Facundo I. Altuna¹, Borja Fernández-d’Arlas², M. Angeles Corcuera², Arantxa Eceiza², Mirta I. Aranguren³, Pablo M. Stefani^3*

Journal of Renewable Materials, Vol.4, No.4, pp. 275-284, 2016, DOI:10.7569/JRM.2016.634120

Abstract Mixtures of biomass-derived polyols were used to synthesize rigid polyurethane (PU) foams. A commercial polymerized methylene diphenyl diisocyanate (pMDI) was used as crosslinker, and distilled water served as foaming agent. The morphology and mechanical properties of foams with different glycerol and water contents were compared in order to evaluate the most suitable formulations. The rigid foams with higher water contents had larger and more anisotropic cells, explaining their lower density. Compressive moduli ranged from about 2.5 MPa to above 20 MPa and collapse stresses from 55 kPa to more than 1 MPa for densities between More >

Oscar F. Aguilar Gutierrez, Alejandro D. Rey^*

Journal of Renewable Materials, Vol.4, No.4, pp. 241-250, 2016, DOI:10.7569/JRM.2016.634119

Abstract Biological plywoods are solid analogues of liquid crystalline phases whose building blocks, including cellulose, collagen and chitin, present multifunctionality, providing in some cases protection, camouflage, self-healing and/or adaptability to the surrounding environment. The 3D ordered structure is the main factor for these fascinating properties, and the assessment of the structure-property relationship will be a powerful tool in terms of future material design and innovation. Cross-section observations lead to characteristic patterns depending on the specific arrangement of the plywood’s building blocks. Twisted plywood architectures, known as the Bouligand structure, lead to the widely observed arced patterns… More >

D. Puglia^1*, F. Dominici¹, M. Badalotti², C. Santulli³, J.M. Kenny¹

Journal of Renewable Materials, Vol.4, No.3, pp. 199-205, 2016, DOI:10.7569/JRM.2016.634102

Abstract In this work, cocoa bean shells (CBS), which were ground, then sieved to less than 150 μm and dried in a vacuum oven, have been introduced in a polycaprolactone (PCL) matrix in three different amounts, 10, 20 and 30% wt. The obtained composites were tested under tensile loading, which indicated an enhanced rigidity with a slight decrease of strength with respect to the neat polymer and a reduced elongation, particularly evident for composites with 30 wt% CBS, where final collapse took place for strains only slightly exceeding the yielding point. Differential scanning calorimetry (DSC) indicated More >

Karina Cruz-Aldaco¹, Erika Flores-Loyola², Cristóbal Noé Aguilar-González¹, Nuria Burgos³, Alfonso Jiménez^3*

Journal of Renewable Materials, Vol.4, No.3, pp. 178-184, 2016, DOI:10.7569/JRM.2016.634107

Abstract The use of vegetable oils to replace fossil feedstock has become an area of opportunity and a priority for study in the field of polymer science. Vegetable oils are considered as renewable resources with high potential, low cost and full availability. The aim of this study is the synthesis of biobased polyols from cottonseed oil (Gossypium barbadanse) and corn oil (Zea mays) as feedstock. Their synthesis was successfully performed, as can be concluded from the determination of their hydroxyl index as well as the structural and thermal characterization carried out in this work. Polyurethanes from More >

Estefanía Lidón Sánchez-Safont¹, Jennifer González-Ausejo¹, José Gámez-Pérez¹, José María Lagarón², Luis Cabedo^1*

Journal of Renewable Materials, Vol.4, No.2, pp. 123-132, 2016, DOI:10.7569/JRM.2015.634127

Abstract Novel biodegradable composites based on poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBV) and different contents of purifi ed alpha-cellulose fi bers (3, 10, 25 and 45%) were prepared by melt blending and characterized. The composites were characterized by scanning electron microscopy (SEM), wide-angle X-ray scattering (WAXS) experiments, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanic analysis (DMA) and Shore D hardness measurements. Disintegrability under composting conditions was studied according to the ISO 20200 standard. Morphological results showed that high dispersion of the fi bers was achieved during mixing. Good adhesion on the fi ber-matrix interface was also detected by More >

Dragomir Vassilev^1*, Nadezhda Petkova², Milena Koleva¹, Panteley Denev²

Journal of Renewable Materials, Vol.4, No.1, pp. 24-30, 2016, DOI:10.7569/JRM.2015.634125

Abstract This article presents the results obtained by the ultrasound-assisted synthesis of sucrose and fructooligosaccharides (FOS) esters with fatty acids (palmitic and 10-undecylenic), the identifi cation of the products and the study of their possible application as plasticizers in plastics processing. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹H and ¹³C NMR) spectroscopy were used to identify the synthesized carbohydrate esters. The plasticizing effect of the sucrose palmitate applied in polyvinyl chloride (PVC) was evaluated by the glass transition temperatures; the decrease of the T_g with the increase of the ester content could be accepted as… More >

M. Ohsaki¹, T. Miyamura², J. Y. Zhang³

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.4, pp. 303-333, 2016, DOI:10.3970/cmes.2016.111.303

Abstract A simple constitutive model, called semi-implicit model, for cyclic loading is proposed for steel materials used for structures such as building frames in civil engineering. The constitutive model is implemented in the E-Simulator, which is a software package for large-scale seismic response analysis. The constitutive relation is defined in an algorithmic manner based on the piecewise linear combined isotropic-kinematic hardening. Different rules are used for the first and subsequent loading states to incorporate characteristics such as yield plateau and Bauschinger effect of rolled mild steel materials. An optimization method is also presented for parameter identification More >

Ryan Weisman³, Manoranjan Majji⁴, Kyle T. Alfriend⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.3, pp. 269-304, 2016, DOI:10.3970/cmes.2016.111.269

Abstract This paper presents a closed form solution to Liouville's equation governing the evolution of the probability density function associated with the motion of a body in a central force field and subject to J2. It is shown that the application of transformation of variables formula for mapping uncertainties is equivalent to the method of characteristics for computing the time evolution of the probability density function that forms the solution of the Liouville's partial differential equation. The insights derived from the nature of the solution to Liouville's equation are used to reduce the dimensionality of uncertainties More >

Hadil Abu Khalifeh¹, Hadi Belhaj²

FDMP-Fluid Dynamics & Materials Processing, Vol.12, No.3, pp. 124-135, 2016, DOI:10.3970/fdmp.2016.012.124

Abstract In this work, asphaltenes precipitation and deposition induced by applying an electric field to Abu Dhabi crude oil sample were studied. The asphaltic particle electrical charge and asphaltic deposits mass at different operating conditions were determined. Direct current (DC) was applied between two graphite electrodes dipped in crude oil/synthetic formation water mixture of 240K ppm salinity. Three current densities of 10, 20, and 30 A/m2 were applied. Deposits were collected on the electrodes surfaces and their mass was recorded using low capacity load cells (up to 50g). Anodic and cathodic deposits were observed at different… More >

S.D. Akbarov^1,2, T. Kocal³, T. Kepceler¹

CMC-Computers, Materials & Continua, Vol.51, No.2, pp. 105-143, 2016, DOI:10.3970/cmc.2016.051.105

Abstract The paper studies the dispersion of axisymmetric longitudinal waves in the bi-material compound circular cylinder made of linear viscoelastic materials. The investigations are carried out within the scope of the piecewise homogeneous body model by utilizing the exact equations of linear viscoelasto-dynamics. The corresponding dispersion equation is derived for an arbitrary type of hereditary operator and the algorithm is developed for its numerical solution. Concrete numerical results are obtained for the case where the relations of the constituents of the cylinder are described through fractional exponential operators. The influence of the viscosity of the materials… More >