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.     

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.     

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     

Computer simulation method for calculating concentration profiles in polyurethane/polystyrene interpenetrating polymer network membranes

Interpenetrating polymer networks (IPNs) of polyurethane (PU) and polystyrene (PS; 90/10 and 75/25) were synthesized by the condensation reaction of castor oil with methylene diisocyanate and styrene, with benzoyl peroxide as an initiator. The IPN membranes were characterized for physicomechanical, optical, and X‐ray diffraction properties. Computer‐simulated concentration profiles of aqueous salt solutions through PU/PS IPN membranes were generated with Fick's second‐order differential equation, and the results were examined in terms of diffusion anomalies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 122–128, 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     

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     

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.     

Effect of zeolite particulate filler on the properties of polyurethane composites

Polymer-Zeolites composites have been prepared, using castor oil based polyurethane (PU) as a host and AlPO₄-5 as particulate filler. The prepared PU/zeolite composites have been characterized for mechanical properties such as tensile strength and tensile modulus. These PU composites exhibited an improved mechanical performance compared to the unfilled PU. Thermo gravimetric analyzer (TGA) curve shows that all the chain-extended PUs are stable up to 250 °C and maximum weight loss occurs at 490 °C. The thermal stability of composites increases with increase in zeolite content. Microcrystalline parameters and micro voids of composites have been measured by using wide-angle X-ray scattering (WAXS) and Positron Annihilation Lifetime (PALS) methods respectively. The microcrystalline parameters and micro-voids from PALS indicate the interaction of the filler with the matrix is stronger beyond 5% of the filler which reflect the mechanical performance as well. Surface morphology of composites has been studied using Scanning Electron Microscopy (SEM). The photomicrograph of SEM indicates a uniform distribution of zeolite filler in the PU matrix.     

Microstructural behaviors of polyaniline/CB Composites by SAXS

Polyaniline doped with dodecylbenzene sulfonic acid and conductive carbon black (PAn.DBSA/CB) hybrid materials have been prepared by in situ polymerization. The electrical resistivity of the PAn/CB was measured as a function of CB. The minimum resistivity was noticed for the composites with 25 wt % of CB as compared to other systems. Small angle x‐ray diffraction data was used to characterize the molecular arrangements of these composites. The refinement parameters such as periodicity (L), phase lengths (<Y> and <Z>), phase ratio (<Y>/<Z>), and probability distribution of phases [γ_Z (crystalline), γ_Y (amorphous)] for PAn, CB, and PAn/CB composites have been measured by SAXS data. It was observed that there is decrease in the crystallinity with increase in CB content in the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Investigations on the influence of graphite filler on dry sliding wear and abrasive wear behaviour of carbon fabric reinforced epoxy composites

In this experimental study, the dry sliding wear and two-body abrasive wear behaviour of graphite filled carbon fabric reinforced epoxy composites were investigated. Carbon fabric reinforced epoxy composite was used as a reference material. Sliding wear experiments were conducted using a pin-on-disc wear tester under dry contact condition. Mass loss was determined as a function of sliding velocity for loads of 25, 50, 75, and 100 N at a constant sliding distance of 6000 m. Two-body abrasive wear experiments were performed under multi-pass condition using silicon carbide (SiC) of 150 and 320 grit abrasive papers. The effects of abrading distance and different loads have been studied. Abrasive wear volume and specific wear rate as a function of applied normal load and abrading distance were also determined.The results show that in dry sliding wear situations, for increased load and sliding velocity, higher wear loss was recorded. The excellent wear characteristics were obtained with carbon-epoxy containing graphite as filler. Especially, 10 wt.% of graphite in carbon-epoxy gave a low wear rate. A graphite surface film formed on the counterface was confirmed to be effective in improving the wear characteristics of graphite filled carbon-epoxy composites. In case of two-body abrasive wear, the wear volume increases with increasing load/abrading distance. Experimental results showed the type of counterface (hardened steel disc and SiC paper) material greatly influences the wear behaviour of the composites. Wear mechanisms of the composites were investigated using scanning electron microscopy. Wear of carbon-epoxy composite was found to be mainly due to a microcracking and fiber fracture mechanisms. It was found that the microcracking mechanism had been caused by progressive surface damage. Further, it was also noticed that carbon-epoxy composite wear is reduced to a greater extent by addition of the graphite filler, in which wear was dominated by microplowing/microcutting mechanisms instead of microcracking.