Influence of Graphene Oxide Contents on Mechanical Behavior of Polyurethane Composites Fabricated with Different Diisocyanates.

Nadia Akram,Khalid Mahmood Zia,Muhammad Saeed,Nida Mumtaz,Waheed Gul Khan,Irfan Mahmood,Muhammad Usman,Asim Mansha,Fozia Anjum

doi:10.3390/polym13030444

Nadia Akram, Khalid Mahmood Zia + Show 7 more

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https://doi.org/10.3390/polym13030444

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Abstract

The exceptional behavior of graphene has not yet been entirely implicit in the polymer matrix. To explore this fact in the present work, two series of Polyurethan (PU) composites were synthesized. The structural modification was observed by the use of two different diisocyanate of methylene diisocyanate (MDI) and hexamethylene diisocyanate (HMDI) in hydroxylterminated polybutadiene (HTPB) by using I,4 Butane diol (BD) as the chain extender. The variation in hard segment up to 25 (wt.%) in both series led to significant changes in the mechanical behavior of graphene oxide (GO) induced composites. Both series were prepared by an in situ polymerization process. Fourier transform infrared (FTIR) analysis showed a peak in the region of 1700 cm−1, which confirmed the conversion of the NCO group into urethane linkages. Thermal gravimetric analysis (TGA) revealed a thermal stability up to 450 °C @ 90% weight loss. The swelling behavior showed the optimum uptake of 30% of water and 40% of dimethyl sulfoxide (DMSO) with aliphatic diisocyanate. The values of storage modulus (E′), complex modulus (E*), and compliance complex (D*) were observed up to 7 MPa, 8 Mpa, and 0.7 MPa−1, respectively. The degree of entanglement (N) values were calculated from DMA and were found in the range of 1.7 × 10−4 (mol/m3). Phase segregation of PU was observed by scanning electron microscopy (SEM), elucidating the morphology of composites.

Highlights

All the monomers including hydroxylterminated polybutadiene (HTPB), methylene diisocyanate (MDI), hexamethylene diisocyanate (HMDI), butane diol (BD), and graphene oxide (GO), polyurethane blank, and GO reinforced composites were subjected to Fourier transform infrared (FTIR) analyses
The hegemony of polyurethane in the vast polymer domain is not accidental, and the innumerable properties and tendency to be molded with numerous raw materials has specified its position among polymers
As the stoichiometry is the critical factor to evaluate the desired properties, two series of PU composites were synthesized, the matrix consisted of hydroxyl terminated polybutadiene (HTPB) as macrodiol, while the diisocyanate in both series were varied in nature

Summary

Introduction

Two dimensional graphene and its derivatives have emerged as multipurpose fillers that can be used for the composites They play a consequential part in the development of the structural, physicochemical, and mechanical properties of various polymers in the presence of several reactive functionalities such as epoxy, carboxyl, carbonyl, and hydroxyl groups [1,2]. Graphene has the potential to gain thermal stability and can offer a large surface area with excellent mechanical strength to the matrix. This behavior makes it one of most powerful reinforcing agents for the fabrication of composites [6,7]

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