In addition to the preparation of carbon nanotube (CNT)/epoxy shape memory composites, the thermo-mechanical
properties of the composites are focused on. Furthermore, the factors which would influence thermo-mechanical
properties of the composites are studied too. Four types of test were carried out, namely, differential scanning
calorimetry (DSC), dynamic mechanical analyzer (DMA) test, quasi-static tension test and shape memory behavior. The
results of DSC show that CNT decreases the glass transition temperature of the composites. From DMA test, a sharp
drop can be found in each composite, which indicates that the composites are typical shape memory polymer materials.
And elastic ratio of the composites decreases with increasing CNT content. Tensile test indicates that tensile strength
increases and then decreases with the increasing CNT content ranging from 1 wt% to 3 wt%. Study on shape recovery
behaviors of the composites showed that each composite can reach a shape recovery ratio near 99%.
As a novel smart material, shape memory polymer possesses the special thermo-mechanical property of shape memory
effect. Its shape memory effect is closely related to the glass transitions between the glass state and rubber state induced
by temperature changing. It is of engineering and theoretical meaning to investigate and describe the glass transition
behaviors of shape memory polymer. In this study the glass transition behaviors of an epoxy-based shape memory
polymer containing linear epoxy monomer are investigated using the tests of dynamic mechanical analysis. Results show
both glass transition critical temperatures and storage modulus at rubber state of the epoxy-base shape memory polymer
decrease as the content of linear monomer in such material increases. However the transition temperature width increases
as the linear monomer content increases. A new glass transition model is supposed to describe the glass transition
behaviors of epoxy-based shape memory polymer based on the experimental results. Numerical simulations show that
the new glass transition model well predicts the glass transition behaviors of the epoxy-based shape memory polymer
containing linear epoxy monomer.
As a new class of smart material, shape memory polymer (SMP) receives more and more attention. In this paper, in
addition to the fabrication of a new type of epoxy SMP, the thermo-mechanical properties of the polymer with/without
gamma irradiation were investigated and compared systematically. The radiation source is Co-60 and the total dosage of
radiation is 1×104Gy. Changes of network structures of the polymer were investigated by Fourier Transform Infrared
(FTIR) spectroscopy. The influence of gamma irradiation on thermo and mechanical properties of the polymer were
investigated by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and tensile test,
respectively. Furthermore, shape recovery behaviors of the polymer before/after the irradiation were compared too.
Results show that the epoxy SMP possesses good chemical stability, glass transition temperature (Tg) determined by
DSC decreased by 7°C after the irradiation. The gamma radiation has a slight influence on storage modulus, loss
modulus and tan delta, respectively. No considerable change was found both in tensile strength and elongation at break
after the gamma radiation. Finally, the shape recovery ratio of the polymer is near 100% with and without the gamma
irradiation. Based on the above results, it can be demonstrated that the epoxy SMP prepared in the study possesses not
only good thermo-mechanical properties but unique anti irradiation performance. The epoxy SMP shows potential for
application of aerospace fields.
Shape memory polymer (SMP) is a new class of smart material which attracts great interest in recent years. In this paper,
in addition to the synthesizing of three types of epoxy SMPs with various linear epoxy monomer contents, their
mechanical properties are focused on. Structure characteristic, dynamic mechanical property and quasi-static tension
property and shape memory behavior of the epoxy SMPs are presented. Results indicate that glass transition temperature
determined by dynamic mechanical analysis (loss modulus) varies from 69 to 113 °C for the epoxy SMPs. And it should
be noted that the linear monomer has no effect on storage modulus in glass state but decrease the storage modulus in
rubber state for the polymers. From tensile test, it is found that the content of linear monomer has significant effect on
the tensile deformation behavior which varies from a brittle response to elastomeric response at room temperature. And
the strength varies from 15 to 62MPa with the corresponding elastic modulus ranging from 2.5 to 1.7GPa for the epoxy
system. Characterization of the shape memory effect in epoxy SMP suggests a high (above 99%) shape recovery ratio at
100 °C, besides, the epoxy SMP with higher linear monomer content shows a quicker shape recovery speed. Moreover,
effect of linear monomer content on glass transition temperature and thermo-mechanical property is also investigated.
Results indicate that, epoxy SMP fabricated in this study possess not only unique shape memory effect but also excellent
mechanical properties, which will be the leading candidate for applications in engineering fields.
Shape memory polymer (SMP) receives increasing attention along with its derivants - SMP composite and SMP foam in
recent years. In this paper, after fabricating thermoset styrene-based SMP, SMP/carbon black (CB) composite and SMP
foam, we studied their shape recovery speed in bending. Different from those reported in the literature, we propose a new
approach, i.e., using infrared light, for actuating SMP materials for shape recovery. The results show that SMP, SMP/CB
composite and SMP foam can recover to their original shape perfectly in a wide temperature range. Shape recovery
speed of SMP composite is not uniform during the overall recovery process, and it is the same trend with SMP but not
prominent with SMP foam. Repeatability of shape recovery speed for styrene-based SMP and SMP/CB composite are
similarly stable and the former is the better, but it is so worse for SMP foam. Temperature-dependent of shape recovery
speed test for styrene-based SMP and SMP/CB composite reveal that higher temperature increases their shape recovery
speed.
Thermally activated shape memory polymers (SMPs) receive increasing attention in recent years. Different from those
reported in the literature, in this paper we propose a new approach, i.e., using infrared light, for heating SMPs for shape
recovery. We compare this approach with the traditional water bath method in terms of shape recovery speed in bending
at both vacuum and no vacuum conditions. The results reveal that the shape recovery speed in infrared heating at vacuum
condition is about eight times slower than that by hot water. However, the recovery time is more than doubled if without
vacuum.
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