Preparation and Electron Beam Irradiation of PVC/ENR/CNTs Nanocomposites

Poly (vinyl chloride), PVC/epoxidized natural rubber blend, ENR/carbon nanotubes, CNTs nanocomposites were prepared using melt intercalation and solution blending methods. In both preparation methods PVC: ENR: CNTs ratios were fixed at 50:50:2, while the 50/50 PVC/ENR blend without the addition of CNTs was used as control. The PVC/ENR/CNTs nanocomposites were exposed to electron beam (EB) irradiation at doses ranging from 0–200 kGy. The effects of two different preparation methods on the tensile properties, gel fraction and morphology of the PVC/ENR/CNTs nanocomposites were studied. Prior to EB irradiation, the addition of 2 phr of CNTs caused a drop in the tensile strength (Ts) of the 50/50 PVC/ENR blend, implying poor distribution of CNTs in the PVC/ENR blend matrix. However upon EB irradiation, the nanocomposites prepared by the melt blending method exhibited higher values of Ts as compared to the neat PVC/ENR blend due to occurrence of radiation-induced cross-linking in the PVC/ENR blend matrix. Transmission electron microscopy (TEM) images proved that a better dispersion of CNTs in PVC/ENR blend matrix can be achieved by melt intercalation compared to solution blending and the dispersion of CNTs was improved by irradiation. Scanning electron microscopy (SEM) results showed a distinct failure surface with formation of rough structure for the irradiated nanocomposites, which explains the higher values of tensile properties compared to the non-irradiated nanocomposites.     

Improving the properties of reclaimed waste tire rubber by blending with poly(ethylene‐co‐vinyl acetate) and electron beam irradiation

Scrap rubber reclamation is one of the most desirable approaches to solve the disposal problem of used tires. However, reclaimed tire rubber (RTR) has not gained enough attention due to its poor properties. In this work, the effects of poly(ethylene‐co‐vinyl acetate) (EVA) addition and electron beam (EB) irradiation on the properties of RTR were studied. The RTR/EVA blends containing 100–0 wt % of RTR were prepared in the internal mixer followed by EB irradiation with doses ranging from 50 to 200 kGy. The RTR/EVA blends were subjected to mechanical, gel content, thermal, and morphological analysis. It was found that the addition of EVA to RTR improved the mechanical properties of RTR. However, results revealed that RTR undergoes irradiation‐induced crosslinking in a relatively lesser extent as compared to EVA. This observation is associated with the stabilization and radical scavenging effects of additives, which are present in the RTR matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41649.     

Melt-rheological properties of PP/EVA blend

This paper describes a study of melt-rheological properties of the binary blend of isotactic polypropylene (PP) and ethylene–vinyl acetate copolymer (EVA) at varying blending ratios (from 0 to 40 wt % EVA content) and using three samples of EVA containing different vinyl acetate contents (VA %), viz. 9, 12, and 19%. Measurements made on a capillary rheometer at three different temperatures (210, 220, and 230°C) in a shear stress range of 10⁴–10⁶ Pa (shear rate 10¹–10⁴ s^?1) are presented and discussed for the effects of blend composition and shear stress on the flow curves, melt viscosity and melt elasticity. Morphology of the blend studied through scanning electron microscopy revealed distinct differences in size and number density of dispersed EVA droplets, which are discussed in terms of the variation of average size and number density of the dispersed EVA droplets as a function of blend composition and shear stress. Melt-rheological properties and morphology of dispersion are correlated and found quite consistent.     

Investigating the effects of processing parameters on poly(lactic acid) properties – a central composite design approach

ABSTRACT

This study attempts to optimise poly(lactic acid) processing parameters using central composite design approach which is well known statistical tool in design of experiments. Three factors and five levels were chosen for carrying out the analysis. The parameters include mixing temperature (180–210°C), screw speed (50–100?rev min^?1) and mixing time (5–10?min), which were varied independently. The results were evaluated based on maximum stress, tensile modulus, and impact strength under different conditions and the significant factors were determined using variance analysis (ANOVA). An optimum balance between the mechanical properties was obtained when the samples were blend at 180°C at 100?rev min^?1 rotor speed for 10?min. Moreover, validation of the predicted results confirmed the optimised parameters, which were further complemented by morphological and thermal studies.     

Measurement of PCI connector tilts using phase-shift fringe projection

The tilt angles of peripheral component interconnect (PCI) connectors on a printed circuit board assembly (PCBA) were measured using the phase-shift fringe projection method. The inspection system developed consists of a personal computer, digital camera, a standard projector and a mirror. The projector was used for projecting a sinusoidal fringe pattern onto the connectors. Phase-shifting was achieved by using a mirror mounted on a rotary stage in the path of the projected fringes. Since the light source used is non-collimated, calibration was performed to obtain an equation for the incident angle of the beam along the length of the object surface for different object heights. Glass blocks of known dimensions were used to test and verify the measurement system. The phase-shifting technique was applied to determine the tilt angles on the glass blocks and later applied to actual connectors. The vision-based inspection system developed using phase-shifting technique demonstrates successful tilt angle measurement on a PCBA.     

Role of MgO nanoparticles on zirconia-toughened alumina-5 wt-% CeO2 ceramics mechanical properties

The poor hardness of zirconia-toughened alumina (ZTA) with 5?wt-% CeO₂ (ZTA5CeO₂) ceramic has limited its applications as a cutting insert. Therefore, in this work, the possibility of MgO nanoparticles (20?nm) as reinforcement to ZTA5CeO₂ ceramics was investigated. Mgo nanoparticles with different weight percentages (0-2?wt-%) were added to ZTA5CeO₂ ceramics. ZTA5CeO₂ with 0.5?wt-%MgO showed the highest fracture toughness of 9.14?MPa.√m. The addition of 0.5?wt-%MgO nanoparticles showed the excellent role of MgAl₁₁CeO₁₉ grains as a crack deflector, which consequently produced a reasonable hardness value of 1591?HV and lowered the wear areas to 0.0528?mm².     

Effect of trimethylolpropane triacrylate (TMPTA) on the properties of irradiated epoxidized natural rubber (ENR‐50), ethylene‐(vinyl acetate) copolymer (EVA), and an ENR‐50/EVA blend

The effect of trimethylolpropane triacrylate (TMPTA) monomer on the tensile properties, dynamic mechanical properties, and morphology of irradiated epoxidized natural rubber (ENR‐50), ethylene‐(vinyl acetate) copolymer (EVA), and an ENR‐50/EVA blend was investigated. The ENR‐50, EVA, and ENR‐50/EVA blend were irradiated by using a 3.0‐MeV electron‐beam apparatus at doses ranging from 20 to 100 kGy. The improvement of tensile properties and morphology with irradiation indicated the advantage of having irradiation‐induced crosslinks in these materials. Observation of the properties studied confirmed that TMPTA was efficient in enhancing the irradiation‐induced crosslinking of ENR‐50, EVA, and the ENR‐50/EVA blend. Addition of TMPTA improved the adhesion between the ENR‐50/EVA blend phases by forcing grafting and crosslinking at a higher irradiation dose (100 kGy). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers.     

Generation and detection of higher-order mode clusters of guided waves (HOMC-GW) using meander-coil EMATs

This paper reports on a new means of generating higher-order mode clusters of guided waves (HOMC-GW) using a meander-coil (MC) electromagnetic acoustic transducer (EMAT) in plates at frequencies significantly higher than the lower-order plate modes. These wave modes are considerably less dispersive and they occur at much higher frequency-thickness (f x d) products. Our studies cover the f x d range of 13 to 20 MHz·mm. Experimental measurements were carried out on Al plate samples of different thicknesses using three different EMAT coil periods. To understand the generation and propagation characteristics of HOMC-GW with EMATs, several simulations were carried out using 2-D finite element models at different f x d products. These simulations captured all features observed in the experiments. The time-frequency smoothed pseudo Wigner-Ville distribution (SPWVD) was used to analyze the HOMC-GW modes. Defect detection measurements using HOMC-GW generated using EMATs were made on Al plates with machined defects.     

Prediction of surface roughness and dimensional deviation of workpiece in turning: a machine vision approach

In the past, roughness values measured directly on machined surfaces were used to develop mathematical models that are used in predicting surface roughness in turning. This approach is slow and tedious because of the large number of workpieces required to obtain the roughness data. In this study, 2-D images of cutting tools were used to generate simulated workpieces from which surface roughness and dimensional deviation data were determined. Compared to existing vision-based methods that use features extracted from a real workpiece to represent roughness parameters, in the proposed method, only simulated profiles of the workpiece are needed to obtain the roughness data. The average surface roughness R _a, as well as dimensional deviation data extracted from the simulated profiles for various feed rates, depths of cut, and cutting speeds were used as the output of response surface methodology (RSM) models. The predictions of the models were verified experimentally using data obtained from measurements made on the real workpieces using conventional methods, i.e., surface roughness tester and a micrometer, and good correlation between the two methods was observed.     

In-cycle detection of built-up edge (BUE) from 2-D images of cutting tools using machine vision

The built-up edge (BUE) phenomenon that appears under certain machining condition, such as low-to-moderate cutting speed, high depth of cut, dry cutting, cutting of ductile material, etc. is known to have a major effect on the surface quality of the finished workpiece. In the published literature, BUE has been measured using scanning electron microscope and optical microscopes to study its effect on tool life and surface quality. Such measurement methods are only applicable in off-the-machine inspection. Since the BUE extending beyond the tool nose alters the tool geometry and, thus, influences the workpiece roughness profile, detection of BUE outside the nose region is important. This research proposes a new method for detecting BUE from 2-D images of the nose region of the tool using a machine vision approach. Two methods of determining the BUE area are proposed—the subtraction method and polar-radius transformation method. Application of both methods is successfully demonstrated using simulated and real cutting tool images.