Effect of Cenosphere on the Performance of Polyurethane/Polystyrene Interpenetrating Polymer Network Green Composites

Effect of Cenosphere on the Performance of Polyurethane/Polystyrene Interpenetrating Polymer Network Green Composites

Roopa S. (Sri Jayachamarajendra College of Engineering, India & JSS Science and Technology University, India) and Siddaramaiah (Sri Jayachamarajendra College of Engineering, India)
Copyright: © 2018 |Pages: 28
DOI: 10.4018/978-1-5225-3023-7.ch007
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Abstract

The effect of cenosphere content on the performances of polyurethane/polystyrene (PU/PS, 90/10) interpenetrating polymer network (IPN) based green composites have been studied. The PU/PS IPNs have been prepared using castor oil, toluene diisocyanate and styrene. IPN/cenosphere composites have been prepared with different weight fractions viz., 0, 5, 10, 20 and 30 wt % of cenosphere. The prepared IPN composites have been characterized by physico – mechanical, chemical and thermal behavior. The tensile strength of unfilled IPN was 1.79 MPa and a significant improvement in tensile strength (34%) was noticed for 10% cenosphere loaded IPN composite. The swelling behavior of the composites has been studied in different organic solvents. Thermal characteristics of the composites have been measured using differential scanning calorimeter, thermogravimetric analysis and dynamic mechanical analysis (DMA). A slight improvement in thermal stability was noticed for filler loaded specimens. Morphological features of cryo-fractured IPN/cenosphere green composites have been analyzed using SEM.
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Introduction

An interpenetrating polymer network (IPN), can be defined as a combination of two polymers in network form, at least one of which is synthesized and/or crosslinked in the immediate presence of the other. An IPN can be distinguished from simple polymer blends, blocks and grafts in two ways: (a) an IPN swells, but does not dissolve in solvents and (b) creep and flow are suppressed (Sperling, 1981). They have been among the fastest growing areas in the field of blends during the past twenty years.

During the formation of IPNs, the polymer networks are interlocked permanently, which shows the better thermodynamic compatibility of the two polymers that results in fine disperse microphase‐separated morphologies. The majority of the IPNs except homo-IPNs, undergo phase separation, which is essential for the development of newer materials with good properties. Due to excellent compatibility of the two polymers, IPNs exhibit enhanced mechanical strength, broad frequency range of damping, high conductivity and stimuli‐responsive behavior as compared to polymer blends, alloys, graft and block copolymers. In addition, IPNs can keep the separate phases together when they are subjected to stress (Sperling, 1981; Kim, 2007; Wu 2007; James, 2016).

Over the past decade polyurethane (PUs) the 6th most used classes of heteropolymer has gained tremendous attention in several applications like coatings, adhesives, furniture, foams electrical/electronic potting and encapsulation, construction, water proofing membranes, asphalt extended membranes, highway sealants, sound and vibration damping, automotive and rubber parts, etc., due to their unique properties i.e., it offers the elasticity of rubber combined with the toughness and durability of metals, owing to their exceptional mechanical properties and impeccable chemical resistance and scratch resistance (Krol, 2007; Zhang, 2012; Houton, 2015; Li, 2015; Rokicki, 2015; Das, 2017). Despite the substantial benefits of PU, it even presents some drawbacks, including poor degradability and toxicity due to the use of isocyanates, which have evoked researchers to get more environmentally friendly starting materials. Accordingly, there have been recent extensive research interests in producing bio-based polyols and PUs from renewable resources (Mariano, 2014). The physical properties of PUs are derived from their molecular structure, as well as the supramolecular structure caused by interaction between the polymer chains. The segmental flexibility, the chain entanglement, the interchain forces and the crosslinking influence on the properties and they determine the use of the end products. Mainly two routes can adjust the properties of the PUs. The first route is based on the chemistry of PUs, formulating the PU based on different isocyanate/polyol ratio and using different amounts of chain extender. The second route is altering the properties of the PUs with different fillers and reinforcements (Zhang, 2003). The addition of reinforcing filler particles into PUs greatly increases their versatility by extending the range of mechanical properties that can be achieved and possibly incorporating further functionalities.

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