Determination of the Sequence Distribution of Chlorines in Chlorinated Polyethylenes with the Aid of Monte Carlo Simulation

Abstract

simulation was carried out to specify the most probable model sequence and to reveal the sequence distribution of chlorines in chlorinated polyethylene(CPE). The simulation was also applied to study those of hydrogenated poly-(vinyl chloride)(HPVC) and vinyl chloride-ethylene copolymer(VC-Et) for a comparison with those of CPE. The simulation was executed with the conditional probabilities of the second order defined in terms of the actual existence probabilities of triads which can be obtained by NMR spectroscopy. Monitor quantities relating to long methylene sequence and degree of chlorination were introduced into the simulation as a criterion of a convergence. When the convergence conditions were satisfied after a few trials, a linear model sequence composed of one thousand carbons was considered to be the most probable. From the inspection of the model sequence thus determined, it can be pointed out that the distribution of chlorine atoms along the CPE chain is substantially random, being different from those of HPVC and VC-Et. The sequence distribution of various chemical units in the molecular chain was also determined readily and quantitatively without any contradiction by reckoning each sequential unit along the model sequence.

Kinetics of the Solid-State Chlorination of High-Density Polyethylene

“…Dependence of the specific total volume of pores V R (1, 0) and the average pore walls thickness l av (2,9) on the degree of chlorination. Figure 8.…”

“…On this basis, the specific total pores volume V R (cm 3 N g -1 ) and the specific surface area (S m 2 N g -1 ) were calculated. According to Dzhagatspanjan, [21] the pores in the polymer particles can be regarded as a complicated network of tubular rings of wall thickness marked as l. The average thickness of the pore walls l av cm was determined as follows: [21] l av = 2 6 10 -4 /S.q (2) where q (g N cm -3 ) is the volume density of CPE determined at 296 K, according to the Bulgarian State Standard BDS ISO 1183. [22] Kinetic Processing of the Experimental Results…”

“…The chlorination in both the suspension and solid state results in macroscopic distribution, i. e., predominant chlorination in the polymer particles occurs, depending mainly on temperature. [2] In this case, chlorine atoms are localized in the amorphous as well as in the crystalline polymer regions, which in turn leads to the corresponding decrease of the degree of structural arrangement for the latter. [3 -6] Organic peroxides and hydroperoxides, azonitriles, Lewis acids, c-irradiation, UV-and sunlight irradiation, have all been employed as initiators of the chlorination process so far.…”

NMR Analysis of Stereo Regular Copolymers

“…Thus, in considering the conversion of a polymer containing A-units to one containing B-units~ the rate of the process and the relative amounts of the various structural features present at a given conversion may depe~d on the relat~ve reactivities of A-units centered in AAA (k ) ~ (~+AAB) (k 1 ) and ~ (k z ) triads. Theoretical [~4-4lJ~ numerical [42] and Monte Carlo methods [43][44][45][46][47] have been developed for calculating these various quantities from values of k o , kl and k z . In addition~ convenient methods for deducing k o , kl and kz from nmr spectral information are available [48,49].…”

Application of the Monte Carlo simulation method to the investigation of peculiar free‐radical copolymerization reactions: Systems with both reactivity ratios greater than unity (rA > 1 and rB > 1)

“…A review of the related literature reveals the importance of probability theories, particularly Monte Carlo methods, in the investigation of polymer properties, regardless of the limitations of other methods. [1][2][3][4] Monte Carlo methods have been proved to be powerful tools for modeling the compositional heterogeneities, molecular weight distribution, effects of depropagation reactions, crystallization, and rationalization of processes such as adsorption and premature phase separation. [5][6][7][8][9] However, they can simply be used in the case of very complex reactions, such as multicomponent copolymerization reactions, for which conventional methods require a high level of sophistication and include many simplifying assumptions.…”