Light Activated Shape Memory Polymer Characterization—Part II

2011 ◽  
Vol 78 (6) ◽  
Author(s):  
Richard V. Beblo ◽  
Lisa Mauck Weiland
Keyword(s):  
Shape Memory ◽  
Thickness Distribution ◽  
Glassy State ◽  
Shape Memory Polymer ◽  
Chemical Kinetic ◽  
Chemical Kinetic Model ◽  
Polymer Characterization ◽  
Thermally Activated ◽  
Rubbery State ◽  
Consistent Method

Presented are the experimental results of two light activated shape memory polymer (LASMP) formulations. The optical stimulus used to activate the materials is detailed including a mapping of the spatial optical intensity at the surface of the sample. From this, results of energy calculations are presented including the amount of energy available for transitioning from the glassy state to the rubbery state and from the rubbery state to the glassy state, highlighting one of the major advantages of LASMP as requiring less energy to transition than thermally activated shape memory polymers. The mechano-optical experimental setup and procedure is detailed and provides a consistent method for evaluating this relatively new class of shape memory polymer. A chemical kinetic model is used to predict both the theoretical glassy state modulus, as only the sample averaged modulus is experimentally attainable, as well as the through thickness distribution of Young’s modulus. The experimental and model results for these second generation LASMP formulations are then compared with earlier LASMP generations (detailed previously in Beblo and Mauck Weiland, 2009, “Light Activated Shape Memory Polymer Characterization,” ASME J. Appl. Mech., 76, pp. 8) and typical thermally activated shape memory polymer.

Light Activated Shape Memory Polymer Characterization

2008 ◽  
Vol 76 (1) ◽  
Author(s):  
Richard V. Beblo ◽  
Lisa Mauck Weiland
Keyword(s):  
Shape Memory ◽  
First Generation ◽  
Light Stimulus ◽  
Incident Light ◽  
Shape Memory Polymer ◽  
Temporal Variations ◽  
Chemical Kinetic ◽  
Thermal Stimulus ◽  
Chemical Kinetic Model ◽  
Characterization Methods

Since their development, shape memory polymers (SMPs) have been of increasing interest in active materials and structures design. In particular, there has been a growing interest in SMPs for use in adaptive structures because of their ability to switch between low and high stiffness moduli in a relatively short temperature range. However, because a thermal stimulus is inappropriate for many morphing applications, a new light activated shape memory polymer (LASMP) is under development. Among the challenges associated with the development of a new class of material is establishing viable characterization methods. For the case of LASMP both the sample response to light stimulus and the stimulus itself vary in both space and time. Typical laser light is both periodic and Gaussian in nature. Furthermore, LASMP response to the light stimulus is dependent on the intensity of the incident light and the time varying through the thickness penetration of the light as the transition progresses. Therefore both in-plane and through-thickness stimulation of the LASMP are nonuniform and time dependent. Thus, the development of a standardized method that accommodates spatial and temporal variations associated with mechanical property transition under a light stimulus is required. First generation thick film formulations are found to have a transition time on the order of 60 min. The characterization method proposed addresses optical stimulus irregularities. A chemical kinetic model is also presented capable of predicting the through-thickness evolution of Young’s modulus of the polymer. This work discusses in situ characterization strategies currently being implemented as well as the current and projected performance of LASMPs.

Characterizations of Silicon Carbide Whisker-Filled in Benzoxazine-Epoxy Shape Memory Polymers

2015 ◽  
Vol 659 ◽  
pp. 373-377 ◽  
Author(s):  
Chutiwat Likitaporn ◽  
Sarawut Rimdusit
Keyword(s):  
Silicon Carbide ◽  
Shape Memory ◽  
Polymer Composites ◽  
Binary Systems ◽  
Glassy State ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Polymer Materials ◽  
External Stimulation ◽  
Silicon Carbide Whisker

Shape memory polymers (SMPs) are polymer materials that can fix the temporary shape and then recover to their original permanent shape by external stimulation, i.e. applied heat. In this research, shape memory polymer composites (SMPCs) from benzoxazine (BA-a)-epoxy binary systems reinforced with adamantine silicon carbide whisker (SiCw) are investigated. The SiCw contents are controlled to be in range of 0 to 15% by weight. All specimens were fabricated by compression molding technique. The results revealed that the shape memory polymer composites showed higher glassy state storage modulus with increasing amount of the whisker suggesting substantial reinforcement effect of the whisker used. The glass transition temperature (Tg) was also improved from 102°C of the based polymer to the value about 122°C with the addition of about 15% by weight of the silicon carbide whisker. Finally, shape recovery stress systematically increased from the value about 1.5MPa of the unfilled polymer matrix to the value about 3.2MPa with an addition of 15% by weight of the silicon carbide whisker. The positive effect on thermal stability from SiCw addition is expected from the modification and will be reported in this work.

Thermo-Mechanical Testing of Epoxy Shape Memory Polymer Composites

2012 ◽  
Vol 570 ◽  
pp. 15-23 ◽  
Author(s):  
Abdul Basit ◽  
Gildas L’Hostis ◽  
Bernard Durand
Keyword(s):  
Composite Material ◽  
Glass Transition ◽  
Transition Temperature ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Epoxy Composites ◽  
Shape Memory Property ◽  
Recovery Test ◽  
Thermally Activated ◽  
Displacement Measurements

In this work the two epoxy composites the controlled behavior of composite material (CBCM) and the thermally activated symmetrical composite (SYMM) have been tested for their shape memory property. These composites have been heated above their glass transition temperature (Tg) and deformed to the same displacement. The activated position has been taken as the reference point for displacement measurements during the fixing cycle. During the recovery, two types of tests have been conducted: Unconstrained recovery test and constrained recovery test. It has been found that the recovery of CBCM plate is better as compared to the SYMM plate (unconstrained recovery test). Similarly, it has been found that CBCM plate produces larger forces of recovery than SYMM plates (constrained recovery test).

scholarly journals The effect of organoclay addition on the properties of an acrylate based, thermally activated shape memory polymer

2014 ◽  
Vol 102 ◽  
pp. 41-50 ◽  
Author(s):  
Michael J. Barwood ◽  
Chris Breen ◽  
Francis Clegg ◽  
Carol L. Hammond
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Thermally Activated

scholarly journals Development of Thermo-Responsive Polycaprolactone–Polydimethylsiloxane Shrinkable Nanofibre Mesh

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1427
Author(s):  
Chia-Hsuan Hsieh ◽  
Nur Adila Mohd Razali ◽  
Wei-Chih Lin ◽  
Zhi-Wei Yu ◽  
Dwita Istiqomah ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Biomedical Applications ◽  
Memory Performance ◽  
Shape Memory Polymer ◽  
Electrospinning Process ◽  
Degree Of Crystallinity ◽  
Thermal And Mechanical Properties ◽  
Thermally Activated ◽  
Shape Fixity

A thermally activated shape memory polymer based on the mixture of polycaprolactone (PCL) and polydimethylsiloxane (PDMS) was fabricated into the nanofibre mesh using the electrospinning process. The added percentages of the PDMS segment in the PCL-based polymer influenced the mechanical properties. Polycaprolactone serves as a switching segment to adjust the melting temperature of the shape memory electro-spun PCL–PDMS scaffolds to our body temperature at around 37 °C. Three electro-spun PCL–PDMS copolymer nanofibre samples, including PCL6–PDMS4, PCL7–PDMS3 and PCL8–PDMS2, were characterised to study the thermal and mechanical properties along with the shape memory responses. The results from the experiment showed that the PCL switching segment ratio determines the crystallinity of the copolymer nanofibres, where a higher PCL ratio results in a higher degree of crystallinity. In contrast, the results showed that the mechanical properties of the copolymer samples decreased with the PCL composition ratio. After five thermomechanical cycles, the fabricated copolymer nanofibres exhibited excellent shape memory properties with 98% shape fixity and above 100% recovery ratio. Moreover, biological experiments were applied to evaluate the biocompatibility of the fabricated PCL–PDMS nanofibre mesh. Owing to the thermally activated shape memory performance, the electro-spun PCL–PDMS fibrous mesh has a high potential for biomedical applications such as medical shrinkable tubing and wire.

scholarly journals Hot Embossing of Micro-Pyramids into Thermoset Thiol-Ene Film

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2291
Author(s):  
Dalius Jucius ◽  
Algirdas Lazauskas ◽  
Viktoras Grigaliūnas ◽  
Asta Guobienė ◽  
Linas Puodžiukynas
Keyword(s):  
Surface Roughness ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Hot Embossing ◽  
High Fidelity ◽  
Roughness Parameters ◽  
Force Microscopy ◽  
Rubbery State ◽  
Atomic Force ◽  
Shape Memory Films

This paper presents the first attempt to texturize a fully crosslinked thermoset shape memory polymer using a hot embossing technique. UV-cured thiol-ene films were successfully embossed with anisotropically-etched Si (100) stamps at a temperature of 100 °C, which is about 50 °C above the glass transition temperature of the polymer. The low storage modulus of the polymer in a rubbery state allowed us to permanently emboss random micro-pyramidal patterns onto the surface of the film with high fidelity by applying 30 MPa pressure for 1 h. Atomic force microscopy (AFM) investigation showed perfect replication of the stamp micropattern with typical height of the largest inverted pyramids close to 0.7 µm and lateral dimensions in the range of 1–2 µm. Changes in surface roughness parameters of the embossed thiol-ene films after annealing them at 100 °C for 1 h or storing for 2 months in air at standard room conditions were negligible. The achieved results open new perspectives for the simple and inexpensive hot embossing technique to be applied for the micropatterning of prepolymerized thermoset shape memory films as an alternative to micropatterning using UV casting.

scholarly journals The chemistry of cool circumstellar envelopes

1987 ◽  
Vol 122 ◽  
pp. 551-552
Author(s):  
L.A.M. Nejad ◽  
T. J. Millar
Keyword(s):  
Kinetic Model ◽  
Chemical Kinetic ◽  
Time Dependent ◽  
Circumstellar Envelopes ◽  
Chemical Kinetic Model ◽  
Ion Molecule Reactions ◽  
Cool Stars

We have developed a time-dependent chemical kinetic model to describe the chemistry in the circumstellar envelopes of cool stars, with particular reference to IRC + 10216. Our detailed calculations show that ion-molecule reactions are important in the formation of many of the species observed in IRC + 10216.

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