Search

This work deals with a dynamic mechanical analysis (DMA) study on the effect of a novel interfacial agent containing maleated grafts on an industrial waste origin atactic polypropylene. This contains 3% of bridge-, backbone-, and terminal-grafted succinic anhydride groups (aPP-SA/SA). By considering a polymer blend as a special case of composite where the dispersed phase is mobile, it is assumed that both the amounts of polyamide 6 (PA6) and the interfacial agent (aPP-SA/SA) cause changes in the glass transition temperature of the polypropylene phase in the blend. In this work, we have used DMA parameters to evidence the real interfacial modifications caused by the presence of aPP-SA/SA in the isotactic polypropylene (iPP)/PA6 system at the iPP glass transition temperature on the basis that this is an unfavorable scenario for the action of aPPSA/SA. Since each component of the blend is interacting with each other, and to include the influence of the dispersed phase, it is possible to use a Box-Wilson experimental design model by resembling the so-called 'agent based models' to obtain algorithms forecasting the dynamic mechanical parameters (storage, E', and loss moduli, E') at the glass transition of iPP, in all the composition range of whatever iPP/PA6/aPP-SA/SA-modified blend., INTRODUCTION From an applied perspective, the polyamide/polyolefin blend system has been a prime subject for many years due to the potential industrial applications mainly related to the enhancement of impact [...]

This work deals with the study of the evolution (with temperature) of the in-phase (E') and the out-of-phase (E') moduli of polypropylene/mica composites with improved interfacial interactions by the presence of an industrial waste based interfacial modifier named as p-phenylenbis-maleamic (pPBMA) acid grafted atactic polypropylene (aPP-pPBMA). This additive contains 15% w/w grafted pPBMA (5.0-[10.sup.-4] g [mol.sup.-1]) obtained from polymer industrial wastes in the Polymer Engineering Group (GIP) labs. The purpose of the work is twofold. One, dynamic mechanical analysis (DMA) has been used to evidence the improvement in properties due to the interfacial modifications by the addition of the novel interfacial modifier (aPP-pPBMA). And two, to obtain a mathematical model to predict the DMA moduli of the composite at [alpha] and [beta] transition temperatures. So, a Box-Wilson experimental design considering the amount of mica particles and of interfacial agent as independent variables, and the modulus as the dependent ones at each transition was used. Thus, the final purpose of the work is obtaining forecasts for the DMA parameters as a function of the composite components and of the type of temperature dependent relaxation phenomena taking place., INTRODUCTION The use of interfacial agents have proved to be one of the most effective strategies to promote the interactions between the components in heterogeneous materials based on polymers as [...]

The present work checks on the efficiency of a grafted atactic polypropylene, with a high level of succinic anhydride-grafted groups, as an interfacial modifier in Polypropylene/Short Carbon Fiber composites (iPP/SCF) by mean of Dynamic Mechanic Analysis (DMA). Additionally, Differential Scanning Calorimetry to determine the crystalline content of the different materials comes in support of the DMA results. Hence, this work has been designed as an exploratory study for incoming works wherein recovered carbon fibers (rSCF) will be evaluated as reinforcement of thermoplastic composites. Consequently, we studied two different polypropylene-based composites with extreme amounts, 15% and 40% w/w, of a commercial sized SCF. Notwithstanding, just to notice that the main relaxation processes associated to the iPP matrix in the pristine composites appear sharply affected by the SCF amount, influencing also the crystalline content of the iPP matrix. The glass transition region of the iPP matrix shows significant variations well correlated with both the processing history of both the pristine iPP and the composites, and evidences the efficiency of the interfacial modifier (aPP-SA/ SA) revealed as a good candidate for improving the performance in PP/rSCF composites., INTRODUCTION In an overall context of sustainability and circular economy [1-3], lower operation costs combined with the high versatility and easy processability of the polyolefins, and more specifically the polypropylene [...]

Introduction: We previously reported that systemic delivery of dystrophin expressing chimeric (DEC) cells of normal (wt) and dystrophin-deficient (mdx) myoblast (MB) or mesenchymal stem cell (MSC) origin restored dystrophin expression and improved cardiac function in the mdx mouse model of Duchenne muscular dystrophy (DMD). Aim: This study evaluated the effect of intraosseous delivery of murine DEC lines of MB (MBwt/MBmdx) and MSC (MBwt/MSCmdx) origin on function of gastrocnemius muscle (GM). Material and methods: DEC lines created by ex vivo fusion were tested in the mdx mouse model of DMD: Group 1 - vehicle (control), Group 2 - non-fused 0.25 × 106 MBwt and 0.25 × 106 MSCmdx (control), Group 3 - fused 0.5 × 106 MBwt/MBmdx DEC and Group 4 - fused 0.5 × 106 MBwt/MSCmdx DEC. In situ and in vitro muscle force tests assessed GM function at 90 days post-transplant. Results: Application of MBwt/MSCmdx and MBwt/MBmdx DEC significantly improved the fatigue ratio of GM compared to vehicle-injected controls detected by in vivo muscle force tests (0.567 ±0.116, p = 0.045 and 0.489 ±0.087, p < 0.05, respectively). MBwt/MSCmdx DEC recipients presented enhanced maximum force at tetanus (0.145 ±0.040 g/mg, p < 0.05); furthermore, recipients of MBwt/MBmdx DEC showed a significant increase in the maximum force generation rate compared to vehicle controls (4.447 ±1.090 g/s/mg, p < 0.05). The ex vivo GM force testing in MBwt/MSCmdx DEC recipients detected increased average GM force compared to vehicle and non-fused controls. Conclusions: Systemic-intraosseous administration of MBwt/MBmdx and MBwt/MSCmdx DEC therapy combining the myogenic and immunomodulatory properties of MB and MSC significantly improved skeletal muscle (GM) function of force and resistance to fatigue in an mdx mouse model of DMD. [ABSTRACT FROM AUTHOR]

A number of 16S to 23S spacers of 354 bp were sequenced from six Escherichia coli strains belonging to the ECOR collection. Four phylogenetically informative variable sites were identified. Findings from comparisons indicated the presence of two major phylogenetic branches in this species. Intercistronic heterogeneity was observed in strain ECOR35 and its closest relatives, in which at least one of the operons has undergone a major mutagenic event or has an independent phylogenetic origin.