Average Molar Mass Of Polymer Research Articles

Polymerization of ε-caprolactone with degraded PET for its functionalization

Poly(caprolactone) (PCL) was synthesized from the polymerization of e-caprolactone (CL) with degraded poly(ethylene terephthalate) (PET) for its functionalization using heptamolybdate of ammonium and tin(II) 2-ethylhexanoate, as catalyst and initiator, respectively. Polymerization of CL with bis(2-hydroxyethyl) terephthalate (BHET) was carried out to make a comparison. From the analysis by FTIR, the functional groups of polycaprolactone and degraded PET were identified by FTIR. The chemical shift at 165.59 ppm obtained by NMR corresponded to the chemical bond between the carbonyl of the PCL bound to the -CH2CO2-C10H8O4 of the degraded PET. The number average molar mass of polymer obtained was determined and its chemical structure was proposed. Crystallinity and the temperatures of melting and degradation depended of the mass of degraded PET used in the synthesis. Based on the proposed chemical structure, the synthesized polymer could be used in the preparation of other polymers.

Synthesis and characterization of a new biobased poly(urethane‐ester) from ricinoleic acid and its use as biopolymeric matrix for magnetic nanocomposites

This work presents a new biobased poly(urethane‐ester) synthesized from ricinoleic acid (RA), 1,6‐diisocyanatehexane, and glycerol through bulk polymerization. RA‐modified magnetic iron oxide nanoparticles, previously obtained through coprecipitation technique, were introduced in situ to produce a magnetic nanocomposite. DSC analyses revealed that the glass transition (Tg) of the biobased poly(urethane‐ester) was equal to −75°C, and for the magnetic biobased poly(urethane‐ester) the Tg was reduced in approximately 3°C. DTG analyses were used to measure the thermal stability and the amount of magnetic nanoparticle dispersed into the polymeric matrix, indicating that the polymeric materials exhibit good thermal stability and the fraction of nanoparticles dispersed into the biobased poly(urethane‐ester) matrix was equal to 2.19 wt%. Infrared spectroscopy and NMR were used to recognize functional groups in structures and follow the reaction evolution. Magnetic force, hysteresis loops and XRD essays used to provide magnetic features of the materials, showed that crystallite size of the mono domains was equal to 7.6 nm and that magnetic materials exhibit superparamagnetic behavior. GPC was used to evaluate average molar mass of polymer, determined equal to 2569 Da and molar mass dispersity equal to 2.4.Practical applications: Introducing magnetic nanoparticles into polymeric matrix leads to composites with unique properties, allowing different applications. Besides, the use of vegetable oils to produce polymer has many advantages such as biocompatibility and renewability. Due to their physico‐chemical and biocompatibility properties the magnetic nanocomposites using castor bean oil prepared in the present work may have potential candidates for several applications, like biomedical implants, tissue engineering, and controlled drug delivery.This article describes the preparation of a new biobased poly(urethane‐ester) synthesized from ricinoleic acid (RA), 1,6‐diisocyanatehexane, and glycerol and its use as polymeric matrix in magnetic nanocomposite. The polymer is characterized by FTIR, 1H NMR, TG, and DSC. The composite is studied by magnetic force exhibiting superparamagnetic behavior.

Synthesis and characterization of differently substituted phenyl hepta isobutyl‐polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

Variously substituted polyhedral oligomeric silsesquioxanes (POSSs)/polystyrene (PS) nanocomposites of general formula R7R′(SiO1.5)8/PS (where R = isobutyl and R′ = 4‐methoxyphenyl, 4‐methylphenyl, 3,5‐dimethylphenyl, 4‐fluorophenyl, 2,4‐difluorophenyl, 4‐chlorophenyl) were prepared by in situ polymerization of styrene in the presence of 5% w/w of POSS. The actual filler concentration in the obtained nanocomposites was checked by 1H NMR spectroscopy. Scanning electron microscopy and FTIR spectroscopy evidenced the presence of filler‐polymer interactions. Inherent viscosity (ηinh) determinations indicated that the average molar mass of polymer in halogenated derivatives was lower than neat PS, and were in agreement with calorimetric glass transition temperature (Tg) measurements. Finally, a comparative study concerning the thermal stability of synthesized nanocomposites was carried out in both inert (flowing nitrogen) and oxidative (static air) atmospheres into a thermobalance, in the scanning mode, at 10°C min−1, and the temperatures at 5% mass loss (T5%), of various compounds were determined. The results were discussed and interpreted. POLYM. COMPOS., 35:151–157, 2014. © 2013 Society of Plastics Engineers

Variously substituted phenyl hepta cyclopentyl-polyhedral oligomeric silsesquioxane (ph,hcp-POSS)/polystyrene (PS) nanocomposites

A comparative study concerning the thermal stability of polystyrene (PS) and six POSS/PS nanocomposites of general formula R7R′(SiO1.5)8/PS (where R = cyclopentyl and R′ = phenyl, 4-methoxyphenyl, 4-tolyl, 3,5-xilyl, 4-fluorophenyl, and 2,4-difluorophenyl) was carried out in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Nanocomposites were prepared by in situ polymerization of styrene in the presence of 5 % w/w of POSS, but the actual filler concentration in the obtained nanocomposites, determined by 1H NMR spectroscopy, was in all cases slightly higher than that in the reactant mixtures. FTIR spectra of nanocomposites evidenced the presence of filler-polymer interactions. Inherent viscosity (ηinh) determinations indicated that the average molar mass of polymer in methylated and fluorinated derivatives was lower than neat PS, and were in agreement with calorimetric glass transition temperature (Tg) measurements. Degradations were performed into a thermobalance, in the scanning mode, at 10 °C min−1, and the temperatures at 5 % mass loss (T5 %), of various nanocomposites were determined. The effects of various substituents of the POSS phenyl group on the thermal stability of nanocomposites were evaluated. The results were discussed and interpreted.

Thermal study on phenyl, hepta isobutyl‐polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

AbstractA comparative study concerning the thermal stability of polystyrene (PS) and three polyhedral oligomeric silsesquioxane/polystyrene (POSS/PS) nanocomposites of formula R7R′(SiO1.5)8/PS (where R = isobutyl and R′ = phenyl), at various (3, 5, and 10%) POSS concentration was carried out in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Nanocomposites were synthesized by in situ polymerization of styrene in the presence of POSS and the experimental filler concentration in the obtained compounds, determined by 1H NMR spectroscopy, was in all cases slightly higher than that in the reactant mixtures. Inherent viscosity (ηinh) determinations indicated that the average molar mass of polymer in the nanocomposites was practically the same than neat PS and were in agreement with calorimetric glass transition temperature (Tg) measurements. The temperature at 5% mass loss (T5%) and the activation energy (Ea) of degradation process of synthesized nanocomposites were determined and compared with each other and with those of unfilled PS. On the basis of the results from thermal and IR spectroscopy characterizations, nanocomposite with 5% of molecular filler appears the most thermally stable. The results were also compared with literature data on similar PS‐based nanocomposites. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers

Phenyl hepta cyclopentyl – polyhedral oligomeric silsesquioxane (ph,hcp-POSS)/Polystyrene (PS) nanocomposites: the influence of substituents in the phenyl group on the thermal stability

Some new Polystyrene (PS) nanocomposites were prepared by using two Polyhedral Oligomeric Silsesquiox- anes (POSSs), namely RR'7(SiO1.5)8 (where R = 4-methoxyphenyl or 2,4-difluorophenyl and R' = cyclopentyl), as fillers, and their degradation was studied to investigate the effect of the electron-donor or electron-withdrawing character of the phenyl group substituents on thermal stability. Nanocomposites were synthesized by in situ polymerization of styrene in the presence of various concentrations of POSS. Proton nuclear magnetic resonance ( 1 H NMR) spectra indicated that the POSS content in the obtained nanocomposites was higher than that in reactant mixtures. Inherent viscosity (!inh) and glass transi- tion temperature (Tg) determinations indicated that the average molar mass of polymer in 4-methoxynanocomposites was the same than neat PS, while it was much lower in 2,4-difluoro derivatives. Degradations were carried out in both flowing nitrogen and static air atmospheres, in the scanning mode, at various heating rates, and temperature at 5% mass loss (T5%) and the activation energy (Ea) of degradation of various nanocomposites were determined. The values obtained for 4- methoxyderivatives were higher than unfilled PS thus indicating higher thermal stability. Conversely, the values found for 2,4-difluoro derivatives were lower, in some cases even than those of neat PS. The results were discussed and interpreted.