Fracture behaviour of pressure die-cast aluminium-graphite composites

Fracture toughness values of pressure die-cast Al-7Si-3 Mg-5 graphite composites were measured and found to be in the range 8–10 MPa m^1/2. Detailed microstructure of the composite and the fractured surfaces were examined. Defects such as clusters, agglomerations and segregation of graphite particles, play a dominant role in accelerating the fracture process. In addition, the acicular silicon phase present in the matrix and the casting defects, such as gas and shrinkage porosities, also initiated and accelerated the crack, thus lowering the fracture toughness of the composites.     

Elastic Properties of Alkali Phosphomolybdate Glasses

Ultrasonic velocities at 10 MHz have been measured in two series of lithium, sodium, and potassium phosphomolybdate glasses with two fixed P₂O₅ concentrations. Elastic moduli, Poisson's ratio, and Debye temperature have been calculated. The composition dependence of most of the properties of lithium glasses exhibits a trend opposite to that of potassium glasses. Properties of sodium glasses lie between the other two alkali systems. Alkali oxide modification is suggested to be accompanied by ring reformation in lithium and sodium glasses. Ring size effects have been shown to account for all of the composition dependence.     

Poly(alkyl lactate acrylate)s having tunable hydrophilicity

Four alkyl lactates and alkyl lactate acrylates having methyl, ethyl, propyl, and butyl as alkyl moiety were synthesized by azeotropic distillation. Their formation was confirmed by Fourier transform infrared (FTIR), mass, ¹H nuclear magnetic resonance (NMR) and proton decoupled ¹³C NMR spectroscopic techniques. Solution polymerization was carried out for these alkyl lactate acrylates and the formed homopolymers were characterized by FTIR, ¹H NMR, proton decoupled ¹³C NMR spectroscopic, and gel permeation chromatographic techniques. Shear thinning behavior was observed for all the polymers. Wide angle X‐ray Diffraction studies showed that the polymers were amorphous in nature and also exhibited odd‐even effect among alkyl lactate groups with respect to average molecular interchain spacing. Depending on the length of the alkyl lactate groups, relative humidity and time, the hydrophilicity of the polymers decreased with increase in the length of the alkyl lactate group among the odd and even series. Among the studied polymers, poly(ethyl lactate acrylate) may have the potential for hydrogel applications, due to its highly hydrophilic nature. T_g decreased with increase in length of alkyl lactate groups. Trend observed on the thermal stabilities of poly(alkyl lactate acrylate)s could be explained on the basis of average molecular interchain spacing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40962.     

Porous polymers prepared via high internal phase emulsion polymerization for reversible CO2 capture

A series of porous polymers with different pore volumes, pore sizes, and crosslinking densities were synthesized by high internal phase emulsion (HIPE) polymerization. The crosslinked polymerized HIPEs (polyHIPEs) were formed by the copolymerization of 4-vinylbenzyl chloride and divinylbenzene using water droplets in conventional or Pickering HIPEs as the templates. These porous materials were further modified by quaternization and ion exchange to introduce quaternary ammonium hydroxide groups. The resulting polyHIPEs were utilized as sorbents for reversible CO₂ capture from air using the humidity swing. The effect of pore structure on the CO₂ adsorption and desorption processes was studied. The polyHIPEs containing large pores and interconnected porous structures showed improved swing sizes and faster adsorption/desorption kinetics of CO₂ compared to a commercial Excellion membrane with similar functional groups.     

Chemical phosphorylation improves the moisture resistance of soy flour‐based wood adhesive

A green‐chemistry approach to improve the moisture resistance of soy flour (SF)‐based wood adhesive is described. Chemical phosphorylation of SF (PSF), using POCl₃ as the phosphorylating agent, dramatically increased its wet bond strength. The optimum POCl₃:SF ratio that produced maximum wet bond strength was about 0.15 (g g^?1). The increase in wet bond strength of PSF (PSF0.15) was mostly due to the phosphate groups incorporated into the proteins and carbohydrates, and to a lesser degree to phosphorylation‐induced protein denaturation. The attached phosphate groups acted as cross‐linking agents, either via covalent esterification with hydroxyl groups on wood chips or via ionic and hydrogen‐bonding interactions with functional groups in wood chips. At hot‐press temperatures above 160°C the wet bond strength of PSF0.15 was >2.6 MPa, a level that might be acceptable for interior‐used hardwood plywood and particleboard. POCl₃ is a low cost, general‐purpose reagent and therefore PSF‐based adhesive is expected to be environmentally friendly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40451.     

Protein Stabilization of Emulsions and Foams

ABSTRACT: Proteins play an important role as macromolecular surfactants in foam and emulsion-type food products. The functioning of proteins in these applications is determined by their structure and properties in the adsorbed layers at air-water and oil-water interfaces. In addition, because typical food proteins are mixtures of several protein components, interaction between these components in the adsorbed layer also impacts their ability as surfactants to stabilize dispersed systems. In this paper, recent progress in our understanding of the molecular mechanisms involved in the formation and stability of protein-stabilized foams and emulsions has been reviewed.