Polymer Engineering and Science articles from February 2008

Polymer Engineering and Science archives from February 2008

Coefficient of thermal expansion for Twaron[R] fibers using crystallographic data.(Technical report)
February 1, 2008... INTRODUCTION Twaron[R] fibers, commercially available from Akzo Nobel, The Netherlands, are made up of poly(p-phenylene terephthalamide) or PPTA [1], the structural formula of which is shown below (i). [FORMULA NOT REPRODUCIBLE IN...

Processability studies of silica-thermoset polymer matrix nanocomposites.(Technical report)
February 1, 2008... INTRODUCTION Silicate and silica nanocomposites form two types of dispersed phase: (a) clays form layered silicates consisting of microplatelets of nanometers thickness; (b) silica nanocomposites contain dispersed silica nanoparticles....

Elongational viscosity of LDPEs and polystyrenes using entrance loss data.(low density polyethylene)(Technical report)
February 1, 2008... INTRODUCTION Owing to their long chain molecules, polymers exhibit very complex rheological behavior. Some of the phenomena due to this macromolecular structure of polymers such as die swell and rod climbing in shear flow [1] are unique to...

Structural characterization and mass transfer properties of dense segmented polyurethane membrane: influence of hard segment and soft segment crystal melting temperature.(Technical report)
February 1, 2008... INTRODUCTION Segmented polyurethanes (SPUs) are composed of flexible soft segment and rigid hard segment (HS). Soft block is usually polyether or polyester diol, while the hard block or HS is typically composed of low molecular weight...

Morphology of PA-6 vibration welded joints and its effect on weld strength.(Technical report)
February 1, 2008... INTRODUCTION The use of vibration welding has grown significantly in the automotive industry, due to its advantages. In particular, vibration welded polyamide (PA) composites are commonly used in manufacturing a variety of automotive...

Interaction of thermoplastic polyurethane with polyamide 1212 and its influence on the thermal and mechanical properties of TPU/PA1212 blends.(Technical report)
February 1, 2008... INTRODUCTION Thermoplastic polyurethanes (TPUs) are linear block copolymers, composed of multiple hard segments and soft segments. The hard segments are based on diisocyanates and short diol or diamine, and the soft segments consist of...

Optical monitoring of polypropylene crystallization during injection molding.(Technical report)
February 1, 2008... INTRODUCTION Polymer crystallization can occur without the influence of mechanical stresses (quiescent crystallization) or under its influence (flow induced crystallization). During processing, a polymer is subjected to high gradients of...

Macroscopic failure of multilayered viscoelastic polymers.(Technical report)
February 1, 2008... INTRODUCTION Multilayered polymers are currently used in numerous applications where a single polymer cannot provide the required material properties. For example, multilayered polymers that provide gas, liquid, and optical barrier...

A study of nano-mechanical and macro-mechanical properties of ethylene vinyl acetate.(Technical report)
February 1, 2008... INTRODUCTION Nano-mechanical properties of polymeric materials [1-4] are becoming an importance design issue in the contact performance of surfaces. In bio applications, nano-mechanical properties affect tissue growth and cell...

Thermal residual stress development for semi-crystalline polymers in rotational molding.(Technical report)
February 1, 2008... INTRODUCTION Rotational molding is a process used to manufacture hollow plastic products. The entire process involves heating of a rotating mold filled with polymeric powders. The plastic powders gradually melt and form a coating on the...

Tribological properties of blends of melamine-formaldehyde resin with low density polyethylene.(Technical report)
February 1, 2008... INTRODUCTION Polymers have widespread applications in industry, and continue to gain increasing importance as technology advances because of their unique characteristics including low density and advantageous electrical and mechanical...

Thermoplastic polyurethane elastomers based on polycarbonate diols with different soft segment molecular weight and chemical structure: mechanical and thermal properties.(Technical report)
February 1, 2008... INTRODUCTION Thermoplastic polyurethane elastomers are versatile materials that behave as cross-linked elastomers at room temperature but, unlike conventional elastomers, they can be processed, shaped, and formed upon heating via numerous...

A macroscopic mathematical model for tensioned-web slot coating.(Technical report)
February 1, 2008... INTRODUCTION Owing to the fast growth of the liquid crystal display (LCD) industry, different types of optical films are needed to serve as key components for the LCD panels. These optical films include antireflection, antiglare,...

Numerical study of nonisothermal polymer extrusion flow with a differential viscoelastic model.(Technical report)
February 1, 2008... INTRODUCTION The numerical prediction of viscoelastic flow patterns under real flow conditions has both scientific interest and industrial relevance. It presents an efficient way to perform the investigation of complex flow mechanism...

Reversible thermal gelation of soft semi-crystalline polyethylene microparticles with surface interactions in squalane.(Technical report)
February 1, 2008... INTRODUCTION Polymer suspensions consist of a suspended and continuous phase, typically with a polymer particle suspended in an organic or aqueous medium of lower molecular weight such as water or a hydrocarbon. The suspended polymer can...

Conventional and nanometric nucleating agents in poly([epsilon]-caprolactone) foaming: crystals vs. bubbles nucleation.(Technical report)
February 1, 2008... INTRODUCTION In the industrial practice of thermoplastic foaming, it is of vital importance the use of nucleating agents, in order to control the final foam morphology [1, 2]. Traditional nucleating agents are generally made out of talc,...

Synthesis and studies of the physical properties of polyaniline and polyurethane-modified epoxy composites.(Technical report)
February 1, 2008... INTRODUCTION Among the different types of conducting polymers, polyaniline (PANI) may have the greatest potential for commercial application because of its unique electrochemical properties and environmental stability [1-3]. In addition,...

Electromagnetic interference shielding with polyaniline nanofibers composite coatings.(Technical report)
February 1, 2008... INTRODUCTION Since the findings by Huang at al. [1] that polyaniline (PANI) nanofibers can be facilely prepared by interfacial polymerization in 2003, PANI nanofibers has been extensively investigated worldwide in both the synthesis and...

Prediction of environmental stress cracking resistance in linear low density polyethylenes.(Technical report)
February 1, 2008... INTRODUCTION Environmental stress cracking (ESC) occurs because of the combined effects of mechanical stress and chemical exposure and can result in the brittle failure of plastics at significantly lower stresses than would normally be...

Cracking formation on the surface of extruded photodegraded polypropylene plates.(Technical report)
February 1, 2008... INTRODUCTION The petrochemical industry is the largest segment of chemical industry. Within petrochemicals, commodity plastics are the most important components with a share of over 50% by volume. Commodity polymers have relatively low...

Mechanical, thermal, and morphological behavior of the polyamide 6/acrylonitrile-butadiene-styrene blends irradiated with gamma rays.(Technical report)
February 1, 2008... INTRODUCTION During the last five decades, blending of dissimilar polymers has been a major path to tailor materials with new properties [1]. Especially in the plastics industry, blending technology has gained broad acceptance as a tool...

Weathering of recycled photo-degraded polyethylene.(Technical report)
February 1, 2008... INTRODUCTION The market for recycled plastic is growing all the time because of both consumer demand and government legislation. Post-consumer waste is now being collected, sorted, and reprocessed either by blending it with virgin material...

Influence of molecular weight on the electrification of linear polyethylenes during extrusion: identification of Two Different Mechanisms for Charge Generation.(Technical report)
February 1, 2008... INTRODUCTION The phenomenon of electrification is the accumulation of electric charge in a material. The electric charge on a polymeric surface is usually removed by the air with the help of antistatic agents commonly added during its...

Fiber orientation in injection molding with rotating flow.(Technical report)
February 1, 2008... INTRODUCTION The manipulation of fiber orientation during injection molding is a well-established route to enhance the mechanical properties and dimensional stability of glass fiber reinforced injection molded parts [1]. The effect of...

Sharkskin and oscillating melt fracture: why in slit and capillary dies and not in annular dies?(Technical report)
February 1, 2008... INTRODUCTION The instabilities that occur in the extrusion of molten polymers are fascinating from the scientific perspective, but troublesome and frequently catastrophic from the industrial one [1]. Over the past 50 years, there has been...

Viscoelastic evaluation of effects of fiber size and composition on cellulose-polypropylene composite of high filler content.(Technical report)
February 1, 2008... INTRODUCTION Wood-plastic-composites (WPC) have attracted attention as an effective method of utilizing low quality and/or waste wood and plastic in recent years. As a result, the Industrial Standard (JIS) for WPC prepared from recycled...