Preparation of Nanocomposites from Styrene and Modified Graphite Oxides

Graphite oxide was prepared and modified with several ammonium salts and these modified graphite oxides were used to prepare nanocomposites with polystyrene by in situ polymerization of styrene monomer and by melt blending with polystyrene. Nanocomposites were characterized by X-ray diffraction, cone calorimetry, thermogravimetric analysis and the evaluation of mechanical properties. Nanocomposites are formed by in situ polymerization but not by melt blending; the graphite oxide undergoes thermal degradation at the temperature of melt blending so nanocomposite formation would be unlikely. Mechanical properties of the melt blended nanocomposites are improved relative to the virgin polystyrene while those prepared by in situ polymerization are decreased, except in the case of Young\u27s Modulus, where melt blended and in situ polymerized materials show similar results

Polystyrene/Graphite Nanocomposites: Effect on Thermal Stability

Nanocomposites consisting of polymer and clay have been shown to exhibit a significant reduction in flammability and an increase in mechanical properties. This work examines the effect of thermal stability and mechanical properties of nanocomposites prepared from potassium graphite and styrene. Synthesis of nanocomposites was accomplished by using potassium graphite (KC8) as the initiator in the polymerization of styrene. A slight increase in thermal stability is observed but mechanical properties are decreased

Understanding interface effects in perovskite thin films

The control of matter properties (transport, magnetic, dielectric,...) using synthesis as thin films is strongly hindered by the lack of reliable theories, able to guide the design of new systems, through the understanding of the interface effects and of the way the substrate constraints are imposed to the material. The present paper analyses the energetic contributions at the interfaces, and proposes a model describing the microscopic mechanisms governing the interactions at an epitaxial interface between a manganite and another transition metal oxide in perovskite structure (as for instance $\rm SrTiO_3$). The model is checked against experimental results and literature analysis

The Arizona Kith and Kin Project Evaluation, Brief #4

Despite the prevalence of family, friend, and neighbor (FFN) child care (NSECE, 2015), relatively little is known about the characteristics of this type of care, quality of care, and the features of effective quality improvement initiatives for FFN care providers. In general, the early childhood field has remained relatively silent about FFN child care in policy and research discourses surrounding child well-being and quality initiatives (Shivers, 2012; Whitebook et al., 2004). The overall goal of the analyses described in this brief, Brief #4 in a series of four, was to explore and analyze FFN providers’ awareness and use of community resources. This sample was obtained by collecting data from providers involved in a 14-week training-support group intervention known as the Arizona Kith and Kin Project. The providers in the Arizona Kith and Kin Project represent a critical population of providers who are serving young children in Arizona

The Arizona Kith and Kin Project Evaluation, Brief #3

Professional Development with Family, Friend, and Neighbor Providers: Implications for Dual Language Learners. Indigo Cultural Center, for the Association for Supportive Child Care, with support from First Things First and Valley of the Sun United Way

Polybutadiene Cross-Linked With Various Diols – Effect On Thermal Stability

The relationship between cross-linking and thermal stability as related to polybutadiene is the focus of current research. Cross-linked polybutadienes have been prepared using various diols as the cross-linking agent. Cross-linked polymers have been characterized by gel content, swelling ratios, infrared spectroscopy, and thermal analysis. These polymers are not highly cross-linked, as seen by gel content and swelling ratios, and cross-linking does not have a large effect on the onset temperature of the degradation. Nonetheless, extensive formation of a non-volatile residue occurs

Threat and Punishment in Public Good Experiments

Experimental studies of social dilemmas have shown that while the existence of a sanctioning institution improves cooperation within groups, it also has a detrimental impact on group earnings in the short-run. Could the introduction of pre-play threats to punish have enough of a beneficial impact on cooperation, while not incurring the cost associated with actual punishment, so that they increase overall welfare ? We report an experiment in which players can issue non-binding threats to punish others based on their contribution levels to a public good. After observing others' actual contributions, they choose their actual punishment level. We find that threats increase the level of contributions significantly. Efficiency is improved, but only in the long run. However, the possibility of sanctioning differences between threatened and actual punishment leads to lower threats, cooperation and welfare, restoring them to levels equal to or below the levels attained in the absence of threats.Threats; cheap talk; sanctions; public good; experiment