Mayte M. Quispe^1,*, Olivia V. López¹, Marcelo A. Villar^1,2

Journal of Renewable Materials, Vol.7, No.4, pp. 383-391, 2019, DOI:10.32604/jrm.2019.04276

Abstract Among biopolymers, thermoplastic starch (TPS) is a good candidate to obtain biomaterials because of its natural origin, biodegradable character, and processability. Exposure to ultraviolet (UV) radiation causes significant degradation of starch-based materials, inducing photooxidative reactions which result in breaking of polymer chains, production of free radical, and reduction of molar mass. These changes produce a deterioration of TPS mechanical properties, leading to useless materials after an unpredictable time. In this work, changes induced on TPS by UV radiation, analyzing structural properties and mechanical behavior, are studied. TPS was obtained through thermo-mechanical processing of native corn starch in the presence of… More >

Chengquan Wang¹, Yonggang Shen^2,*, Yun Zou¹, Tianqi Li¹, Xiaoping Feng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.1, pp. 75-93, 2018, DOI:10.3970/cmes.2018.114.075

Abstract The failure behavior of the precast prestressed concrete T girder was investigated by destructive test and finite-element analysis, and the mid-span deflection, girder stiffness and the variation of the cross section strain in the loading process were obtained, and the mechanical properties, mechanical behavior, elastic and plastic behavior and ultimate bearing capacity of T girder with large span were revealed. Furthermore, the relationship between the beam stiffness degradation, the neutral axis in cross-section, steel yielding and concrete cracking are investigated and analyzed. A method was proposed to predict the residual bearing capacity of a bridge based on the variation of… More >

Deli Gao, Zengxin Zhao

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.1, pp. 29-30, 2011, DOI:10.3970/icces.2011.016.029

Abstract The research on casing corrosion in sour environment by a synergism of sweet corrosion and H2S corrosion has become the basis of casing selection and casing string safety evaluation with more and more sour reservoirs containing high H2S concentration being developed. It is essential to scientifically utilize casing service ability and reasonably control production rate of gas well to achieve the effective and safe developing of gas resources during the safety period of casing service with a precise casing life prediction. Scanning electron microscopy and tensile testing were applied to investigate the corrosion of TP110TS tube steel in stimulant solution… More >

Kahina Iggui^1,2,*, Mustapha Kaci¹, Mohamed Mahlous³, Nicolas Le Moigne⁴, Anne Bergeret⁴

Journal of Renewable Materials, Vol.7, No.9, pp. 807-820, 2019, DOI:10.32604/jrm.2019.06778

Abstract In this paper, the effects of gamma irradiation on Cast poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and PHBV/Cloisite 30B (C30B) (3 wt%) bionanocomposite prepared by melt compounding, were evaluated at various doses, i.e., 5, 15, 20, 50 and 100 kGy at room temperature in air. Changes in molecular weight, morphology and physical properties were investigated. The study showed that the main degradation mechanism occurring in gamma irradiation in both Cast PHBV and C-PHBV/3C30B bionanocomposite is chain scission, responsible for the decrease of molecular weight. Differential scanning calorimetry (DSC) data indicated a regular decrease in crystallization temperature, melting temperature and crystallinity index for all irradiated… More >

Larissa Stieven Montagna, Isabela CÉSAR Oyama, Rita de CÁSSIA Barbosa Camargo Lamparelli, Ana Paula Silva, THAÍS Larissa do Amaral Montanheiro, Ana Paula Lemes^*

Journal of Renewable Materials, Vol.7, No.2, pp. 117-128, 2019, DOI:10.32604/jrm.2019.00036

Abstract Biodegradable polymers have been increasingly used for scientific and commercial applications because they are similar to some conventional thermoplastics and exhibit the ability of self-degradation. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanocomposites films with 1 and 2 wt% of carbon nanotubes (CNT) were prepared by solution mixing, followed by solvent evaporation. In this work, PHBV/CNT nanocomposites were submitted to biodegradation in an aqueous medium for 34 days through a respirometric system. Then, the PHBV films were analyzed by the CO2 production and mineralization as a response of a microbial attack, which was monitored by back titration during all the experiment. The films were also… More >

Anna Kundys^1,*, Justyna Ostrowska², Urszula Chojnacka¹, Zuzanna Grodzka¹, Aleksandra Lange¹, Magdalena Paluch²

Journal of Renewable Materials, Vol.6, No.6, pp. 611-618, 2018, DOI:10.32604/JRM.2018.00134

Abstract The degradation of thermoplastic starch blend in the presence of commercial α-amylase and unpurified amylase of microbial origin was investigated. The blends consisting of thermoplastic starch and poly(butylene succinate) have potential use in packaging applications thus, it is essential to establish susceptibility to degradation. Molar mass loss, gravimetric weight loss, and molecular structure were evaluated. The changes in the surface were observed with scanning electron microscopy. It was confirmed that there was a significant difference in gravimetric weight loss between the blends degraded in two different solutions. Unpurified enzymes of microbial origin, produced by Rhizopus oryzae cultures decomposed analyzed materials… More >

Zakia Khelifi^1,2, Mohammed Amine Allal², Nabil Abou-bekr², Saïd Taïbi¹, Benoît Duchemin^1*

Journal of Renewable Materials, Vol.6, No.3, pp. 336-346, 2018, DOI:10.7569/JRM.2018.634102

Abstract The in-soil biodegradation of Stipa tenacissima (alfa) leaves was examined. Non-linear mechanical testing was performed at various biodegradation stages. Tensile strength, loading and unloading Young's moduli and dissipation energy decreased with the burial time, whereas plasticity increased. Field-emission scanning electron microscopy (FE-SEM) showed that the fracture cracks propagated in the longitudinal direction in the raw material, resulting in a fracture mode consisting of a mixture of middle lamella delamination and fiber pull-out. In contrast, the cracks were perpendicular to the stem axis in the biodegraded material, demonstrating an important strength loss of the load-bearing fibers. This strength loss was correlated… More >

Kahina Iggui^1,2,*,†, Mustapha Kaci², Nicolas Le Moigne¹, Anne Bergeret¹

Journal of Renewable Materials, Vol.6, No.3, pp. 288-298, 2018, DOI:10.7569/JRM.2017.634184

Abstract The effects of accelerated photooxidation on the molecular weight and thermal and mechanical properties of Cast PHBV and PHBV/Cloisite 30B (3 wt%) bionanocomposites are investigated herein. Through size exclusion chromatography (SEC) analysis, a significant decrease in both weight and number average molecular weights was observed for all irradiated samples over time, resulting from the chain scission mechanism. Differential scanning calorimetry (DSC) data indicated a decrease in degree of crystallinity and melting temperature after UV exposure, with the appearance of double melting peaks related to the changes in the crystal structure of PHBV. Thermal stability, tensile and thermo-mechanical properties were also… More >

M. L. Lambri^1,2, E. D. Giordano^2,3, P. B. Bozzano⁴, F. G. Bonifacich², J. I. Pérez-Landazábal^5,6, G. I. Zelada², D. Gargicevich², V. Recarte^5,6, O. A. Lambri^2*

Journal of Renewable Materials, Vol.4, No.4, pp. 251-257, 2016, DOI:10.7569/JRM.2016.634111

Abstract The denaturation processes of collagen in the temperature range between 450 K and 670 K are revealed through studies performed on cow rib bones by means of mechanical spectroscopy, differential scanning calorimetry, thermogravimetry, scanning electron microscopy and infrared spectroscopy. The conformational change of the collagen molecules from a triple helix structure to a random coil was found at around 510 K. It was determined that the transformation is developed through the viscous movement of fibrils with an activation energy of (127 ± 8) kJ/mol. The second stage of massive bulk deterioration of the collagen was found at around 600 K,… More >

Sudhakar Muniyasamy^1,2, Osei Ofosu^1,2, Maya Jacob John^1,2, Rajesh D. Anandjiwala^1,2*

Journal of Renewable Materials, Vol.4, No.2, pp. 133-145, 2016, DOI:10.7569/JRM.2016.634104

Abstract The present study investigates the mineralization of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-covalerate) (PHBV), and PLA/PHBV blend in compost and soil burial environments. The mineralization was assayed on the basis of carbon dioxide (CO2) release from the test materials incubated in compost and soil for a period of 200 days. The degradation was followed by means of fragmentation, thermogravimetric (TGA), FTIR spectroscopy and scanning electron microscopy (SEM) analyses. The results showed that PLA, PHBV and blend of PLA/PHBV achieved almost 90% biodegradation under composting conditions, while PHBV, PLA/PHBV blend and PLA respectively achieved only 35%, 32% and 4% biodegradation under soil… More >