Search results for "Mold"

Processing and Mechanical Properties of Natural Fiber Reinforced Thermoplastic Starch Biocomposites

2007

Natural fiber reinforced starch polymers are processed by compression molding. Potato, sweet potato, and corn starch are used as matrices. Three types of natural fibers, namely sisal, jute, and cabuya, are used in concentrations varying from 2.5 to 12.5% w/w in the composites. Different plasticizers are used for the starch polymers, such as water and glycerol. Mechanical properties are assessed by tensile and impact tests. In both cases, improved mechanical properties are obtained at increasing fiber contents. Tensile strength appears to be markedly improved with the addition of 10% by weight of sisal fibers, while the best results for impact strength are obtained for cabuya fibers.

Thermomechanical Properties of Radiation-Modified Polyethylene/Ethylene-Propylene-Diene Copolymer/Liquid-Crystalline Copolyester Blends

1999

Radiation-modified blends of high-density polyethylene (PE) with ethylene-propylene-diene copolymer (EPDM; 10-65 wt.%) and thermotropic liquid-crystalline polymer (LCP; 10 wt.%) were investigated. The LCP was a liquid-crystalline copolyester of 40% poly(ethylene terephthalate) with 60% 4-hydroxybenzoic acid. The constituents were blended using a circular extruder, the specimens were prepared by compression molding and irradiated by 60Co γ-radiation up to 200 kGy. Mechanical, thermal, and morphological properties in wide temperature range were investigated for the irradiated and non-irradiated specimens. The effects of irradiation on the thermomechanical behaviour of the PE matrix are discus…

The use of the indentation test for studying the solidification behaviour of different semicrystalline polymers during injection moulding

2005

Summary: An in-line method for monitoring the solid-ificationprocess during injection molding of semicrystallinepolymers (demonstrated previously in J. Appl. Polym. Sci.2003, 89, 3713) is based on a simple device, where anadditional ejector pin is pushed on the injection molded partatdifferenttimesduringthesolidificationphase.The‘inden-tation depth profile’, i.e., residual deformation as a functionoftime,wasobtainedandallowedtodeterminetheevolutionof the solidification front in the mold as a function of thecooling time. The present work shows the reliability andthe powerfulness of the aforementioned method for a largevariety of different semicrystalline polymers (PET, PBT,polyamide-6 PA6, isota…

Analysis of gate freeze-off time in injection molding

2004

Gate solidification time is an important topic in injection molding technology, as it determines cycle time, which itself is an important issue in the economics of the production process. In this work, a study of the effect of both gate and cavity geometries on gate solidification time was conducted, using a commercial polymer, injection molded with constant holding pressure into a rectangular cavity. Three cavity lengths were used, and for each, two cavity thicknesses were adopted. Spe- cial dies containing different gates were assembled in the mold. Gate thickness was found to be the most important factor determining gate sealing time. However, the cavity geometry is also quite important.…

A New System for Choosing the Form and Size of Complete Denture Anterior Teeth

2016

Introduction: In the absence of pre-extraction records, the choice of the size an form of anterior complete denture teeth can be extremely subjective. Several clinical and statistical parameters are usually used for choosing the correct size and form of the complete denture anterior teeth. Clinical Innovation: The technique consists of a system that allows the dentist to choose and, if necessary, easily change the dental mold during maxillomandibular recording session. The unique feature of the system is that six teeth of each mold are represented by veneers, which are connected to each other on the lingual surface by a fiber that allows each veneer some degree of movement. Discussion: This…

Solidification during the filling stage of injection molding: a simulation-oriented study

2011

Rapid Assessment of Gray Mold (Botrytis cinerea) Infection in Grapes with a Biosensor System

2015

Abstract: Botrytis cinerea is the causative agent of gray mold disease, which causes considerable economic losses to winemakers. The extent of gray mold infection of winegrapes is commonly visually estimated, a method that is prone to assessor bias. Here, we used rapid and simple enzyme-based screening consisting of carbon-electrode, screen-printed amperometric biosensors to estimate gluconic acid and glycerol concentration in winegrapes infected with different degrees of B. cinerea. The lower limits of quantification of the screen-printed amperometric biosensors were 3 mg/L for gluconic acid (corresponding to an infection rate of less than 1%) and 35 mg/L for glycerol; the response times w…

Research on the machining process modeling of a rotational mold using CAM applications

2021

Rotational molding is a unique process, with a high growth rate, which allows the use of geometries and materials adapted to particular needs. It is superior to other manufacturing methods in terms of low cost, break-even point and size of parts that can be manufactured. Rotational molding products are often a substitute, with a lower mass, for traditionally used materials. In this scientific paper it is analyzed the recent literature related to the field of rotational molding processes. It also addresses the issue of processing a rotational mold, with the main purpose of optimizing the cutting regime. In this context, it is highlighted the way of processing the surface of the outer mold ba…

Quo vadis SANEPID? A cross-country analysis of public health reforms in 10 post-Soviet states

2010

Abstract Background The public health systems of the post-Soviet states have evolved from the san-epid system, which dominated public health practice throughout the former Soviet Union. Since independence, reforms have taken different directions. This article provides a cross-country comparison of public health reform processes and contents in 10 post-Soviet states. Methods The study is descriptive and comparative, based on a literature review of the major health databases, the Health Systems in Transition (HiT) volumes and grey literature. Search terms included terms on public health, the san-epid services and organizational reforms in one or several post-Soviet states. Results Public heal…

Hybrid nanocomposites with ultra-low filling content by nano-coating fragmentation

2021

In the current study, a new technique for the manufacturing of polymer nanocomposites (PNCs) with ultra-low filling content (<0.05 wt%) is presented. Specifically, this method has been validated through the production of polypropylene (PP) nanocomposites with Ag nanoparticles. The presented method first consisted in a metal nano-film deposition on PP pellet substrates by a physical vapor deposition (PVD) sputtering equipment. Subsequently, a percentage of the coated pellet was mixed to uncoated ones via an injection molding machine to produce the PNC in a single step. Different mixing percentages of coated PP pellet to the uncoated ones were studied. As a result, the fragmentation of the…