Effects of Polybenzoxazine on Properties of Shape-Memory Polyurethanes with Glassy and Crystalline Soft Segments

Shape memory polymers (SMPs) have attracted significant attention from both industrial and academic fields because of their useful and fascinating functional preperties. Of particular interests are shape memory polyurethane (SMPUs), which have strong potential in biomedical and consumer applications. However, some factors, such as low values of recovery stress (RS), recovery ratio (RR), and low transition temperature (Ttrans), limit their applications. Researchers focused on improving the shape-memory properties mainly by incorporating nanofillers and chemical additives. In the current study, a typical polybenzoxazine (PB) formulation was incorporated in SMPUs in order to augment the shape memory properties of SMPU. The thermal transition temperature was determined by the glassy or crystalline soft domain of polyurethanes (PU) with respectively glass transition temperature (Tg) or melting temperature (Tm). The study exploited the miscibility of the benzoxazine monomer with the PU prepolymer. The benzoxazine monomer was polymerized into PB after PU prepolymer was chain extended. The materials covered in this study were divdied into two classes, Tg-based SMPU (System I) and Tm-based (System II), respectively for glassy and rubbery soft segments. In System I, benzoxazine was blended with the Tg-based PU prepolymer derived from 4,4'-methylenebis (phenyl isocyanate) ¬¬¬¬¬(MDI) and poly(tetramethylene)glycol (PTMG) with average molecular weight of 650 g/mol. These materials showed an increase of soft segment Tg from 10 °C for PU to 70 °C for PU/PB system with ~12 wt% PB. Such an increase in Tg also induced the shape memory behaviors in PU/PB compounds at room temperature. The presence of PB also significantly improved the value of RR, PB which is attributed to acting as additional hard domains in PU matrix. In System II, the effect of PB on Tm-based PU series prepared from MDI, 1,4-butanediol (BD) and poly(caprolactone)diol [Mw ˜ 4000 g mol-1] was examined. The sample with 8.8wt% of PB produced the RS and RR values of 1.8 MPa and 98.0% respectively, compared to RS of 1.0 MPa and RR of 94.1% for pristine PU.

Name thesis:degree_name

Master of Science in Polymer Engineering

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Polymer Engineering

Grantor dc:publisher

University of Akron

Year dc:date

2013

Author dc:creator

• Gu, Senlong

Contributors dc:contributor

• Jana, Sadhan

• Polymers

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=akron1365700744

OAI identifier oai:identifier

oai:etd.ohiolink.edu:akron1365700744