Diana Paiva

University of Porto | UP · Departamento de Engenharia Química

Out of the 50 to 70 million tons of lignin that are produced annually, only 1 to 2% are used for value-added products. Currently, 90% of the total market of this compound corresponds to lignosulphonates (LS). The most successful industrial attempts to use lignin for wood adhesives rely on using it as a partial substitute in phenol–formaldehyde or u...

Studies that aim to produce flexible films of composite materials based on ionomers-PZT, and volume fractions lower than 10% PZT, in order to monitor damage in aeronautical structures are seldom investigated. The growing emphasis on the use of polymers capable of self-healing after damage or activation by heating has motivated the application of se...

Cork, the bark of Quercus suber L., in addition to presenting several notable physical-mechanical properties, possesses a distinctive look and feel that make it attractive for interior surfaces, such as in furniture, wall paneling, or flooring. This work envisaged the development of a coating based on cork granules, a subproduct from the wine stopp...

Polylactic acid (PLA) fibres present, in their pristine state, a strain-rate-dependent behaviour. Their mechanical properties evolve during in vitro biodegradation. Tensile tests of PLA fibres are performed at five different strain rates 0.0001, 0.001, 0.01, 0.05 and 0.1/s and at seven degradation stages, 0, 20, 40, 60, 90, 120 and 150 days in a ph...

Microparticles of corn starch and chitosan crosslinked with glutaraldehyde, produced by the solvent exchange technique, are studied as reinforcement fillers for thermoplastic corn starch plasticized with glycerol. The presence of 10% w/w chitosan in the microparticles is shown to be essential to guaranteeing effective crosslinking, as demonstrated...

The mechanical behavior of agglomerated cork, made of cork granules bound with polyurethane moisture-cured adhesive is investigated and compared to natural cork in the small strain regime (strain <5%). Dynamic mechanical analysis (DMA) of the agglomerated material revealed two distinct thermal transitions, one at −45 °C, related to the glass transi...

Hybrid scaffolds composed of hydroxyapatite (HAp), in particular in its nanometric form (n-HAp), and chitosan (CS) are promising materials for non-load-bearing bone graft applications. The main constraints of their production concern the successful implementation of the final purification/neutralization and sterilization steps. Often, the used puri...

Advancements in materials technology and the use of innovative designs have led to extensive application of adhesive bonding techniques in the electric appliance industry. While the static strength of such joints is sufficient for the intended applications, long term durability remains a major concern, mainly due to creep effects. Conventional cree...

Natural cork stopper manufacturing produces a significant amount of cork waste, which is granulated and combined with synthetic glues for use in a wide range of applications. There is a high demand for using biosourced polymers in these composite materials. In this study, xanthan gum (XG) and chitosan (CS) were investigated as possible natural bind...

Recent studies point out that bolaamphiphiles can be used in nonviral gene therapy. Due to their bipolar character, they may span a membrane and thus stabilize or destabilize it which could be relevant for DNA transfer across a biological membrane. Since there are only very few studies on bolaamphiphile application in DNA transfection, it is diffic...

Graft copolymers of chitosan and maltodextrin were synthesized by reductive amination of a low molecular weight chitosan. The degree of substitution is 70% or above, as quantified by nuclear magnetic resonance spectroscopy, at molar ratios of chitosan glucosamine units and maltodextrin of 1 : 1 and 1 : 5. The high substitution degree generates a wa...

Monolayers of the cationic lipid DOTAP (1,2-dioleoyl-3-trimethylammonium-propane) and cholesterol or heptafluorocholesterol were prepared, and their interaction with DNA was characterized. The mixture of DOTAP with each of the sterols at 1:1 molar ratios leads to monolayers in a liquid expanded state, similarly to that of DOTAP alone. The area per...

Liposomes of the cationic lipid DOTAP (1,2-dioleoyl-3-trimethylammonium-propane) and the fluorinated cholesterol derivative heptafluorocholesterol (F7-CHOL) were tested at the molar ratio of 1:1 for DNA compaction and transfection. Their properties were correlated with the characteristics of the well-known system, DOTAP and cholesterol (CHOL). The...