Thermal and crystallization behavior of engineering polyblends. I. Glass reinforced polyphenylene sulfide with polyethylene terephthalate

The thermal and crystallization behavior of blends of glass fiber reinforced polyphenylene sulfide (PPS) with polyethylene terephthalate (PET) has been reported. The blends showed two overlapping melting peaks and two separate crystallization peaks. The heat of crystallization of PPS was found to decrease continuously with increasing PET content, whereas the heat of crystallization of PET was found to increase with increasing PPS content. This indicates that the degree of crystallinity of PPS is reduced whereas that of PET is increased as a result of blending. It is interesting to note that the combined heats of fusion of the blends were marginally higher than those calculated by proportional additivity rule in spite of the drop in the heat of crystallization of PPS. The temperature onset of crystallization of PET in the blends shifted to higher temperature whereas there was no significant change in the crystallization temperature of PPS. The increase in the temperature of crystallization of PET indicates enhanced nucleation. The isothermal crystallization studies of the component polymers revealed that both the component polymers crystallized at a relatively faster rate in the blend. The crystallization rate of PPS was found to increase significantly with increasing PET content. A significant increase in the rate of crystallization of PET was also observed in the blends. The acceleration of crystallization rate of PET in the blends was more pronounced as compared to that of PPS. The acceleration in the PET crystallization rate was attributed to the presence of glass fibers and crystallized PPS.     

Coupled dynamical system based arm–hand grasping model for learning fast adaptation strategies

Performing manipulation tasks interactively in real environments requires a high degree of accuracy and stability. At the same time, when one cannot assume a fully deterministic and static environment, one must endow the robot with the ability to react rapidly to sudden changes in the environment. These considerations make the task of reach and grasp difficult to deal with. We follow a Programming by Demonstration (PbD) approach to the problem and take inspiration from the way humans adapt their reach and grasp motions when perturbed. This is in sharp contrast to previous work in PbD that uses unperturbed motions for training the system and then applies perturbation solely during the testing phase. In this work, we record the kinematics of arm and fingers of human subjects during unperturbed and perturbed reach and grasp motions. In the perturbed demonstrations, the target’s location is changed suddenly after the onset of the motion. Data show a strong coupling between the hand transport and finger motions. We hypothesize that this coupling enables the subject to seamlessly and rapidly adapt the finger motion in coordination with the hand posture. To endow our robot with this competence, we develop a coupled dynamical system based controller, whereby two dynamical systems driving the hand and finger motions are coupled. This offers a compact encoding for reach-to-grasp motions that ensures fast adaptation with zero latency for re-planning. We show in simulation and on the real iCub robot that this coupling ensures smooth and “human-like” motions. We demonstrate the performance of our model under spatial, temporal and grasp type perturbations which show that reaching the target with coordinated hand–arm motion is necessary for the success of the task.     

Core content and stability of n‐octadecane‐containing polyurea microencapsules produced by interfacial polymerization

Microencapsulation of phase change material (PCM) n‐octadecane was carried out by interfacial polymerization technique using core and bulk monomers as toluene‐2,4‐diisocyanate (TDI) and diethylene triamine (DETA), respectively. Cyclohexane was used as the solvent for TDI and n‐octadecane, which formed the oil phase. The effect of encapsulation procedure, core‐to‐monomer ratio (CM ratio) and PCM‐to‐cyclohexane (PC) ratio was investigated on core content, encapsulation efficiency, and stability of microcapsules. Using a modified procedure, the core content was found to increase with the increasing CM ratio and reached a maximum at 3.7, while the encapsulation efficiency continuously decreased with the increasing CM ratio. Also the encapsulation efficiency was found to have a strong dependence on PC ratio and a maximum encapsulation efficiency of 92%, along with the core content of 70% was obtained with CM ratio of 3.7 along with the PC ratio of 6. The microcapsules were well shaped, i.e., round and regular, with narrow size distribution at these conditions. The PCM microcapsules were found to be stable to heat treatment at 150°C for 8 h. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of Lactose Monolaurate and High Intensity Ultrasound on Crystallization Behavior of Anhydrous Milk Fat

Crystallization behavior of anhydrous milk fat (AMF) was studied with the addition of 0.025 and 0.05 % lactose monolaurate (LML). The crystallization behavior was studied at low (ΔT = 3 °C) and high supercooling (ΔT = 6 °C). Polarized light microscopy and laser turbidimetry indicated a delay in crystallization on addition of 0.025 % and 0.05 % LML or Tween 20 to AMF. High intensity ultrasound (HIU) was applied to AMF samples with 0.05 % LML and lower supercooling (T _c = 31 °C; ΔT = 3 °C). HIU application in AMF and AMF + 0.05 % LML induced crystallization (p < 0.05) changing the induction time (τ) at 31 °C from 34.20 ± 1.67 min (AMF) and 47.07 ± 1.27 min (AMF + 0.05 % LML) to 23.23 ± 3.26 min (AMF) and 25.00 ± 0.87 min (AMF + 0.05 % LML). Melting enthalpies (ΔH) of AMF were significantly higher (p < 0.05) than the ones observed for AMF + 0.05 % LML when crystallized without HIU, while enthalpy values increased significantly in AMF + 0.05 % LML samples when crystallized with HIU reaching similar values to the ones obtained for AMF without LML. The viscosity of AMF significantly decreased (p < 0.05) on addition of 0.05 % LML and significantly increased on HIU application.     

α-Glucosidase, α-amylase inhibition kinetics,in vitro gastro-intestinal digestion,and apoptosis inducing abilities of Ficus microcarpa L. f. and Ficus racemosa L. fruit polysaccharides

Food Science and Biotechnology - A rich source of nutrients, figs have a number of clinically validated benefits. This study aimed to evaluate the in vitro simulated gastrointestinal digestion, and...     

Synthesis and characterization of high molecular weight polyaniline for organic electronic applications

High molecular weight polyaniline (PANI) was synthesized by a combined procedure incorporating various synthesis methods. Temperature and open circuit potential of the reaction mixture were collected to monitor the reaction progress. The polymer is characterized by various techniques including gel permeation chromatography, dynamic light scattering, infrared spectroscopy, solid‐state nuclear magnetic resonance, and differential scanning calorimetry for elucidating the molecular architecture obtained by this method. As‐synthesized PANI was found to possess high molecular weight, reduced branching, reduced cross‐linking, and to predominantly consist of linear polymer chains. This polymer was also found to be more stable in solution form. J–V characteristics of as‐synthesized PANI films indicate a high current density which is due to increased free pathways and less traps for the charge transport to occur in PANI films. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Rheology of nylon 6 containing metal halides

Addition of metal halides to nylons has been shown to be advantageous in a number of ways. The decrease in melting temperature, increase in glass transition temperature and melt viscosity by such additions have allowed more convenient processing of low molecular weight polymers and thermally unstable polymers. Rheological data depicting the variation of melt viscosity with shear rate at temperatures relevant to processing are necessary in optimizing and trouble-shooting plastics processing operations. In the present paper, a method has been proposed to estimate, complete flow curves or rheograms of nylon—metal halide systems with the use of a master curve knowing the melt flow index and glass transition temperature of the system. The validity of the approach has been verified for the nylon 6—lithium chloride system and shown to hold good for any nylon—metal halide combination.     

Role of stuffer layers and fibre volume fractions on the mechanical properties of 3D woven fabrics for structural composites applications

Using weaving technology, possible manipulations can be done so as to derive maximum advantage from the reinforcements towards desired mechanical properties of the composites. Thus with different sets of weaving parameters and tow linear densities, an attempt has been made to investigate tensile, impact and knife penetration performance of different stuffer layers and fibre volume fractions of 3D orthogonal and interlock E-glass fabrics as reinforcements for composite applications. The tensile properties were effectively influenced by warp tow crimp%, number of stuffer tows per unit width of the fabric and fabric assistance. The tow linear density, fabric sett and the number of cross over points play a determining role towards impact energy absorption capacity. The fabric sett along with tow linear densities also play a vital role towards peak energy during knife penetration test. The number of cross over points were found to be least important in the knife penetration results analysis.