Abstract The traditional melt index test (ASTM D 1238) is widely used in the plastics industry to characterize polymer processability. data from this measurement must be interpreted cautiously, however, because polymers are usually processed under conditions that far removed those of test. In study, (MI) values a series polystyrene, polypropylene, linear low‐density polyethylenes (butene and octene copolymers), high‐density were measured related molecular weight distributions these...

Polyetheretherketone (PEEK) polymers are increasingly used in tribological applications. An important aspect of PEEK tribology is the surface temperature reached during sliding. At present, most knowledge frictional heating based on post-hoc analysis debris and wear surfaces. In this study, infrared thermography was to observe full field map against sapphire counterface ball-on-disc The measured temperatures matched closely those predicted by flash models. Additionally, friction studies were...

Abstract A commercial‐grade LLDPE resin was cross‐linked using three different dialkyl peroxides, at concentrations. The peroxides were ranked in order of their Cross‐linking efficiency and effectiveness increasing the storage modulus virgin cure temperature. chemical mechanism by which cross‐linking occurs is shown to be closely related changes concentrations reactive vinyl species on polyethylene molecules, follows well with proposed mechanisms previous publications. Finally, a direct...

Polyetheretherketone (PEEK) is one of the most commonly used High Performance Polymers (HPP) although its high temperature performance poor. In this study, polybenzimidazole (PBI), a HPP with highest glass transition temperatures currently available, blended to PEEK form 50:50 blend (TU60). Tribological (TU60) was investigated by rubbing it against steel at up 280 °C. Results obtained are compared those from neat and PBI. All three polymers were thermally stable during duration tests....

This paper presents methodologies to quantify the relationships among molecular weight distribution (MWD), steady-shear non-Newtonian viscosity (i.e., flow curve), and melt index (MI) of three linear low-density polyethylenes manufactured using same technology. With aid computer-aided process simulation tools (such as POLYMERS PLUS), polymer producers can predict accurately MWD from manufacturing conditions. Our help extend their model curves MI MWD. To do this, this employs (1) a modified...

Abstract The effects of molecular structure on the dicumyl peroxide crosslinking two low density polyethylenes have been studied. Peroxide efficiency was determined largely by content terminal vinyls in polymers. Differences weight distribution and branch had comparatively little influence gel but hot creep resistance vulcanized materials affected. Scorching affected, also, presence vinyl unsaturations polymer.

Abstract The mechanical properties and thermal stability of several grades poly(aryletherketone)s (PAEKs) were investigated using thermal, rheological, dynamic characterization. Detailed rheological characterization revealed that poly(etheretherketone) (PEEK) exhibit relaxation behavior characteristic a long‐chain branched structure. potentially PEEKs showed greater damping than the linear‐chain PEEKs. molecular weight dependence on zero‐shear viscosity for polymers indicates behave as rigid...

Polybenzimidazole (PBI) is a high performance polymer that can potentially replace metal components in some temperature conditions where lubrication challenging or impossible. Yet most characterisations so far have been conducted at relatively low temperatures. In this work, the tribological properties of PBI were examined with steel ball-PBI disc contact 280 °C under load and sliding speed conditions. The dry friction coefficient decreases modestly increasing applied load. Surface analysis...

Abstract Proton nuclear magnetic resonance (NMR) spin‐spin relaxation measurements were made on three commercial‐grade polyethylenes in the melt state, free of solvent. All samples exhibit a three‐component behavior, with components being assigned to amorphous low‐molecular weight material (non‐network fraction), entangled network fraction, and an ordered or high‐segmental‐density order decreasing times. Sample thermal history is shown have considerable effect overall therefore relative...

Abstract In this paper we address the aspects associated with shear modification of low density polyethylene by extrusion. By successive passes polymer through an extruder it can be shown that both melt viscosity and elasticity are reduced modification. These reversible variations not accompanied significant changes in molecular weight distribution. The major effects extrusion to decrease amount elastically effecitve material. Study proton relaxation times at 150°C shows comprises regions...

Demands for engineering applications of high performance polymers, such as the polyaryletherketone families, have grown significantly in recent years. Fundamental knowledge on mechanical behavior especially under harsh environments, is still lacking. In this study, and interfacial phenomena a blend polybenzimidazole (PBI) particles having sizes about 50 μm polyetheretherketone (PEEK) matrix at 50:50 weight ratio was characterized. PBI PEEK are known to be incompatible with each other dry...

Abstract Incorporation of reinforcing nanoparticles, like multi‐walled carbon nanotubes (MWCNTs), in a polymer matrix is an effective way to enhance mechanical properties and expand structural applications engineering polymers such as poly(ether‐ether‐ketone) (PEEK). Good dispersion MWCNTs critical for achieving optimal properties. In this work, simple solution mixing approach was utilized prepare PEEK nanocomposites reinforced with MWCNTs. By direct PEEK/dichloroacetic acid MWCNT/ N...

It has been shown in a previous article that melt blending of low levels commercial poly(dimethyl siloxane) (PDMS) fluid with thermoplastic polyurethanes significant positive impact on the coefficient friction (CoF) and mechanical wear properties polyurethanes. The improvements CoF resistance were expected due to surface modification polymer; however, much more than expected. Evidence presented earlier publication suggests changes are not alone, but largely bulk by PDMS. In this model is...

Abstract A commercial linear low density polyethylene (1‐hexene comonomer) was reacted with dicumyl peroxide at appropriate levels to initiate chain extension without crosslinking. The modification carried out both in the presence and absence of a common hindered phenolic antioxidant. Thermal treatment resin also completed antioxidant present evaluate contribution classical thermooxidative degradation process. In terms pure thermal degradation, found be effective prevention reduction...

Abstract Blends of polyaryletherketones (PAEK) with polybenzimidazole (PBI) are commercial interest due to their improved upper service temperatures and wear properties when compared the PAEK analogs examined date. The retention PBI component generally thought be disadvantageous in more thermally or chemically aggressive environments is not well understood, nor specifics interactions between components a melt dry blend systems. In this initial investigation, focus placed on behavior...

ABSTRACT Blends of polyaryletherketones (PAEK), such as polyetheretherketones (PEEK) and polyetherketoneketones (PEKK), with polybenzimidazole (PBI) are commercial interest due to their improved high‐temperature stability wear properties. The changes PBI its PEEK‐ PEKK‐blends (50 : 50 wt %) after immersing them in liquid H 2 O D O, exposing steam at elevated temperatures pressures investigated by multinuclear solid‐state NMR IR spectroscopy. Macroscopic morphological chemical on the...