Search results for "polypropylene"

Laser Welding - Suitable for Vascular Anastomosis?

1994

Carotid arteries of 21 piglets were transsected and reanastomosed either by laser welding (Neodym:YAG laser) or by conventional suture anastomosis. Histological specimens of the anastomoses obtained 2 to 32 days after the operation showed less foreign body reaction and intimal hyperplasia after laser welding than after suturing. There was, however, no significant difference when comparing occurrence of thrombosis, patency rate, or growth of the anastomosis in growing animals. Neither our study nor a review of the literature of laser-assisted vascular anastomosis in microvessels and large arteries up to 5 mm diameter could establish a definite clinical application for laser welding in vascul…

Chemical composition and particle size influence the toxicity of nanoscale plastic debris and their co-occurring benzo(α)pyrene in the model aquatic …

2021

Little is known about how particle chemical composition and size might influence the toxicity of nanoscale plastic debris (NPD) and their co-occurring chemicals. Herein, we investigate the toxicity of 3 × 1010 particles/L polyethylene (PE, 50 nm), polypropylene (PP, 50 nm), polystyrene (PS, 200 and 600 nm), and polyvinyl chloride (PVC, 200 nm) NPD and their co-occurring benzo(a)pyrene (BaP) to Daphnia magna and Danio rerio. During the 21 days of exposure to PE 50 nm and PS 200 nm, the number of broods produced by D. magna decreased compared to other treatments. Exposure to BaP alone did not produce any effects on the reproduction of the daphnids, however, the mixture of BaP with PS (200 or …

Biologic response of inguinal hernia prosthetics: a comparative study of conventional static meshes versus 3D dynamic implants.

2015

Despite improvements in prosthetics and surgical techniques, the rate of complications following inguinal hernia repair remains high. Among these, discomfort and chronic pain have become a source of increasing concern among surgeons. Poor quality of tissue ingrowth, such as thin scar plates or shrinking scars-typical results with conventional static implants and plugs-may contribute to these adverse events. Recently, a new type of 3D dynamically responsive implant was introduced to the market. This device, designed to be placed fixation-free, seems to induce ingrowth of viable and structured tissue instead of regressive fibrotic scarring. To elucidate the differences in biologic response be…

Polypropylene/graphene nanoplatelets nanocomposites subjected to elongational flow

2018

In this work the effect of the presence of graphene nanoplatelets (GnP) on the morphology and mechanical properties of polypropylene/GnP nanocomposites has been investigated when these polymer systems are subjected to non-isothermal elongational flow in a melt spinning operation. The presence of the GnP magnifies the effect of the elongational flow. Indeed, the elastic modulus and the tensile strength increases with the orientation more than that observed for the pure matrix.

Photo-oxidative behavior of PP/GnP nanocomposites

2018

In this work the photo-oxidative behavior of neat polypropylene (PP) and PP based nanocomposites incorporating graphene nanoplatelets (GnP) was studied. In particular, the influence of the amount of incorporated GnP was evaluated. The photo-oxidation has been followed by monitoring the change of the rheological, mechanical and spectroscopic properties upon artificial exposure to UV-B light. The results revealed that the presence of GnP reduced the rate of photooxidation of the PP matrix and, in the investigated composition range, the photo-stabilizing action improved with increasing the GnP content.

Solidification of Polypropylene Under Processing Conditions – Relevance of Cooling Rate, Pressure and Molecular Parameters

2012

HUMAN FIBRIN GLUE SEALING VERSUS SUTURE POLYPROPYLENE FIXATION IN LICHTENSTEIN INGUINAL HERNIORRAPHY: A PROSPECTIVE OBSERVATIONAL STUDY.

2014

Background: Patients who underwent primary inguinal hernia repair still report a high rate of postoperative pain after operation due to effect of mesh fixation by suture. An alternative is the use of human fibrin glue. We compared the two techniques. Methods: 468 patients randomly underwent primary inguinal hernia Lichtenstein repair fixing the mesh by suture or by human fibrin glue (HFG); in both cases themesh was fixed to the posterior wall of the inguinal canal and to the inguinal legament. results: No significant differences were recorded between the two groups in terms of complications, while the sutureless technique reduces the operative time and the postoperative pain. Conclusions: A…

The use of a tailored mesh with special design for ventral hernia repair. Preliminary report

2009

Introduction: The study describes a modified technique for ventral hernia repair based upon a tension free, fixation free, and dynamic compliant implant. Material and methods: A unique geometrical shaped light weighted, large porous polypropylene mesh was created consisting of a large central body and six radial arms, designed to pass through the tissues and hold the mesh in place without tension. We used the mesh in a small exploratory cohort of patients with ventral hernia. The mesh was placed sublay by taking each of the six straps and passing from below the muscle, through the muscle allowing the fixation free strap to sit with friction within the tissues. This was designed to give a te…

Novel silicon microparticles to improve sunlight stability of raw polypropylene

2015

Oxidation of polyolefins by ultraviolet/visible irradiation is a significant limitation for their use in several technological applications. The use of high-tech additives such as silicon microparticles becomes a compositing strategy that can improve the performance of these materials at long-term service conditions. Silicon particles were added to non-additivated raw polypropylene (PP) prepared by hot melt extrusion and subjected to accelerated sunlight irradiation tests. The stability of thermal properties, mechanical performance and thermal decomposition behaviour of composites was evaluated by differential scanning calorimetry, dynamic mechanical thermal analysis and thermogravimetry. T…

Advanced fragmentation stage of oxide coating on polymer substrate under biaxial tension

2005

Crack patterns of 100-nm-thick silicon oxide coating on polypropylene film subjected to equibiaxial stress loading are studied experimentally. The loading is achieved by means of a bulging cell mounted under an optical microscope with stepwise pressurization of film specimens. The evolution of the coating fragment area distribution at relatively high strains is modeled using Weibull statistics to describe the coating strength. The fragment area distribution at an advanced fragmentation stage is shown to scale with the average fragment area, the latter being a power function of the applied biaxial strain.