A multicomponent bimodal poly(vinyl acetate) (PVAc) polymer composite has been scientifically designed to increase biaxial plastic flow stabilization for the achievement of large biaxial deformations. For this, a systems-based approach was used for the computational materials design of a high performance bubblegum whose mean in-vivo bubble diameter exceeds that of its predecessor by 50% and is capable of inflation to diameters up to ~11 inches. Furthermore, the designed bubblegum has bubble diameters comparable or greater than those of more complex, empirically developed, commercial bubblegums. The relatively simpler bubblegum contains a bimodal PVAc molecular weight distribution (MWD) which imparts optimal biaxial flow stabilization through the use of a parametrically designed molecular weight ratio (MWR) and high molecular weight (HMW) fraction. The HMW portion of the PVAc gum base strain hardens during plastic deformation for the stabilization of uniform biaxial plastic flow. A parametric thickness reduction model was developed from a literature survey of PE film blowing technology for the design of PVAc MWR and HMW fraction in bimodal PVAc gum base. A secondary model describing the effects of gum base composition on gum viscosity was developed for the constraint of bimodal PVAc bubblegum designs to acceptable chew viscosities. These models were combined in the computational systems design of bubblegum prototypes. In-vivo gum performance was characterized and mechanistically correlated to constitutive uniaxial exponential strain hardening behavior in gum base. A model was developed which indicates a transition from unstable to stable biaxial plastic flow at a uniaxial strain hardening parameter (k = 1/σ*dσ/dε) of ~1.5 and indicating an onset of fracture mediated plastic flow at k-values above ~4.5. More directly, stabilizing exponential biaxial flow behavior was demonstrated using a semi-(in vitro) biaxial inflation technique. Conceptual alternative molecular architectures were also investigated for the potential development of novel gum base systems. In this work, characterization was performed on two block copolymers with potential for enhanced biaxial strain hardening. Both systems demonstrated potential but were found to ultimately be insufficient for use as gum base additives for biaxial flow stabilization.

Last modified

• 09/18/2018

Creator

• Leslie Dale Morget

DOI

• https://doi.org/10.21985/N2C723

Subject

• Materials Science and Engineering

Keyword

• Engineering

Date created

• 2008-11-25

Resource type

• Dissertation

Rights statement

• In Copyright