Grafted d/l-lactide to cellulose acetate by reactive melt processing: Its role as CA/PLA blend compatibilizer

AbstractCellulose acetate (CA) with a degree of substitution (DS) of 2.5 and polylactic acid (PLLA) were plasticized by melt extrusion using triacetin. Blends of resulting thermoplastic materials were then prepared and characterized by their tensile strength and differential scanning calorimetry (DSC). Thermal analysis revealed the invariability of the PLLA glass transition temperature in all blends, indicating that the compounds were immiscible. Grafted d/l lactide to CA copolymers were prepared by reactive melt processing using CA with different degree of substitution i.e. 2.1 and 2.5 and evaluated as CA/PLLA blend compatibilizer. The compatibility of the blends was investigated by scanning electron microscopy (SEM). Results showed that blend compatibility was improved evidencing the best performance of grafted copolymers with long grafted chains as blend compatibilizer of CA/PLLA blends. Finally, compatibilized blends compositions with enhanced ultimate elongation were achieved by using plasticized PLLA instead of neat PLLA

A benzoxazine/substituted borazine composite coating: A new resin for improving the corrosion resistance of the pristine benzoxazine coating applied on aluminum

In this paper, laboratory synthesized Phenol-paraPhenyleneDiAmine (P-pPDA) benzoxazine containing different amounts of B-trimesityl-N-triphenylborazine was applied by spin coating on aluminum and thermally cured. The addition of the borazine derivative (borazine 1) does not appear to modify the curing characteristics of the P-pPDA matrix itself as shown by FTIR, DSC and DEA analyses; however, some interactions - chemical and/or physical (co-crystallization) – between P-pPDA and borazine 1 cannot be excluded. The microstructure of the composites is characterized by a two phase system consisting of a dispersion of nanosized (10–20 nm) clusters for the lowest borazine 1 concentration (0.5 wt%), evolving towards bigger (100–200 nm), agglomerated clusters for higher borazine 1 concentrations (3 wt%) and finally, continuous, dendritic structures within the P-pPDA matrix for the highest borazine 1 concentration (10 wt%). The benzoxazine composite coating containing 0.5 wt% trimesitylborazine derivative showed a largely increased and durable ability to protect the aluminum substrate. It is shown that a highly capacitive behavior and durable barrier properties can be obtained for P-pPDA coatings containing such a low amount of borazine derivative homogeneously dispersed in the benzoxazine matrix. For concentrations of 3 wt%, as agglomeration took place and dendrites appeared for the highest concentration of borazine derivative (10 wt%), the corrosion resistance decreased with time

Development of Low-Viscosity and High-Performance Biobased Monobenzoxazine from Tyrosol and Furfurylamine

This work details the scalable and solventless synthesis of a potential fully biobased monobenzoxazine resin derived from tyrosol and furfurylamine. The structure of the monomer was studied by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR). The curing of the precursors was characterized by differential scanning calorimetry (DSC), rheological measurements, and thermogravimetric analysis (TGA). The properties of the resulting biobased polybenzoxazine were then determined by thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMA). A thermally stable resin was obtained with 5% and 10% weight-reduction-temperature (Td5 and Td10) values of 349 and 395 °C, respectively, and a char yield of 53%. Moreover, the low melting temperature, low viscosity, and excellent thermomechanical behavior make this fully biobased resin a promising candidate for coating applications

New prospects in flame retardant polymer materials: From fundamentals to nanocomposites

The objective of this review is to make the field of “flame retardants for polymer materials” more accessible to the materials science community, i.e. chemists, physicists and engineers. We present the fundamentals of polymer combustion theory, the main flame retardant properties and tests used to describe fire behavior, together with the nature and modes of action of the most representative flame retardants and the synergistic effects that can be achieved by combining them. We particularly focus on polymer nanocomposites, i.e. polymer matrices filled with specific, finely dispersed nanofillers, which will undoubtedly pave the way for future materials combining physicochemical and thermo-mechanical performances with enhanced flame retardant behavior.Objectif-1 Hainaut: Materia Nov

Easy, Flexible and Standardizable Anti-Nascent Biofilm Activity Assay to Assess Implant Materials

Medical implants have improved the quality of life of many patients. However, surgical intervention may eventually lead to implant microbial contamination. The aims of this research were to develop an easy, robust, quantitative assay to assess surface antimicrobial activities, especially the anti-nascent biofilm activity, and to identify control surfaces, allowing for international comparisons. Using new antimicrobial assays to assess the inhibition of nascent biofilm during persistent contact or after transient contact with bacteria, we show that the 5 cent Euro coin or other metal-based antibacterial coins can be used as positive controls, as more than 4 log reduction on bacterial survival was observed when using either S. aureus or P. aeruginosa as targets. The methods and controls described here could be useful to develop an easy, flexible and standardizable assay to assess relevant antimicrobial activities of new implant materials developed by industries and academics