Details

Autor(en) / Beteiligte

• van der Mee, Mark Adrianus Johannes

Titel

Thermoreversible cross-linking of elastomers: A comparative study between ionic interactions, hydrogen bonding and covalent cross-links

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2007

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Elastomers have to be cross-linked to obtain typical rubber properties, such as good elasticity, high toughness and solvent resistance. The main industrial rubber cross-linking techniques, i.e., sulfur vulcanization and peroxide curing, yield permanent (irreversible) chemical cross-links, which prevent melt (re)processing and result in time-consuming and, hence, expensive multi-step production processes. This has led to the development of thermoplastic elastomers (TPEs), which ideally combine the service properties of cross-linked elastomers with the melt processability of thermoplastics. The cross-links in TPEs are of thermoreversible nature: they weaken or disappear at elevated temperatures, thereby allowing flow, and behave effectively similar to permanent cross-links at service temperatures. This behavior allows the use of standard thermoplastic processing techniques, in particular extrusion and injection molding, resulting in short production times and lower production costs. The main objective of this study is to compare several alternative approaches for the thermoreversible cross-linking of the same precursor, i.e., maleated ethylene/propylene rubber (MAn-g-EPM). These methods include ionic interactions, (multiple) hydrogen bonds and covalent cross-links. The versatile and high reactivity of the grafted maleic anhydride groups allows the use of a variety of modification and cross-linking reactions. Structure-property and structure-processing relationships are established with the final objective to determine which thermoreversible cross-linking method(s) yield(s) the best property-processing balance. All reactions are initially performed via a solution route to obtain homogeneously cross-linked materials, while no processing oil or reinforcing fillers are added to keep the analysis as straightforward as possible. (Abstract shortened by UMI.)