A new technique to provide melt elasticity using flexible fine fibers prepared from a polymer with high melting point is demonstrated. A polymer composite of poly(propylene) with a small amount of fine fibers of poly(butylene terephthalate) shows marked strain‐hardening behavior in elongational viscosity, i.e., a rapid increase in the transient elongational viscosity with time or strain. The blend also shows prominent normal stress difference at steady shear. These elastic properties have not been observed for polymer composites with rigid fibers and can be applicable to the modification of rheological properties and thus the improvement of processability.

Morphology development of polytetrafluoroethylene (PTFE) caused by applied flow history in molten isotactic polypropylene (PP) is investigated, employing a cone-andplate rheometer and a capillary rheometer as mixing devices. Since the flow history is applied at 190 °C, PTFE is in the solid state whereas PP is in the molten state. It is found that primary PTFE particles tend to be agglomerated together by mechanical interlocking. Then they are fragmented into fibers by hydrodynamic force with reorganization process of crystalline phase. The diameter of the fragmented fibers is the same as that of the original ellipsoidal particles. Further, fine fibers whose diameter is in the range from 50 to 100 nm are also generated by yielding behavior of the particles. The prolonged shearing leads to a large number of fibers, although the diameter and length are hardly affected by the exposure time of shearing and shear stress. Moreover, the flow type (i.e., drag or pressure flow) does not affect the morphology to a great extent, although the drag flow is not efficient to reduce large agglomerated particles. The fibers form an interdigitated network structure, which is responsible for the marked melt elasticity.

Metal matrix composite (MMC) is a combination of two or more materials in a metal matrix, and is being widely used nowadays due to its excellent properties. This paper presents the surface integrity of LM6 aluminum MMC when machined with two different cutting tools; high speed steel (HSS) and uncoated carbide. The experiments were carried out with a constant cutting speed, feed rate and axial depth of cut, but differ in the radial depth of cut under dry cutting conditions. Results indicated that machining LM6 with uncoated carbide cutting tools provides a lower surface roughness and fine surface profile compared to HSS cutting tools, due to its edge stability. A lower radial depth of cut produced a fine surface finish and vice versa. Most of the machined surface was dominated by the feed mark effect due to path overlap from the cutting tool. This study is expected to provide a database of suitable cutting tools and cutting parameters for machining MMC based materials.

Accuracy of machined component is one of the challenging tasks for manufacturer. In the aerospace industry, machining process is widely used for fabrication of unitized-monolithic component that contains a thin-walled structure. During machining, the cutting forces cause deflection to the thin-wall section, leading to dimensional form errors that cause the finished part to be out of specification or failure. Most of the existing research for machining thin-wall component only concentrated on the process planning and the effects of cutter geometric feature is often neglected. Tool geometric feature has a direct influence on the cutting performance and should not be neglected in the machining consideration. This paper reports on the effect of helix angle on the magnitude of wall deflection. The established effects will be used for the development of high performance cutting tool for specifically machining thin-wall component.

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When polyetheretherketone is used in structural applications it generally undergoes additional machining operations in order to form components. Machining PEEK can be a challenging task for manufacturers, however, especially when using a conventional cutting tool. This paper deals with the influence of a cutter's geometrical features when machining polyetheretherketones engineering plastic on their machining performances. Three categories of end mills were designed and fabricated with varying rake angles, clearance angles and helix angles to investigate effects on machining surface roughness and burr formation. From the investigations conducted, it is evident that end mill geometrical features (rake angle, clearance angle and helix angle) have significant effects on machining surface roughness and burr formation. Increasing the rake angle and helix angle value will improved the machining surface roughness, however, in the case of varying clearance angles, there are no significant results for the surface roughness produced. It could be observed, however, that a 12° clearance angle produced better surface roughness compared to other angles. The findings from the deliberately conducted experiments can be used for the development of high performance cutting tools, especially for machining polyetheretherketones engineering plastic material.

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Linear and nonlinear viscoelastic properties for binary blends composed of isotactic polypropylene and polytetrafluoroethylene (PTFE) are studied. It is found that blending a small amount of PTFE greatly enhances the storage modulus in the low frequency region. Further, drawdown force and normal stress difference increase with the PTFE content. Electron microscope observation reveals that PTFE deforms into fine fibers whose diameter is smaller than 0.5 μm. The network structure composed of the fibers is responsible for the marked elastic properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2008–2014, 2009