Kinetic Analysis of the Thermal Degradation of Polystyrene-Montmorillonite Nanocomposite

Nanocomposites exhibit a combination of unique properties, such as increased heat distortion temperature, reduced permeability, reduced flammability and improved mechanical properties. In this work, a polystyrene (PS) clay nanocomposite was prepared via bulk polymerization using a novel organically modified montmorillonite (MMT). The organic-modifier is the N,N-dimethyl-n-hexadecyl-(4-vinylbenzyl) ammonium chloride (VB16). The thermal stability of PS–VB16 compared to pure PS is examined in pyrolytic and thermo-oxidative conditions. It is then studied using a kinetic analysis. It is shown that the stability of PS is significantly increased in the presence of clay. The thermal behavior of PS and PS nanocomposite is modeled and simulated. A very good agreement between experimental and simulated curves both in dynamic and isothermal conditions is observed. Using kinetic analysis associated to the reaction to fire of PS nanocomposite simulated in a cone calorimeter, the peak of heat release rate is half that of virgin PS, it is suggested that the clay acts as a char promoter slowing down the degradation and providing a protective barrier to the nanocomposite. The combination of these two effects is an important factor lowering the HRR

Further Studies on Fire Retardant Polystyrene by Friedel–Crafts Chemistry

The combination of a copolymer of 4-vinylbenzyl alcohol and styrene with 2-ethylhexyldiphenylphosphate (DPP) and with metal chlorides has been studied by TGA, radiative gasification, Cone Calorimetry, and oxygen index measurements. Evidence is presented in support of a cross-linking reaction with the additives and the copolymer, which proceeds through a Friedel–Crafts mechanism. This approach reduces the peak heat release rate (HRR) by 60% as measured in the Cone Calorimeter. There is a significant reduction in the mass loss rate during the thermal degradation, and evidence of char formation is observed in the radiative gasification experiments

Alien Registration- Gilman, Frank W. (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/24182/thumbnail.jp

Gz, a guanine nucleotide-binding protein with unique biochemical properties

Cloning of a complementary DNA (cDNA) for Gz alpha, a newly appreciated member of the family of guanine nucleotide-binding regulatory proteins (G proteins), has allowed preparation of specific antisera to identify the protein in tissues and to assay it during purification from bovine brain. Additionally, expression of the cDNA in Escherichia coli has resulted in the production and purification of the recombinant protein. Purification of Gz from bovine brain is tedious, and only small quantities of protein have been obtained. The protein copurifies with the beta gamma subunit complex common to other G proteins; another 26- kDa GTP-binding protein is also present in these preparations. The purified protein could not serve as a substrate for NAD-dependent ADP- ribosylation catalyzed by either pertussis toxin or cholera toxin. Purification of recombinant Gz alpha (rGz alpha) from E. coli is simple, and quantities of homogeneous protein sufficient for biochemical analysis are obtained. Purified rGz alpha has several properties that distinguish it from other G protein alpha subunit polypeptides. These include a very slow rate of guanine nucleotide exchange (k = 0.02 min^-1), which is reduced greater than 20-fold in the presence of mM concentrations of Mg2+. In addition, the rate of the intrinsic GTPase activity of Gz alpha is extremely slow. The hydrolysis rate (kcat) for rGz alpha at 30 degrees C is 0.05 min^-1, or 200-fold slower than that determined for other G protein alpha subunits. rGz alpha can interact with bovine brain beta gamma but does not serve as a substrate for ADP-ribosylation catalyzed by either pertussis toxin or cholera toxin. These studies suggest that Gz may play a role in signal transduction pathways that are mechanistically distinct from those controlled by the other members of the G protein family

Some Rearrangement Reactions of Organosodium and Organolithium Compounds

In continuation of rearrangement reactions of organometallic compounds, it was desirable to ascertain whether R-Metal combinations (free of halogen or other acidic groups) would react after the manner of benzylmagnesium chloride types with compounds like formaldehyde, for example. This last reaction gives not only the normal product (beta-phenylethyl alcohol), but also o-tolyl carbinol. It has been shown that the corresponding organosodium and organolithium compounds behave in a similar manner. Incidentally, it is possible to prepare some organolithium compounds, like phenyl-lithium, very conveniently, in a short time, and in excellent yields in the customary three-necked flasks

Dyes Containing Long-Chained Aliphatic Radicals

The investigation of the synthesis and properties of compounds containing long-chained aliphatic radicals has been extended to the preparation of several azo dyes, coupling products of ß-naphthol with the appropriately substituted aromatic diazonium chlorides. The dyes prepared include those from a series of three p-alkoxyanilines, ROC6H4NH2, where R is n-C12H25-, n-C14H29-, and n-C16H33-, all deep red in color; and two brighter red compounds from p-( N-alkylsulfonamido )-anilines, H2 NC6H4S02NHR, where R is n-C12H25- and n-C18H37-. These compounds are crystalline solids, soluble in the usual organic solvents and in fats and oils. The melting points of the compounds are such that they might serve as derivatives for the corresponding anilines. The compounds prepared and their melting points are: 1- (p-dodecoxyphenylazo )-2-naphthol, m. 80-82°; 1-(p-tetradecoxyphenylazo )-2-naphthol, m. 81.5-83°; 1-(p-hexadecoxyphenylazo )-2-naphthol, m. 82-84°; 1-[p-(N-dodecylsulfonamido )-phenylazo ]-2-naphthol, m. 163-164 ° ; and 1- [p-( N-octadecylsul fonamido) - phenylazo ]-2-naphthol, m. 158-159.5°

Editorial - Travelling together along the Yellow Brick Road for Small Business and Entrepreneurship

Introduction and overview to ‘Understanding and Promoting Small Business Growth and Entrepreneurship’, Part

New Stream Mitigation Requirements in Coastal South Carolina: Providing Mitigation in an Atmosphere of Dynamic Policy and Emerging Science

2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur

Trajectories of body mass index and waist circumference in four Peruvian settings at different level of urbanisation: the CRONICAS Cohort Study

BACKGROUND: Studies have reported the incidence/risk of becoming obese, but few have described the trajectories of body mass index (BMI) and waist circumference (WC) over time, especially in low/middle-income countries. We assessed the trajectories of BMI and WC according to sex in four sites in Peru. METHODS: Data from the population-based CRONICAS Cohort Study were analysed. We fitted a population-averaged model by using generalised estimating equations. The outcomes of interest, with three data points over time, were BMI and WC. The exposure variable was the factorial interaction between time and study site. RESULTS: At baseline mean age was 55.7 years (SD: 12.7) and 51.6% were women. Mean follow-up time was 2.5 years (SD: 0.4). Over time and across sites, BMI and WC increased linearly. The less urbanised sites showed a faster increase than more urbanised sites, and this was also observed after sex stratification. Overall, the fastest increase was found for WC compared with BMI. Compared with Lima, the fastest increase in WC was in rural Puno (coefficient=0.73, P<0.001), followed by urban Puno (coefficient=0.59, P=0.001) and Tumbes (coefficient=0.22, P=0.088). CONCLUSIONS: There was a linear increase in BMI and WC across study sites, with the greatest increase in less urbanised areas. The ongoing urbanisation process, common to Peru and other low/middle-income countries, is accompanied by different trajectories of increasing obesity-related markers