scholarly journals A novel kind of room temperature self-healing poly(urethane-urea) with robust mechanical strength based on aromatic disulfide

2021 ◽  
Vol 28 (4) ◽  
Author(s):  
Jin He ◽  
Fangfang Song ◽  
Xiong Li ◽  
Liyi Chen ◽  
Xingyu Gong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Room Temperature ◽  
Toluene Diisocyanate ◽  
Self Healing ◽  
Isophorone Diisocyanate ◽  
Elongation At Break ◽  
Strength Based ◽  
Hard Segments ◽  
Poly Propylene

AbstractAn innovative poly(urethane-urea) elastomer, which exhibited excellent stretchability, thermal stability and autonomous self-healing abilities, was synthesized from the commercially available poly(propylene glycol) (PPG), isophorone diisocyanate (IPDI), 2,4 / 2,6-toluene diisocyanate (80: 20, w / w) (TDI-80) and bis (2-aminophenyl) disulfide (DSDA). This aromatic disulfide containing poly(urethane-urea) (ss-PUs) achieved both rapid room temperature self-healing abilities and robust mechanical strength (the ultimate tensile strength was up to 4.20 ± 0.10 MPa and elongation at break was up to 954 ± 35.6%), through facile metathesis of the aromatic disulfides which embedded in hard segments. After the ss-PUs was cut into two-halves and reconnected, the mechanical properties could recover to ~ 90% of those of the original samples within 12 h at room temperature without extra self-healing agents or any change of environmental conditions.

scholarly journals Crystallization, Structure and Significantly Improved Mechanical Properties of PLA/PPC Blends Compatibilized with PLA-PPC Copolymers Produced by Reactions Initiated with TBT or TDI

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3245
Author(s):  
Lixin Song ◽  
Yongchao Li ◽  
Xiangyu Meng ◽  
Ting Wang ◽  
Ying Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Average Molecular Weight ◽  
Toluene Diisocyanate ◽  
Chain Extension ◽  
Poly Lactic Acid ◽  
Cooling Process ◽  
Material Degradation ◽  
Elongation At Break ◽  
Poly Propylene

Poly (lactic acid) (PLA)-Poly (propylene carbonate) (PPC) block copolymer compatibilizers are produced in incompatible 70wt%PLA/PPC blend by initiating transesterification with addition of 1% of tetra butyl titanate (TBT) or by chain extension with addition of 2% of 2,4-toluene diisocyanate (TDI). The above blends can have much better mechanical properties than the blend without TBT and TDI. The elongation at break is dramatically larger (114% with 2% of TDI and 60% with 1% of TBT) than the blend without TDI and TBT, with a slightly lower mechanical strength. A small fraction of the copolymer is likely formed in the PLA/PPC blend with addition of TBT, and a significant amount of the copolymer can be made with addition of TDI. The copolymer produced with TDI has PPC as a major content (~70 wt%) and forms a miscible interphase with its own Tg. The crystallinity of the blend with TDI is significantly lower than the blend without TDI, as the PLA blocks of the copolymer in the interphase is hardly to crystallize. The average molecular weight increases significantly with addition of TDI, likely compensating the lower mechanical strength due to lower crystallinity. Material degradation can occur with addition of TBT, but it is very limited with 1% of TBT. However, compared with the blends without TBT, the PLA crystallinity of the blend with 1%TBT increases sharply during the cooling process, which likely compensates the loss of mechanical strength due to the slightly material degradation. The added TDI does not have any significant impact on PLA lamellar packing, but the addition of TBT can make PLA lamellar packing much less ordered, presumably resulted from much smaller PPC domains formed in the blend due to better compatibility.

Autonomous self-healing polyisoprene elastomers with high modulus and good toughness based on the synergy of dynamic ionic crosslinks and highly disordered crystals

2020 ◽  
Vol 11 (41) ◽  
pp. 6549-6558
Author(s):  
Yohei Miwa ◽  
Mayu Yamada ◽  
Yu Shinke ◽  
Shoichi Kutsumizu
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Self Healing ◽  
High Modulus ◽  
Disordered Crystals ◽  
Ionic Crosslinks

We designed a novel polyisoprene elastomer with high mechanical properties and autonomous self-healing capability at room temperature facilitated by the coexistence of dynamic ionic crosslinks and crystalline components that slowly reassembled.

scholarly journals Recyclable Self-Healing Polyurethane Cross-Linked by Alkyl Diselenide with Enhanced Mechanical Properties

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 773 ◽  
Author(s):  
Yuqing Qian ◽  
Xiaowei An ◽  
Xiaofei Huang ◽  
Xiangqiang Pan ◽  
Jian Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Amide Bond ◽  
Self Healing ◽  
Healing Efficiency ◽  
Polyurethane Networks ◽  
Combined Action ◽  
Cross Linker ◽  
Dynamic Structures ◽  
External Interventions

Dynamic structures containing polymers can behave as thermosets at room temperature while maintaining good mechanical properties, showing good reprocessability, repairability, and recyclability. In this work, alkyl diselenide is effectively used as a dynamic cross-linker for the design of self-healing poly(urea–urethane) elastomers, which show quantitative healing efficiency at room temperature, without the need for any catalysts or external interventions. Due to the combined action of the urea bond and amide bond, the material has better mechanical properties. We also compared the self-healing effect of alkyl diselenide-based polyurethanes and alkyl disulfide-based polyurethanes. The alkyl diselenide has been incorporated into polyurethane networks using a para-substituted amine diphenyl alkyl diselenide. The resulting materials not only exhibit faster self-healing properties than the corresponding disulfide-based materials, but also show the ability to be processed at temperatures as low as 60 °C.

A room-temperature self-healing elastomer with ultra-high strength and toughness fabricated via optimized hierarchical hydrogen-bonding interactions

2022 ◽  
Author(s):  
Liangliang Xia ◽  
Ming Zhou ◽  
Hongjun Tu ◽  
wen Zeng ◽  
xiaoling Yang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Mechanical Strength ◽  
Room Temperature ◽  
Polymeric Materials ◽  
High Strength ◽  
Self Healing ◽  
High Mechanical Strength ◽  
Hydrogen Bonding Interactions ◽  
Healing Efficiency ◽  
Good Healing

The preparation of room-temperature self-healing polymeric materials with good healing efficiency and high mechanical strength is challenging. Two processes are essential to realise the room-temperature self-healing of materials: (a) a...

scholarly journals Characteristics of Self-Healable Copolymers of Styrene and Eugenol Terminated Polyurethane Prepolymer

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1674 ◽  
Author(s):  
Jing-Yu Liang ◽  
Se-Ra Shin ◽  
Soo-Hyoung Lee ◽  
Dai-Soo Lee
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fossil Fuel ◽  
Renewable Resource ◽  
Self Healing ◽  
Elongation At Break ◽  
Good Thermal Stability ◽  
Healing Property ◽  
Polyurethane Prepolymer ◽  
Reversible Nature

With limited biomass that can be currently utilized as a renewable resource, it is important to develop a method to convert biomass into materials that can replace fossil fuel product. In this paper, eugenol, a bio-based allyl chain-substituted guaiacol, was used to synthesize self-healable copolymers. Eugenol terminated polyurethane prepolymer (ETPU) was synthesized from eugenol and polyurethane prepolymers terminated with isocyanate groups. ETPU contained two allyl groups. Self-healing copolymer networks were obtained by copolymerization of ETPU and styrene monomer via free radical polymerization. Effects of ETPU content on the properties of copolymers were then studied. These copolymers containing ETPU exhibited good thermal stability and mechanical properties. These copolymers showed higher tensile strength and elongation at break than PS. Their maximum tensile strength reached 19 MPa. In addition, these copolymers showed self-healing property at elevated temperature due to the reversible nature of urethane units in ETPU.

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

2021 ◽  
Vol 1 (109) ◽  
pp. 5-16
Author(s):  
Z.K. Alobad ◽  
M. Albozahid ◽  
H.Z. Naji ◽  
H.S. Alraheem ◽  
A. Saiani
Keyword(s):  
Mechanical Properties ◽  
Ethylene Glycol ◽  
Exothermic Peak ◽  
Thermoplastic Polyurethanes ◽  
Main Challenge ◽  
New Type ◽  
Hard Segments ◽  
Poly Ethylene ◽  
Poly Propylene ◽  
Hydrogen Bonded

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.

Preparation of Room-temperature Self-healing Elastomers with High Strength Based on Multiple Dynamic Bonds

2021 ◽  
pp. 110614
Author(s):  
Wencong Zhang ◽  
Minhui Wang ◽  
Jiahui Zhou ◽  
Yeming Sheng ◽  
Min Xu ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Strength ◽  
Self Healing ◽  
Strength Based

Processing, mechanical properties and oxidation behavior of TaC and HfC composites containing 15 vol% TaSi2 or MoSi2

2009 ◽  
Vol 24 (6) ◽  
pp. 2056-2065 ◽  
Author(s):  
Diletta Sciti ◽  
Laura Silvestroni ◽  
Stefano Guicciardi ◽  
Daniele Dalle Fabbriche ◽  
Alida Bellosi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Mechanical Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Oxidation Behavior ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Better Than

Fully dense HfC and TaC-based composites containing 15 vol% TaSi2 or MoSi2 were produced by hot pressing at 1750–1900 °C. TaSi2 enhanced the sinterability of the composites and nearly fully dense materials were obtained at lower temperatures than in the case of MoSi2-containing ones. The TaC-based composites performed better than HfC composites at room temperature, showing values of mechanical strength up to 900 MPa and a fracture toughness of 4.7 MPa·m1/2. However, preliminary oxidation tests carried out in air at 1600 °C revealed that HfC-based composites have a superior high temperature stability compared to TaC-based materials.

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