Mechanical and chemical recycling of solid plastic waste.

The Analysis of Variance.

https://ir.nctu.edu.tw:443/bitstream/11536/14909/1/000297489400002.pdf

POSS related polymer nanocomposites

Effects of resin hydrophilicity on water sorption and changes in modulus of elasticity.

Quercetin is a bioactive compound that is widely used in botanical medicine and traditional Chinese medicine due to its potent antioxidant activity. In recent years, antioxidant activities of quercetin have been studied extensively, including its effects on glutathione (GSH), enzymatic activity, signal transduction pathways, and reactive oxygen species (ROS) caused by environmental and toxicological factors. Chemical studies on quercetin have mainly focused on the antioxidant activity of its metal ion complexes and complex ions. In this review, we highlight the recent advances in the antioxidant activities, chemical research, and medicinal application of quercetin.

Antioxidant Activities of Quercetin and Its Complexes for Medicinal Application.

The characteristics of sorption and diffusion of water in an amine-cured epoxy system based on tetraglycidyl diaminodiphenylmethane and a novolac glycidyl ether resin were studied as a function both of the polymer microstructure, known from previous works, and the temperature. Water-sorption experiments and dynamic mechanical analysis (DMA) were performed. Tensile stress–strain and Rockwell hardness tests were conducted to investigate the effects of absorbed water on the mechanical properties of the material. Competing effects of the sorption of water in the free volume and of strong interactions between water molecules and polar groups of the network were used to explain the diffusional behavior observed, which followed Fick's second law. DMA analysis seemed to be sensitive to the water effects and the viscoelastic behavior was related both to the water-sorption processes and to the microstructure of the system. An important impact of water uptake on the tensile properties at break was also appreciated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 71–80, 2001

Effect of water sorption on the structure and mechanical properties of an epoxy resin system

A polyhedral oligomeric silsesquioxane (POSS) containing one epoxy group and seven isobutyl groups per molecule was incorporated into an epoxy network following a two-stage process. In the first stage, POSS was reacted with an aromatic diamine, employing a 1:1 molar ratio of both reactants. The distribution of species at the end of reaction, determined by size exclusion chromatography (SEC), was close to the ideal one. In a second step, this precursor was reacted with the stoichiometric amount of an aromatic diepoxide to generate an organic−inorganic hybrid material containing 51.8 wt % POSS. A primary liquid−liquid phase separation process occurred at the time of adding the diepoxide to the POSS−diamine precursor. This led to a macrophase separation into epoxy-rich and POSS-rich regions, possibly derived from the incompatibility of the isobutyl groups attached to the POSS with the aromatic epoxy−amine network. A secondary phase separation occurred in the epoxy-rich phase in the course of polymerization, ...

Epoxy Networks Containing Large Mass Fractions of a Monofunctional Polyhedral Oligomeric Silsesquioxane (POSS)

Using dynamic mechanical analysis (DMA) we have studied thermal degradation for a system containing a diglycidyl ether of bisphenol A (DGEBA) and 1,3-bisaminomethylcylohexane (1,3-BAC). The changes of dynamic mechanical properties during thermal degradation indicated a shift of the glass transition temperature (Tg) to higher temperatures and a decrease in the peak value of the dynamic loss factor (tan δ) with an increasing of aging time. The value of dynamic storage modulus (E′) at the rubbery state showed an increase with aging time, whiteE′ at the glassy state only underwent a moderate change with increased thermal degradation. From these results it can be argued that thermal degradation during the stage prior to the onset of the severe degradation involves structural changes in the epoxy system, as further crosslinking and loss of dangling chains in the crosslinked network.

Dynamic mechanical analysis

Epoxy/POSS organic–inorganic hybrids: ATR-FTIR and DSC studies

The structural order of native starch granules with different crystalline patterns was analyzed by combined X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) and the results were compared to that of X-ray diffraction (XRD). The FTIR spectra of 13 starch samples were evaluated by principal component analysis (PCA). The main differences among the polymorphs were observed in the intensity of two regions: the OH vibration region, 3650–3000 cm−1, and the region of major adsorption bands, 1200–800 cm−1. The variation in these regions showed that two different groups can be distinguished, one for B-type starches and one for A- and C-type starches. A-type starches exhibited a well-resolved band at 1022 cm−1, suggesting that A-type starch granules have a greater amount of ordered short-range double helices than B-type starches. The intensity and shape of the OH band were different for the three starches and were associated with different local molecular environments of the two water populations of the starch granule. The PCA analysis for X-ray diffraction patterns showed a clear segregation between A- and B-type starches, defined by three typical diffraction peaks at 2θ = 15.0°, 18.1° and 23.1° for A-type starches. There was no correlation in the crystallinity degree obtained by the FTIR and XRD methods.

Luis Barral

Papers

Effect of water sorption on the structure and mechanical properties of an epoxy resin system

Epoxy Networks Containing Large Mass Fractions of a Monofunctional Polyhedral Oligomeric Silsesquioxane (POSS)

Dynamic mechanical analysis

Epoxy/POSS organic–inorganic hybrids: ATR-FTIR and DSC studies

Study of the structural order of native starch granules using combined FTIR and XRD analysis