Use of glutaraldehyde crosslinking agent in the synthesis of liquid polysulfide

Research subject: This study employs a novel approach to the synthesis of liquid polysulfide. One of the drawbacks of synthesizing liquid polysulfide is the use of 1,2,3-trichloropropane (TCP) as a crosslinking agent, which poses significant toxicity and carcinogenic hazards. Glutaraldehyde (GLH) was utilized as a crosslinking agent in this study, as it is safer than TCP.
Research approach: Bis(2-chloroethyl) formal and sodium tetrasulfide (Na2S4) monomers were used in a surface suspension reaction to create liquid polysulfide, with glutaraldehyde (GLH) serving as a crosslinking agent. The organic monomer, bis(2-chloroethyl) formal, was also produced by reacting ethylene chlorohydrin with paraformaldehyde. The organic monomer's synthesis and purity were assessed using gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR). The produced liquid polysulfide was then subjected to FTIR, viscometry, T-peel, tensile, and hardness tests for analysis. This study examined the effect of GLH concentration on the flowability, mechanical, and adhesion properties of liquid polysulfide by varying its proportion in the polymer.
Main results: The viscosity of liquid polysulfide with 1.5 to 2 wt. % GLH (LP-3 and LP-4) was 6800 and 11000 mPa.s, respectively, surpassing that of samples with 0.5 to 1 wt. % GLH (LP-1 and LP-2), with viscosities of 3900 and 4100 mPa.s, respectively. Samples LP-3 and LP-4 exhibited superior tensile strength compared to samples LP-1 and LP-2. The adhesion to metal in samples LP-1 and LP-2 exceeded that of samples LP-3 and LP-4. The optimal GLH composition, based on tensile properties and hardness, lies between 1.5 and 2 wt.%. However, due to the elevated viscosity of liquid polysulfide containing 2 wt.% GLH (LP-4) and its inadequate fluidity at ambient temperature as a sealant, along with the lower adhesion of sample LP-4, samples LP-2 and LP-3 were identified as the most suitable compositions in terms of viscosity, hardness, tensile strength, and peel strength for formulating a reliable liquid polysulfide sealant.