Search results for "Molding"
showing 10 items of 61 documents
Influence of poloxamers on the dissolution performance and stability of controlled-release formulations containing Precirol® ATO 5
2005
Abstract Lipid excipients are usually used for the development of sustained-release formulations. When used in relatively high quantities, Precirol ® ATO 5 imparts sustained-release properties to solid oral dosage forms, by forming a lipid matrix. To control or adjust the drug release kinetics from such lipid matrix however, one must often resort to complementary ingredients or techniques. This study investigates the influence of poloxamers (Lutrol ® ) included in lipid matrices composed of glyceryl palmitostearate (Precirol ® ATO 5) on their dissolution performance and their stability. The addition of these hydrophilic polymers in the lipid matrix increased the amount of theophylline relea…
Bubble motion through non-crimp fabrics during composites manufacturing
2008
Bubbles motion through interbundle channels in biaxial non-crimp fabrics is modelled. The scenario is that formed bubbles move with the resin through these channels and are trapped if the channels become too narrow. By usage of a permeability network model, existing criteria on bubble deformation and a variety of analytical and probabilistic methods it is found that the paths of the bubbles depend significantly on the position of the threads keeping the fabric together and the number of fibres crossing the interbundle channels. Another result is that the pressure difference over a trapped bubble increases with 50% in a 3D geometry possible helping the bubble to escape. A third result is tha…
El futuro de los plásticos o los plásticos del futuro
2020
espanolEn los ultimos tiempos politicos, activistas ambientales, periodistas y otros lideres de opinion han dirigido sus armas contra los plasticos. Este mal concepto nace como resultado de los cambios en el entorno como consecuencia de la utilizacion de nuevas fuentes de energia, tanto nuclear como la de combustibles fosiles y el desarrollo de la industria petroquimica en especial la de los plasticos que se da a partir del descubrimiento del petroleo. Sin embargo y a pesar de las consideraciones ambientales el plastico ha construido nuestro mundo hasta el punto en que hoy es dificil imaginar nuestra vida sin el. Muchos disenadores han sostenido desde mediados del siglo XX, que los articulo…
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…
Improved experimental characterization of crystallization kinetics
2005
Polymer solidification occurring in many processes, like for instance injection molding, compression molding and extrusion, is a complex phenomenon, strongly influenced by the thermo-mechanical history experienced by the material during processing. From this point of view, characterization of polymer crystallization in the range of processing con- ditions, i.e. including high cooling rate, is of great technological and academic interest. Quiescent, non-isothermal crys- tallization kinetics of two polypropylene resins were investigated using a new method, based on fast cooling of thin samples with air/water sprays and optical detection of the crystallization phenomenon. The range of cooling …
Stiffness and strength of flax fiber/polymer matrix composites
2006
Flax fiber composites with thermoset and thermoplastic polymer matrices have been manufactured and tested for stiffness and strength under uniaxial tension. Flax/polypropylene and flax/maleic anhydride grafted polypropylene composites are produced from compound obtained by coextrusion of granulated polypropylene and flax fibers, while flax fiber mat/vinylester and modified acrylic resin composites are manufactured by resin transfer molding. The applicability of rule-of-mixtures and orientational averaging based models, developed for short fiber composites, to flax reinforced polymers is considered. POLYM. COMPOS. 27:221–229, 2006. © 2006 Society of Plastics Engineers
New Developments in Soft Lithography
2003
Abstract The burgeoning area of soft lithography is reviewed with special emphasis on developments within the past three years. Applications in electronics have driven such developments, but more recently, other kinds of device structures and 3D prototyping have also found application, in part, through soft lithography. Microcontact printing (μCP), “lift off” μCP nano transfer printing (nTP), micromolding in capillaries (MIMIC), solvent assisted micromolding (SAMIM), replica molding (REM), and microtransfer molding are the main soft lithography schemes discussed.
Covalent RGD modification of the inner pore surface of polycaprolactone scaffolds
2011
Scaffold production for tissue engineering was demonstrated by means of a hot compression molding technique and subsequent particulate leaching. The utilization of spherical salt particles as the pore-forming agent ensured complete interconnectivity of the porous structure. This method obviated the use of potentially toxic organic solvents. To overcome the inherent non-cell-adhesive properties of the hydrophobic polymer polycaprolactone (PCL) surface activation with a diamine was performed, followed by the covalent immobilization of the adhesion-promoting RGD-peptide. The wet-chemical approach was performed to guarantee modification throughout the entire scaffold structure. The treatment wa…
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…
Applied study on the rotational molding and processing technology of rotational molds
2021
Computer-aided manufacturing involves a set of computerized activities related to the preparation, launch and follow-up of manufacturing. Computer-aided manufacturing is a tool that allows the use of 3D models based on computer-aided design. This paper addresses the process of rotational formation, with an effective focus on the technology of processing a rotational mold using CAM simulation as a research method. In this sense, the right choice of CNC and cutting tools is essential. The use of numerically controlled machine tools and high-performance cutting tools reduces the number of operations. The manufacturing route realized is specific to the parts machining on numerical control machi…