Co-authors​ :

 Pustahija LUCIJA (AUSTRIA), Kern WOLFGANG (AUSTRIA) 

The increasing interest in the production of sustainable composites led to the idea of utilising carbon black (CB) which is left over as a by-product after pyrolysis of methane and biomass. Although the production of hydrogen is the primary objective of methane pyrolysis, the use of CB has significant potential. CB can be utilised in a broad range of applications, such as an adsorbent in wastewater treatment, an additive in polymer composites, a black pigment in tyre manufacturing, and many more. The main obstacle to the application of CB is its low dispersibility, which results from its tendency to form agglomerates. Understanding the structure of CB - which is frequently described as turbostratic -helps to explain its macroscopic properties. A turbostratic structure refers to a mixture of amorphous and crystalline carbon. Surface functionalization and modification of the surface is a widespread strategy to address the low polarity of materials and associated problems. The functionalization of carbon surfaces mostly involves attaching different molecular entities such as silanes, amines, thiols, etc., which can either be used as agents to change the polarity of the carbon surface, or as coupling agents. These agents form “bridges” between, e.g., an inorganic material (in this case, CB) and a polymer matrix (e.g., epoxies, PUs). Additional methods for altering the surface properties of carbon comprise graphene chemistry, involving the application of various cycloadditions ([4+2], [3+2], [2+1] etc.) as well as free radical chemistry.
The focus of this work is on altering the surface chemistry of two types of carbon black. One is produced by methane pyrolysis (gas pyrolyzed carbon, GPC), and the other is made by pyrolysis of biomass (coconut shells, CSC). The surface functionalization of both types of pyrolytic carbon was carried out using amino- and glycidoxyorganosilanes (APTMS and GPTMS). First, solvothermal oxidation and plasma oxidation of CB were used to generate oxygen groups on the carbon surface. The reduction of carbonyl (C=O) rich surfaces with lithium aluminium hydride (LiAlH4) was the next step. This yields a carbon surface bearing superficial hydroxyl (OH) groups that are necessary to bond with silane moieties and create stable Si-O-C bonds. Successfully silanized CBs were further used to create carbon composites with epoxy and polyurethane resins acting as binders for the CB particles. In addition to thermal curing, CB composites were also cured using radiation (i.e., e-beam or X-ray). The thermomechanical properties of these composites were investigated, and possible applications (e.g., for wastewater treatment) were explored.