Etude comparative de la chloration des polyethylenes lineaire et ramifie

Quenum, Bienvenu-Magloire; Berticat, Philippe; Pham, Quang Tho

doi:10.1016/0014-3057(71)90021-8

Cited by 16 publications

(9 citation statements)

References 9 publications

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“…!Cl-CHC1-) structures are present in large amount in the chains of the photochlorinated (branched) CPE samples or the photochlorinated (linear) CPE samples 5 and the thermal-chlorinated (linear) CPE samples, which indicates that PVC heterotactic tetrads TTGT, TTG'T, and TTTG, and PVC syndiotactic sequences TTTT were present in large quantity when the PVC sequences reached their maximum length (Figures 1 and 3).…”

Section: Injfuence Of the Chlorination Time Up To The Maximum Chlorinmentioning

confidence: 98%

“…5 The characteristics of this mechanism are: the decrease of the DP n; the increase of the ratio, nb CHCljnb CH2 , while the ratio, CljC, is still constant and equal to 1. the decrease of the proportions of am, f3m, and f3u structures while those of au and a 1 increase. 5 This mechanism is a rearrangement one: As poly(vinylidene chloride) (PVDC) structures cannot be changed into au structure by photochlorination at room temperature 6 the steps ( 1) ( l ') are the more likely to occur. This rearrangement mechanism takes place at room temperature only with the CPB samples produced from a branched polyethylene.…”

Section: Influence Of the Chlorination Time Beyond The Minimum Schedumentioning

confidence: 99%

“…7 The extension of the chlorination time beyond the minimum scheduled chlorination time necessary to obtain the 73-% chlorine content level. 5 The chlorination method. 7 The chlorination temperature.…”

Section: I Imentioning

confidence: 99%

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Chlorinated Polyethylene. II. Mechanisms of Chlorination

Quenum

Berticat

Vallet

1975

Polym J

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ABSTRACT:The present paper deals with the mechanisms of photochlorination and thermal chlorination of polyethylene as influenced by the microtacticity evolution of the polymer under chlorination. The investigations have been carried out on a branched low-density polyethylene and a linear high-density polyethylene, both chlorinated under various conditions which enabled us to study the influences of the chlorination time, the chlorination temperature, the chlorination method, the solvents used, etc., on the mechanisms of chlorination. The high-resolution nuclear magnetic resonance analyses published elsewhere,5•6,12 the infrared spectroscopy,8 the ratios (Cl/C), and (number of CHCl units/number of CH2 units) and the degree of polymerization are the main results discussed.

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Section: Injfuence Of the Chlorination Time Up To The Maximum Chlorinmentioning

confidence: 98%

Section: Influence Of the Chlorination Time Beyond The Minimum Schedumentioning

confidence: 99%

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Chlorinated Polyethylene. II. Mechanisms of Chlorination

Quenum

Berticat

Vallet

1975

Polym J

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“…5 Those chlorinated at saturation level (73-% Cl2): i.e., branched polyethylene samples (type Ila) and linear polyethylene samples (type Ila') photochlorinated at 20°C in carbon tetrachloride (CCl4) during 4-6-8 hr; 7 branched polyethylene samples (type lib) and linear polyethylene samples (type Ilb')photochlorinated during 4 hr at 20°C; 40°C; 60°C 8 …”

Section: Methodsmentioning

confidence: 99%

“…All the experimental CPE samples of type II used in the isothermal process were fractions of the highest number-average molecular weight (HMn) obtained by fractionation of the initial samples in a 70/30 mixture of tetrahydrofuran and methyl alcohol at room temperature. 7 For each experiment, isothermal or dynamic, 20 mg of powdered CPE sample were used. All the experiments were conducted in nitrogen atmosphere; the rate-flow of the gas through the sample and the reference tubes ( Figure 1) was 6 ljhr.…”

Section: Thermogravimetric Studiesmentioning

confidence: 99%

Chlorinated Polyethylene. III. Relationships of Microstructure and Thermal Properties

Quenum

Berticat

Vallet

1975

Polym J

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ABSTRACT:The thermal properties (viz., second-order transitions, melting points, dynamic and isothermal heat behaviour) of chlorinated polyethylene (CPE) samples are studied here. Thermomechanical analysis (TMA), differential thermal analysis (DTA), and thermogravimetric analysis (TGA) results are listed together to correlate the thermal properties and the microstructure of CPE samples, of various chlorine contents by weight, produced from thermal chlorinated or photochlorinated linear and branched polyethylene samples. The dehydrochlorination rate of a CPE sample is shown to be strongly dependent on its microtacticity up to a 56-61-% chlorine content by weight value· Beyond this 56-61-%Cb interval the microtacticity influence is screened by the steric hindrance introduced by the err (-CHz-C!:!Cl-CCb-or -CHCl-C!:!Cl-CCb-), an -CHCl-C!:!Cl-CHCl-or -CHz-C!:!Cl-CHCl-), and [3n (-CHCl-C!:!z-CCb-) structures. At the saturation level (73-% Clz), the higher a CPE ratio, nb CHCllnb CHz, is, the lower is its maximum dehydrochlorination rate. When its ratio, nb 2 CHCllnb CHz, is less than 4, a saturated (73%) CPE sample has a unique global dehydrochlorination activation energy (Ea); when this ratio stands between 4 and 6, there are two global dehydrochlorination E.. The structures which could be regarded as responsible for these different global Ea and the second-order transitions are specified.KEY WORDS Chlorinated Polyethylene I Thermomechanical Analysis I Differential Thermal Analysis I Thermogravimetric Analysis I Second-Order Transitions I Maximum Dehydrochlorination Rate I Very few studies have been published about the thermal properties of CPE. The first one, made by Oswald and Kubu 1 dealt with glass-transition temperatures (Tg)· Era and Lindberg 2 showed the effect of heat treatment on crystallinity. Abu I sa 3 studied the dechlorination mechanism and the effect of added antimony oxide on the rate of dehydrochlorination. Saglio, et at., 4 studied the degradation of saturated (73 %) CPE and showed that fibers of saturated CPE can be used as a carbon fiber precursor.relate their microstructure and thermal properties in this paper.In carbon backbone high polymers secondary transitions can be detected besides the main second-order transition, i.e., the glass-transition temperature (T g), and the main first-order transition, i.e. the solid-liquid-transition or the melting temperature. They are:(1) The secondary second-order transitions occuring, generally, at temperatures less than Tg. They are related to the motion of short segments of the polymer's backbone (viz., branchings, substituants, "crankshaft" or "kink" mechanisms11'12) related to motions in the amorphous or crystalline phase.The CPE samples used for the above studies were, generally, commercial ones supplied without the specific conditions of their preparation which are required 5 to correlate microstructure and properties. In addition, their microstructural characterizations have been made only with infrared analysis, which is not sufficient.Since we have...

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Polymer Reactions

Cheng

2007

Encyclopedia of Magnetic Resonance

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Etude comparative de la chloration des polyethylenes lineaire et ramifie

Cited by 16 publications

References 9 publications

Chlorinated Polyethylene. II. Mechanisms of Chlorination

Chlorinated Polyethylene. II. Mechanisms of Chlorination

Chlorinated Polyethylene. III. Relationships of Microstructure and Thermal Properties

Polymer Reactions

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