SbstractPolylactic acid (PLA) is an attractive candidate for replacing petrochemical polymers because it is from renewable resources. In this study, a specific PLA 2002D was melt-mixed with two plasticizers: triethyl citrate (TEC) and acetyl tributyl citrate (ATBC). The plasticized PLA with various concentrations were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), melt flow index (MFI), thermogravimetric analysis (TGA), X-ray diffraction (XRD), UV-Visible spectroscopy and plasticizer migration test. Differential scanning calorimetry demonstrated that the addition of TEC and ATBC resulted in a decrease in glass transition temperature (T g ), and the reduction was the largest with the plasticizer having the lowest molecular weight (TEC). Plasticizing effect was also shown by decrease in the dynamic storage modulus and viscosity of plasticized mixtures compared to the treated PLA. The TGA results indicated that ATBC and TEC promoted a decrease in thermal stability of the PLA. The X-ray diffraction showed that the PLA have not polymorphic crystalline transition. Analysis by UV-Visible spectroscopy showed that the two plasticizers: ATBC and TEC have no effect on the color change of the films. The weight loss plasticizer with heating time and at 100°C is lesser than at 135 °C. Migration of TEC and ATBC results in cracks and changed color of material. We have concluded that the higher molecular weight of citrate in the studied exhibited a greater plasticizing effect to the PLA.

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Abstract Triethyl citrate (TEC) and acetyl tributyl citrate (ATBC) were used as plasticizer for poly(lactic acid) (PLA). The treated and plasticized PLA at various concentrations were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and opacity. DSC was used to evaluate the crystallinity and thermal property of all the samples. It was found that the glass transition temperature (Tg) and the melting temperature (Tm) decreased as the amount of citrate esters increased. Additionally, the presence of TEC or ATBC tended to increase the crystallinity of PLA. This result was supported by XRD. DMA of plasticized PLA indicates that a decrease in Tg is obtained with increasing plasticizer content. FTIR spectra indicate that there are some molecular interactions by intermolecular hydrogen bonds between PLA and citrate esters. The effect of the concentration of plasticizer on the opacity of the films was negligible.

International audienceSunflower oil (SO) is a renewable resource that can be epoxidized, and the epoxidized SO has potential uses as an environmentally friendly in polymeric formulations, especially for poly (vinyl chloride) (PVC). Epoxidized sunflower oil (ESO) was prepared by treating the oil with peracetic acid generated in situ by reacting glacial acetic acid with hydrogen peroxide. Epoxidation was confirmed using spectroscopic and titration methods. ESO was used as a coplasticizer in PVC for the partial replacement of di-(2-ethyl hexyl) phthalate (DEHP). The effect of ESO on the thermal stability of plasticized PVC was evaluated by using synmero scale for the sheets. In presence of ESO plasticized PVC samples showed a reduction in discoloration and the number of conjugated double bonds. By using thermogravimetry, the incorporation of 15/45 of ESO/DEHP in PVC presents the lowest weight loss. The results of the shore hardness and mechanical properties showed that a proportion of DEHP could be substituted by ESO. By use of DMA, the formulation which contains 25 % wt of ESO in plasticizer system shifts the glass transition temperature (Tg) to ambient temperature. The migration phenomenon was studied on PVC based samples plasticized with DEHP and ESO in varying amounts. The migration was monitored by the weight loss percentage of the samples immersed into n-hexane or heated in an oven. The amount of extracted or volatilized DEHP is proportional to the added ratio of ESO in plasticizer system. All of this favored the partial replacement of DEHP by ESO as biobased plasticizer for flexible PVC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 201

ABSTRACT:The objective of this work was to study the effectiveness of low-cost commercial compatibilizers and several processes (internal mixer, single-and twin-screw extruders) for two types of plastic blends: high-density polyethylene/polypropylene and high-density polyethylene/ polystyrene blends, to gain insight into the recycling of wastes from those frequently encountered mixed plastics. Blends going from a pure A to a pure B component, with and without a compatibilizer, were prepared using an internal mixer, a corotating twin-screw extruder, as well as a single-screw extruder to follow an industrial-convenient process. In both cases, the analyses of blend morphologies highlighted the poor adherence between the two phases in the uncompatibilized blends. Compatibilized blends display better adherence between phases and the ability to process blends made from both single-and twin-screw extruders. When adding a compatibilizer, the viscosity of each blend (PE/PP or PE/PS) increased due to a better adhesion of the phases. Charpy impact tests showed that the presence of the compatibilizer in PE/PS blends increased their impact properties. Indeed, the improvement of the adhesion between the two phases enabled stress transfer at the interface. A singlescrew extruder seems to be efficient as a processing method on an industrial scale when a compatibilizer is used.

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.

The objective of this work is to study the properties of blends that could result from the recycling of end‐of‐life vehicles (ELV). While ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) have been used extensively as elastomeric additives in poly(propylene) (PP), they can be substituted by ethylene‐1‐octene copolymer (EOC). As a consequence, the matter resulting from the sorting of ELV might be more complex and made of PP, EPR, and EOC. The effect of incorporating EOC [that is a polyethylene elastomer (PEE)] and maleic anhydride grafted polypropylene (PP‐g‐MAH) on the rheological, thermal, and morphological properties of PP/EPR blends has been investigated. Blends of various compositions (with and without compatibilizer) were prepared using a corotating twin‐screw extruder. The results were compared to the ones presented by a commercial (PP/EPR) blend. The EPR phase is dispersed in the form of spherical particles in (PP/EPR). The EOC phase is dispersed in the form of aggregated particles. Dynamic viscoelastic and differential scanning calorimetry properties of (PP/EPR)/EOC blends shows the incompatibility of the components even in presence of PP‐g‐MAH copolymer. POLYM. ENG. SCI., 47:1009–1015, 2007. © 2007 Society of Plastics Engineers

The objective of this work was to study the effectiveness of commercial compatibilizers (E-EA-MAH copolymer) on the morphology of blends of polypropylene/ ethylene polypropylene rubber (PP/EPR) (78/22) and metallocenic ethylene-octene copolymer (EOC) polluted by (poly (vinyl chloride) (PVC) and by an oil for engine. Blends of various compositions (with and without compatibilizer or pollutant), were prepared using a corotating twin-screw extruder. In both cases, the analyses of blend morphologies highlighted the poor adherence between the two phases in the uncompatibilized blends. Compatibilized polluted blends display better adherence between phases. Dynamic mechanical thermal analysis and differential scanning calorimetry show that the compatibilizer improves the adhesion between both phases and enables stress transfer at the interface.