Mihaela Pascu

Modification of polymer blend properties by argon plasma/electron beam treatment: surface properties

Blends of isotactic polypropylene (IPP)/epoxy-modified lignin (LER)/glycidyl methacrylate grafted polypropylene (PP-g-GMA) have been subjected to both argon plasma exposure and electron beam bombardment, for different treatment conditions. The changes of their surface properties with respect to the untreated samples have been followed by means of contact angle measurements, ultraviolet-visible (UV-Vis) ellipsometry, X-ray photoelectron spectroscopy (XPS), and optical microscopy in polarized light. It was obvious that both treatment types led to the incorporation of polar groups on the exposed polymer films, groups responsible for all the observed modifications in their properties. The effects induced by the electron beam are higher when compared with those attributed to plasma exposure. Aging of the plasma exposed/electron beam bombarded polymer blends has been followed, evidencing different behaviors depending on LER content in IPP matrix.

Surface modifications of some nanocomposites containing starch

Polymer-layered silicate nanocomposites have attracted strong interest in todays materials research, due to the possible impressive enhancements of material properties, comparatively with those of pure polymers. Several starch/poly(vinylalcohol)/montmorillonite nanocomposites have been subjected to surface modification by physical treatments such as dielectric barrier discharge (DBD) exposure and coating with proteins (albumin) or polysaccharides (chitosan), for improving their biocompatibility. Untreated and treated surfaces have been comparatively studied by contact angle measurements, FT-IR and 2D-FT-IR spectroscopy and optical microscopy. It has been established that enhancement of the surface characteristics depends on the type and number of incorporated nanoparticles as well as on the treatment applied. Coupling of DBD exposure and coating techniques appears to be highly efficient.

Polyester/lignosulfonate blends with enhanced properties

The compatibility of poly(ethylene terephthalate) and its copolymer containing isophthalate units with epoxy-modified lignin has been studied. The following methods have been used: DSC, thermogravimetry, IR spectroscopy, contact angle measurements and dielectric properties determination. The optimum compatibility ratios and the necessity of a partial crosslinking with 4,4′-diaminodiphenylmethane to obtain a stable morphology have been established. Die Vertraglichkeit von Polyethylenterephthalat und des Copolymeren mit Isophthalsaureeinheiten mit epoxy-modifiziertem Lignin wurde mittels DSC, Thermogravimetrie, IR-Spektroskopie, Kontaktwinkelmessungen und der Bestimmung dielektrischer Eigenschaften untersucht. Das optimale Vertraglichkeitsverhaltnis wurde ermittelt, und die Notwendigkeit der teilweisen Vernetzung mit 4,4′-Diaminodiphenylmethan wurde festgestellt.

Modification of Polymer Blends Properties by Plasma/Electron Beam Treatment. I. Plasma Diagnosis and Bulk Properties of Plasma Treated Blends

Films of isotactic polypropylene/epoxy modified lignin have been plasma and electron beam treated, in order to improve the surface properties and their response to environmental factors. The optimal conditions for the treatment have been established by a detailed plasma diagnosis. The effect of the treatment on the films has been followed by: IR-spectroscopy, X-ray diffraction and differential scanning calorimetry. All results have been comparatively discussed with those corresponding to the untreated samples. It has been established that plasma and electron beam treatments are very efficient in imparting a high polarity and an increased hydrophylicity to the polyolefin-based blends.

Thermoxidative decomposition of some polysulfones under dynamic conditions of heating

Kinetic aspects of the first step of thermoxidative decomposition, under dynamic conditions of heating, of some polysulfones have been studied.The dependence of the kinetic parameters on the heating rate and conversion degree has been established. The compensation effect and conversion function have also been discussed.Polysulfone decomposes by the breaking of the main chain, a process involving very high activation energy.Chemically modified polysulfones show the first step of thermoxidative decomposition at relatively low temperatures. This step corresponds to the elimination of functional side - groups for the bromomethylated polysulfone while in the case of the carboxylated polysolfone, the loss of the carboxyl group is probably accompanied by a crosslinking reaction.

Poly(Ethylene Terephthalate) Films with Different Content of Acid-Base Functionalities. I. Surface Modifications

Abstract Treatments of PET in an ion beam-low density plasma system, in oxygen, have been realised. Low energy (100–500 eV), but relatively high does (3.0.1015–9.0.1016 ions/cm2) for ions were used. In this first part, the surface modifications of PET films (investigated by IR spectroscopy, X-ray diffraction, contact angle measurements, XPS angle resolved) are presented. Both chemical and physico-structural modifications take place simultaneous during ion beam treatments. The initial polar group content, immediately after the treatment, but more than this the physico-structural modifications like cross-linking and a restructured crystalline content determine the dynamic effects which control the ageing mechanisms.

Study of electroless copper plating onto PVDF modified by radio frequency plasma treatment

Surface properties of polyvinylidene fluoride (PVDF) films have been modified by treatment in a radio frequency (RF) nitrogen plasma, at different treatment powers (25, 50 and 75 W). The surface properties of the PVDF films before and after RF plasma treatment, as well as the quality of the deposited copper layer, were investigated by various investigation methods (Scanning electron microscopy, atomic force microscopy, ATR-FTIR and contact angle measurements). RF plasma treatment significantly improved the adherence and the quality of the deposited metal layer. The results obtained for PVDF RF plasma treated were compared with those corresponding to a microwave plasma treatment.

Polyester/lignosulfonate blends, 2. Accelerated aging behavior

The behavior of the poly(ethylene terephthalate)-co-(ethylene isophthalate)] copolymer/epoxy-modified lignosulfonate (LER) blends has been studied during aging, in the conditions of sewage sludge test. The bulk and surface properties of the aged blends have been followed by electron microscopy, DSC, TG/DTG, IR spectroscopy and contact angle measurements, and compared with undegraded samples. It has been established that the UV-irradiated blends undergo more important changes in their properties after aging than the unirradiated samples. The physical treatment and increase of LER content in the blend could be a way to obtain materials with a good balance of properties and environmental degradation.

Modification of PVDF properties by dielectric barrier discharge treatment

Abstract Films of polyvinylidene fluoride (PVDF) were treated in a dielectric barrier discharge (DBD) in helium, for different exposure times. Modification of PVDF properties was followed by: contact angle measurements, ATR-FTIR spectrometry and scanning electron microscopy. The applied treatment led to the obtainment of polar surfaces, with biocompatibility characteristics. These enhancements in PVDF properties after plasma exposure, associated with the possible increase of the polymer roughness, could lead to an enhanced adhesion with other materials, condition which has to be fulfilled for a series of applications (e.g.: biosensors).

Poly (Ethylene Terephthalate) Films with Different Content of Acid-Base Functionalities. II. Gas Phase Analysis and Proposed Mechanisms

Abstract The data about the plasma gas phase analysis and also a contribution to the mechanisms involved in such modifications are presented in this second part. Main 16 neutral species and their evolution in time, with and without PET sample in the treatment system, were investigated by MS. The fluences of atomic and molecular oxygen ions at the polymer surface were determined. A decreased content in neutral species higher is the ion energy is stood out when the PET sample is inside the treatment system. Appreciable differences between the treatments made in saturation regime and those in reimplantation regime were stood out. An enhanced etching mechanism is active in the treatments with ions of 100 and 300 eV, at the lowest dose, while an etching mechanism in stationary regime in a competition with a cross-linking process are important for the treatment with of 500 eV, the same dose. Treatments at this dose do not confer a prevalent acidic or basic character of the PET surface. A diminished etching proc...