Influence of hard segments content on thermal, morphological and mechanical properties of homo and co-polyurethanes: a comparative study

Abstract

Purpose: This work aims to study the effect of hard segments (HS) content on the thermal, morphological and mechanical properties of polyurethane polymers based on 1.5 pentanediol chain extenders. Design/methodology/approach: Two comparable series of polyurethanes were synthesised including homo-polyurethane (Homo-PU) and copolyurethane (Co-PU). The Homo-PU consists of 100% wt. of hard segments (HS). The Co-PU composes of 30%wt. of soft segments (SS) using a poly(ethylene glycol)-block-poly(propylene glycol)-blockpoly( ethylene glycol) material. The effect of hard segments content on the morphology of Homo-PU and Co-PU was also studied. Findings: The Homo-PU and Co-PU materials show three distinct degradation steps with the higher thermal stability of the Co-PU compared to the Homo-PU. Enthalpy of fusion (ΔHM) and heat capacity (ΔCP) of polyurethane (PU) samples decrease with decreasing HS content. In the cooling cycle, the higher exothermic peak of crystallization is observed in the Co-PU. In contrast, the cold crystalline peak is observed in the 2nd heating cycle of the Homo-PU. Melting temperature (TM) increases with increasing SS content. Glass transition temperature (Tg) of PU samples shifts to higher temperature with increasing HS content. Storage modulus (E’) of the Co-PU is higher than E’ of the Homo-PU. All N-H groups in PU samples are hydrogen-bonded, whilst most of the C=O groups are hydrogen-bonded. The degree of hydrogen bonding in PU samples decreases with decreasing HS content. The Homo-PU shows better hardness than the Co-PU and higher brittleness at low temperature. WAXS results of the Homo-PU display better crystallinity compared to the Co-PU. Research limitations/implications: The main challenge in this work was how to synthesis Thermoplastic polyurethanes (TPUs) with specific properties to compete other common polymer such as Polyamides (PA) and Polypropylene (PP).Practical implications: Thermoplastic polyurethanes (TPUs) can be used in various application such as backageing, foot,automobiles and constructions. Originality/value: A new type of TPUs that synthesized using different type of chain extender (1.5 pentanediol). Two different types of TPUs were synthesized one contained 30% SS and 70% HS and a second one contained 100% HS.

Thermal, Mechanical, and Morphological Characterisations of Graphene Nanoplatelet/Graphene Oxide/High-Hard-Segment Polyurethane Nanocomposite: A Comparative Study

“…The weight loss is plotted with a temperature range from 0 °C to 700 °C. It can be seen that thermal degradation of the polymers can be divided into three steps: the complete degradation of the main chains, the rupture of the side chains with volatile products, and the formation of char residues [ 48 , 49 ]. It was observed that the onset temperature (T onset ) of pure PU started increasing after the addition of GNPs and GO, and thus both the PU/GNP and PU/GO samples showed a similar trend of thermal stability enhancement, even at a low nanofiller loading.…”

“…However, the first heating scan illustrates several variations between the first and second heating scan due to the thermal history [ 60 , 61 ]. The second heating scan appears to be more precise compared to the first scan, as the manufacturing parameters varied during the production process owing to the absence of the thermal history [ 14 , 48 , 49 ]. Thus, an improvement in the PU nanocomposites can be seen in the presence of GNP and GO [ 7 ].…”

Epoxidized esters of succinic acid, oleic acid and propylene glycol as an effective bioplasticizer for PVC: A study of processing conditions on the physico‐chemical properties

“…Therefore, one measure of plasticizer effectiveness is the ability of a plasticizer to lower the T g . 12,55 The T g values are summarized in Table 7. As for TGA measurements, no significant…”

Study on the effect of tailoring the hard copolymer polyurethane on the thermal, mechanical and electrical properties of hard copolymer polyurethane/multi-walled carbon nanotubes nanocomposites

“…However, immiscibility between the hard and soft domains leads to a structural phenomenon called a microphase-separated structure. 18,19 Aspects of mechanical performance, such as the modulus, tensile strength, elastic recovery and flexibility, depend on the microphase-separated morphology, the chemical backbone, the ratio of the hard and soft phases and fabrication circumstances, and so on. 20 For instance, at low weight percentages of hard segments, the formation of a discrete hard domain represents points of physical cross-linking and/or rigid filler that are dispersed in an amorphous matrix of soft segments.…”