Paper-Based Laminates Impregnated with a Hybrid Lignin-Phenol-Formaldehyde Resin

In this study, high-pressure laminates (HPL) impregnated with phenol-formaldehyde (PF) resins enriched with kraft lignin were developed. Pulverised kraft lignin was added to the commercial PF resin in the amounts of 1% and 5% (solid to solid). Laminates were manufactured using pressure impregnation of the resins into the papers and using hot pressing of HPL in a laboratory press. Laminates with a lignin content of 1% (L-LPF-1) showed the highest bending strength (72.42 MPa) and Brinell hardness (9.41); they also exhibited the best moisture uptake (9.61) and thickness swelling after immersion in water (3.32%). Except for impact bending, laminates with a lignin content of 5% (L-LPF-5) had worse properties. However, the differences between the variants are mostly not statistically significant and are comparable with the results of commercial PF resin. Scanning electron microscopy confirmed the homogenous structure of produced laminates and the occurrence of cohesive failures in ruptured L-LPF-1 laminates, whereas in ruptured L-LPF-5 laminates adhesive failures were also observed. Based on the conducted research it can be said that the utilisation of kraft lignin as an additive to PF resin (in the amount of 1%) has a positive effect on the produced HPL

Fire-Resistant Sandwich-Structured Composite Material Based on Alternative Materials and Its Physical and Mechanical Properties

The development of composite materials from alternative raw materials, and the design of their properties for the intended purpose is an integral part of the rational management of raw materials and waste recycling. The submitted paper comprehensively assesses the physical and mechanical properties of sandwich composite material made from particles of winter rapeseed stalks, geopolymer and reinforcing basalt lattices. The developed composite panel is designed for use as a filler in constructions (building or building joinery). The observed properties were: bending characteristics, internal bonding, thermal conductivity coefficient and combustion characteristics. The results showed that the density of the particleboard has a significant effect on the resulting mechanical properties of the entire sandwich panel. On the contrary, the density of the second layer of the sandwich panel, geopolymer, did not have the same influence on its mechanical properties as the density of the particleboard. The basalt fibre reinforcement lattice positively affected the mechanical properties of sandwich composites only if it was sufficiently embedded in the structure of the particle board. All of the manufactured sandwich composites resisted flame for more than 13 min and the fire resistance was positively affected by the density of the geopolymer layer

Impact of Flax and Basalt Fibre Reinforcement on Selected Properties of Geopolymer Composites

The submitted paper deals with the physical and mechanical properties of geopolymer composite materials reinforced with natural fibres. For this study, we aimed to develop a geopolymer composite reinforced with long flax fibres, which were implemented in the geopolymer in the form of a nonwoven fabric that reinforced the structure of the geopolymer over the entire thickness of the board. In order to compare the properties of the developed composite with natural fibres, a geopolymer without fibres and a geopolymer reinforced with basalt fibres were also produced. The monitored mechanical properties were impact bending, bending strength and compressive strength. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and microscopic analysis were also carried out. The results clearly showed the positive effect of the addition of natural fibres on impact bending and bending strength. However, the addition of natural fibres in the form of a nonwoven fabric significantly increased the variability of the properties of the developed composites. In addition, a different pattern of joint failure was noted between geopolymer reinforced with flax fibres and geopolymer reinforced with basalt fibres

Permeable water-resistant heat insulation panel based on recycled materials and its physical and mechanical properties

: This paper deals with the development and characteristics of the properties of a permeable water-resistant heat insulation panel based on recycled materials. The insulation panel consists of a thermal insulation core of recycled soft polyurethane foam and winter wheat husk, a layer of geopolymer that gives the entire sandwich composite strength and fire resistance, and a nanofibrous membrane that permits water vapor permeability, but not water in liquid form. The observed properties are the thermal conductivity coefficient, volumetric heat capacity, fire resistance, resistance to long-term exposure of a water column, and the tensile strength perpendicular to the plane of the board. The results showed that while the addition of husk to the thermal insulation core does not significantly impair its thermal insulation properties, the tensile strength perpendicular to the plane of these boards was impaired by the addition of husk. The geopolymer layer increased the fire resistance of the panel for up to 13 min, and the implementation of the nanofibrous membrane resulted in a water flow of 154 cm2 in the amount of 486 g of water per 24 h at a water column height of 0.8 m