In this work, a new flame retardant additive [2-phenyl-1,3,2 oxazaphospholidine 2-oxide (POPO)] containing phosphorus and nitrogen is synthesized using phenyl phosphonic dichloride, ethanol amine, and copper (II) chloride, as catalyst. POPO is characterized by 1 H-NMR, 13 C-NMR, and 31 P-NMR and used as additive in polyurethane composites. Moreover, two commercial flame retardant additives [tricalcium diphosphate and hexabromocyclododecane (HBCD)] as well as nanoclay are used to compare flame retardancy of the synthesized additive. Limited oxygen index (LOI) and time burning (flammability test) of polyurethane composites and nanocomposites are evaluated. The results of the LOI test demonstrate that POPO is an excellent flame retardant additive and can be used to improve flame retardancy of polyurethane composites. In addition, increasing the additive content leads to an improvement of the flame retardancy of the samples. The LOI results show, however, that POPO is a good flame retardant, but the high synthesis cost of this flame retardant is a major disadvantage. Thermogravimetric analysis results show that using POPO in polyurethane matrices leads to low thermal stability and high char residue. Moreover, the nanocomposite has better thermal stability than the other samples. Scanning electron microscope micrographs have been used to evaluate the char residue of the samples. These micrographs indicate that POPO is an intumescent flame retardant and HBCD follows a nonintumescent mechanism. Exfoliated/ intercalated structures have been shown for nanocomposites by transmission electron microscope.

ABSTRACT:We have developed flame-retardant polyurethanes (FRPUs) and polyurethane (PU) nanocomposites via in situ polymerization. Three series of thermoplastic elastomeric PUs were synthesized to investigate the effect of incorporating 3-chloro-1,2-propanediol (CPD) and nanoclay on mechanical, thermal properties, and also resistance to burning. PU soft segments were based on poly(propylene glycol). Hard segments were based on either CPD or 1,4-buthane diol (BDO) in combination with methyl phenyl di-isocyanate named PU or FRPU, respectively. In the third series, CPD was used as chain extender also nanoclay (1% wt) and incorporated and named as flame-retardant polyurethane nanocomposites (FRPUN). Mechanical properties and LOI of PUs and nanocomposites have been evaluated. Results showed that increasing the hard segment (chlorine content) leads to the increase in flame retardancy and burning time. Addition of nanoclay to CPD-containing PUs leads to obtain self-extinguish PUs using lower CPD contents, higher Young's modulus, and strength without any noticeable decrease in elongation at break. Investigation of the TGA results showed that copresence of nanoclay and chlorine structure in the PU backbone can change thermal degradation pattern and improve nanocomposite thermal stability. X-ray diffraction and transmission electron microscopy studies confirmed that exfoliation and intercalation have been well done.

Recycling of polyethylene terephthalate (PET) by aminolysis breeds environmental benefits. In this work Polyethylene terephthalate in the form of waste fibers were subjected to depolymerization through aminolysis using excess amount of ethanolamine in the presence of sodium acetate, as catalyst. Obtained product, bis (2-hydroxy ethylene) terephthalamide (BHETA) was in its pure form with sufficiently high yields. The purified product was characterized by FTIR, 1 HNMR and 13 CNMR spectroscopy as well as melting point determination. Since catalyst and raw materials have low price, synthesis of this material is economical and could be used as diol to synthesis of polyurethanes. In this search, polyurethanes have been synthesized based on BHETA, HDI and polyethylene glycol via prepolymer method. Termogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) were carried out to study thermal stability, thermal transitions, T m and T g of synthesized polyurethanes. Effect of BHETA content in the main chain of synthesized polyurethanes on thermal stability of polyurethanes, strength and stiffness has been evaluated. BHETA based polyurethanes show Young's modulus about 300 MPa and elongation at break as 130% due to its aromatic structure.

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