Viscometric studies of starch-g-polyacrylamide composites

Composites of starch-g-polyacrylamide, starch, and polyacrylamide have been prepared by gamma radiation-initiated polymerization of acrylamide in the presence of starch in aqueous medium. The polymerization was studied as a function of the (i) amount of water (ii) monomer concentration, and (iii) total dose. The optimum conditions for maximum conversion of the monomer to homopolymer and graft copolymer have been evaluated. Percentage of grafting of polyacrylamide could not be determined precisely as both the homopolymer and the graft are soluble in common solvents and all attempts to separate the graft from the homopolymer were unsuccessful. However, the formation of the starch-g-polyacrylamide copolymer was confirmed by the turbidimetric studies using acetone as a nonsolvent. The products of polymerization of acrylamide in the presence of starch consisted of unreacted starch, starch-g-polyacrylamide, and polyacrylamide and is referred to as the composite. Acrylamide was also polymerized in the absence of starch using γ-rays as means of initiation and the optimum conditions for maximum conversion of acrylamide to polyacrylamide have been evaluated. Viscosity behavior of the composite and polyacrylamide was studied in aqueous medium at 30±0.04°C. The reduced specific viscosity of the aqueous solution of acrylamide and the composite as well was found to increase with increasing dilution, the effect being more pronounced in the composite. This tends to indicate that both the homopolymer and the composite behave as polyelectrolytes. An attempt has been made to explain the polyelectrolytic behavior of the homopolymer and the composite. © 1993 John Wiley & Sons, Inc.     

Formation of Nanocrystalline Calcia by the Decomposition of Calcite

Formation of nanocrystalline calcia from calcite has been studied in situ via transmission electron microscopy. The crystallographic transformation occurred via two mechanisms: the first is by distortion of the cleaved rhombohedron of calcite, formed by {104} planes in hexagonal coordinates, into a cube. This produced a microstructure of oriented, elongated nanocrystals of calcia with planar boundaries. In the second mechanism, the micrometer-sized parent calcite particles broke up into nano-sized grains as the decomposition began, leading to irregularly shaped, randomly oriented nanocrystals of calcia.     

Studies on chemical resistance of polyesters

Chlorendic anhydride based polyester ( I ,) tetrachlorophthalic anhydride based polyester ( II ), dibromoneopentyl glycol based polyester ( III ,) general purpose polyester ( IV ,) blend of dibromoneopentyl glycol based polyester with general purpose polyester ( V ,) chlorendic anhydride and dibromoneopentyl glycol based polyester ( VI ), and a blend of chlorendic anhydride based polyester and dibromoneopentyl glycol based polyester ( VII ) were prepared and their chemical resistance and moisture absorption studied in various reagents, acid, alkali, and water, at 25 and 65°C. It is found that the polyester ( III ) is the least affected in the presence of the acids. In 20% NaOH, there was a decrease in weight for all polyesters at both the temperatures compared to the control except the polyester ( VII ). Increase in weight of all the polyesters was observed during the absorption of moisture both at 25 and 65°C. The increase was higher at higher temperature. Polyester ( III ) thus shows the least absorption of moisture.     

Thermal stability of PVC/chlororubber-20-graft polyblend–styrene–acrylonitrile blends. I

Thermal stability of PVC blends with chlororubber-20-graft polyblend-styrene-acrylonitrile [CR-20gp-SAN (2:1)] was studied by HCI evolution techniques and thermogravimetry under isothermal condition. The thermal stability of PVC/CR-20gp-SAN (2:1) blends has been compared with those of PVC/CR-20 and PVC/KM-365B blends. It has been observed that the thermal stability of modified PVC is less than that of unmodified PVC. The CR-20gp-SAN (2:1) modified PVC blends were found to be more stable than PVC/CR-20 blends but less stable than PVC/KM-365B blends. The rate of degradation in PVC blends were observed to be unaffected by the concentration of the modifiers, but the PVC/KM-365B blends were found to be degrading slower in comparison with PVC/CR-20 and PVC/CR-20gp-SAN (2:1) blends. The rate of degradation for PVC/CR-20 blends at lower concentrations (<10%) of modifiers is almost equal to that of PVC/CR-20-gp-SAN (2:1) blends, but more at higher concentrations of modifiers (>10%). The experimental results have been explained on the basis of the chemical nature of the modifiers and their miscibility with PVC.     

Note: The Use of Triallyl Cyanurate in Bonding PVC Plastisols to Steel

The use of diallyl phthalate as the basis for a non-extractable plasticizer for poly(vinylchloride) (PVC) is well-known. Used in conjunction with a primary plasticizer and a polymerization initiator, a plastisol coating for steel can be formulated which is oil or grease tolerant and can also be used for bonding some structural steel parts if the area is relatively large compared with the load to be applied. Defrayne and Twiss¹ describe the bonding of automobile hood assemblies by vinyl plastisol adhesives and Schneberger² emphasizes their use in the automobile industry though neither article gives the formulations employed. Commercial formulations giving pull-off strengths of the order of 1 to 4 MN. m^-2 always incorporate a proportion of a phenolformaldehyde resin or even an epoxy, but sound-deadening and other coatings of steel do not necessarily need this reinforcement. Phillips and Longworth³ particularly studied the use of diallylphthalate (DAP) as a polymerizable plasticizer and the consequent improvement in adhesion to mild steel. Sherlock⁴ used a simple formulation without additives when investigating the effect of surface cleaning and conversion coatings (oxides and phosphates). It was suggested that, as outlined below, improved adhesion would be expected if a small proportion of triallyl cyanurate (TAC) were added to the polymerizable plasticizer. This paper shows this expectation to be achieved although the proportion of the more expensive TAC needed for substantial increase in bond strength is greater than was hoped.     

A free space frequency‐time‐domain technique for electromagnetic characterization of materials using reflection‐based measurement

In this report, a free space frequency‐time‐domain technique is presented for characterizing the electrical properties and thickness of the sample using multiple reflections and fabry‐perot resonance phenomenon. The retrieval of constitutive electromagnetic parameters of the sample has been carried out by comparing the measured reflection coefficient data from the sample at two different incident angles. The relative permittivity as well as relative permeability along with the thickness of different samples viz., beryllia, silicon, and plexiglass have been evaluated with high accuracy in the frequency range 1 to 15 GHz. The method is also experimentally validated by successfully reconstructing the unknown material properties of two different samples. The unique advantage of this method lies in non‐requirement of any prior knowledge of the sample's thickness for measuring the complex relative dielectric constant as well as relative permeability of the sample. To determine the electromagnetic properties of the sample, the sole knowledge of reflection coefficient data are needed. Moreover, the method does not involve any additional measurement for the reference calibration. The simple, cost‐effective proposed scheme is quite useful in many applications like accurate determination of signal strength in indoor wireless communication, through wall imaging, food industry, and so on.     

Liver disorder detection using variable- neighbor weighted fuzzy K nearest neighbor approach

The human liver disorder is a genetic problem due to the habituality of alcohol or effect by the virus. It can lead to liver failure or liver cancer, if not been detected in initial stage. The aim of the proposed method is to detect the liver disorder in initial stage using liver function test dataset. The problem with many real-world datasets including liver disease diagnosis data is class imbalanced. The word imbalance refers to the conditions that the number of observations belongs to one class having more or less than the other class(es). Traditional K- Nearest Neighbor (KNN) or Fuzzy KNN classifier does not work well on the imbalanced dataset because they treat the neighbor equally. The weighted variant of Fuzzy KNN assign a large weight for the neighbor belongs to the minority class data and relatively small weight for the neighbor belongs to the majority class to resolve the issues with data imbalance. In this paper, Variable- Neighbor Weighted Fuzzy K Nearest Neighbor Approach (Variable-NWFKNN) is proposed, which is an improved variant of Fuzzy-NWKNN. The proposed Variable-NWFKNN method is implemented on three real-world imbalance liver function test datasets BUPA, ILPD from UCI and MPRLPD. The Variable-NWFKNN is compared with existing NWKNN and Fuzzy-NWKKNN methods and found accuracy 73.91% (BUPA Dataset), 77.59% (ILPD Dataset) and 87.01% (MPRLPD Dataset). Further, TL_RUS method is used for preprocessing and it improved the accuracy as 78.46% (BUPA Dataset), 78.46% (ILPD Dataset) and 95.79% (MPRLPD Dataset).

     

Multi-objective Optimization Based Recursive Feature Elimination for Process Monitoring

Neural Processing Letters - Process monitoring helps to estimate the quality of the end products, equipment health parameters, and operational reliability of chemical processes. This is an area in...     

Entropy based spatial domain image watermarking and its performance analysis

Digital image watermarking technique based on LSB Substitution and Hill Cipher is presented and examined in this paper. For better imperceptibility watermark is inserted in the spatial domain. Further the watermark is implanted in the Cover Image block having the highest entropy value. To improve the security of the watermark hill cipher encryption is used. Both subjective and objective image quality assessment technique has been used to evaluate the imperceptibility of the proposed scheme.Further, the perceptual perfection of the watermarked pictures accomplished in the proposed framework has been contrasted and some state-of-art watermarking strategies. Test results demonstrates that the displayed method is robust against different image processing attacks like Salt and Peppers, Gaussian filter attack, Median filter attacks, etc.

     

Interactive sonification to assist children with autism during motor therapeutic interventions

Personal and Ubiquitous Computing - Interactive sonification is an effective tool used to guide individuals when practicing movements. Little research has shown the use of interactive sonification...