Search results for "Elastic Modulus"

Structure and Mechanical Properties of Melt Intercalated Po1lypropylene–Organomontmorillonite Nanocomposites

2010

The preparation and properties of polymer nanocomposites, obtained by melt-compounding of polypropylene (PP) and organomontmorillonite (OMMT) modified by different alkyl ammonium salts, are described. A copolymer of maleic anhydride and PP was used as a compatibilizing additive. Nanocomposites with OMMT content of 1, 5 and 10 wt% were prepared and tested. The influence of OMMT content on the tensile stress–strain curves, elastic modulus, yield and tensile strength, and ultimate elongation of the nanocomposites is determined. The results of measuring the microhardness and impact strength of polymer nanocomposites are presented. Long-term creep tests were performed to predict the long-term de…

Accelerated weathering of polypropylene/wood flour composites

2008

Abstract Wood–plastic composites (WPCs) have received increasing attention during the last decades, because of many advantages related to their use. Some of their main applications are represented by outdoor furnishing and decking; therefore, it is important to assess their behaviour under UV exposure. In this work, polypropylene/wood flour composites were prepared and their resistance to photooxidation investigated. The composites were prepared by extrusion and compression moulding, and were subjected to mechanical tests, FTIR analysis and molecular weight measurements. The results showed that the composites retained a higher fraction of the original mechanical properties after accelerated…

Characterization of blends of polypropylene with a semirigid liquid-crystal copolyester

1991

Abstract Blends with a liquid-crystal polymers (LCP) as one component show, in general, very interesting properties. Reduction of shear viscosity and improvement of mechanical properties are very remarkable. High melting temperatures and high costs of the LCP limit the use of these blends. A new class of thermotropic LCPs with flexible spaces, with relatively low melting temperatures, can overcome the first problem. In this work, rheological and mechanical properties of blends of polypropylene with low contents of this LCP are presented. Torque during extrusion and viscosity decrease with LCP content. Elastic modulus is remarkably increased when the LCP phase is oriented.

“Effect of Filler Type and Processing Apparatus on the Properties of the Recycled “Light Fraction” from Municipal Post-Consumer Plastics”

2001

Plastic waste or scraps are generated from two main sources: industrial wastes and post-consumer wastes. By using the flotation method, generally two fractions are obtained from municipal post-consumer wastes: a light fraction, floating on water, and a heavy fraction. The former is essentially made of low and high density polyethylene—LDPE, HDPE—and polypropylene—PP; the heavy fraction is formed by poly(vinyl chloride)—PVC—and poly(ethylene terephthalate)—PET. In this work, the recycling of a light fraction from municipal post-consumer plastics has been studied, considering also the effect of filler type—glass fibres, calcium carbonate and wood fibres—and processing apparatus—discountinous …

Integration of PCL and PLA in a monolithic porous scaffold for interface tissue engineering.

2016

A novel bi-layered multiphasic scaffold (BLS) have been fabricated for the first time by combining melt mixing, compression molding and particulate leaching. One layer has been composed by polylactic acid (PLA) presenting pore size in the range of 90-110µm while the other layer has been made of polycaprolactone (PCL) with pores ranging from 5 to 40µm. The different chemo-physical properties of the two biopolymers combined with the tunable pore architecture permitted to realize monolithic functionally graded scaffolds engineered to be potentially used for interface tissues regenerations. BLS have been characterized from a morphological and a mechanical point of view. In particular, mechanica…

PBAT Based Composites Reinforced with Microcrystalline Cellulose Obtained from Softwood Almond Shells

2021

This study explores the processability, mechanical, and thermal properties of biocompostable composites based on poly (butylene adipate-co-terephthalate) (PBAT) as polymer matrix and microcrystalline cellulose (MCC) derived from softwood almond (Prunus dulcis) shells (as-MCC) as filler at two different weight concentration, i.e., 10 wt% and 20 wt%. The materials were processed by melt mixing and a commercial MCC (c-MCC) was used as filler comparison. The fibrillar shape of as-MCC particles was found to change the rheological behavior of PBAT, particularly at the highest concentration. The melt mixing processing allowed obtaining a uniform dispersion of both kinds of fillers, slightly reduci…

Increasing the elastic modulus of polyamides

1977

Enhanced Mechanical Properties in Organofluorosilica Thin Films

2008

Fluorinated hybrid organic-inorganic silicates (ORMOSIL) thin films display exceptional mechanical properties in terms of both hardness and elastic modulus that can be finely tuned by varying the angular velocity of the spin coating process. Hence, as traditional alkyl-modified silica xerogels generally show poor mechanical behavior, these materials offer a solution to a major limitation to applicability of ORMOSIL-based films.

Improving surface detection on nanoindentation of compliant materials

2010

Nanoindentation is a versatile tool for monitoring mechanical properties on a local scale. Accurate knowledge of a contact area, and therefore an initial contact, is however necessary for translating the force curve into sample mechanical properties. It is shown that methods for sensing an initial contact by depth sensing instruments (DSI) may be severely in error for compliant materials. With the hardware adopted in this work, the threshold is determined by the elastic modulus; hence the error potentially increases if the material becomes more compliant. A simple method is therefore suggested to determine with accuracy the initial contact on compliant materials whereby the surface contact …

Film blowing of silane-modified polyethylene

2009

The grafting of vinyltriethoxysilane (VTES) onto polyethylene (PE) with the help of small amounts of peroxides was investigated to film-blow these modified materials. The degree of crosslinking was kept very low to achieve good melt processability and improved mechanical properties. The possibility of obtaining modified PE films with improved properties and regularly distributed crosslinking with a single processing step demonstrates the uniqueness of this study. The additive concentration was established through preliminary studies; with a batch mixer, it was possible to process the modified PE in the film-blowing operation. Water treatment of the modified films after film blowing allowed …