Masters Theses

Date of Award

8-1994

Degree Type

Thesis

Degree Name

Master of Science

Major

Polymer Engineering

Major Professor

R.S. Benson

Committee Members

Donald Bogue, Maureen Dever

Abstract

Polypropylene (PP) and poly(vinyl alcohol) (PVOH) resins of varying degree of hydrolysis were mechanically blended. A (90/5) composition was blended with 5 and 10% polypropylene-grafted-maleic anhydride copolymer (g-PP). The blends were characterized by Differential Scanning Calorimetry (DSC), Tensile Testing, Dynamic Mechanical Analysis (DMA), Fourier Transform Infrared Spectroscopy (FTIR), and X- Rays Diffraction. Additionally, study of the morphology and examination of water uptake of the blended systems were conducted.

The study of thermal properties of the blended systems show a shift in the crystallization temperature (Tc) of PP towards higher temperatures. This change in the Tc of PP along with the growing of PP spherulites surrounding PVOH particles implies that the PVOH acts as a nucleating agent.

A change of PVOH content in PP/PVOH blends and the presence of water, affects both the mechanical and dynamic mechanical properties. The tensile strength and elongation to break of PP/PVOH blend systems, as well as the modulus for wet samples decrease with PVOH content, while an increase in the modulus of dry samples is observed with increasing PVOH content. Results of tensile tests and DMA suggest that water acts as a plasticizer in the blends.

The addition of g-PP promotes an enhancement of the mechanical properties of the blends and a finer dispersion of the PVOH particles in the PP matrix, which indicates that g-PP acts as a compatibilizing agent. FTIR spectra of the blends indicate formation of hydrogen bonding when g-PP is present in the systems.

Due to the fact that PVOH is a water-soluble polymer, blends of PP/PVOH have shown the ability to absorb water for certain periods of time, before partial or complete dissolution of PVOH occurs.

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