Effects of benzoxazine resin on property enhancement of shape memory epoxy: A dual function of benzoxazine resin as a curing agent and a stable network segment

• Published in: Express polymer letters 2015-09, Vol.9 (9), p.824-837
• Main Authors: Tanpitaksit, T., Jubsilp, C., Rimdusit, S.
• Format: Article
• Language: English
• Subjects: Aliphatic epoxy; Polybenzoxazine; Polymer blends and alloys; Shape memory polymers; Smart polymers
• ISSN: 1788-618X; 1788-618X
• DOI: 10.3144/expresspolymlett.2015.77

An ability of bisphenol-A/aniline based benzoxazine resin (BA-a) to simultaneously acts as a curing agent and a stable or rigid network segment for shape memory epoxy, i.e. a two component system, is demonstrated. This significantly simplifies a formulation of present shape memory epoxy systems, i.e. a three or four component system. A suitable content of BA-a in the aliphatic epoxy (NGDE)/polybenzoxazine (PBA-a) samples for good shape memory performance is in a range of 30 to 50 mol%. The storage modulus of the obtained NGDE/PBA-a shape memory polymers (SMPs) was increased from 3.57 GPa for 30 mol% BA-a content to 4.50 GPa for 50 mol% BA-a content. Glass transition temperature of the sample was also substantially increased with increasing BA-a fraction, i.e. from 51°C to 140°C. Flexural modulus and strength at room temperature of the samples at 50 mol% BA-a were found to be as high as 3.97 GPa and 132 MPa compared to the maximum values of 2.54 GPa and 100 MPa of SMP based on cyanate ester-epoxy. All samples exhibited a high value of shape fixity close to 100%. A presence of the BA-a in the samples also imparted a greater recovery stress ranging from 0.25 to 1.59 MPa. Consequently, the obtained NGDE/PBA-a copolymers are highly attractive for shape memory materials to be used in a broader range of applications particularly at elevated temperature and a higher recovery stress value.