Modification of lignin by hexamethylene diisocyanate to synthesize lignin-based polyurethane as an organic polymer for marine polyurethane anticorrosive coatings

Abstract

A green and facile preparation was used to synthesize modified lignin (ML) from alkaline lignin by using hexamethylene diisocyanate (HDI) as the modifier and tetrahydrofuran as the solvent without a catalyst. Then, the as-synthesized ML was dispersed in hydroxy acrylic resin and used to prepare modified lignin-based polyurethane composites by using HDI trimer as the curing agent and dibutyltin dilauric acid as the catalyst at room temperature. Fourier transform infrared (FTIR) and elemental analysis confirmed that the main chemical in ML was lignin urethane when the amount of HDI was 0.2 g. The tensile strength of the modified lignin-based polyurethane (MLPU-0.2) film using ML-0.2 reached 12.07 MPa, which was improved by 23.2% and 68.3% compared with that of the pure polyurethane (PU) film (9.79 MPa) and lignin-based polyurethane (LPU) film prepared using unmodified lignin (7.17 MPa), respectively. After the addition of lignin or ML, the elongation at break of the polyurethane film increased. The water contact angle of MLPU-0.2 increased up to 96o, which was higher than that of PU (74o) and LPU (68o). The pencil hardness of MLPU-0.2 (3 H) was higher than that of PU (H) and LPU (2 H). Modified lignin-based polyurethane shows promise for marine anticorrosive coatings.

Synthesis, characterization, and potential application of polyurethane foam as an effective alternative for dental aspiration substrate in liquid absorption/retention and mechanical properties

“…PUFs with different chain extension factors, based on Static water contact angle, qualitatively evaluated their hydrophilic and hydrophobic performance. The smaller the water contact angle, the better the hydrophilicity 28 . Figure 5 and Table 3 summarize the contact states and contact angles of DI water on the surfaces of PUFs with different chain extension coefficients and traditional commercial absorbent hemostatic cotton.…”

“…The smaller the water contact angle, the better the hydrophilicity. 28 T A B L E 2 Degree of hydrogen bonding of PUF with different chain extension coefficients. Figure 5 and Table 3 summarize the contact states and contact angles of DI water on the surfaces of PUFs with different chain extension coefficients and traditional commercial absorbent hemostatic cotton.…”

A guide to lignin valorization in biorefineries: traditional, recent, and forthcoming approaches to convert raw lignocellulose into valuable materials and chemicals

“…271,302,318,319 Isolated lignin fractions can be employed for the synthesis of PUs either directly or aer chemical modi-cation/fractionation. [321][322][323] The latter is aimed at increasing lignin solubility and reactivity with cyanate groups. 318,319,324,325 In particular, oxypropylation is commonly employed to extend the distance between hydroxyl groups in the lignin matrix and reduce steric hindrance effects.…”

Lignin-Based Covalent Adaptable Network Polymers─When Bio-Based Thermosets Meet Recyclable by Design

“…(ii) diols 22 and dicarboxylic acids, 23 which are employed to produce polyester-based CANs; (iii) hexamethylene diisocyanate (HDI) 24 and toluene diisocyanate (TDI) that are usually selected for the formation of polyurethane-based CANs; (iv) methyl methacrylate (MMA) 25 and butyl acrylate (BA), which are commonly chosen to formulate acrylate-based CANs; and (v) phenol and formaldehyde 26 are preferred to develop phenolbased CANs. Despite their varying compositions, all of these materials are petroleum-based, which is no longer acceptable, given the current environmental crisis.…”

“…Classical thermosets describe a generic family of polymers including, for example, unsaturated polyesters, vinyl esters, epoxy, and polyurethane resins, typical representatives of CANs encompass epoxy-, polyester-, polyurethane-, polyacrylate- and phenolic-based resins. Among the most common monomer units used in CAN design are (i) bisphenol A diglycidyl ether (BADGE) and diglycidyl ether of bisphenol F (DGEBF), which are used to prepare epoxy-based CANs; (ii) diols and dicarboxylic acids, which are employed to produce polyester-based CANs; (iii) hexamethylene diisocyanate (HDI) and toluene diisocyanate (TDI) that are usually selected for the formation of polyurethane-based CANs; (iv) methyl methacrylate (MMA) and butyl acrylate (BA), which are commonly chosen to formulate acrylate-based CANs; and (v) phenol and formaldehyde are preferred to develop phenol-based CANs. Despite their varying compositions, all of these materials are petroleum-based, which is no longer acceptable, given the current environmental crisis.…”