Search results for " Polypropylene"

An Additive Model to Predict the Rheological and Mechanical Properties of Polypropylene Blends Made by Virgin and Reprocessed Components

2021

In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit fo…

Morphogenetically-Active Barrier Membrane for Guided Bone Regeneration, Based on Amorphous Polyphosphate

2017

We describe a novel regeneratively-active barrier membrane which consists of a durable electrospun poly(ε-caprolactone) (PCL) net covered with a morphogenetically-active biohybrid material composed of collagen and inorganic polyphosphate (polyP). The patch-like fibrous collagen structures are decorated with small amorphous polyP nanoparticles (50 nm) formed by precipitation of this energy-rich and enzyme-degradable (alkaline phosphatase) polymer in the presence of calcium ions. The fabricated PCL-polyP/collagen hybrid mats are characterized by advantageous biomechanical properties, such as enhanced flexibility and stretchability with almost unaltered tensile strength of the PCL net. The pol…

Modified fixation free plug technique using a new 3D multilamellar implant for inguinal hernia repair: a retrospective study of a single operator cas…

2013

Aim: Implant fixation, mesh shrinkage and poor quality of tissue ingrowth are unresolved issues in modern hernia repair. Many complications reported in the literature such as bleeding, nerve entrapment, hematoma, pain, discomfort, and testicular complications, are considered to be a direct results of implant fixation. This article describes the outcomes of a procedure carried out using a handcrafted implant that addresses the issues consequent to point fixation. Methods: This was a retrospective study on the short, medium and long-term results of placing a-modified, fixation free three-dimensional polypropylene implant in 61 patients who underwent inguinal hernia repair using a novel delive…

THERMOMECHANICAL DEGRADATION OF A POLYPROPYLENE/GRAPHENE NANOCOMPOSITE

2016

In this work the morphology and the rheological and mechanical properties of a nanocomposite made of a polypropylene with graphene nanoplatelets (GNP) have been investigated as a function of the compounding parameters to evaluate the thermomechanical degradation behaviour of this system. The presence of graphene seems to reduce the thermomechanical degradation of the matrix. A better dispersion of the GNP seems the cause of this behaviour.

Multifunctional biosourced materials : durability of unidirectional recycled matrix composites reinforced with flax fibers

2022

Now more than ever, many engineering sectors are turning to natural fiber composites because of the need for more environmentally friendly solutions. One of the main challenges in developing the use of biocomposites in outdoor applications is the lack of knowledge about their long-term durability. The main objective of this work is to provide a better understanding of the mechanisms involved in photooxidative aging of unidirectional composites made of a virgin or recycled polypropylene matrix, reinforced with long flax fibers. In addition, this work aims to study the potential use of a recycled matrix by comparing the evolution of its behavior to photooxidative aging with a virgin matrix. T…

Impact of different texture of polypropylene mesh on the inflammatory response.

2008

Intraperitoneal coated polypropylene hernia meshes: the dark side of the moon.

2014

To date, the use of meshes in repairing abdominal wall defects has brought many advantages, especially in terms of recurrence prevention, but it is not exempt from complications, such as chronic pain, entero-cutaneous fistulas and intestinal obstruction. Here we report a case of intestinal obstruction in a patient with a large umbilical hernia treated laparoscopically by means of a composite polypropylene mesh, six year before.A 49-year-old man came to our care with a 3-day history of central and right lower abdominal quadrant pain and a clinical picture of intestinal obstruction. Six years before the patient underwent a laparoscopic intervention to repair his umbilical hernia, with the pos…

Rheological, mechanical and morphological characterization of monopolymer blends made by virgin and photo-oxidized polypropylene

2021

In this work, monopolymer blends of virgin polypropylene and photo-oxidized polypropylene were prepare and characterized. The polypropylene samples were subjected to accelerated ageing to simulate the effects of outdoor exposure of polypropylene. After exposure, samples were pelletized and mixed with the same virgin polymer. The rheological, mechanical and morphological characterization was conducted on both the polymers and the blends. Both viscosity and mechanical properties decrease with increases in the content of recycled, photo-oxidized components and of the level of degradation of this component. In addition, the experimental data were compared with a model that takes into account bo…

Morphology, reorganization and stability of mesomorphic nanocrystals in isotactic polypropylene

2006

Abstract The morphology and thermodynamic stability of crystals of isotactic polypropylene (iPP) were analyzed as a function of the path of crystallization by atomic force microscopy (AFM) and differential scanning calorimetry (DSC). Samples were melt-crystallized at different rates of cooling using a “controlled rapid cooling technique”, and subsequently annealed at elevated temperature. Mesomorphic equi-axed domains with a size less than 20 nm were obtained by fast cooling from the melt at a rate larger about 100 K s−1. These domains stabilize on heating by growing in chain direction and cross-chain direction, to reach a maximum size of about 40–50 nm at a temperature of 433 K, with the q…

Effect of a Compatibilizer on the Morphology and Properties of Polypropylene/Polyethylentherephthalate Spun Fibers

2017

Fibers spun by melt spinning of binary and ternary polypropylene/ polyethylenetherephthalate blends have been produced and characterized in order to investigate the effect of a compatibilizer on their morphology and mechanical properties. The compatibilizer was a maleic anhydride-functionalized rubber copolymer. The effect of the compatibilizer was well evident in the isotropic state, as the morphology became very fine, the size of the dispersed particles was very small, and the adhesion was better. The effect of the compatibilizer on the mechanical properties is very relevant, especially in the elongation at break. On the contrary, no relevant effect was observed in the anisotropic oriente…