Effect of music on test scores of students in chemistry and accounting

This study examined classical music’s effect on exam performance in a college setting by randomising students to listen to Richard Stoltzman’s Maid with the Flaxen Hair while taking a test for a science and a non-science subject, namely Chemistry as well as Accounting and Finance, respectively. We controlled for: prior knowledge on the subject matter, year in college and age. Findings revealed that there was a slight improvement on Accounting and Finance exam performance when the music was played during the test by a 7.9% and 2.8% increase in two assessments respectively, however Chemistry students exam performance with music declined by 0.3% and 13.5% in both assessments respectively

Reinforcement of graphene nanoplatelets on plasticized poly (lactic acid) nanocomposites: mechanical, thermal, morphology, and antibacterial properties

Plasticized poly(lactic acid) (PLA)‐based nanocomposites filled with graphene nanoplatelets (xGnP) and containing poly(ethylene glycol) (PEG) and epoxidized palm oil (EPO) with ratio 2 : 1 (2P : 1E) as hybrid plasticizer were prepared by melt blending method. The key objective is to take advantage of plasticization to increase the material ductility while preserving valuable stiffness, strength, and toughness via addition of xGnP. The tensile modulus of PLA/2P : 1E/0.1 wt % xGnP was substantially improved (30%) with strength and elasticity maintained, as compared to plasticized PLA. TGA analysis revealed that the xGnP was capable of acting as barrier to reduce thermal diffusion across the plasticized PLA matrix, and thus enhanced thermal stability of the plasticized PLA. Incorporation of xGnP also enhanced antimicrobial activity of nanocomposites toward Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes

Plasticized poly(lactic acid) with low molecular weight poly(ethylene glycol) : mechanical, thermal, and morphology properties

Poly(lactic acid) PLA was plasticized with low molecular weight poly(ethylene glycol) PEG-200 to improve the ductility of PLA, while maintaining the plasticizer content at maximum 10 wt%. Low molecular weight of PEG enables increased miscibility with PLA and more efficient reduction of glass transition temperature (Tg). This effect is enhanced not only by the low molecular weight but also by its higher content. The tensile properties demonstrated that the addition of PEG-200 to PLA led to an increase of elongation at break (>7000%), but a decrease of both tensile strength and tensile modulus. The plasticization of the PLA with PEG-200 effectively lowers Tg as well as cold-crystallization temperature, increasing with plasticizer content. SEM micrographs reveal plastic deformation and few long threads of a deformed material are discernible on the fracture surface. The use of low molecular weight PEG-200 reduces the intermolecular force and increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA

Processing and characterization of high environmental efficiency composites based on PLA and hazelnut shell flour (HSF) with biobased plasticizers derived from epoxidized linseed oil (ELO)

[EN] Different amounts of epoxidized linseed oil (ELO) have been added to poly(lactic acid)-PLA composites with hazelnut shell flour (HSF) to provide a plasticizing effect and improve the low intrinsic ductile properties of PLA/HSF composites. Mechanical, thermal, thermo-mechanical and dynamic mechanical properties have been studied in terms of the weight percentage ELO. Mechanical resistant properties in both tensile and flexural tests decrease with wt.% ELO while a remarkable increase with wt.% ELO is obtained. These results reveal a clear plasticization effect of ELO but, in addition, internal structure of PLA/HSF/ELO composites shows good PLA-HSF (matrix-particle) interactions so that indicating that ELO also provides a coupling effect between PLA matrix and HSF filler. ELO addition leads to a decrease in storage modulus (G ) obtained by dynamic mechanical thermal analysis (DMTA) in torsion mode thus giving clear evidence of the plasticization effect of ELO. Overall, the use of ELO in PLA/HSF composites is an attracting way to improve the low intrinsic fragility of these green composites; furthermore, ELO provides an improvement on thermal stability and a coupling effect between the polymer matrix and the surrounding lignocellulosic filler.This research was supported by the Ministry of Economy and Competitiveness - MINECO, Grant Number: MAT2014-59242-C2-1-R. Authors also thank to "Conselleria d'Educacio, Cultura i Esport" - Generalitat Valenciana, Grant Number: GV/2014/008 for financial support.Balart Gimeno, JF.; Fombuena Borrás, V.; Fenollar Gimeno, OÁ.; Boronat Vitoria, T.; Sánchez Nacher, L. (2016). Processing and characterization of high environmental efficiency composites based on PLA and hazelnut shell flour (HSF) with biobased plasticizers derived from epoxidized linseed oil (ELO). Composites Part B: Engineering. 86:168-177. https://doi.org/10.1016/j.compositesb.2015.09.063S1681778

A Comparative Study on the Mechanical, Thermal and Morphological Characterization of Poly(lactic acid)/Epoxidized Palm Oil Blend

In this work, poly(lactic acid) (PLA) a fully biodegradable thermoplastic polymer matrix was melt blended with three different epoxidized palm oil (EPO). The aim of this research was to enhance the flexibility, mechanical and thermal properties of PLA. The blends were prepared at various EPO contents of 1, 2, 3, 4 and 5 wt% and characterized. The SEM analysis evidenced successful modification on the neat PLA brittle morphology. Tensile tests indicate that the addition of 1 wt% EPO is sufficient to improve the strength and flexibility compared to neat PLA. Additionally, the flexural and impact properties were also enhanced. Further, DSC analysis showed that the addition of EPO results in a decrease in Tg, which implies an increase in the PLA chain mobility. In the presence of 1 wt% EPO, TGA results revealed significant increase in the thermal stability by 27%. Among the three EPOs used, EPO(3) showed the best mechanical and thermal properties compared to the other EPO’s, with an optimum loading of 1 wt%. Conclusively, EPO showed a promising outcome to overcome the brittleness and improve the overall properties of neat PLA, thus can be considered as a potential plasticizer

The effect of maleinized linseed oil as biobased plasticizer in poly (lactic acid)-based formulations

[EN] The use of maleinized linseed oil (MLO) as a potential biobased plasticizer for poly(lactic acid) (PLA) industrial formulations with improved toughness was evaluated. MLO content varied in the range 0-20 phr (parts by weight of MLO per hundred parts by weight of PLA). Mechanical, thermal and morphological characterizations were used to assess the potential of MLO as an environmentally friendly plasticizer for PLA formulations. Dynamic mechanical thermal analysis and differential scanning calorimetry revealed anoticeable decrease in the glass transition temperature of about 6.5 degrees C compared to neat PLA. In addition, the cold crystallization process was favoured with MLO content due to the increased chain mobility that the plasticizer provides. PLA toughness was markedly improved in formulations with 5 phr MLO, while maximum elongation at break was obtained for PLA formulations plasticized with MLO content in the range 15-20 phr. Scanning electron microscopy revealed evidence of plastic deformation. Nevertheless, phase separation was detected in plasticized PLA formulations with high MLO content (above 15-20 phr MLO), which had a negative effect on overall toughness. (C) 2017 Society of Chemical IndustryThis research was funded by the Ministry of Economy and Competitiveness - MINECO, ref. MAT2014-59242-C2-1-R. The authors also thank Conselleria d'Educacio, Cultura i Esport - Generalitat Valenciana, ref. GV/2014/008, for financial support. DG-G thanks the Spanish Ministry of Education, Culture and Sports for financial support through an FPU grant (FPU13/06011).Ferri, J.; Garcia-Garcia, D.; Montanes, N.; Fenollar, O.; Balart, R. (2017). The effect of maleinized linseed oil as biobased plasticizer in poly (lactic acid)-based formulations. Polymer International. 66(6):882-891. https://doi.org/10.1002/pi.5329S88289166

Mechanical, Thermal and Morphological Properties of Poly(lactic acid)/Epoxidized Palm Olein Blend

Poly(lactic acid) (PLA) is known to be a useful material in substituting the conventional petroleum-based polymer used in packaging, due to its biodegradability and high mechanical strength. Despite the excellent properties of PLA, low flexibility has limited the application of this material. Thus, epoxidized palm olein (EPO) was incorporated into PLA at different loadings (1, 2, 3, 4 and 5 wt%) through the melt blending technique and the product was characterized. The addition of EPO resulted in a decrease in glass transition temperature and an increase of elongation-at-break, which indicates an increase in the PLA chain mobility. PLA/EPO blends also exhibited higher thermal stability than neat PLA. Further, the PLA/1 wt% EPO blend showed enhancement in the tensile, flexural and impact properties. This is due to improved interaction in the blend producing good compatible morphologies, which can be revealed by Scanning Electron Microscopy (SEM) analysis. Therefore, PLA can be efficiently plasticized by EPO and the feasibility of its use as flexible film for food packaging should be considered