About crosslinking of low molecular weight ethylene‐propylene(‐diene) copolymer‐based artificial latices

Abstract

Crosslinking of artificial latices based on ethylene-propylene copolymers (EPM) and/or ethylene-propylene-diene copolymers (EPDM) has not thoroughly been studied yet. Moreover, crosslinking of EPM and/or EPDM particles is a prerequisite for the formation of a shell using seeded emulsion polymerization of, for example, methyl methacrylate (MMA), as described elsewhere. Therefore, the aim of this article is to improve the general understanding of the chemistry involved in the crosslinking process. This work especially emphasizes the influence of the initiation method, that is, a peroxide or a pulsed electron-beam, on crosslinking efficiency. All crosslinking efficiencies were obtained after extraction of the soluble polymer by tetrahydrofuran. The incorporation of the coagent, that is, divinylbenzene, into the EPM/EPDM phase was studied on a microscopic level by solid-state 13 C and 1 H nuclear magnetic resonance (NMR). Crosslinking of a low molecular weight EPM/ EPDM latex requires the presence of a coagent, for example, divinylbenzene, 1,6-hexanediol diacrylate, or poly(1,2-butadiene). The efficiency of crosslinking initiated by a pulsed electron-beam was improved to a great extent by the presence, in the aqueous phase, of potassium nitrosodisulfonate, also referred to as Fremy salt. Matrix Assisted Laser Desorption/Ionization-Time of Flight-Mass Spectrometry (MALDI-TOF-MS) was used to determine the influence of electron-beam irradiation on the chemical stability of surfactants. It was demonstrated that sodium dodecyl benzene sulfonate (SDBS) is not degraded by the irradiation, and is therefore the surfactant of choice for the stabilization of EPM/EPDM-based latices subjected to electron-beam irradiation. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3600-3615, 2005

Segmental Mobility in the Non‐crystalline Regions of Semicrystalline Polymers and its Implications on Melting

“…Spin-spin relaxation is a better measure for polymer chain motion than the spectral line shape, because the latter is also broadened by other mechanisms, which are eliminated in the Hahn-echo experiment. 1 H NMR T 2 relaxometry is therefore a regular tool to determine entanglement-and crosslink density in rubbers, [29,30,31,32] and polymers melts. [33,34] At T ) T g chain mobility at timescales <10 À3 s is controlled by chemical crosslinks and physical entanglements with lifetimes >10 À3 s. For simplicity of data analysis it is assumed that polymer motions can be divided into fast and slow dynamics compared to 10…”

The role of the amorphous phase in melting of linear UHMW-PE; implications for chain dynamics

“…Spin-spin relaxation is a better measure for polymer chain motion than the lineshape, because the latter is also broadened by other mechanisms, which are eliminated in the Hahn-echo experiment. 1 H NMR T 2 relaxometry is therefore a regular tool to determine entanglement and cross-link density in rubbers [24][25][26][27] and polymer melts [28,29]. At T T g chain mobility at timescales < 10 −3 s is controlled by chemical cross-links and physical entanglements with lifetimes > 10 −3 s. The underlying assumption is that polymer motions are divided into fast and slow polymer motions at the 10 −3 s timescale without significant intermediate fraction.…”

About morphology in ethylene–propylene(-diene) copolymers-based latexes

“…Two homogenizer products were submitted to a crosslinking reaction, as described elsewhere [13], prior to the grafting experiment, giving rise to latexes S2 and S3. Crosslinking was performed using benzoyl peroxide (BPO) as initiator.…”