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The susceptibility of starch-based biomaterials to enzymatic degradation by a-amylase and peroxidase enzymes was investigated. A polymeric blend of corn starch with polyethylene, designated by SLDPE, was studied. The degradation was evidenced by gravimetry, scanning electron microscopy (SEM), FTIR spectroscopy, and X-ray diffraction. Analysis performed showed that starch blend is susceptible to enzymatic degradation, significantly in the presence of ionic liquid, as evidenced by increased weight loss and reducing sugars in solution. SEM analysis evidenced the presence of fractures and pores at the materials surface as a result of starch degradation by a-amylase. FTIR spectra confirmed a decrease on the band corresponding to glycosidic linkage (-C-O-C-) of starch. Keywords: corn starch, LDPE/starch blends, degradability, enzymes, ionic liquid

Research and Development National Institute for Chemistry and Petrochemistry–ICECHIM, 202 Splaiul Independenþei, 060021, Bucharest, Romania The curing reactions at microwaves for two different systems consisting of diglycidyl ether of bisphenol A (DGEBA) and 4-aminoazobenzene (AAB) and diglycidyl ether of ethylene glycol (DGEEG) and AAB were studied through differential scanning calorimetry (DSC) and FTIR spectroscopy. Keywords : epoxy, azo, microwaves, FTIR, calorimetry

Various telechelic bifunctionalized siloxane derivatives were reacted with titanocene dichloride. The reactant functionality is favorable for the formation of the poly(ester), poly(amine), poly(ether), and poly(silyl-ether) depending on the functional groups of the used siloxane precursors. The interfacial condensation technique was applied and, excepting polyesters, in the other cases, the inverse interfacial system was used. CHCl3 was used as a solvent for siloxane phase and triethyl amine was added as a hydrochloric acid acceptor. The very fast reactions occurred at room temperature with colour change from red-orange to yellow. The poly(ester) was also synthesized in solution by using DMF as a solvent. The formation of new structures was verified by FTIR and their thermal behaviour was investigated by TGA and DSC. SEM and Energy Dispersive X-Ray system (EDX) were used to show the morphology of the poly(ether). The repartition of Ti was investigated by EPR. Keywords: siloxane-titanocene copolymers; polycondensation; metallocene; siloxane

Mechanism and kinetics of dispersion polymerization of styrene in the presence of a new macromer based on 2-ethyl-2-oxazoline have been investigated. Partial conversion-time curves have been obtained by continuous NMR measurements. Final conversion of styrene was 88% in contrast to 35% for oxazoline macromonomer. The kinetic data proved that particles become sterical stable at 15% conversion. The weight average molecular weight and polydispersity index are in the range of typical dispersion polymerization. The thermal stability and glass transition temperature are increased when a higher amount of stabilizer is used. The presence of the macromer on the surface of the final beads and the fraction of grafted stabilizer were evaluated by XPS. Keywords: dispersion polymerization, macromonomers, 2-ethyl-2-oxazoline, X-ray photoelectron

New formaldehyde resins were synthesized by the polymerization of a mixture of 4,4’-methylenedianiline (MDA) and p-tert-butylphenol (p-TBPH) with formaldehyde (FA) (at a molar ratio monomers/formaldehyde, 1/1), in the presence of an acid catalyst (HCl).The mixture of DMF/toluene was used as reaction medium and as carrier for the aqueous condensation. These polymers were characterized by elemental, spectral and thermal analysis and used as hardener for epoxy resins (diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of hydroquinone (DGEHQ)). The obtained resins have low molecular weight and are soluble in medium and high polar solvents. The curing and the temperature behaviour of epoxy resin/formaldehyde resin systems were investigated using differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques. The activation energies of the curing reactions are situated in the range of 52 to 66 kJ×mol-1 for DGEBA systems and at 54 to 72 kJ×mol-1 for DGEHQ systems. The cured products have good thermal properties, and the activation energies of the degradation reactions have values between 36-65 kJ×mol-1 for epoxy systems. Keywords: formaldehyde resins, epoxy resin, crosslinking reactions, thermal properties

The present study is aimed to investigate the effect of damage due to hygrothermal fatigue on the mechanical behaviour of CFRP (Carbon Fiber Reinforced Polymer) laminates as well as on the skin-core interfacial stress field in sandwich structures having CFRP laminates as core material and aluminum as skin. The above behaviour was both experimentally and analytically studied using a model recently developed by the CMG group at University of Patras. Keywords: hygrothermal fatique, polymeric composite laminates, sandwich structures, interfacial phenomena

Damping capacity is comparatively analyzed for a composite with polymer matrix (vinyl ester) and a shape memory alloy (copper-zinc-aluminium). A good damping capacity of shape memory alloy results in structural transformation domain in detriment of composite material. The theoretical model developed on the analyzed material behaviour describes qualitatively the temperature dependence of the dissipation capacity. Keywords: polymer, shape memory alloy, dissipation capacity, fractal

Thin foils of poly (vinyl alcohol) (PVA) with different thickness were prepared and dried without modifying their separation surfaces. The induced by stretching under heating birefringence of PVA films was measured under with a Babinet Compensator. An increase of birefringence versus the stretching degree of the PVA foils was evidenced for all studied samples. The dependence of the birefringence on the films thickness was evidenced in this paper. Keywords: birefringence, Babinet Compensator, stretching degree

Coefficient of thermal expansion of multiphase composite materials plays an important role in the process of engineered materials design especially while approaching thermal management issues. Tailoring and designing material combinations in order to develop a composite structure to prove stability over a wide range of temperatures, from cryogenic to high values, to withstand extreme environmental conditions is the dream and purpose of any engineering team involved in such study/research area. The paper aims to approach and present the variations of the CTE with extreme environmental conditions (e.g. cryogenic conditioning) for particular combinations of particle-fibers multiphase polymeric composite materials. Influencing factors will be underlined to accompany the experimental research. Keywords: multiphase, polymer, composite, cryogenic, coefficient of linear thermal expansion

The implants surfaces investigated in the present study were modified with the films of poly (vinyl) alcohol (PVA) which were formed in physiological serum (0.9% NaCl). Surfaces evaluation included electrochemical measurements such as linear potentiometry (LP) and electrochemical impedance spectroscopy (EIS). These suggest that PVA acts by adsorption at site on the metal surface and formed a compact, adherent and uniform layer. The composition of layer was estimated using Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/ EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques, which confirm the adsorption of PVA on the surfaces, through –OH groups, with a specific affinity to the titanium sub­strate. Keywords: titanium electrode; electrochemical measurements; poly (vinyl) alcohol; SEM/ EDX; XPS