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Molding Technique (molding + technique)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Versatile Crack-Free Ceramic Micropatterns Made by a Modified Molding Technique

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010
Marzellus Grosse Holthaus
Crack-free ceramic micropatterns made of oxidic ceramic powders, e.g. alumina, titania, zirconia, and nonoxidic calciumphosphate ceramic powders were fabricated by a novel, simple, and low-cost modified micromolding (m-,M) technique via polydimethylsiloxane stamps. By means of this m-,M technique it is possible to fabricate monolithic ceramic bodies with a micropatterned surface with very high accuracy on surface detail. Our produced micropatterns can feature various geometries, e.g. cylinders, holes, channels, and struts with diameters ranging from 8 to 140 ,m in diameter or widths and from 8 to 30 ,m in depth or height. The oxidic and nonoxidic ceramic micropatterns could be removed from the molds and dried without any cracks. Even after sintering, these micropatterned samples showed no cracks or fissures. The reported technique has a very high potential for fully automatized up-scale fabrication of micropatterned ceramic surfaces. [source]

Fabrication of Crack-Free C12A7 Nano-Ceramics Composite from Eutectic Glass in the C12A7,CaYAlO4 System

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2006
Naonori Sakamoto
Crack formation in the C12A7 nano-composite during crystallization was successfully avoided by using the eutectic glass in the C12A7,CaYAlO4 system. The crystal phases from the eutectic glass were identified to be C12A7 (major phase) and CaYAlO4 (minor phase) by X-ray diffraction and high-resolution transmission electron microscope. It was indicated that origin of cracks upon crystallization of C12A7 glass was the volume expansion caused by crystallization of C12A7 in the glass and the cracking could be avoided by the volume shrinkage by crystallization of CaYAlO4. By using a conventional molding technique, we have also succeeded to fabricate a bulk C12A7 composite with arbitrary shapes. [source]

Dynamic viscoelasticity of hybrid kevlar and glass fiber reinforced LLDPE in the molten state

POLYMER COMPOSITES, Issue 4 2002
S. A. R. Hashmi
Kevlar and glass fibers were used to reinforce linear low density polyethylene (LLDPE), and composite sheets of 0.8, 1.5 and 2.5 mm thicknesses were obtained by using a compression molding technique. Dynamic viscoelastic properties of non-hybrid and hybrid composites of various compositions at 200°C are evaluated. Storage modulus (G,) and loss modulus (G,) increase with angular frequency (,) and reinforcement. Replacement of glass fiber by Kevlar at constant loading of fibers in LLDPE increases the value of G,, G, and ,,. The fractured surface of composite shows the gradient orientation of fibers particularly in 2.5 mm thick sheet. Top and bottom layers show relatively two-dimensional orientation as compared to the middle layer, which shows random orientation. The orientation of fibers decreases G, and ,, of Kevlar fiber and hybrid fiber hybrid fiber reinforced LLDPE composites. The effect of change in distance between parallel plate of rheometer (change in strain amplitude) on dynamic rheological properties is studied and reported here. [source]

Dynamic mechanical behavior of LCP fiber/glass fiber,reinforced LLDPE composites

POLYMER COMPOSITES, Issue 2 2001
S. A. R. Hashmi
Liquid crystalline polymer (LCP) fibers and glass fibers have been used to rein force linear low density polyethylene (LLDPE) by using an elastic melt extruder and the compression molding technique. The impact behavior of hybrid composites of different composition is compared and is explained on the basis of the volume frac tion of the fibers. Addition of glass fibers decreases the Izod impact strength LLDPE. The impact strength of the composites increases when glass fibers are placed by LCP fibers. Dynamic mechanical , and , relaxations are studied and effect of variation of fiber composition on these relaxations is reported in the tem perature range from ,50 to 150°C at 1 Hz frequency, a relaxation shifts toward higher temperatures with addition of fibers in LLDPE. Addition of fibers increases the storage modulus of LLDPE. [source]

Replication of sub-micron features using amorphous thermoplastics

POLYMER ENGINEERING & SCIENCE, Issue 7 2002
Kari mönkkönen
A comprehensive experimental study was carried out to replicate sub-micron features using the injection molding technique. For the experiments, five different plastic materials were selected according to their flow properties. The materials were polycarbonate (PC), styrene-butadiene block copolymer (SBS), impact modified poly(methyl methacrylate), methyl methacrylate-acrylonitrile-butadiene-styrene polymer (MABS), and cyclic olefin copolymer (COC). Nanofeatures down to 200-nm line width and with aspect ratios (aspect ratio = depth/width) of 1:1 could be replicated. In all selected materials, the greatest differences between the materials emerged when the aspect ratio increased to 2:1. The most favorable results were obtained with the use of high flow polycarbonate as the molding material. The best replication results were achieved when melt and mold temperatures were higher than normal values. [source]