Modeling the Mechanics of Crystallizable Shape Memory Polymers With Two Crystallizing Phases for Crystallization Under Constant Strain

2012 ◽  
Author(s):  
Swapnil Moon ◽  
I. Joga Rao
Keyword(s):  
Shape Memory ◽  
Crystalline Phase ◽  
Smart Materials ◽  
Phase 1 ◽  
Polymer Networks ◽  
Shape Memory Polymers ◽  
Original Shape ◽  
Aerospace Technology ◽  
Multiple Natural Configurations ◽  
External Stimuli

Shape Memory Polymers are a promising class of smart materials with applications ranging from biomedical devices to aerospace technology. SMPs have a capacity to retain complex temporary shapes involving large deformations and revert back to their original shape when triggered by external stimuli such as heat. Crystallizable SMPs are a subclass of SMPs where the transient shape is retained by formation of a crystalline phase and return to the original shape is due to melting of this crystalline phase [1]. Recently CSMPs with multiphase polymer networks containing two different crystallizable segments have been reported which have the capability to switch between three shapes when stimulated by changes in temperature [2,4]. These properties open up many new possibilities for applications. Our research is focused upon modeling the mechanics associated with these CSMPs. The model is developed using a framework based upon theory of multiple natural configurations [3]. The developed model is then used to simulate results for typical boundary value problems.

Application of a Constitutive Modeling for Light Activated Shape Memory Polymer to Circular Shear

2012 ◽  
Author(s):  
Fangda Cui ◽  
I. J. Rao
Keyword(s):  
Shape Memory ◽  
Constitutive Modeling ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Polymer Chains ◽  
Covalent Bonds ◽  
The Past ◽  
Original Shape ◽  
Multiple Natural Configurations ◽  
New Type

Shape memory polymers (SMP’s) are polymers that have the ability to retain a temporary shape, which can revert back to the original shape on exposure to specific triggers such as increase in temperature or exposure to light at specific wavelengths. A new type of shape memory polymer, light activated shape memory polymers (LASMP’s) have been developed in the past few years. In these polymers the temporary shapes are fixed by exposure to light at a specific wavelength. Exposure to light at this wavelength causes the photosensitive molecules, which are grafted on to the polymer chains, to form covalent bonds. These covalent bonds are responsible for the temporary shape and act as crosslinks. On exposure to light at a different wavelength these bonds are cleaved and the material can revert back to its original shape. A constitutive model of LASMP’s which based on the notion of multiple natural configurations has been developed (see Sodhi and Rao[1]). In this work we use this model to analyze the mechanical behavior of LASMP’s under a specific boundary value problem, namely, the problem of circular shear. We use this model problem to study the behavior of the LASMP’s when a temporary configuration is formed by exposing the polymer to light. In addition we show that these materials are able to undergo complex cycles of deformation due to the flexibility with which these temporary configurations can be formed and removed by exposure to light.

Light Activated Shape Memory Polymers: Some Inhomogeneous Deformation Examples

2011 ◽  
Author(s):  
Jaskirat S. Sodhi ◽  
I. Joga Rao
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Uv Light ◽  
Large Family ◽  
Shape Memory Polymers ◽  
Space Structures ◽  
Inhomogeneous Deformation ◽  
Mems Devices ◽  
Multiple Natural Configurations ◽  
Specific Frequency

Shape memory polymers (SMP’s) belong to a large family of shape memory materials, which are defined by their capacity to store a deformed (temporary) shape and recover an original (parent) shape. SMP’s have the ability to change size and shape when activated through a suitable trigger. This trigger, which can be heating the polymer or exposing it to light of a specific frequency, is responsible for the new temporary shape. Return to the original shape can be achieved by a suitable reverse trigger. Light Activated Shape Memory Polymers (LASMP) are recently developed smart materials which are synthesized with special photosensitive molecules. These molecules when exposed to Ultraviolet (UV) light at specific wavelengths, form covalent crosslinks that are responsible for providing LASMP with their temporary shape. Light activation removes temperature constraints faced by thermoresponsive SMP for medical applications and also brings the added advantage of remote activation. Thus LASMP find use in a variety of applications ranging from MEMS devices to widespread usage for biomedical devices such as intravenous needles and stents. Furthermore, the aerospace industry has found use for these materials for applications ranging from easily deployable space structures to morphing wing aircraft. The authors have introduced a constitutive model to model the mechanics of these LASMP [1]. The modeling is done using a framework based on the theory of multiple natural configurations. A few homogenous and inhomogeneous examples were solved in [1], but with tacit understanding that the intensity of light and hence the extent of reaction is homogenous throughout the polymer sample. In this paper we use the developed model to solve the cases of inhomogeneous deformation with inhomogeneous exposure to light.

Modeling the Circular Shear in Light Activated Shape Memory Polymers With Three Networks

2013 ◽  
Author(s):  
Fangda Cui ◽  
I. J. Rao
Keyword(s):  
Shape Memory ◽  
Deformation Process ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Polymer Chains ◽  
Covalent Bonds ◽  
The Past ◽  
Original Shape ◽  
Multiple Natural Configurations ◽  
New Type

Shape memory polymers (SMP’s) are polymers that have the ability to retain a temporary shape, which can revert back to the original shape on exposure to specific triggers such as increase in temperature or exposure to light at specific wavelengths. A new type of shape memory polymer, light activated shape memory polymers (LASMP’s) have been developed in the past few years. In these polymers the temporary shapes are fixed by exposure to light at a specific wavelength. Exposure to light at this wavelength causes the photosensitive molecules, which are grafted on to the polymer chains, to form covalent bonds. These covalent bonds are responsible for the temporary shape and act as crosslinks. On exposure to light at a different wavelength these bonds are cleaved and the material can revert back to its original shape. A constitutive model of LASMP’s which based on the notion of multiple natural configurations has been developed (see Sodhi and Rao [1]). It has been applied to model the circular shear of light activated shape memory polymer with two networks. In this work we use this model to analyze the mechanical behavior of LASMP’s with three different networks undergoing a circular shear deformation cycle. This involves study of the behavior of the LASMP’s when two temporary configurations are formed by exposing the polymer to light at different time during the deformation process. In addition, we show that these materials are able to undergo complex cycles of deformation due to the flexibility with which these temporary configurations can be formed and removed by exposure to light.

Modeling Circular Shear in Shape Memory Polymers With Triple Shape Effect Subjected to Crystallization Under Constant Shear

2015 ◽  
Author(s):  
Swapnil Moon ◽  
I. Joga Rao ◽  
Fangda Cui
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
First Generation ◽  
Shape Change ◽  
Shape Memory Polymers ◽  
Shape Effect ◽  
Crystalline Phases ◽  
Thermally Induced ◽  
Multiple Natural Configurations ◽  
Permanent Shape

The capacity of a material to sense its environment and to change its shape on demand in a predefined way has tremendous technological significance for a wide variety of application areas. Shape memory polymers (SMPs) belong to this category of smart materials as they have the ability to undergo a shape change in a predetermined manner under the influence of an external stimulus. SMPs can recover their permanent shape after undergoing large deformation to a temporary shape on exposure to external triggers such as light, PH values and heat. Thermally induced SMPs are first generation SMPs and have been widely recognized. Crystallizable SMPs are a class of thermally induced SMPs whose temporary shape is due to formation of crystalline phases, and they will revert back to their permanent shape when the crystallization phase is melted through heating. Traditional crystallizable SMPs can only perform dual-shape memory cycles and this limits applications of crystallizable SMPs. Recently SMPs with triple shape effect have been reported that can switch from a second temporary shape to the first temporary shape and from there to the permanent shape under stimulation by heat. Our research focuses on modeling the mechanical behavior of these SMPs with triple-shape effect. The framework used in developing the model is built upon the theory of multiple natural configurations [3]. In order to model the mechanics associated with these polymers different stages of the shape fixation and recovery cycle and different phases of the material during this cycle need to be characterized. This includes developing a model for the amorphous phase and the subsequent semi-crystalline phases with different stress free states and melting of these phases. The model subsequently has been used to simulate results for a typical deformation cycle involving circular shear.

Three-dimensional Graphene Coated Shape Memory Polyurethane Foam with Fast Responsive Performance

2021 ◽  
Author(s):  
Tianjiao Wang ◽  
Jun Zhao ◽  
Chuanxin Weng ◽  
Tong Wang ◽  
Yayun Liu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Polyurethane Foam ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Practical Applications ◽  
External Stimuli ◽  
Shape Memory Polyurethane

Shape memory polymers (SMPs) that change shapes as designed by external stimuli have become one of the most promising materials as actuators, sensors, and deployable devices. However, their practical applications...

Modeling the Behavior of Crystallizable Shape Memory Polymers Subject to Inhomogeneous Deformations

2010 ◽  
Author(s):  
Mahesh Khanolkar ◽  
Jaskirat Sodhi ◽  
I. Joga Rao
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Research Work ◽  
Shape Memory Polymers ◽  
Inhomogeneous Deformation ◽  
The Past ◽  
Constant Shear ◽  
Multiple Natural Configurations ◽  
Constant Moment

The constitutive model for the mechanics of crystallizable shape memory polymers (CSMP) has been developed in the past [1, 2]. The model was developed using the theory of multiple natural configurations and has been successful in addressing a diverse class of problems. In this research work, the efficacy of the developed CSMP model is tested by applying it to the torsion of a cylinder, which is an inhomogeneous deformation. The crystallization of the cylinder is studied under two different conditions i.e. crystallization under constant shear and crystallization under constant moment.

Novel Behavior in Smart Polymeric Materials: Stress Memory and its Potential Applications

2016 ◽  
Vol 97 ◽  
pp. 93-99
Author(s):  
Jin Lian Hu ◽  
Harishkumar Narayana
Keyword(s):  
Magnetic Field ◽  
Shape Memory ◽  
Smart Materials ◽  
Shape Memory Polymers ◽  
Polymeric Materials ◽  
External Stimulus ◽  
Artificial Muscles ◽  
Recovery Stress ◽  
Stress Memory ◽  
Potential Applications

Materials, structures and systems, responsive to an external stimulus are smart and adaptive to our human demands. Among smart materials, polymers with shape memory effect are at the forefront of research leading to comprehensive publications and wide applications. In this paper, we extend the concept of shape memory polymers to stress memory ones, which have been discovered recently. Like shape memory, stress memory represents a phenomenon where the stress in a polymer can be programmed, stored and retrieved reversibly with an external stimulus such as temperature and magnetic field. Stress memory may be mistaken as the recovery stress which was studied quite broadly. Our further investigation also reveals that stress memory is quite different from recovery stress containing multi-components including elastic and viscoelastic forces in addition to possible memory stress. Stress memory could be used into applications such as sensors, pressure garments, massage devices, electronic skins and artificial muscles. The current revelation of stress memory potentials is emanated from an authentic application of memory fibres, films, and foams in the smart compression devices for the management of chronic and therapeutic disorders.

Shape Memory Behavior of Carbon Composites With Functional Interlayer

2018 ◽  
Author(s):  
L. Santo ◽  
L. Iorio ◽  
G. M. Tedde ◽  
F. Quadrini
Keyword(s):  
Carbon Fiber ◽  
Shape Memory ◽  
Polymer Composites ◽  
Polymer Matrix ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Carbon Composites ◽  
Three Point Bending ◽  
Functional Behavior

Shape Memory Polymer Composites (SMPCs) are smart materials showing the structural properties of long-fiber polymer-matrix together with the functional behavior of shape memory polymers. In this study, SM carbon fiber reinforced (CFR) composites have been produced by using a SM interlayer between two CFR prepregs. Their SM properties have been evaluated in comparison with traditional structural CFR composites without the SM interlayer by using an especially designed test. Active and frozen forces are measured during a thermo-mechanical cycle in the three-point bending configuration. Experimental results show that SMPCs are able to fix a temporary deformed shape by freezing high stresses.

scholarly journals Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4246 ◽  
Author(s):  
Yujie Chen ◽  
Chi Chen ◽  
Hafeez Ur Rehman ◽  
Xu Zheng ◽  
Hua Li ◽  
...  
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Recent Progress ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Artificial Muscles ◽  
Linkage Design ◽  
Wide Range ◽  
Liquid Crystal Elastomers ◽  
Made In

Shape-memory materials are smart materials that can remember an original shape and return to their unique state from a deformed secondary shape in the presence of an appropriate stimulus. This property allows these materials to be used as shape-memory artificial muscles, which form a subclass of artificial muscles. The shape-memory artificial muscles are fabricated from shape-memory polymers (SMPs) by twist insertion, shape fixation via Tm or Tg, or by liquid crystal elastomers (LCEs). The prepared SMP artificial muscles can be used in a wide range of applications, from biomimetic and soft robotics to actuators, because they can be operated without sophisticated linkage design and can achieve complex final shapes. Recently, significant achievements have been made in fabrication, modelling, and manipulation of SMP-based artificial muscles. This paper presents a review of the recent progress in shape-memory polymer-based artificial muscles. Here we focus on the mechanisms of SMPs, applications of SMPs as artificial muscles, and the challenges they face concerning actuation. While shape-memory behavior has been demonstrated in several stimulated environments, our focus is on thermal-, photo-, and electrical-actuated SMP artificial muscles.

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