Naima Belhaneche-Bensemra

Study of the miscibility and the thermal degradation of PVC/PMMA blends

The aim of this paper is to study the miscibility and the thermal degradation of PVC/PMMA blends. For that purpose, blends of variable compositions from 0 to 100 wt % were prepared with and without plasticizer. Their physico-chemical characterization was carried out by differential scanning calorimetric analysis (DSC) and Fourier transform infrared spectroscopy (FTIR). Their thermal degradation under nitrogen at 185°C was studied and the HCl evolved from PVC was measured by the pH method. Degraded samples were characterized, after purification, by FTIR and UV- visible spectroscopy. The DSC analysis showed polymer miscibility up to 60 wt % of PMMA. This miscibility is due to a specific interaction of hydrogen bonding type between carbonyl groups (C=O) of PMMA and hydrogen from (CHCI) groups of PVC as evidenced by FTIR analysis. On the other hand, it was found that PMMA exerted a stabilizing effect on the thermal degradation of PVC by reducing the zip dehydrochlorination and by leading to the formation of short polyenes.

Study of the migration of additives from plasticized PVC

The aim of this paper is to study the interactions between packaging and food. For that purpose, additives were first characterized. Kinetic studies of their specific migrations have been carried out by using different analytical methods such as gas chromatography, Fourier transform infrared spectroscopy, atomic absorption spectrometry and differential scanning calorimetric analysis. The influence of various parameters such as temperature, agitation, nature of food simulant and initial concentration of plasticizer was considered.

Study of the properties of PVC/ABS blends

The aim of this work is to study the properties of PVC and ABS blends. For that, variable compositions of blends from 0 to 100 wt% were realized. Their physico-chemical properties were determined by differential scanning calorimetric analysis (DSC) and Fourier transform infra-red spectroscopy (FTIR). The variation of the mechanical properties such as tensile behaviour, impact resistance and hardness was studied according to the composition of blend. The influence of a plasticizer introduced at a level of 30 wt % on the same mechanical properties has been considered.

Study of the influence of atmospheric pollutants on the natural ageing of rigid polyvinyl chloride

The aim of this work is to study the natural ageing of rigid polyvinyl chloride (PVC) used in building and construction areas. For that purpose the PVC bars have been exposed in Algiers for 24 months in three sites where the concentrations of atmospheric pollutants (NO x , O 3 , hydrocarbons) are known. Samples were taken every three months. The evolution of mechanical properties was followed by tensile and hardness tests whereas the modification structure of polymer was followed by Fourier transform infrared spectroscopy (FTIR) and UV-visible spectroscopy. The results have shown a little drop in strain at break and stress at break, whereas hardness remains practically constant. IR and UV- visible analysis have shown apparition of chemical structures due to the polymer degradation (carbonyl and hydroperoxide groups and polyenes) since the first months of exposure in the three sites.

Migration of Epoxidized Sunflower Oil and Dioctyl Phthalate from Rigid and Plasticized Poly(vinyl chloride)

The aim of this paper is the determination of the specific migration of epoxidized sunflower oil (ESO) from rigid and plasticized poly(vinyl chloride) (PVC) into food simulants. ESO was obtained by epoxidation of commercial sunflower oil and used as a thermal organic co-stabilizer for PVC. For that purpose, rigid and plasticized (0, 15, 30, and 45 wt% of dioctyl phthalate or DOP) PVC films stabilized with ESO in the presence of Zn and Ca stearates were used to perform migration testing in olive oil. The test conditions were 12 d at 20 and 40°C and 2 h at 70°C with and without agitation. The determination of ESO migration was carried out by gas chromatography-mass spectrometry (GC-MS). ESO was quantified by an external standard addition method, using linoleic acid (C18:2) as the external standard. The influence of various parameters, such as the agitation and time of contact, the temperature, the presence or the absence of the plasticizer, and the plasticizer concentration, was considered.

The effect of di-(-2-ethyl hexyl) phthalate (Dehp) as plasticizer on the thermal and mechanical properties of pvc/pmma blends

Plasticizers play a key role in the formulation of polymers and in determining their physical properties and processability. This study examines the effect of di(2-ethyl hexyl)phthalate (DEHP) as plasticizer on the thermal and mechanical properties of PVC/PMMA blends. For that purpose, blends of variable composition, from 0 to 100 wt%, were prepared in the presence (15, 30 and 50 wt %) and in the absence of di(2-ethyl hexyl)phthalate. The thermal degradation of the blends was investigated by thermogravimetric analysis (TGA) in an atmosphere of synthetic air in the temperature range of 50-550°C. The variation of the mechanical properties, such as tensile behavior, hardness and impact resistance, were investigated for all blend compositions. The effect of the plasticizer on the same properties was considered. The results obtained show that a range of properties can be generated according to the blend compositions. Therefore, the addition of PMMA to the blends stabilized PVC, for the initial thermal degradation, and the addition of the plasticizer caused a decrease of stress at break and Young modulus.

Isothermal and Dynamic Thermogravimetric Degradation of Rigid and Plasticized Poly(Vinyl Chloride)/ Poly(Methyl Methacrylate) Blends

The thermal degradation of rigid and plasticized poly(vinyl chloride) (PVC)/poly (methyl methacrylate) (PMMA) blends was investigated by means of isothermal and dynamic thermogravimetric analysis in a flowing atmosphere of air. For that purpose, blends of variable composition from 0 to 100 wt% were prepared in the presence (15, 30 and 50 wt%) and in the absence of di-(2-ethyl hexyl) phthalate (DEHP) as plasticizer. The thermal degradation of the blends was investigated by isothermal thermogravimetry at 180°C during 120 min. It was found that the main processes are the dehydrochlorination of PVC and depolymerization of PMMA. The dynamic thermogravimetric experiments were carried out in the temperature range of 30 − 550°C. The results showed that the thermal degradation of rigid and plasticized PVC/PMMA blends in this broad range of temperatures is a three-step process and that PMMA exerted a stabilizing effect on the thermal degradation of PVC during the first step by reducing the dehydrochlorination.

Kinetic Study of the Specific Migration of an Organotin Heat Stabilizer from Rigid Poly(vinyl chloride) into Food Simulants by FTIR Spectroscopy

The aim of this paper is the determination of the specific migration of an organotin heat stabilizer (Irgastab 17 MOK) from rigid poly(vinyl chloride) (PVC) into food simulants. For that purpose, two fatty simulants were used: hexane and ethanol. The test conditions were 15 d at 4 and 40°C and 3 h at 70°C. The rate of the mass loss of the films was followed as a function of time. FTIR spectroscopy was used to investigate the migration phenomena and to estimate the diffusion coefficients and the activation energy of diffusion by using mathematical models. The influence of various parameters such as temperature, time of contact and the nature of food simulant was considered. The results show that FTIR spectroscopy is a simple, low cost and rapid method which can be used to investigate the migration phenomena.

Valorization of waste jute fibers in developing low-density polyethylene /poly lactic acid bio-based composites

This work deals with the valorization of waste jute fibers coming from carpet industries in the development of biocomposites based on blends of low-density polyethylene and poly lactic acid. First, low-density polyethylene /poly lactic acid blends of variable composition (100/0, 80/20, 50/50, 20/80, 0/100) were prepared. Their tensile properties and morphology were characterized. Tensile strength of the blends was lower compared to the pure poly lactic acid and the elongation decreased significantly with increasing poly lactic acid which is due to poor adhesion as evidenced by SEM analysis. These results indicated the incompatibility between low-density polyethylene and poly lactic acid. Thus, the aim of the second step was to find a relevant compatibilizer. For that purpose, five functionalized polyolefins were tested: poly(ethylene-co-glycidyl methacrylate) (8% glycidyl methacrylate) (PE-g-GMA), poly(propylene-co-ethylene-grafted maleic anhydride) (1.4% maleic anhydride) (PP-g-MA), poly(ethylene-co-acrylic-ester-co-glycidyl methacrylate) (E-AE-GMA) (8% glycidyl methacrylate, 24% methyl acrylate), polypropylene-grafted maleic anhydride (PP-g-MA) (high percentage maleic anhydride), poly(ethylene-co-butylacrylate-co-maleic anhydride) (E-BA-MAH) (6% butyl acrylate, 3% maleic anhydride). PE-g-GMA exhibited the best results in terms of tensile properties and morphology. Low-density polyethylene/poly lactic acid /PE-g-GMA (20/80/5) reinforced with 0–40 wt% jute fibers were prepared and characterized (tensile properties, charpy impact strength, morphology and thermal properties) in the last step. The results showed an improvement of tensile properties and a satisfactory interfacial adhesion between jute fibers and polymer blends. Furthermore, thermal stability was affected by the incorporation of 10% of jute fiber but varied very little with the increase in load.

Algerian pearl millet ( Pennisetum glaucum L.) contains XIP but not TAXI and TLXI type xylanase inhibitors

An XIP (xylanase inhibiting protein) type xylanase inhibitor was purified from Algerian pearl millet ( Pennisetum glaucum L.) grains and characterized for the first time. Cation exchange and affinity chromatography with immobilized Trichoderma longibrachiatum glycoside hydrolase (GH) family 11 xylanase resulted in electrophoretically pure protein with a molecular mass of 27-29 kDa and a pI value of 6.7. The experimentally determined N-terminal amino acid sequence of the purified XIP protein is 87.5%, identical to that of sorghum ( Sorghum bicolor L.) XIP and 79.2% identical to that of wheat ( Triticum aestivum L.) XIP-I. The biochemical properties of pearl millet XIP are comparable to those described earlier for sorghum XIP, except for the higher specific activity toward a T. longibrachiatum GH family 11 xylanase. On the basis of immunoblot neither TAXI nor TLXI type xylanase inhibitors were detected in pearl millet grains.