Preparation and characterization of microencapsulated polythiol

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, OFCM Institute, School of Chemistry and Chemical Engineering, Zhongshan University, Guangzhou 510275, PR China
Polymer (Impact Factor: 3.56). 05/2008; 49(10):2531-2541. DOI: 10.1016/j.polymer.2008.03.044


Microcapsules containing curing agent for epoxy were successfully prepared by in situ polymerization with poly(melamine–formaldehyde) (PMF) as the shell material and high-activity polythiol (pentaerythritol tetrakis (3-mercaptopropionate), PETMP) as the core substance. Having been encapsulated, the core material PETMP had the same activity as its raw version. The synthesis approach was so improved that the consumption of polythiol was reduced to a low level. By carefully analyzing the influencing factors including catalyst concentration, reaction time, reaction temperature, feeding weight ratio of core/shell monomers, dispersion rate and emulsifier content, the optimum synthetic conditions were found out. The results indicated that not only core content and size of the microcapsules but also thickness and strength of the shell wall can be readily adjusted by the proposed technical route. The relatively thin shell wall (∼0.2 μm) assured sufficient core content even if the microcapsules were very small (1–10 μm). The polythiol-loaded microcapsules proved to be qualified for acting as the mate of epoxy in making two-part microencapsulated healing agent of self-healing composites.

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    • "The incorporation of 2.5 wt.% microcapsules significantly decreases the hardness of the epoxy composite without SCFs to about 198 MPa due to the much lower hardness of the microcapsules than that of the epoxy matrix. The increased microcapsule content to 10 wt.% further decreases the hardness of the epoxy composite to about 91 MPa [7] [11] [14] [16] [30] [31]. The increased microcapsule content from 2.5 to 10 wt.% consistently decreases the hardness of the epoxy composites with 8 wt.% SCFs from about 373 to 241 MPa. "
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    ABSTRACT: The effects of wax lubricant filled microcapsule content on the tribological properties of epoxy composites without or with 8 wt.% short carbon fibers (SCFs) were systematically investigated. The core percentage of the microcapsules used in this study was about 70 wt.%. The tribological results clearly showed that the friction and wear of the epoxy composites without or with SCFs tested against a 6mm steel ball significantly decreased with increased microcapsule content from 2.5 to 10 wt.% as a result of the increased amount of released wax lubricant to lubricate rubbing surfaces. The epoxy composites with 8 wt.% SCFs exhibited the lower friction and wear than the ones without SCFs due to the combined lubricating effects of SCFs and released wax lubricant and the improved mechanical strength of the composites. It can be concluded that the higher microcapsule content gives rise to the lower friction and wear of the epoxy composites as the epoxy composites with 8 wt.% SCFs have the better tribological performance than the ones without SCFs.
    Full-text · Article · Oct 2014 · Journal of Applied Mechanics
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    • "During unloading, the portion mainly represents the elastic behavior with elastic displacement being recovered [5] [15].The displacement is around 0.2 μm which is about the thickness of shell [14]. The displacement is small compared to the average microcapsule size of 50 to 100 μm. "
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    ABSTRACT: Nanoindentation is a widely used method for measuring the micromechanical properties of thin films and micro scale materials. Self-healing polymeric materials have the built-in capability to substantially recover their load transferring ability after damage. One of the main self-healing strategies incorporates microencapsulated healing agents within a polymer matrix to produce a polymer composite capable of self-healing. In this study, microcapsules containing, respectively, epoxy (resin) and mercaptan (hardener) were investigated with poly (melamine-formaldehyde) (PMF) as the shell material. The micromechanical behavior of microcapsules was tested using nanoindentation. The results show that the PMF shell material behaves as a viscoelastic plastic material. The modulus and hardness of the microcapsules were determined quantitatively. The size and loaded-component of microcapsules (i.e., hardener or resin) have a significant effect on the micromechanical properties of the microcapsules.
    Full-text · Article · Jun 2012 · Materials Letters
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    ABSTRACT: Not Available
    No preview · Conference Paper · Sep 1992
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