Wood-fiber insulation boards produced with polylactic acid as a binder by hot press and hot air

Abstract

Traditionally, there are two types of wood fiber insulation boards (WFIB), the rigid ones produced in the industry by a continuous steam process, bonded with polymer diphenylmethane diisocyanate (pMDI), with densities between 80 and 200 kg/m³, and the flexible ones with densities under 80 kg/m³ produced by hot air, usually with bicomponent fibers as a binder. In this work, wood fiber insulation boards (WFIB) were produced with polylactic acid (PLA) as a binder by hot press (HP) and hot air (HA). WFIB with densities of 60 kg/m³, 80 kg/m³, 100 kg/m³ and 5%, 10% and 15% of PLA percentage were produced by hot press (HP) and hot air (HA). Wood and PLA fibers were examined by scanning electronic microscope (SEM) and optical microscope. The WFIB were assessed for physical properties as density and short-term water absorption as well as for their resistance to compression as a mechanical property. Thermal properties such as thermal conductivity and thermogravimetric analysis (TGA) were also tested. In the produced WFIB, the values of density follow the same pattern as water absorption, compression strength, and thermal conductivity. The polylactic acid (PLA) content improves mechanical value like compression and diminishes physical value such as short-term water absorption in WFIB. In conclusion, wood fiber insulation boards (WFIB) were successfully produced with polylactic acid (PLA) as a binder, by hot press (HP) and hot air (HA), reaching remarkably lower thermal conductivity values, comparable with commercial ones.