Bulk copolymerization of 1,3,5-trioxane and 1,3-dioxolane in presence of phosphotungstic acid catalyst and tetrahydrofuran as retarder: crystallinity and thermal properties

Abstract

In this study, cationic ring opening in situ copolymerization of 1,3,5-trioxane (TOX) and 1,3-dioxolane (DOX) occurred during bulk polymerization in the presence of phosphotungstic acid as a catalyst. In another part of the study, copolymerization occurred in the presence of retarder tetrahydrofuran (THF), and its effect on the crystallization and thermal stability of the samples was also investigated. The findings from 1 HNMR spectrometry indicated that the synthesized samples of random acetal copolymer are comprised of an independent oxyethylene unit in an oxymethylene main-chain sequence. The findings from DSC indicated that crystallinity decreases with increasing comonomer content. Furthermore, the sample with retarder revealed greater crystallinity than the samples without retarder. From TGA results, it was revealed that the sample with retarder caused a larger quantity of comonomer to enter the chain and increased the thermal stability compared to the samples without retarder.

Preparation and characterizations of inherent flame retarded polyamide 66 containing the phosphorus linking pendent group

“…The crystallinity decreased from 34.58% for PA66 to 26.14% for FRPA66‐5. X c was calculated by Equation , where ΔH m is the melting enthalpy of FRPA66 samples measured by DSC and is the melting enthalpy of the 100% crystalline PA66 . The value of is 190.0 J·g −1 for PA66 …”

Study on Ring-Opening Copolymerization of Trioxymethylene and Second Monomer Initiated by Phosphotungstic Acid

“…In all three plots of Figure 2, the methylene proton signal (H a ) of the oxymethylene unit is observed at 4.89 ppm. The presence of the signal peak at 3.75 ppm in Figure 2(a) represents methylene protons in between two oxymethylene units (H b ), indicating the comonomer units have entered the oxymethylene chain successfully [28]. In Figure 2(b), the proton peak (H c ) of -OSi(CH 3 ) 2 is observed at 0.12 ppm [31].…”

“…The peak integral areas of the 1 H-NMR spectrum correlated to the number of each type of protons. Thus, the mole ratio of each monomer in the polymer chain can be calculated through the following [28]. The calculation results are shown in Table 1.…”

“…It would finally lead to the decomposition of POM. In comparison, the boron trifluoride initiating system and the heteropolyacid initiating system [27,28] can initiate polymerization at a smaller dosage. Thereby using this system benefits the posttreatment process.…”

Anionic copolymerization of nylon 6/12: A comprehensive review

“…Initiation by water, known as hydrolytic polymerization, is carried out in the industrial polymerization of ε-caprolactam (CL) to form nylon 6; however, it is seldom used for other lactams [2,[6][7][8][9]. Cationic initiation involving positively charged intermediate with acids has not interested many researchers due to the low conversion and the low-molecular weight of polyamides produced by this procedure [9][10][11][12][13][14].…”