Structure‐property relationship in polyaniline‐filled castor oil based chain extended polyurethanes

A series of polyaniline (Pani)‐filled chain extended polyurethanes (PUs) were prepared by condensation polymerization of castor oil with methylene diisocyanate (MDI) as crosslinker and diamino diphenyl sulfone (DDS) as chain extender. The effect of different amounts of Pani (varying from 5% to 25%) on the chain extended PUs has been reported. The Pani‐filled chain extended PU sheets were characterized by their physico‐mechanical properties such as density, tensile strength, percentage elongation at break and surface hardness. Electrical properties, such as volume and surface conductivity, also have been reported. These results are corroborated with microcrystalline parameters of PU/Pani estimated using wide angle X‐ray scattering (WAXS). Polym. Eng. Sci. 44:772–778, 2004. © 2004 Society of Plastics Engineers.     

Studies on thermal behavior,moisture absorption,and biodegradability of ginger spent incorporated polyurethane green composites

Ecological concern on accumulation of neutraceutical industrial waste material and the demands for newer composite materials have promoted extensive research on utilizing industrial wastes materials. Therefore, in the present study finely powdered ginger spent (GS), filled polyurethane (PU) green composites with varying amount viz., 0, 2.5, 5, 7.5, and 10 wt % of GS have been fabricated. The prepared PU/GS green composites have been characterized for their mechanical properties, density and void content. Interaction between filler and matrix has been confirmed from Fourier transform infrared spectroscopy studies. Moisture absorption and desorption studies have been performed at different relative humidity (RH). The moisture absorption and desorption studies, shows that as the hydrophilic GS content increases in the matrix the RH also increases. Water uptake behavior of PU/GS were measured in different chemical environments such as 5% sodium chloride solution, cold water at different temperature and in hydrochloric acid solution. The water uptake values increases as increase in GS concentration. Equilibrium water content, diffusivity and equilibrium time taken for all PU/GS composites have been investigated. Biodegradation studies reveals that as the GS content increases the weight loss also increases. Thermal properties have been performed using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). From DSC and DMA thermograms it is revealed that increase in T_g with increase in GS content. RH and contact angle measurement have been performed to understand the hydrophilic nature of the prepared composite. The morphological behavior of composites has been studied using scanning electron microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41614.     

Feasibility of xanthan gum–sodium alginate as a transdermal drug delivery system for domperidone

The present investigation comprises the formulation and in vitro evaluation of domperidone loaded transdermal drug delivery system (TDDS) for controlled release. The polymer membranes were prepared using xanthan gum (XG) and sodium alginate (SA) by varying the blends compositions viz., 10:0, 8:2, 6:4, 5:5, 4:6, 2:8, and 0:10 (XG/SA, wt/wt, %). The drug loaded membranes were evaluated for thickness, content uniformity, tensile behaviours, and in vitro drug release studies. Domperidone was found to be compatible with the prepared formulation as revealed by Fourier transform infrared (FTIR) spectroscopy studies. In vitro release studies were carried out in open glass diffusion cell for a period of 8 h and it showed controlled release of drug from the XG/SA matrix. The present study concludes that, the prepared transdermal films can be used to achieve controlled release of drug and improved bioavailability.     

Sorption and diffusion of water into melamine–formaldehyde‐incorporated poly(vinyl acetate)–polyester nonwoven fabric composites

A series of composites were fabricated by impregnating a polyester nonwoven fabric with melamine–formol (MF)‐incorporated poly(vinyl acetate) (PVAc) latex. The effect of different weight ratios of MF/PVAc, i.e. 0/100, 5/100, 10, 100, 15/100 and 20/100 (dry, wt/wt), on the water sorption and diffusion into the composites was evaluated. Water sorption studies were carried out at different temperatures, i.e. 30, 50 and 70 °C, based on the immersion weight gain method. From the sorption results, the diffusion (D) and permeation (P) coefficients of water penetrant were calculated. A significant increase in the diffusion and permeation coefficients was observed with an increase in the temperature of sorption. Drastic reductions in diffusion and permeation coefficients were noticed with increasing MF content in the composites. Attempts were made to estimate the empirical parameters like n, which suggests the mode of transport, and K, a constant which depends on the structural characteristics of the composite in addition to its interaction with water. The temperature dependence of the transport coefficients was used to estimate the activation energy parameters for diffusion (E_D) and permeation (E_p) processes from Arrhenius plots. Copyright © 2006 Society of Chemical Industry     

Studies on SLS doped polyaniline and its blend with PC

Electrically conductive polyaniline (PANI) and its blend with polycarbonate (PC) was prepared by one-step emulsion polymerization technique in which sodium lauryl sulfate (SLS) acts as surfactant and as a protonating agent for the resulting polymer. The prepared PANI and its blends were characterized by density, percentage of water absorption, and electrical conductivity. PANI–PC blend exhibits a conductivity value of 4.70 × 10⁻² S/cm (PANI–PC1) and 5.68 × 10⁻⁵ S/cm (PANI–PC3) with a change in dopant from p-toluene sulfonic acid (TSA) to SLS, respectively. By using a more general method, which takes into account the presence of disorder of the second kind in polymers proposed by Hosemann, crystal size (〈N〉) and lattice strain (g in %) values were estimated. The variation of conductivity in doped PANI and PANI–PC blend has been explained on the basis of these microcrystalline parameters. TGA thermograms of PANI and PANI-PC blend show three-step degradation behavior. Thermal stability of PANI was improved after blending with PC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 383–388, 2001     

Microwave assisted improvement in physico-mechanical properties of poly(vinyl alcohol)/poly(ethylene imine)/gelatin blends

Blends of poly (vinyl alcohol) (PVA), poly-N-acyl ethyleneimine (PEI) and gelatin (PVA/ PEI/Gel) in the weight ratios 100/0/2, 95/5/2, 90/10/2, 85/15/2, 80/20/2 and 70/30/2 were prepared by solution casting method. The effects of poly (ethylene imine) component in the blend and microwave irradiation on the mechanical and microstructural properties have been investigated using various techniques along with Positron Annihilation Lifetime Spectroscopy (PALS). We observed tremendous improvement in mechanical properties after microwave irradiation for 60 s in 5 wt% of PEI component blend. These results are supported by the SEM data as well the optical data. The free volume data from positron results showed minimum free volume at 5 wt% of PEI after 60 s of irradiation due to cross linking through hydrogen bond formation and possible estrification among the blend components. These results correlate well the mechanical properties like tensile strength and modulus.     

Thermal and morphological properties of SA/HPMC blends

Sodium alginate (SA) was blended with varying amounts of hydroxypropyl methylcellulose (HPMC) viz., 10, 20, and 30 wt % by solution casting process. Thus, the obtained blends were characterized by using different analytical techniques such as differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microcopy (SEM). FTIR studies reveal the hydrogen bond formation between hydroxyl groups of SA and HPMC polymer chains. DSC analysis shows single glass transition temperature (T_g) for SA/HPMC blends indicating compatibility and physical interaction between SA and HPMC polymer chains. TGA analysis indicates variation of thermal stability of SA with change in compositions of HPMC. SEM studies reveal uniform distribution of second phase in the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of cenosphere filler additions on the three‐body abrasive wear behavior of glass fiber‐reinforced epoxy composites

The dry three‐body abrasive wear behavior of bi‐directional glass fabric reinforced epoxy composites with and without cenosphere filler have been studied using dry sand/rubber wheel abrasion tester. The angular silica sand particle sizes in the range 200–250 μm were used as dry and loose abrasives. The wear experiments have been conducted at two different loads viz., 22 and 32 N and different abrading distances viz. 270, 540, 810, and 1,080 m. The wear volume increases with an increase in load/abrading distance for all composites. From the experimental wear data it was observed that the abrasive wear of the composites dependent on the applied load and abrading distance. Further, the cenospheres filler inclusion in glass fiber reinforced epoxy (G‐E) composite showed poor abrasive wear performance. Scanning electron microscopy was used to study the morphology of the worn surface features of composites and to understand the mechanisms involved in the wear analysis. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Modeling of moisture sorption isotherms of poly(vinyl alcohol)/starch films

Studies on the moisture sorption characteristics of poly(vinyl alcohol)/starch blends for water activity (a_w) values of 0.1–0.9 were performed at 27°C. The equilibrium moisture content at different a_w values was used to fit different sorption isotherm models proposed in the literature. The ranges of a_w applicable for the different sorption isotherms were reported. The model constants of the sorption equations were determined by linear fitting. The value of the coefficient of determination (0.98 ± 0.01) confirmed the goodness of fit of the equations studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3874–3881, 2003     

Studies on physico‐mechanical and optical properties,and WAXS of castor oil based polyurethane/polyacrylates interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) of polyurethane (PU)/polyacrylates have been synthesized by sequential polymerization of castor oil, methylene diisocyanate (MDI), and acrylate monomers such as methyl acrylate (MA), methyl methacrylate (MMA), and ethyl acrylate (EA); with benzoyl peroxide (BPO) and ethylene glycol dimethyl acrylate (EGDM) as an initiator and crosslinker, respectively. The physico‐mechanical properties, such as density, surface hardness, tensile strength, percentage elongation at break, and tear strength; and the optical properties, like total transmittance and haze, of PU/polyacrylate IPNs have been reported. Microcrystalline parameters of IPNs have been computed by using wide angle X‐ray scattering (WAXS) recordings. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 764–773, 2005