Comparison of the rheological properties of polyamide-6 and its nanocomposites with montmorillonite obtained by melt intercalation

Each varying parameter which can contribute to the quality of final products plays an important role in the processing of polymer nanomaterials. Rheological properties are useful in proper formulation of new polyamide-6 (PA-6) based materials and selecting processing parameters. However, the measured rheological properties depend strongly on the sample preparation method, humidity regulation, and time-temperature history during the measurement and not least on the kind of rheometer being used. The results of the preliminary investigation show the changes in visco-elastic properties of two types of PA-6 and their nanocomposites with montmorilonite

Mild hydration of didecyldimethylammonium chloride modified DNA by 1H-nuclear magnetic resonance and by sorption isotherm

The gaseous phase hydration of deoxyribonucleic acid and didecyldimethylammonium chloride (C19H42ClN) complexes (DNA-DDCA) was observed using hydration kinetics, sorption isotherm, and high power nuclear magnetic resonance. Three bound water fractions were distinguished: (i) a very tightly bound water not removed by incubation over silica gel, (ii) a tightly bound water saturating with the hydration time t(1)(h) (0.596 +/- 0.04) h, and a loosely bound water fraction, (iii) with the hydration time t(2)(h) (20.9 +/- 1.3) h. Proton free induction decay was decomposed into the signal associated with the solid matrix of DNA-DDCA complex (T-2S approximate to 30 mu s) and two liquid signal components coming from tightly bound (T-2L1 approximate to 100 mu s) and from loosely bound water fraction (T-2L2 approximate to 1000 mu s)

Photoinduced Gratings in Functionalized Azo-Carbazole Compounds in Picosecond Regime

We report results of diffraction grating inscription on thin films prepared from epoxy resin doped with azo-carbazole based dyes. Diffraction gratings were recorded at the wavelength 532 nm and monitored through intensity of first order of diffraction (632 nm). Atomic force microscope scans of the gratings show that a surface relief grating also appeared

The influence of The mold temperature on the properties of polyamide composites

Each varying parameter which can contribute to the quality of received applications plays an important role in the processing of polymer materials. The influence of mold temperature on the molded parts’ properties and density was investigated during the optimization of injection molding process parameters of polyamide-6 (PA-6) as well as polyamide-6/montmorillonite (PA-6/MMT) composites. The hardness and Izod notched impact strength were determined for the obtained PA-6-based materials

Physicochemical and Biological Characterisation of Diclofenac Oligomeric Poly(3-hydroxyoctanoate) Hybrids as β-TCP Ceramics Modifiers for Bone Tissue Regeneration

Nowadays, regenerative medicine faces a major challenge in providing new, functional materials that will meet the characteristics desired to replenish and grow new tissue. Therefore, this study presents new ceramic-polymer composites in which the matrix consists of tricalcium phosphates covered with blends containing a chemically bounded diclofenac with the biocompatible polymer-poly(3-hydroxyoctanoate), P(3HO). Modification of P(3HO) oligomers was confirmed by NMR, IR and XPS. Moreover, obtained oligomers and their blends were subjected to an in-depth characterisation using GPC, TGA, DSC and AFM. Furthermore, we demonstrate that the hydrophobicity and surface free energy values of blends decreased with the amount of diclofenac modified oligomers. Subsequently, the designed composites were used as a substrate for growth of the pre-osteoblast cell line (MC3T3-E1). An in vitro biocompatibility study showed that the composite with the lowest concentration of the proposed drug is within the range assumed to be non-toxic (viability above 70%). Cell proliferation was visualised using the SEM method, whereas the observation of cell penetration into the scaffold was carried out by confocal microscopy. Thus, it can be an ideal new functional bone tissue substitute, allowing not only the regeneration and restoration of the defect but also inhibiting the development of chronic inflammation

An experimental study of dynamic behaviour of graphite polycarbonatediol polyurethane composites for protective coatings

Segmented polycarbonatediol polyurethane (PUPH) has been synthesized and modified with different amounts of graphite conductive filler (from 0 to 50 wt%). Thermal and dynamical thermal analysis of the composites clearly indicates changes in the polyurethane relaxations upon addition of graphite. Broadband dielectric spectroscopy has been used to study the dielectric properties of the (PUPH) and one composite in the frequency range from 10−2 to 107 Hz and in the temperature window of −140 to 170 ◦C. Relaxation processes associated with different molecular motions and conductivity phenomena (Maxwell–Wagner–Sillars and electrode polarization) are discussed and related to the graphite contentWe acknowledge the financial support of the Ministry of Finances and Competitiveness through the Grant CDS2010-0044 belonging to the "Consolider-Ingenio Programme" and for the Grant MAT2012-33483. The authors thank UBE Chem Eur for the PCD supply for this work.Gómez, C.; Culebras, M.; Cantarero Saez, A.; Redondo Foj, MB.; Ortiz Serna, MP.; Carsí Rosique, M.; Sanchis Sánchez, MJ. (2013). An experimental study of dynamic behaviour of graphite polycarbonatediol polyurethane composites for protective coatings. Applied Surface Science. 275:295-302. https://doi.org/10.1016/j.apsusc.2012.12.108S29530227

Evaluation of the drug solubility and rush ageing on drug release performance of various model drugs from the modified release polyethylene oxide matrix tablets

Hydrophilic matrix systems are currently some of the most widely used drug delivery systems for controlled-release oral dosage forms. Amongst a variety of polymers, polyethylene oxide (PEO) is considered an important material used in pharmaceutical formulations. As PEO is sensitive to thermal oxidation, it is susceptible to free radical oxidative attack. The aim of this study was to investigate the stability of PEO based formulations containing different model drugs with different water solubility, namely propranolol HCl, theophylline and zonisamide. Both polyox matrices 750 and 303 grade were used as model carriers for the manufacture of tablets stored at 40 °C. The results of the present study suggest that the drug release from the matrix was affected by the length of storage conditions, solubility of drugs and the molecular weight of the polymers. Generally, increased drug release rates were prevalent in soluble drug formulations (propranolol) when stored at the elevated temperature (40 °C). In contrast, it was not observed with semi soluble (theophylline) and poorly soluble (zonisamide) drugs especially when formulated with PEO 303 polymer. This indicates that the main parameters controlling the drug release from fresh polyox matrices are the solubility of the drug in the dissolution medium and the molecular weight of the polymer. DSC traces indicated that that there was a big difference in the enthalpy and melting points of fresh and aged PEO samples containing propranolol, whereas the melting point of the aged polyox samples containing theophylline and zonisamide was unaffected

Physicochemical and biological characterisation of diclofenac oligomeric poly(3-hydroxyoctanoate) hybrids as β-TCP ceramics modifiers for bone tissue regeneration

Nowadays, regenerative medicine faces a major challenge in providing new, functional materials that will meet the characteristics desired to replenish and grow new tissue. Therefore, this study presents new ceramic-polymer composites in which the matrix consists of tricalcium phosphates covered with blends containing a chemically bounded diclofenac with the biocompatible polymer—poly(3-hydroxyoctanoate), P(3HO). Modification of P(3HO) oligomers was confirmed by NMR, IR and XPS. Moreover, obtained oligomers and their blends were subjected to an in-depth characterisation using GPC, TGA, DSC and AFM. Furthermore, we demonstrate that the hydrophobicity and surface free energy values of blends decreased with the amount of diclofenac modified oligomers. Subsequently, the designed composites were used as a substrate for growth of the pre-osteoblast cell line (MC3T3-E1). An in vitro biocompatibility study showed that the composite with the lowest concentration of the proposed drug is within the range assumed to be non-toxic (viability above 70%). Cell proliferation was visualised using the SEM method, whereas the observation of cell penetration into the scaffold was carried out by confocal microscopy. Thus, it can be an ideal new functional bone tissue substitute, allowing not only the regeneration and restoration of the defect but also inhibiting the development of chronic inflammation