Preparation, Thermal, and Mechanical Characterization of UV-Cured Polymer Biocomposites with Lignin

Abstract

The preparation and the thermal and mechanical characteristics of lignin-containing polymer biocomposites were studied. Bisphenol A glycerolate (1 glycerol/phenol) diacrylate (BPA.GDA) was used as the main monomer, and butyl acrylate (BA), 2-ethylhexyl acrylate (EHA) or styrene (St) was used as the reactive diluent. Unmodified lignin (L) or lignin modified with methacryloyl chloride (L-M) was applied as an ecofriendly component. The influences of the lignin, its modification, and of the type of reactive diluent on the properties of the composites were investigated. In the biocomposites with unmodified lignin, the lignin mainly acted as a filler, and it seemed that interactions occurred between the hydroxyl groups of the lignin and the carbonyl groups of the acrylates. When methacrylated lignin was applied, it seemed to take part in the creation of a polymer network. When styrene was added as a reactive diluent, the biocomposites had a more homogeneous structure, and their thermal resistance was higher than those with acrylate monomers. The use of lignin and its methacrylic derivative as a component in polymer composites promotes sustainability in the plastics industry and can have a positive influence on environmental problems related to waste generation.

Flammability Tests and Investigations of Properties of Lignin-Containing Polymer Composites Based on Acrylates

“…The largest change in the Young’s modulus is from 2910 MPa to 1440 MPa and the stress at break from 31.00 MPa to 8.00 MPa composition with a 5% addition of unmodified lignin. In compositions based on modified lignin, this biofiller interacts more strongly with the polymer network and exhibits higher breaking strength, comparable to the original polymer (0%P + 0%L) The data presented here show that mechanical properties of the studied compositions changed with the addition of eco-filler, but changes are smaller for the modified lignin [ 45 ]. The addition of a flame retardant in the form of a vinyl derivative does not significantly deteriorate the mechanical properties.…”

“…The first maximum decomposition peak (T max1 ) is observed in the range 396–407 °C. It is related to the main decomposition of polymer network fragments [ 46 ]. The highest temperatures of T max1 are reported for the 0%P + 5%L and 2%P + 5%L P samples, the lowest ones for the reference material (0%P + 0%L) which clearly indicates improvement of thermal stability of studied materials as a result of additives.…”

Preparation, Thermal, and Thermo-Mechanical Characterization of Polymeric Blends Based on Di(meth)acrylate Monomers

“…When analyzing the shape of TG and DTG curves, the decomposition of EGDMA-MMA blends proceeded in several stages. The first stage (T max in the range of 121–137 °C corresponding to 2–3% of mass loss) may be related to the evaporation of residual solvents, moisture and unreacted monomers [ 38 , 39 ]. Subsequent maxima of the rate of mass loss (i.e., T max = 245–258 °C with 7–12% of mass loss and T max = 301–320 °C with 55–64% of mass loss) are probably responsible for the degradation of EGDMA, while the maximum rate of mass loss at T max (temperature range of 396–442 °C and 19–27% of mass loss) is related to the distribution of the fragments derived from MMA.…”

“…The proposed mechanisms of polymer network fragmentation for all studied materials are presented in Figure 7 . The suggested mechanism is based on our earlier research, thermal decomposition of BPA.GDA-derived copolymers and literature data [ 39 , 40 , 41 ]. In the case of polycarbonates, their decomposition is very similar to BPA.GDA due to the presence the same structural fragments (Bisphenol A) and leads to aromatic compounds such as phenol, toluene and benzene, as well as small aliphatic hydrocarbons, alcohols, ketones, and then H 2 O and CO 2 .…”

“…Goliszek et al [ 54 ] described the effect of the addition of lignin on the composite based on BPA.GDA + EHA. The highest Shore-D hardness values were obtained for biocomposites with the addition of 2.5 and 5% lignin.…”