Reactive, intumescent, halogen‐free flame retardant for polypropylene

Abstract

A reactive, intumescent, halogen-free flame retardant, 2-({9- [(4,6-diamino-1,3,5-triazin-2-yl)amino]-3,9-dioxido-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecan-3-yl}oxy)ethyl methacrylate (EADP), was synthesized through a simple three-step reaction from phosphorus oxychloride, pentaerythritol, hydroxyethyl methacrylate, and melamine. EADP exhibited excellent thermal stability and char-forming ability, as revealed by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The TGA results show that the temperature at 5% weight loss was 297.8 C and the char yield at 700 C was 51.75%. SEM observation revealed that the char showed a continuous and compact surface and a cellular inner structure with different sizes. Composite of polypropylene (PP) with a 25 wt % addition of EADP (PP/EADP25) passed the UL-94 V-0 rating and showed a limiting oxygen index value of 31.5. Compared with those of neat PP, the flexural strength and modulus values of PP/EADP25 were somewhat improved, the tensile strength was basically unchanged, and the notched Izod impact strength was slightly decreased. V C 2013 Wiley Periodicals, Inc. J. Appl.Polym. Sci. 2014, 131, 40054.

Crystallization, melting behavior, and crystal structure of reactive, intumescent, flame‐retardant polypropylene

“…Furthermore, the T co and T cp values of the PP/EADP‐30 composite were higher than those of PP/MAPP‐30 by 4.86 and 4.57°C, respectively; this indicated that EADP was more beneficial for heterogeneous nucleation. Because a considerable number of EADP could be bonded to the PP chains during reactive blending and afford good compatibility between PP and EADP, this reduced the free energy of the nucleation process and increased the rate of crystallization …”

“…In particular, β‐form crystals, which have the potential to improve the impact toughness, were formed in the PP/EADP composites . As a result, the PP/EADP composites not only had excellent flame‐retardant properties but also presented good comprehensive mechanical properties …”

“…PP (F401), with a melt flow index of 2.3 g/10 min (230°C/2.16 kg), was obtained commercially from Luoyang Petrochemical Co., Ltd. EADP was synthesized according to a procedure in the literature, and its chemical structure is shown in Figure . A commercial ammonium polyphosphate coated by melamine resin (MAPP), with an average degree of polymerization greater than 1000 and purchased from Puyang Chengke Chemical Technology Co., was used for comparison.…”

“…Composites of PP with EADP (PP/EADP) were prepared through reactive blending. A detailed investigation showed that the PP/EADP composites had good mechanical properties and outstanding flame retardancy . It is well known that the nonisothermal crystallization, melting behavior, and crystal structure of polymer materials are closely related to their molding processes and mechanical properties .…”

Flame-Retardant and Thermal Degradation Mechanism of Caged Phosphate Charring Agent with Melamine Pyrophosphate for Polypropylene

“…Meanwhile, the increased band at about 1620 cm −1 was ascribed to C=C structure [24,25], which was also produced by PEPA and could promote the formation of thermostable residue [19]. When the temperature reached up to 400 ∘ C, there was a new peak around 1100 cm −1 appearing, which corresponded to P-N absorption [26], indicating that the phosphorus-containing compounds could further crosslink with the triazine oligomer produced by MPP [3,27]. With the further increase of pyrolysis temperature, the intensities of the bands at 3200-3500 cm −1 ( N-H and O-H ) decreased gradually and nearly disappeared at 550 ∘ C to 650 ∘ C. However, the bands at 1075 cm −1 ( P-O-C ), 1100 cm −1 ( P-N ), and 1485 cm −1 ( C=N ) were almost invariable.…”