Polymer Engineering and Science articles from May 2008

Polymer Engineering and Science archives from May 2008

The electrical properties of boron-containing poly(vinyl alcohol) derived ceramic organic semiconductor.(Technical report)
May 1, 2008... INTRODUCTION Semiconductor materials based on conjugated polymers are now attracting considerable attention as promising materials for electronics technology [1-5]. The conjugated polymers are generally p-type semiconductor materials....

Fracture prediction in tough polyethylene pipes using measured craze strength.(Technical report)
May 1, 2008... INTRODUCTION It is widely accepted that the ability of polyethylene (PE) materials to form large crack tip craze zones invalidates the use of conventional fracture mechanics theory for failure prediction [1, 2]. Furthermore, although craze...

Multiobjective optimization of polymerization reaction of vinyl acetate by genetic algorithm technique with a new replacement criterion.(Technical report)
May 1, 2008... INTRODUCTION Average molecular weight of any polymer in polymerization reactions has great influence on the other physical properties of polymeric product, so specification of operational conditions to obtain final products with desired...

Semi-empirical, squeeze flow and intermolecular diffusion model. I. determination of model parameters.(Technical report)
May 1, 2008... INTRODUCTION When two surfaces made from the same polymer are brought together in the molten state, the surfaces will conform to each other to achieve intimate contact and over time intermolecular diffusion and chain entanglement results...

The effect of EVA content on the processing parameters and the mechanical properties of LDPE/ground tire rubber blends.(ethylene vinyl acetate copolymer, low-density polyethylene)(Technical report)
May 1, 2008... INTRODUCTION Nowadays, the dwindling of oil sources [1, 2] and the directives of environment protection forced the recycling not only of thermoplastics but also of thermosets (like tires). Among them the economic recycling of worn tires is...

Rheology and curing kinetics of fumed silica/cyanate ester nanocomposites.(Technical report)
May 1, 2008... INTRODUCTION High-temperature thermosetting polymers such as cyanate esters, bismaleimides, and polyimides are generally limited in their use to applications that do not require initial processing at ambient temperatures. A unique cyanate...

Synthesis and photopolymerization kinetics of polymeric one-component type II photoinitiator containing benzophenone moiety and tertiary amine.(Technical report)
May 1, 2008... INTRODUCTION Photopolymerization science and technology has been obtaining much attention in recent years because of its various industrial applications in coatings, adhesives, printing inks, photoresists, and biomaterials [1-4]. A typical...

Effect of weakly interacting nanofiller on the morphology and viscoelastic response of polyolefins.(Technical report)
May 1, 2008... INTRODUCTION So far, serious attempts to investigate the reinforcing mechanism in polymer nanocomposites have been predominantly restricted to systems with amorphous matrices [1-14]. In these matrices above their [T.sub.g], the chains can...

Effect of PMMA addition on characterization and morphology of PVDF.(polymethylmethacrylate, polyvinylidene fluoride)(Technical report)
May 1, 2008... INTRODUCTION Blending of polymers has given a new direction for developing novel materials. It is an easy and inexpensive method of modifying various properties of the polymers. Polymer blending is a widely used technique to improve some...

Preparation and characterization of functionalized low density polyethylene matrix biocomposites.(Technical report)
May 1, 2008... INTRODUCTION Polymeric composite materials containing organic or inorganic fillers exhibit light weight, combined with stiffness and strength and therefore, have found high commercial interest. On the other hand, systems such as plastics...

Structure and properties of novel PMDA/ODA/PABZ polyimide fibers.(pyromellitic dianhydride, oxydianiline, aminobenzimidazole)(Technical report)
May 1, 2008... INTRODUCTION High-performance polymeric fibers with high strength and modulus for use in engineering applications have undergone significant developments in the last two decades. There is now considerable interest in producing heterocyclic...

Novel phenylethynyl-endcapped polyimide oligomers: synthesis and characterization.(Technical report)
May 1, 2008... INTRODUCTION High temperature/high performance polyimides have been widely used in aerospace and microelectronic industries, e.g. as matrices for high performance composites, as thin films and coatings for microelectronic application, as...

Slow crack growth resistance in resin blends of chromium and metallocene catalyzed ethylene-hexene copolymers for pipe applications.(Technical report)
May 1, 2008... 1. INTRODUCTION High density polyethylene (HDPE) is the most commonly used pipe material for the transportation and distribution of water and natural gas for nearly 40 years. In view of the critical nature of this application, both, proper...

Effect of hot-press on electrospun poly(vinylidene fluoride) membranes.(Technical report)
May 1, 2008... INTRODUCTION The electrospinning is a straightforward way to produce ultrafine fibrous membranes from polymer solutions or melts under a high electric voltage [1-5]. Because of the tiny diameter in several hundreds of nanometers and the...

Flexural creep of all-polypropylene composites: model analysis.(Technical report)
May 1, 2008... INTRODUCTION Poly(propylene) (PP) is apparently the major polymeric construction material of future in view of its impressive consumption in the past few decades. Fibers are frequently used for improving the strength and stiffness of this...

Effect of orientation and crystallinity on the photodegradation of poly(ethylene terephthalate) fibers.(Technical report)
May 1, 2008... INTRODUCTION Degradation is a crucial factor, which causes deterioration of the useful properties of polymeric materials. During degradation processes, polymers lose some of its most important properties: strength, flexibility, and the...

Effect of mold temperature on the long-term viscoelastic behavior of polybutylene terepthalate.(Technical report)
May 1, 2008... INTRODUCTION Polybutylene terepthalate (PBT) is one of the most commercially important polyesters nowadays due to its excellent chemical and heat resistance, rapid crystallization rate compared with the other thermoplastic polyesters and...

Poly(phenylene sulfide) magnetic composites. II. crystallization, thermal, and viscoelastic properties.(Report)
May 1, 2008... INTRODUCTION Poly(phenylene sulfide) (PPS) is a high-performance semicrystalline polymer that has been utilized in a variety of market segments such as electrical, electronic, automotive, appliance, industrial, and chemical sectors due to...

Gas-assisted injection molded polypropylene: the skin-core structure.(Technical report)
May 1, 2008... INTRODUCTION Conventional injection molding (CIM), one of the most useful and complicated polymer processing techniques, imparts high stress and rapid cooling as the polymers are formed into various shapes [1]. Isotactic polypropylene...

An in-process ultrasonic approach to investigating the relaxation of orientation and disorientation of polymer melts.(Technical report)
May 1, 2008... INTRODUCTION It is well known that many properties, such as mechanical and optical properties, of polymer materials are strongly influenced by shear induced molecular orientation occurring under various polymer melt processing conditions....

Semiconductive composites from ethylene 1-octene copolymer and polyaniline coated Nylon 6: studies on mechanical, thermal, processability, electrical, and EMI shielding properties.(electromagnetic interference)(Technical report)
May 1, 2008... INTRODUCTION Conducting composites may be used for different electronic or electrical applications like, device for electrostatic charge dissipation (ESD), touch control switch, electromagnetic interference (EMI) shielding material,...

Electrical conductivity and microwave absorbing properties of nickel-coated multiwalled carbon nanotubes/poly(phthalazinone ether sulfone ketone)s composites.(Technical report)
May 1, 2008... INTRODUCTION The development of microwave absorbing techniques continues to attract much attention because of the increasing environmental pollution from nonionizing microwave irradiation and the essential part of a stealth defense system...

Steady plastic flow of a polymer during equal channel angular extrusion process: experiments and numerical modeling.(Technical report)
May 1, 2008... INTRODUCTION Among various forming processes, equal channel angular extrusion (ECAE) allows to introduce very large plastic strains in the material without modifying the geometry of the sample. The process was first introduced in 1981 by...

Organic/inorganic hybrid bismaleimide resin with octa(aminophenyl)silsesquioxane.(Technical report)
May 1, 2008... INTRODUCTION Organic/inorganic hybrid materials with nanoscopic covalent bonding between organic and inorganic components which are composites of organic polymers and inorganic substances in molecular level are widely regarded as one of...