Novel Insulating Material from Renewable Resouerces : Silicate-Lignin Foam Composite

Silicate-Lignin Foam Composites as eco-friendly insulating materials Silvia Bordoni, Inorganic and Physical Chemistry Dept, University of Bologna Laura Genovese, ICIE Architecture Lab for technology transfer in Constructions, Bologna Organic-inorganic composite materials have been extensively studied for a long time, since they combine advantages of the inorganic material (i.e. rigidity, thermal stability) and of the organic phase, which is, in most of cases, a polymer (i.e. flexibility, ductility and processability (1). Among several organic/inorganic hybrid materials, the polymer/silica nano- and meso-composites are the most commonly reported in literature and have attracted both academic and industrial interests. Besides the common applications, including coating, catalysts, devices and sensors, this type of composites can be also employed to realize innovative construction materials (2). Here we report a formulation from renewable sources of a novel thermal- insulating material, able to offer an eco-friendly alternative to the conventional light-weighed synthetic products. The designed material is an organic-inorganic composite of lignosulfonate, as the main waste product of cellulose-production, dispersed into a silicate matrix with the addition of non-food corn starch, acting as gluing agent. The further addition of esterification promoters, foaming and coupling agents, polyol acids as pH-regulators, fungi preservatives and Kenaf fibers as reinforcing agents, confers the tailored targeted features. Addition of a suitable coupling agent (APTES) promotes linkage between the polyol groups of glycerol or the surfactant lignosulfonate with silanol and siloxane moieties of the silicate substrate. The resulting blended biopolymers-microporous silica material (40m) appears as a single phase rigid foam, which conjugates low-density (0.25-0.35g/cm3), low conductivity (λ= 52-61mW/m2K) and acceptable mechanical properties (3). These features make the obtained composite useful for bored-brick filler or as small insulating panels in building applications. Recent efforts to enhance hydrophobicity to reduce biodegradability by starch acetylation and to introduce benign polycarboxylic acids as alternative expanding promoters, more efficient plasticizers (sorbitol) or foam stabilizers and rheology modifiers (xanthane), will be also presented. 1. H.Zou, S. Wu, J.Shen; Chem. Rev. 2008, 108, 3893-3957 2. Common Strategic Framework for Research and Innovation ,“Horizon 2020”. 3. S. Bordoni; An eco-friendly challenge; Festival della scienza, Genova, 2011