114 documents found, page 1 of 12
Toward mechanical recyclability of high barrier food packaging films through fi...
Barros, Carolina; Azevedo, Ana G.; Cerqueira, Miguel Ângelo Parente Ribeiro; Carneiro, O. S.; Machado, A. V.To preserve food from moisture and oxygen, polymers, such as ethylene vinyl alcohol (EVOH) are used in multilayer structures to provide oxygen barrier, while low-density polyethylene (LDPE) is used for a water vapor barrier. While this material combination is functionally ideal, it may not comply with the new packaging recycling guidelines. Some European markets have implemented rules that limit the weight perc...
Active Low-Density Polyethylene-Based Films by Incorporating α-Tocopherol in th...
Azevedo, Ana G.; Barros, Carolina; Miranda, Sónia; Machado, A. V.; Carneiro, O. S.; Silva, Bruno; Andrade, Mariana A.; Vilarinho, FernandaIn this work, alpha-tocopherol (α-TOC) was encapsulated in poly(lactic acid) nanoparticles (PLA NPs) and added to low-density polyethylene (LDPE) films with the aim of producing an active film for food packaging applications. PLA NPs loaded with α-TOC were produced through nanoprecipitation and dried using two methods (freeze-dryer and oven). LDPE-based films with final polymeric matrix concentrations of 10 and...
Feasibility of incorporating recycled multilayer LDPE/EVOH films into flexible ...
Barros, Carolina Lemos; Carneiro, O. S.; Machado, A. V.Multilayer films are widely used in the food industry because they allow the combination of properties of different materials to increase product shelf life without sacrificing product value. Despite the associated benefits, these films are difficult to recycle due to material immiscibility and difficult layer separation. Thus, the purpose of this research is to investigate the feasibility of incorporating recy...
From multilayer LDPE/EVOH flexible film scraps to new multilayer films
Barros, Carolina; Carneiro, O. S.; Machado, A. V.This study explores the mechanical and optical properties of multilayer films incorporating recycled materials, mimicking the structure of industrial films. Using a coextrusion blown film line with a three-layer ABC configuration extrusion head, films were produced using two different recycled multilayer films, from post-industrial scraps, in layers A and B and virgin low-density polyethylene (LDPE) in one of t...
Multi-material fused filament fabrication: an expedited methodology to assess t...
Cunha, P.; Teixeira, R.; Carneiro, O. S.; Ferreira da Silva, AlexandreThe impact of 3D printing and how it is present in everyday life is unquestionable. Provided with almost total freedom of design and a vast list of materials, 3D printing has attracted enormous interest, being the fused filament fabrication (FFF) technique one of the main drivers. Given the vast range of compatible materials, FFF potential is being further developed towards multi-material prints. Still, one of ...
From transparent to opaque: a route towards multifunctional parts injected with...
Pedroso, Luís D.; Pontes, A. J.; Alves, António; Duarte, F. M.; Carneiro, O. S.The technological, social and economic development observed in recent decades brought an exponential increase in consumption and inherent new challenges. Recycling is one of the best solutions to minimize the environmental impact of raw materials. However, multi-material components are difficult or even impossible to recycle. The present work focuses on the reduction in the number of different materials used in...
LDPE-Nanoclay films for food packaging with improved barrier properties
Barros, Carolina; Miranda, Sónia; Castro, Olga; Carneiro, O. S.; Machado, A. V.This study focuses on the development of low-density polyethylene matrix nanocomposite films for food packaging industry and aims at improving low-density polyethylene oxygen barrier properties while maintaining other relevant characteristics, such as processability, easy post-processing, optical and mechanical properties. low-density polyethylene nanocomposites, with 1 and 2.5 wt.% nanoclay (NC) and also compa...
Active flexible films for food packaging: a review
Azevedo, Ana G.; Barros, Carolina Lemos; Miranda, Sónia; Machado, A. V.; Castro, Olga; Silva, Bruno; Saraiva, Margarida; Silva, Ana SanchesActive food packaging is a dynamic area where the scientific community and industry have been trying to find new strategies to produce innovative packaging that is economically viable and compatible with conventional production processes. The materials used to develop active packaging can be organized into scavenging and emitting materials, and based on organic and inorganic materials. However, the incorporatio...
On the reuse of SLS Polyamide 12 powder
Gomes, Pedro C.; Piñeiro, Oscar G.; Alves, Alexandra C.; Carneiro, O. S.In the Selective Laser Sintering (SLS) technique, the great majority of the powder involved is not included in the final printed parts, being just used as a support material. However, the quality of this powder is negatively affected during the process since it is subjected to high temperatures (close to its melting temperature) during a long time, i.e., the printing cycle time, especially in the neighborhood o...
An effective interface tracking method for simulating the extrudate swell pheno...
Fakhari, Ahmad; Tukovic, Zeljko; Carneiro, O. S.; Fernandes, C.The extrudate swell, i.e., the geometrical modifications that take place when the flowing material leaves the confined flow inside a channel and moves freely without the restrictions that are promoted by the walls, is a relevant phenomenon in several polymer processing techniques. For instance, in profile extrusion, the extrudate cross-section is subjected to a number of distortions that are motivated by the sw...