by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). From the morphological study of nanocomposites, it is concluded that exfoliated morphology is obtainable by introduction of 2.5 vol % of nanoclay. The effect of nano‐filler volume content on the mechanical properties of PVC/NBR matrix reinforced by Cloisite 30B was investigated by tensile test. Experimental results show that the Young's modulus and tensile strength of composites can significantly improved with a small amount of nanofiller. Moreover, to investigate the stress–strain behavior of NBR/PVC nanocomposites, seven constitutive models such as Arruda–Boyce, Mooney–Rivilen, Marlow, second order of polynomial, Van der Waals, and third order Odgen were studied and compared with experimental data. Results showed that Malow and second order polynomial model can be used for nanoclay‐filled compound whereas the other models show more deviation from experimental data. Three micromechanical models named liner rule of mixtures (LROM) and the inverse rule of mixtures (IROM). Halpin–Tsai theory was applied to evaluate the dependence of Young modulus of nanocomposites on volume fraction of nanofiller. Two modifying factors were proposed to evaluate the Young's modulus of nanocomposites which could greatly improve the theoretical prediction obtained from inverse rule of mixtures (IROM) and Halpin–Tsai equation. The modifying factors were introduced by adopting an exponential, power‐law and linear factors in the equation. In order to verify the suitability of the modified models, the ensuing theoretical predictions are compared to the other experimental data available in the literature. Good predictability of the modified models is demonstrated in the results. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3229–3239, 2013