Quantity of cross‐linking units of polychloroprene from swelling data

Kawasaki, Nobuhiro; Hashimoto, Tsutomu

doi:10.1002/pol.1973.170110315

Cited by 7 publications

(3 citation statements)

References 4 publications

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“…This value is close to χ 1 = 0.31 which was reported for CR in benzene with δ C6H6 = 18.8 $\left( {{\rm MPa}} \right)^{{{\rm 1} \mathord{\left/{\vphantom {{\rm 1} {}}} \right.\kern-\nulldelimiterspace} {}}{\rm 2}}$ 40. Table II contains the values of volume fraction, molar volume, interaction parameter, crosslink density, and the Young's modulus found for CR and all concentrations of CR NC.…”

Section: Resultssupporting

confidence: 83%

On the swelling of polychloroprene‐MMT nanocomposite films

Soriano‐Luna

Núñez‐Pérez

Estrada

2012

J of Applied Polymer Sci

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For the first time, the effects on the percentage of swelling of fifteen solvents on latex polychloroprene (CR) nanocomposite (NC) films, and typical physical properties were studied. These films were prepared with 2.5, 5.0, 7.5, and 10.0 phr of montmorillonite (MMT) dispersed in water. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results exhibit both exfoliated and intercalated layers in NC films. It was found that the Young's modulus and hardness increased with the MMT content. Calculations of the crosslink density were used to evaluate the effect of MMT concentration on the percentage of swelling. It was observed that in chloroform CR films showed the maximum swelling and it is therefore the best solvent to calculate the Flory-Huggins polymer-solvent interaction parameter as well as the crosslink density. To find the Flory-Huggins polymer-solvent interaction parameter, it was preferred to use the Hoftyser and Van Krevelen polychloroprene solubility parameter of 19.2 (MPa) 1/2 (calculated from the molar attraction constants) instead of using the swelling master curve which is not accurate. In all NC films, swelling by organic solvents was reduced by the addition of MMT. The increasing crosslink density with MMT suggests that dispersed clay emulates chemical bonds by hindering solvent migration throughout the polymer matrix and reducing solvent penetration.

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Section: Resultssupporting

confidence: 83%

On the swelling of polychloroprene‐MMT nanocomposite films

Soriano‐Luna

Núñez‐Pérez

Estrada

2012

J of Applied Polymer Sci

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“…Typically thioureas are used in combination with zinc oxide to effect cure. The accepted mechanism for curing involves reaction of thioureas and zinc oxide at the primary allylic chloride moiety that was formed by sn i 0 rearrangement during polymerization or curing (111,112). Thio ureas such as ethylene thiourea initially react with the primary allylic chloride to yield the thio ether.…”

Section: Commercial Conversion Of Raw Polymers To Final Vulcanizatesmentioning

confidence: 99%

Polychloroprene

Glenn¹

2004

Kirk-Othmer Encyclopedia of Chemical Technology

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The active center of the chain transfer agent reacts with the growing chain to stop further chain propagation. A new free radical, A, is formed from the Vol. 0 POLYCHLOROPRENE POLYCHLOROPRENE Vol. 0Chloroprene-Sulfur Copolymerization. The high reactivities of chloroprene and dichlorobutadiene permit copolymerization with sulfur to yield toluene-insoluble and partially gelled copolymers of high molecular weight. Gelled polymers are highly crosslinked polymers that are insoluble in toluene.In solution or aqueous emulsion polymerization, a growing polychloroprene radical reacts with rhombic (nonpolymeric) sulfur (24) or suitable sulfur donors such as 1,2,3,4-tetrasulfocyclohexane (25) or polysulfides (26) to yield a copolymer. Reaction with elemental sulfur involves cleavage of the eight-membered sulfurGraft Polymerization. Graft polymerization is related to block copolymerization. A block copolymer contains long sequences of two monomers (ie, AAA monomer blocks followed by BBB monomer blocks) along the copolymer chain. Graft copolymers consist of long chains of one monomer with occasional branches consisting of long chains of a second (grafted) comonomer. The branched points are normally formed by allylic atom (typically hydrogen) abstraction by free-radical initiators (eg, peroxides) to yield a resonance-stabilized free radical. The free radical initiates the addition polymerization of a second monomer beginning at the locus of the free radical. Generally grafting is performed to significantly modify polymer properties. In the production of emulsion-polymerized acrylonitrilebutadiene-styrene tripolymer, styrene and acrylonitrile are grafted onto rubbery polybutadiene to improve compatibility between the thermoplastic and rubber matrix used in impact modification (12). Methyl acrylate, acrylonitrile, alkyl methacrylates (eg, methyl, octyl, lauryl), fumaronitrile, methacrylic acid, and dichlorobutadiene have been employed in solution and emulsion graft polymerization with polychloroprene. Generally, solvent resistance, heat resistance, and Vol. 0 POLYCHLOROPRENE 7 POLYCHLOROPRENE Vol. 0 POLYCHLOROPRENE Vol. 0 POLYCHLOROPRENE Vol. 0 9.5. Latex Applications. A good way to remember the applications for latex is to follow the first six letters of the alphabet. A ¼ adhesives, B ¼ binders, C ¼ coatings, D ¼ dipped Goods, E ¼ elasticizers, and F ¼ foam. Vol. 0 POLYCHLOROPRENE 25

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“…6 However, it has been shown that ZnO is capable of promoting the formation of cross-links within the gumstock and therefore acts as a curing accelerator in its own right. [7][8] A number of mechanisms have also been proposed for the mode of action of ETU, with supporting analytical evidence supplied in each case. 9 The precise manner in which ETU accelerates the cross-linking of polychloroprene is of interest scientifically and because of the toxic nature of the compound.…”

Section: Introductionmentioning

confidence: 99%

Mechanism for Cross-Linking Polychloroprene With Ethylene Thiourea and Zinc Oxide

Berry

Liu

Chakraborty

et al. 2015

Rubber Chemistry and Technology

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An investigation into the mechanism by which ethylene thiourea (ETU) cross-links polychloroprene in combination with zinc oxide (ZnO) was undertaken. This was achieved through an examination of the mechanisms of cross-linking polychloroprene rubber (CR) with ETU and ZnO separately and in unison. Spectroscopic and physical characterisation techniques were employed to probe the cross-linking mechanisms of CR using other standard rubber accelerators and model compounds with analogous structures and functionalities to ETU. These investigations have resulted in the proposal of a new mechanism by which ETU and ZnO can synergistically cross-link polychloroprene, in addition to providing new evidence to support concomitant mechanisms already published for cross-linking polychloroprene.

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Quantity of cross‐linking units of polychloroprene from swelling data

Abstract: In general, the vulcanization of polychloroprene is said to proceed by a combination reaction between two 1,a-units containing ally1 halides in the presence of a metal oxide, e.g., ZnO or MgO; the reaction mechanism is presumed to be as shown in eqs. (1)-(3).

Cited by 7 publications

References 4 publications

On the swelling of polychloroprene‐MMT nanocomposite films

On the swelling of polychloroprene‐MMT nanocomposite films

Polychloroprene

Mechanism for Cross-Linking Polychloroprene With Ethylene Thiourea and Zinc Oxide

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