High-Resolution NMR Study of Chlorinated Polyethylenes

Abstract

High-resolution NMR spectra of chlorinated polyethylenes with various chlorine contents were measured on a-dichlorobenzene solutions at ca. 160°C. The chemical shifts for the resonances associated with the distribution of chlorine atoms along the polymer chain were resolved by the triad or pentad units, and content of the chemical units was quantitatively obtained. Chemical units containing geminal dichloride were observed when chlorine content approached ca. 40 wt %. The structure of chlorinated polyethylenes in the region of chlorine content below 40 wt% is characteristic of the statistically random distribution of chlorine atoms along the polymer chain. Various methylenes and methynes in various proton environments were observed, but chemical units such as vinylidene chloride sequences were not observed in the chain. It was found that a chlorination condition slightly affected the chlorine distribution, namely the solution chlorination increased vicinal-dichloride units rather than geminaldichloride units. However, the molecular weight of the parent polymer did not affect the chlorine distribution of chlorinated polyethylenes. The sequence-length distribution of methylenes was also obtained and the contents of longer methylene sequences (-(CH2)n-, were computed using the results of Frensdorff and Ekiner's theoretical treatment. KEY WORDS Chlorinated Polyethylenes I High-Resolution NMR I Assignment I Chlorine Distribution I Methylene-Sequence Length I a, w-Dichloroparaffins I Vinyl Chloride-Ethylene Copolymer I Hydrogenated Poly(Vinyl Chloride) I

Union production of low chlorinated polyethylene and chlorinated paraffin via a carbon tetrachloride solvent free process

“…The 1 H NMR spectra of LCPE1 and LCPE2 were recorded and presented in Figure 5. As shown in Figure 5, the chemical shift can be divided into two bands, i.e., from 1.2 to 2.2 ppm and from 3.8 to 4.2 ppm, corresponding to the proton resonances in CHCl and CH 2  group, respectively, since the first band is absent in polyethylene and thus is unique for LCPE 24, 25. On this basis, the chlorinity of LCPE1 and LCPE2 can be estimated from the corresponding 1 H NMR spectroscopy in terms of the integrated peak areas of the two bands.…”

“…As shown in Figure 5, the chemical shift can be divided into two bands, i.e., from 1.2 to 2.2 ppm and from 3.8 to 4.2 ppm, corresponding to the proton resonances in ACHClA and ACH 2 A group, respectively, since the first band is absent in polyethylene and thus is unique for LCPE. 24,25 On this basis, the chlorinity of LCPE1 and LCPE2 can be estimated from the corresponding 1 H NMR spectroscopy in terms of the integrated peak areas of the two bands. For example, the 1 H NMR integral area for ACHCl and ACH 2 A group is 2.822 and 19.927, respectively, for LCPE1, and thus the chlorine content is calculated as 36.25% by the following equation: where M CHCl and M CH 2 are molar mass of group ACHClA and ACH 2 A, respectively.…”

Unified production of chlorinated isotactic polypropylene and chlorinated paraffin via a solvent free chlorination process

“…In the assignment of the chemical shifts of CIPP, the 1 H-NMR spectra can be divided into three regions of d values which are named low magnetic fields (LMF) 3.4-4.2 ppm, middle magnetic fields (MMF) 1.4-2.5 ppm and high magnetic fields (HMF) 0.75-1.4 ppm. In LMF, the appearance of new peaks can probably be assigned to chlorine-substituted methyl and methylene proton resonances from the spectra of ethylene-vinyl chloride copolymers [28,29] and CPE [30]. For example, the line at about 3.7 ppm is ascribed to the À ÀCHClÀ À group formed by the chlorination of the syn proton [31].…”

Chlorine distribution and structure–property relationship of chlorinated polypropylene

“…(1)-(10) as follows: 4(0, 0, 0) = A (11) 4(0, 1, 0) = 4(0, 0, 1) = 4(1, 0, 0) = 1/2B + F + 1/2H ( The results obtained from eqs. (11)- (14) are summarized in Table VII, together with the mole ratio of primary, secondary, and tertiary chloride groups which were estimated from the values of 1/2H, 1/2B, and F, respectively.…”

“…Recently, high resolution proton magnetic resonance (PAIR) spectroscopy has been applied extensively to the characterization of chlorinated polyethylene (ClPE). [11][12][13] Frendsdorff and Ekiner13 provided an excellent theoretical treatment of the sequence distribution of substituted polymers with Markov transition probability and computed the triad probability and the block-length distribution of methylenes in ClPE. Saito, et all1 also reported quantitative results of various triads and the methylene-sequence distribution of ClPE.…”