Shape memory behaviour

NixAlj x (homogeneous between 42 and 69 at.% Ni) with good mechanical and oxidation resistance properties. By quenching from high temperatures the formation of an ordered martensite is obtained which can be considered for its shape memory behaviour. For a discussion on substitutional additions to CsCl-type alloys (site preference for dilute additions to NiAl, FeAl, CoAl, etc.) see Kao et al. (1994). 

Zhu, G., Xu, S., Wang, Zhang, L., Shape memory behaviour of radiation-crosslinked PCL/PMVS blends. Radiation Physics and Chemistry 2006, 75, 443 48. 

Other industrial applications include the fabrication of two-part epoxy resins (similar to those commonly found in household maintenance stores) [95-97], These were synthesized using triglycerides and diamines. These resins are often used as adhesives these have also been studied using soybean oil, which provided beneficial properties in terms of fast curing, thermal stability and ease of removal (peel strength) [98], A blend of divinylbenzene/styrene/tung oil mix gave a polyurethane-based material which behaved like a smart polymer with shape memory behaviour [66]. 

Diani, J. and Gall, K. (2007) Molecular dynamics simulations of the shape-memory behaviour of polyisoprene. Smart Materials and Structures, 16, 1575-1583. 

Gianoncelh, A., Brisotto, M., Bontempi, E., and Ricco, T. (2013) One-way and two-way shape memory behaviour of semi-crystalline networks based on sol-gel cross-linked poly(e-caprolactone). Polymer, 54 (16), 4253-4265. 

Table 3 Effect of theophyUine (TP) loading on the thermal properties and shape-memory behaviour of oligo( -caprolactone) octole (oCl) derived covalent networks with a differences in the degree of polymerisation (DP) of the precursor arms. Adapted with permission from [40], Copyright 2009, American Chemical Society...

Smola Anna, Dobrzynski Piotr, Cristea Mariana, et al. Bioresorbable terpolymers based on L-lactide, glycoUde and trimethylene carbonate with shape memory behaviour. Polym. Chem. 5 no. 7 (2014) 2442-2452. 

Swain M V, Shape memory behaviour in partially stabilized zirconia ceramics . 

Shape memory materials (SMMs) comprise a class of smart materials able to change their shape following application of an external stimulus. The first materials studied with shape memory behaviour were developed in the middle of the twentieth century. Since then, research into and demand for these materials have both increased, especially in recent years, due to their unique properties, versatility and growing industrial demands. Figure 7.1 shows the total number of scientific publications indexed on ISI Web of Knowledge and the number of research articles about shape memory polymers (SMPs) in the last 30 years in particular, the increase during the last six years is significant. 

ISI publications referring to polymers with shape memory behaviour. (Source ISI Web of Knowledge.)... 

As mentioned above, PLA is a thermoplastic polymer with shape memory behaviour. This polymer can be used as co-monomer with the aim of improving its properties. For instance, copolymers from lactic acid with gly-coUc add (i.e., poly(lactic-co-glycolic add) (PLGA)) (Meng et al, 2009) or -caprolactone (to form poly(I lactide-co-e-caprolactone) (PCLA))(Lu dfl/.,2008) present better shape memory behaviour than the PLA homopolymer. Other copolymers like poly(ethylene oxide) (PEO) with poly(ethylene terephthalate) (PET) have been studied (Luo et /., 2000). In this copolymer PEO is the switching phase with transition temperature between 40°C and 50°C and PET is the fixity phase. 

Blending is a good technique to obtain new polymeric materials and to enhance polymer properties such as thermal behaviour, mechanical properties, etc. Moreover, blending is an easy process to implement at the industrial level (Meng and Hu, 2009). For these reasons it is interesting to develop SMP blends. There are different methods to obtain polymer blends with shape memory behaviour that can be classified in two groups miscible and immiscible blends. 

Light activation has a significant advantage in comparison with the thermal shape memory behaviour,as photo-activation does not produce tissue damage as could be produced by heat treatments. Ihis fad makes light activation attradive... 

Bianchi, M., Scarpa, F.L. and Smith, C.W. (2010) Shape memory behaviour in auxetic foams Mechanical properties. Acra Marmata, 58, 858-865. 

Lin, J. R., Chen, L. W. (1998), Study on shape-memory behaviours of polyether-based polyurethanes. Part I Influence of the hard-segment content, J. Appl Polym. Sci., 69, 1563-74. 

Thermally-induced shape memory behaviour of BIN-SMPUs... 

---