Time filter

Source Type

Campinas, Brazil

Romero R.B.,University of Campinas | Ferrarezi M.M.F.,University of Campinas | Leite C.A.P.,University of Campinas | Alves R.M.V.,Packaging Technology Center | Goncalves M.C.,University of Campinas

This paper deals with the effect of different montmorillonite source clays, including pristine and organophilic montmorillonites, on the structure, morphology and properties of cellulose acetate (CA)/clay nanocomposites. In this study, the nanocomposites were prepared by melt extrusion in the presence of the environmentally friendly triethyl citrate plasticizer. The structure and morphology of the materials were analysed by X-ray diffraction and scattering (SAXS), X-ray microtomography and energy filtered transmission electron microscopy (EFTEM). SAXS and EFTEM results indicated that the nanocomposite morphologies were made up of tactoids together with exfoliated clay platelets in different proportions depending on the clay type. It can be concluded that well distributed clay tactoids and platelets can be achieved in CA nanocomposites prepared by melt extrusion and consequently property improvements can be found by using pristine or organophilic clays. In this case, the addition of a plasticizer, able to intercalate in the clay gallery, seems to be sufficient to promote the clay delamination mechanism under shearing inside the cellulose acetate matrix. © 2012 Springer Science+Business Media Dordrecht. Source

Padula M.,Packaging Technology Center | De Lima P.C.,Packaging Technology Center
18th IAPRI World Packaging Conference

Polymer is used as packaging material in order to prevent physical, chemical and microbiological spoilage of food during transportation, distribution, handling and storage. However, polymers are not inert and some low molecular weight substances (additives, monomers, by-products) can be transferred into food. This process is called migration and becomes important where food safety is concerned due to the possibility of their impact on human health. MERCOSUR/Brazilian legislation on plastic materials is based on two principles, inertness and safety of the material. Restrictions such as positive lists and limits for overall (OML) and specific migration (SML) have been adopted by the legislation. There are several substances with SML and it is necessary to carry out migration tests using food simulants to demonstrate compliance with the legislation. Nevertheless, most of the restricted substances still have no analytical method for the determination of their migration levels, thus making validated mathematical modeling a useful tool to predict migration of additives and other low molecular components from plastic packaging materials. One of the key parameters necessary for estimating migration, besides the coefficients of diffusion and partition between the material and the food, is the initial concentration of the migrant in the polymer. The aim of this study is to validate the application of mathematical modeling to estimate the specific migration of the additive 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene (Uvitex OB®) (CAS 7128-64-5) from Brazilian polyethylene materials. Uvitex OB® is an optical brightening agent used to enhance the brilliant white color in end-use articles. The additive was extracted from polyolefin samples for 8 hours at 70°C with ethanol and the extract was analyzed by high performance liquid chromatography with a diode array detector (DAD) and fluorescence detector (FD). The limit of detection with DAD was 0.010μg.mL-1 while FD was 10 times lower. This is expected due to the characteristic excitation and emission wavelengths of the additive. The quantities of Uvitex in three Brazilian polyolefin samples were determined and the values obtained varied from 4 to 15mg.kg-1. The estimate of the migrated additive using the mathematical model MIGRATESTLite® was between 0.003 and 0.011mg.kg-1 and between 0.017 and 0.040mg.kg-1 for aqueous and fatty simulants, respectively. The samples comply with the specific limit of 0.6mg.kg-1 of simulants established by the legislation. Validating the mathematical modeling for Brazilian conditions will allow the evaluation of compliance of packaging materials with the requirements of the prevailing legislation and in the future will bring about the opportunity to develop a project locally to estimate the exposure of consumers to chemical contamination that originates from the packaging. Source

Coltro L.,Packaging Technology Center | Pitta J.B.,Packaging Technology Center | Madaleno E.,Braskem S.A.
Polymer Testing

Six stretch PVC films have been formulated to have Shore A hardness of approx. 80 and nominal thickness of 15 μm with the aim of evaluating the performance of plasticizers from renewable and non-renewable sources for stretch PVC films intended to be employed as packaging. The reference film was produced with DEHA and ESBO, while the other films were produced with conventional plasticizers (ATBC and Polyadipate), new plasticizers from renewable sources (Mixture of glycerin acetates and Acetic acid esters of mono- and diglycerides of fatty acids) or a plasticizer employed in toy and childcare applications (DEHT) as a third plasticizer. The films were evaluated as to their physical and mechanical properties (durometer hardness, tensile strength and elongation), IR spectroscopy and light transmission. The several plasticizers influenced the mechanical properties of the PVC films to different degrees. All films will probably show adequate performance when used in packaging applications. Nevertheless, the vegetable oil-based plasticizers showed better mechanical performance than the other plasticizers when compared to DEHA. © 2012 Elsevier Ltd. All rights reserved. Source

Coltro L.,Packaging Technology Center | Pitta J.B.,Packaging Technology Center | da Costa P.A.,Chemistry Technical High School Conselheirro Antonio Prado ETECAP | Favaro Perez M.T.,Packaging Technology Center | And 2 more authors.
Food Control

PVC is one of the resins with the higher quantity of additives and the possibility of migration is always a concern when its intended use is food packaging. In this study, the migration of several plasticizers was investigated with the aim of finding out a relationship between migration and conformance with legislation in force, and tensile properties as well. Therefore, six PVC cling films intended to come into contact with foodstuffs have been formulated in order to have same hardness and thickness. The reference film was produced with DEHA and ESBO, while the other films were produced with conventional plasticizers (ATBC and Polyadipate), new plasticizers from renewable resources (Mixture of glycerin acetates - MGA and Acetic acid esters of mono- and diglycerides of fatty acids - AGM) or a plasticizer employed in toy and childcare applications (DEHT). The films were evaluated as to the overall and specific migration to food simulants and the effect of the formulation was studied. The results have shown that the coefficient of apparent partition of DEHT is similar to that of DEHA, whereas MGA and AGM plasticizers displayed higher coefficients of apparent partition than the other plasticizers under study. This difference in migration has been attributed to the different molecular structures of plasticizers. In addition, commercial films have been evaluated as to plasticizers concentration and specific migration into food simulants. It was found that 25% of the samples comply with the specific migration limits for fatty foods contact while 50% might be used for contact with fatty foods with FRF 2-5. On the other hand, all commercial samples showed no restriction for aqueous acidic food contact. Thus, it has been demonstrated that a contact for prolonged time up to 40°C did not promote the migration of plasticizers into acidic foodstuffs, but the migration of plasticizers to fatty foods can be high (75%-90% loss of plasticizers) and limit the use of PVC films as fatty food packaging. © 2014 Elsevier Ltd. Source

Discover hidden collaborations