Antonella Tarzia

Synthesis of a novel cardanol-based benzoxazine monomer and environmentally sustainable production of polymers and bio-composites

A novel pre-polymer deriving from cardanol—a well known renewable organic resource and harmful by-product of the cashew industry—in combination with cellulose based materials (i.e. jute fibres) has been used to produce bio-composites having a high percentage of renewable materials. Cardanol and its derivatives are considered nowadays very attractive precursors to developing new materials from renewable bio-sources to use in eco-friendly processes. This paper deals with the synthesis and characterization of a novel cardanol based benzoxazine monomer used for the preparation of new bio-composites. The new cardanol-based benzoxazine was characterised by 1H and 13C NMR, FT-IR spectroscopies and LC mass spectrometry analysis, while a differential scanning calorimeter was used to study and monitor the polymerization process. Different bio-composites have been obtained by thermal cure of jute fibres impregnated with a cardanol based benzoxazine resin.

Air-Coupled Ultrasound: A Novel Technique for Monitoring the Curing of Thermosetting Matrices

A custom-made, air-coupled ultrasonic device was applied to cure monitoring of thick samples (7-10 mm) of unsaturated polyester resin at room temperature. A key point was the optimization of the experimental setup in order to propagate compression waves during the overall curing reaction by suitable placement of the noncontact transducers, placed on the same side of the test material, in the so-called pitch-catch configuration. The progress of polymerization was monitored through the variation of the time of flight of the propagating longitudinal waves. The exothermic character of the polymerization was taken into account by correcting the measured value of time of flight with that one in air, obtained by sampling the air velocity during the experiment. The air-coupled ultrasonic results were compared with those obtained from conventional contact ultrasonic measurements. The good agreement between the air-coupled ultrasonic results and those obtained by the rheological analysis demonstrated the reliability of air-coupled ultrasound in monitoring the changes of viscoelastic properties at gelation and vitrification. The position of the transducers on the same side of the sample makes this technique suitable for on-line cure monitoring during several composite manufacturing technologies.

Study of a Cardanol-Based Benzoxazine as Reactive Diluent and Toughening Agent of Conventional Benzoxazines

Publisher Summary Benzoxazine chemistry is well known and offers many advantages. Only recently polybenzoxazines with enhanced structural properties are successfully synthesized, alone or formulated with suitable additives. Benzoxazines offer many advantages compared with epoxies and other chemical structures, as they are halogen-free, exhibit better flame-resistance and electrical properties than epoxies, and are characterized by an excellent high temperature resistance and low water absorption values. With this combination of properties, benzoxazines hold great promise for performing in applications such as composites, coatings, adhesives, encapsulants, and others. It focuses on the synthesis of new low viscosity cardanol-based benzoxazines, as possible alternatives to the standard petroleum-based ones. This chapter describes that Cardanol is an industrial oily alkyl-phenolic product obtained by the vacuum distillation of “cashew nut shell liquid” (CNSL), a renewable natural resource obtained from the cashew nut as a byproduct during the process of removing the cashew kernel from the nut. A monofunctional liquid cardanol-based benzoxazine is prepared and used as a reactive diluent and toughening agent for a bisphenol A-based benzoxazine. The thermal, viscoelastic, and mechanical properties of benzoxazine resins obtained from the mixture of a low viscosity CA-a and the BA-a are studied in this chapter. Three different mixtures of BA-a and CA-a, containing 10%, 20%, and 30% by weight of CA-a, are prepared and studied to illustrate how different amounts of the cardanol derivative affect the properties of the final benzoxazine resins. The results obtained from the nonisothermal DSC analysis suggested a copolymerization reaction between the two benzoxazines BA-a and CA-a, occurring in a temperature range similar to that shown by the BA-a resin.

Development and characterisation of jute reinforced natural matrix composites

The aim of this work is the development of composite materials obtained using as matrix a resin derived from renewable resources. New pre-polymers derived from cardanol, a natural phenol extracted from the shell of the cashew nut, were synthesised. In particular cardanol based novolac-type phenolic resins, capable to form thermoset polymers when blended to commercial epoxy or isocyanate monomers, were successfully developed. Composite laminates obtained using a jute fabric were fabricated and characterised. Jute fabrics were used with and without a surface treatment with NaOH and silane coupling agents. An amount larger than 50% of natural originating materials is present in the laminates.