Search

Bacterial infection is one of the most common and universal cause of disease spreading associated with medical and surgical environment. Antimicrobial function of plasticized polyvinyl chloride (PVC) will be useful for making hygienic environments. Here, we synthesized the PVC composite by the addition of inorganic bacteriocide containing silver, zinc and zeolite. And we investigated the growth inhibition rate for Staphylococcus aureus and Klebsiella pneumoniae which were analyzed in the presence of PVC composite with different doses of inorganic bacteriocide (1~15 wt%). Bacterial proliferation was significantly inhibited by 3 wt% of inorganic bacteriocide containing PVC composite. And we found the inhibition of bacterial biofilm formation by 5 wt% of inorganic bacteriocide containing PVC composite by the observation of scanning electron microscopy (SEM). Our data suggested that the antimicrobial effect of inorganic bacteriocide was caused by disturbing the bacterial biofilm formation.

In this study, we investigated the effects of a crosslinking agent and a compatibilizer on the mechanical and rheological properties of waste PP and waste ground rubber tire (WGRT) composites. In order to simulate a commercial TPV, the component of waste PP and WGRT was fixed at 30 and 70 wt%, respectively. With the simple addition of SEBS-g- MA into the waste PP/WGRT composites, the tensile strength of the composite was decreased, whereas both the elongation at break and impact strength were significantly increased because of rubbery characteristics of SEBS-g-MA. In order to further improve the properties of the composites, the waste PP/WGRT/SEBS-g-MA composites was revulcanized with dicumyl peroxide (DCP). As expected, mechanical properties of the revulcanized composites was generally improved. Especially, with 15 and 1 phr of SEBS-g-MA and DCP, elongation at break was highest value of about 183% because of the recrosslinking of WGRT without chain scission of the main chain. It was found that complex viscosity of the revulcanized composite increased which might verify further vulcanization of the WGRT.

We discuss the influence of few-walled carbon nanotubes (FWCNTs) treated with nitric acid and/or sulfuric acid on field emission characteristics. FWCNTs/tetraethyl orthosilicate (TEOS) thin film field emitters were fabricated by a spray method using FWCNTs/TEOS sol one-component solution onto indium tin oxide (ITO) glass. After thermal curing, they were found tightly adhered to the ITO glass, and after an activation process by a taping method, numerous FWCNTs were aligned preferentially in the vertical direction. Pristine FWCNT/TEOS-based field emitters revealed higher current density, lower turn-on field, and a higher field enhancement factor than the oxidized FWCNTs-based field emitters. However, the unstable dispersion of pristine FWCNT in TEOS/N,N-dimethylformamide solution was not applicable to the field emitter fabrication using a spray method. Although the field emitter of nitric acid-treated FWCNT showed slightly lower field emission characteristics, this could be improved by the introduction of metal nanoparticles or resistive layer coating. Thus, we can conclude that our spray method using nitric acid-treated FWCNT could be useful for fabricating a field emitter and offers several advantages compared to previously reported techniques such as chemical vapor deposition and screen printing.

This paper proposes two important models useful for describing heat transfer and temperature profiles in single and modular self-wiping co-rotating twin-screw extruders. One model predicts heat transfer coefficients. Calculations of the barrel and screw heat transfer coefficients are made for various modules in different diameter extruders. We compare the values of the heat transfer coefficients from the model with those from literature. The second model predicts the axial screw temperature profile when the barrel, but not the screw, is heated, Example calculations of the cup mixing and screw temperature profiles are also made for different diameter extruders.

Extensive experimental studies of a starved flow modular tangential screw extruder are described. Die pressures and fill factor profiles along the screw axis are measured and used to determine screw characteristic curves Q vs. AP/L for individual screw elements of varying designs in a Leistritz twin screw extruder. Superior pumping characteristics of matched as opposed to staggered elements is found. The experimental screw characteristic curves are compared with the results of mathematical simulations of the flow. Agreement is generally good.

A model for flow in a Farrel Continuous Mixer based upon cylindrical coordinate hydrodynamic lubrication theory is presented. Pressure and flux fields over the rotor surface are calculated. The pumping characteristics of the various sections of the machine rotors were calculated. Generally Farrel Continuous Mixers are operated under starved conditions. Calculations are presented for continuous mixers operating under starved conditions. Pressure and fill factor profiles are determined. Fill factors are predicted to be increased by increasing throughput, increasing exit gate pressure and reducing screw speed.

Since the first discovery of carbon nanotubes (CNTs) in 1991, CNTs have generated enormous research activities in many areas of science and engineering due to their combined exceptional mechanical, thermal and electronic properties. These properties make nanotubes ideal, not only for a wide range of applications but also as a test-bed for fundamental scientific studies (Baughman et al., 2002). They can be described as a graphite sheet rolled up into a nanoscale tube. Two structural forms of CNTs exist: single-walled (SWCNTs) and multi-walled (MWCNTs) nanotubes. CNT lengths can be as short as a few hundred nanometers or as long as several micrometers. SWCNT have diameters between 1 and 10 nm and normally capped ends. In contrast, MWCNT diameters range from 5 to a few hundred nanometers because their structure consists of many concentric cylinders held together by van der Waals forces. CNTs are synthesized in a variety of ways, such as arc discharge, laser ablation, high pressure carbon monoxide (HiPCO), and chemical vapor deposition (CVD) (Dresselhaus, 1997). CNTs exhibit excellent mechanical, electrical, thermal and magnetic properties. The exact magnitudes of these properties depend on the diameter and chirality of the nanotubes and whether their structure is singleor multi-walled. Fig. 1 shows a segment of a single graphene plane that can be transformed into a carbon nanotube by rolling up into a cylinder. To describe this structure, a chiral vector is defined as OA = na1 + ma2, where a1 and a2 are unit vectors for the hexagonal lattice of the graphene sheet, n and m are integers, along with a chiral angle θ, which is the angle of the chiral vector with respect to the x direction. Using this (n, m) scheme, the three types of nanotubes are characterized. If n = m, the nanotubes are called ‘‘armchair”. If m = 0, the nanotubes are called ‘‘zigzag”. Otherwise, they are called ‘‘chiral”. The chirality of nanotubes has significant impact on their transport properties, particularly the electronic properties. For a given (n, m) nanotube, if (2n + m) is a multiple of 3, then the nanotube is metallic, otherwise the nanotube is a semiconductor. Each MWCNT contains a multi-layer of graphene, and each layer can have different chiralities, so the prediction of its physical properties is more complicated than that of SWCNT (Jin & Yuan, 2003).

In this article, the possibility of obtaining the recycled material based on waste polypropylene (WPP) and waste ground rubber tire powder (WGRT) has been studied. It has been proved that partially replacing WPP with PP-g-MA increased the elongation at break of WPP/WGRT blends, whereas decreased the thermal stability. The presence of compatibilizer increased the elongation at break and thermal stability of WPP/WGRT blends, whereas decreased the processing flowability, as revealed by using universal testing machine (UTM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and capillary rheometer. Moreover, the tendency of the change became more obvious with the content of PP-g-MA and compatibilizer or with the combination of PP-g-MA and compatibilizer. In addition, the improvement of the nonpolar compatibilizer (SEBS) in properties of WPP/WGRT blends was better than that of the polar compatibilizer (SEBS-g-MA).