Molecular and nanoscale reinforcement of polymers

2002 2002

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Abstract (summary)

The reinforcement of polymers using additives of dimensions below one micrometer is presented: those acting at the molecular and nanometer scales. This thesis will describe new additives and morphologies exhibiting high levels of mechanical reinforcement. It is the focus of this work to chronicle the range of physical and material properties that are altered upon inclusion of these modifiers. Additionally, this thesis will establish how these physical-property changes affect the mechanical behavior of the resulting composite.

In the area of molecular reinforcement, a new class of additive, the organophosphate, is shown here to enhance modulus and yield strength in epoxy polymers once cured. Initially, the effect on the physical and thermal properties of the polymer system is investigated as a function of additive molecular weight, solubility, and concentration. The altered properties include T g, density, thermal stability and initial epoxy viscosity. The mechanical properties of the modified epoxy are demonstrated to be a result of the physical changes made to the matrix polymer through the addition of the organophosphorous additive. By increasing the density of the polymer and reducing or eliminating sub-Tg relaxations, the modulus and yield strength of the polymer can be greatly enhanced. These property changes are investigated in a variety of epoxy polymer systems in order to elucidate the effects of both the additive and polymer chemical structure on final mechanical properties.

Polymer modification using nanometer-scale additives and modifiers has been the focus of intense study recently. Heretofore, these studies have focused on the exfoliated, or delaminated, clay morphology to impart the property enhancements, effectively isolating the particulates within the matrix. This thesis focuses on polymer modification at the nanometer scale such that the added clays interact and positively change the composite fracture toughness. By introducing this clay-clay interaction, modulus and strength can be increased together with the toughness. Such a property combination is highly desirable, as most toughening agents reduce modulus and strength. Initially, the intercalated morphology is investigated in an epoxy system. Additionally, new routes to synthesizing intercalated morphologies of clay concentrations approaching 50% are developed.

Indexing (details)

Materials science
0495: Polymers
0794: Materials science
Identifier / keyword
Applied sciences; Pure sciences; Epoxy thermoset; Nanocomposites; Nanoscale; Polymers; Reinforcement
Molecular and nanoscale reinforcement of polymers
Zerda, Adam S.
Number of pages
Publication year
Degree date
School code
DAI-B 63/10, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780493882154, 0493882154
Lesser, Alan J.
University of Massachusetts Amherst
University location
United States -- Massachusetts
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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