Fabrication of rigid polyimide foams with overall enhancement of thermal and mechanical properties

2020 ◽  
pp. 0021955X2095692
Author(s):  
Jianwei Li ◽  
Ni Yu ◽  
Yuanqing Ding ◽  
Tianle Xu ◽  
Guangcheng Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Insulation ◽  
Polymer Chains ◽  
Molar Ratio ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
Foaming Agent ◽  
Molar Ratios ◽  
End Capping ◽  
Tetracarboxylic Dianhydride

Polyimide (PI) foams have been developed for decades and widely used as thermal insulation materials. However, the limited mechanical and thermal properties continually being a serious problem that restrict their further applications. In this study, a series of rigid PI foams with excellent mechanical and thermal performance were fabricated by the reaction of benzophenone-3,3',4,4'-tetracarboxylic dianhydride (BTDA) with two diamines of 2–(4-aminophenyl)-5-aminobenzimidazole (BIA) and 4,4'-diaminodiphenyl ether (ODA) with various molar ratios, and the cis-5-norbornene-endo-2,3-dicarbox-ylic acid (NA) was introduced as end-capping and foaming agent. The results demonstrate that the foaming degree decreases with increasing the BIA molar ratio in the polymer chains owing to the elevated melt viscosity of precursor. Furthermore, the prepared rigid PI foams exhibit excellent thermal and mechanical properties. When the BIA contend up to 40 mol%, the glass transition temperature ( Tg) and the temperature at 10% of weight loss ( Td 10 %) of PI foam increased ∼80°C and ∼35°C in comparison with the pristine PI-0, respectively. In addition, the compressive strength and modulus at 10% strain of PI-4 reached to 5.48 MPa and 23.8 MPa, respectively. For the above-mentioned advantages, the prepared rigid PI foams are promising candidates as thermal insulation and structure support composite materials in the aerospace and aviation industries.

Thermotropic copolyesters from methylhydroquinone, 4,4'-dipbenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid

1995 ◽  
Vol 7 (3) ◽  
pp. 303-311 ◽  
Author(s):  
Toshihide Inoue ◽  
Toru Yamanaka ◽  
Norikazu Tabata ◽  
Shigeru Okita
Keyword(s):  
Mechanical Properties ◽  
Polymer Chain ◽  
Packing Density ◽  
Polymer Chains ◽  
Molar Ratio ◽  
Thermal And Mechanical Properties ◽  
Predominant Role ◽  
Chain Packing ◽  
Molar Ratios ◽  
Orientation Function

Copolyesters from methylhydroquinone (Me-HQ), 4,4'-diphenyldicarboxylic acid (BB) and 2,6-naphthalenedicarboxylic acid (NDA) with various molar ratios were prepared and their thermal and mechanical properties were investigated. The modulus of as-spun fibres from Me-HQ/BB/NDA tends to increase as the orientation function of the nematic domains (F value) increases. As-spun fibre from a polymer with a molar ratio m/n=92.5/7.5 showed the highest modulus of 112GPa at F=0,91. However, the injection-moulded specimens did not show the same tendency and the highest modulus of 44 GPa was observed at the lowest F value of 0.56. From these results, it is assumed that the F value plays a predominant role in determining the modulus of the as-spun fibre, whereas other factors, such as rigidity of polymer chain. packing density of polymer chains and melt flowability, determine the modulus of the injection-moulded specimens.

Corrosion protection and thermal and mechanical properties for epoxy–thiol–imidazole systems of improved performance

2019 ◽  
Vol 32 (3) ◽  
pp. 242-257
Author(s):  
Hanxiao Xing ◽  
Yang Gao ◽  
Peng Zhang ◽  
Baoyi Wang ◽  
Yingfeng Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Peel Strength ◽  
Anticorrosion Property ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
Molar Ratios ◽  
Measurement Results ◽  
Improved Performance ◽  
The One ◽  
Imidazole System

Epoxy–thiol–imidazole system is promising for microelectronic packaging areas, such as underfills and low-temperature fast curing adhesives, but there is little knowledge on the corrosion resistance of this system. In this article, the anticorrosion and thermal and mechanical properties were characterized by theoretical and experimental methods and were understood from a fundamental perspective of structure. The cure behaviors were evaluated by differential scanning calorimeter. The mechanical and thermal properties were characterized by dynamic mechanical, thermomechanical, and thermos-gravimetric methods. The water absorption process was monitored using gravimetric measurement. Results show that among compositions of variable thiol–epoxy molar ratios, the one with ratio 0.25 has the best anticorrosion property and improved mechanical property, as well as good water resistance at room temperature. Both the average tensile strength and modulus increased initially and then declined with the addition of thiol part, while the average peel strength increased to above thrice the value of that of neat epoxy–imidazole system for thiol–epoxy 1:1 system.

Effects of ionic liquid types on the tribological, mechanical, and thermal properties of ionic liquid modified graphene/polyimide shape memory composites

2021 ◽  
pp. 095400832199676
Author(s):  
Yuting Ouyang ◽  
Qiu Zhang ◽  
Xiukun Liu ◽  
Ruan Hong ◽  
Xu Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ionic Liquid ◽  
Composite Materials ◽  
Shape Memory ◽  
Recovery Rate ◽  
Shape Recovery ◽  
Graphene Nanosheets ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
Modified Graphene

Different ionic liquid modified graphene nanosheets (IG) were induced into polyimide (PI) to improve the tribological, thermal, and mechanical properties of shape memory IG/PI composites. The results demonstrated that when using 1-aminoethyl-3-methylimidazole bromide to modify graphene nanosheets (IG-1), the laser-driven shape recovery rate of IG-1/PI composites (IGPI-1) reached 73.02%, which was 49.36% higher than that of pure PI. In addition, the IGPI-1 composite materials reached the maximum shape recovery rate within 15 s. Additionally, under dry sliding, the addition of IG can significantly improve the tribological properties of composite materials. IGPI-1 exhibited the best self-lubricating properties. Compared with pure PI, the friction coefficient (0.19) and wear rate (2.62 × 10–5) mm3/Nm) were reduced by 44.1% and 24.2%, respectively, and the T10% of IGPI-1 increased by 32.2°C. The Tg of IGPI-1 reached 256.5°C, which was 8.4°C higher than that of pure PI. In addition, the tensile strength and modulus of IGPI-1 reached 82.3 MPa and 1.18 GPa, which were significantly increased by 33.6% and 29.8%, respectively, compared with pure PI. We hope that this work will be helpful for the preparation of shape memory materials with excellent tribological, thermal, and mechanical properties.

Mechanical and thermal properties of PP/compatibilized PP/acid treated SWNTs nanocomposites: Effect of different acid treatment times

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Morteza Ghorbanzadeh Ahangari ◽  
Abdolhosein Fereidoon ◽  
Seyfolah Saedodin
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Acid Treatment ◽  
Treatment Process ◽  
Tensile Tests ◽  
Acid Mixture ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
Maleated Polypropylene ◽  
Carboxylic Groups

AbstractIn the present work, the effect of different acid treatment times of singlewalled carbon nanotubes (SWNTs) on the mechanical and thermal properties of polypropylene (PP)/maleated polypropylene (PP-g-MA) nanocomposites was investigated. The acid treatment process was based on a mixture of concentrated sulphuric and nitric acids. The SWNTs were treated with the acid mixture for 1, 3, and 6 h. FTIR, Raman spectroscopy and TEM revealed the values of carboxylic groups, graphitization and morphology of acid treated SWNTs, respectively. The thermal and mechanical properties and the morphology of nanocomposites were investigated by tensile tests, DMTA, DSC, and SEM.

scholarly journals Structure, Mechanical and Thermal Properties of Polyphenylene Sulfide and Polysulfone Impregnated Carbon Fiber Composites

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 684 ◽  
Author(s):  
Chukov ◽  
Nematulloev ◽  
Zadorozhnyy ◽  
Tcherdyntsev ◽  
Stepashkin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Fiber Composites ◽  
Chemical Oxidation ◽  
Interfacial Interaction ◽  
Polyphenylene Sulfide ◽  
Carbon Fiber Composites ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties

The paper studies new high-temperature thermoplastic impregnated unidirectional carbon fiber composites. The research focuses on the effect of thermal and chemical oxidation of the carbon fibers surface on the interfacial interaction between fibers and polysulfone and polyphenylene sulfide as well as thermal and mechanical properties of the composites. The research reveals the interaction between carbon fibers and the polymer matrix depend both on the type of surface treatment and nature of the polymer. The chemical oxidation of carbon fibers results in good interfacial interaction, and the best mechanical properties were observed for tows impregnated with polyphenylene sulfide.

scholarly journals Expansion volume of alkali activated foamed cork composites from tungsten mining mud waste with aluminium

2019 ◽  
Vol 274 ◽  
pp. 03002
Author(s):  
Imed Beghoura ◽  
Joao Castro-Gomes ◽  
Haroon Ihsan ◽  
John Pickstone ◽  
Nuno Estrada
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Mechanical And Thermal Properties ◽  
Porous Structures ◽  
Expansion Process ◽  
Foaming Agent ◽  
Al Powder ◽  
Highly Porous ◽  
Alkali Activated

Several mixes of alkali activated foams from tungsten mud waste (MW), grounded glass (GG) and metakaolin (MK) were developed incorporating expanded granulated cork (EGC). This study presents preliminary results of the expansion process obtained with the addition of aluminium (AL) powder as a foaming agent. 0.3 wt.%, 0.4 wt.% to 0.5wt.% of AL powder were added to the alkali activated matrix. The physical and mechanical properties of the obtained foams, the effects of the type and amount of the foaming agent added are presented and discussed. Highly porous structures were obtained, with overall expansion up to 68.2% when the AL powder was added. The size and distribution of pores are shown. The compressive strength of foams in the case of highly porous structures achieved of 1.2 MPa for the samples containing 0.5 wt.% of AL powder. Mechanical and thermal properties of the cured structure are good and can therefore be used for applications in acoustic panels and lightweight prefabricated components for thermal insulation purposes.

Mechanical and Thermal Properties of Ternary System Based on Starch-Grafted-Polyethylene/High Density Polyethylene/Halloysite Nanocomposites

2019 ◽  
Vol 800 ◽  
pp. 210-215
Author(s):  
Walid Fermas ◽  
Mustapha Kaci ◽  
Remo Merijs Meri ◽  
Janis Zicans
Keyword(s):  
Mechanical Properties ◽  
High Density Polyethylene ◽  
Chemical Structure ◽  
Filler Content ◽  
Halloysite Nanotubes ◽  
High Density ◽  
Flexural Properties ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
Content Ratio

In this paper, the effect of unmodified halloysite nanotubes (HNTs) content on the chemical structure and the thermal and mechanical properties of blends based on starch-grafted-polyethylene (SgP) and high density polyethylene (HDPE) (70/30 w/w) nanocomposites was investigated at various filler content ratios, i.e. 1.5, 3 and 5 wt.%. The study showed the occurrence of chemical interactions between the polymer matrix and HNTs through OH bonding. Further, the addition of HNTs to the polymer blend led to an increase in the crystallization temperature of the nanocomposite samples, in particular at higher filler contents i.e. 3 and 5 wt.%, while the melting temperature remained almost unchanged. Tensile and flexural properties of the nanocomposite samples were however improved compared to the virgin blend with respect to the HNTs content ratio.

Identification and enhancement of the thermal and mechanical properties of two types of plasters successively derived from gypsum: from the Safi basin and the High Atlas of Marrakech, Morocco

2020 ◽  
Author(s):  
imane baba ◽  
Mounsif Ibnoussina ◽  
Omar Witam
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Mechanical Strength ◽  
Setting Time ◽  
Density Measurement ◽  
Raw Material ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
X Ray Diffraction ◽  
High Atlas

<p>Over the past few decades, the construction industry has focused on sustainable, environmentally friendly and easily recyclable materials. The objective of this work is to characterize and enhance the thermal conductivity, mechanical strength and setting time of a composite material based on plaster and lime. This material is designed for use in plasters.</p><p>Two types of gypsum are studied, the first one belongs to the Safi basin, the second one characterizes the High Atlas of Marrakech and precisely Douar Tafza. Geologically speaking, the two sites have many similarities. They are characterized by a Meso-Cenozoic age coverage covering a deformed Paleozoic age basement.</p><p>The characterization of the plaster's raw material, gypsum, was necessary to determine its physical and geotechnical properties, mineralogy, thermal behaviour and microscopic structure. Several analyses have been developed such as: pycnometer density measurement, X-ray diffraction, infrared spectroscopy and scanning electron microscopy.</p><p>We made samples, of standardized dimensions, of two mixtures based on the two types of plaster reinforced by the addition of two types of lime from different localities. The latter are from Marrakech and the Agadir region. The water/plaster mass ratio was set at 0.75 and the addition of lime was achieved by increasing its percentage in slices by 12.5% and up to 50%.</p><p>The reinforcement of plaster with lime has enhanced its thermal and mechanical properties and setting time. The measurements show that the addition of lime has reduced the thermal conductivity and increased the mechanical strength of both types of plaster. In addition, following the addition of lime, the setting time has decreased and the basicity of the material has increased. Noting that the intrinsic properties of the raw material influence the mechanical and thermal properties of the material.</p><p><strong>Keywords:</strong>   plaster, enhancement, properties, mechanical, thermal, Morocco</p>

Effect of chain extender on the mechanical and thermal resistance properties of polyurethane liners for composite propellants

Polyurethanes ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
P. Ross ◽  
G. Sevilla ◽  
J. Quagliano
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Thermal Properties ◽  
Chain Extender ◽  
Molecular Structures ◽  
Polymer Chains ◽  
Mechanical And Thermal Properties ◽  
Thermal Changes ◽  
Ft Ir ◽  
Chain Lengths

AbstractPolyurethane formulations utilized as liners for composite propellants were prepared by the reaction of toluene-2,4-diisocyanate (TDI) and isophorone diisocyanate (IPDI) with hydroxyl terminated polybutadiene (HTPB), while polymer chains were further extended with neopentyl glycol diol, NPG triol and two different triols (monoglyceryl ricinoleate, MRG and trimethylolpropane, TMP). Liners were formulated with micronized titanium dioxide mechanically dispersed in hydroxyl-terminated polybutadiene (HTPB). The molecular structures of liners were confirmed by FT-IR. Thermal properties indicated that the nature of chain extender (crosslinker) only slightly affected the temperatures for decomposition of liners. Two main thermal changes were found at 370∘C and another at around 440–500∘C, depending on the chain extender utilized. On the other side, mechanical properties varied within the range of 0,7-1,8 MPa, consistent with this kind of elastomers. Tensile strength at break was only significantly affected with TMP and MRG-chain extended liners at the lowest concentrations tested of 1,3 and 2% (w/w), respectively. However, the behaviour depended on whether TDI or IPDI isocyanate was utilized for curing. TMP 1,3% crosslinked liner cured with TDI had a tensile strength of 1,82MPa whileMRG-crosslinked liner cured with IPDI had a tensile strength of 1,56 MPa. It was observed that at the higher NCO/OH ratios essayed, tensile strength and hardness increased, improving mechanical properties. Our results confirmed that TMP and MRG triols together with NPG diols can be used to tailor mechanical and thermal properties of liners, considering their different hydroxyl functionalities and chain lengths.

Mechanical and Thermal Properties of Carbon-Nanofiber Infused Polyurethane Foam

2008 ◽  
Author(s):  
Md. Atiqur Bhuiyan ◽  
Mahesh V. Hosur ◽  
Yaseen Farooq ◽  
Shaik Jeelani
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanofibers ◽  
Polyurethane Foam ◽  
High Speed ◽  
Carbon Nanofiber ◽  
Mechanical Analysis ◽  
Mechanical And Thermal Properties ◽  
Diphenylmethane Diisocyanate ◽  
Thermal And Mechanical Properties ◽  
Mechanical Agitator

In this study, thermal and mechanical properties of carbon nanofiber infused polyurethane foam were investigated. Low density liquid polyurethane foam composed of Diphenylmethane Diisocyanate (Part A) and Polyol (Part B) was doped with carbon nanofibers (CNF). A high-intensity ultrasonic liquid processor was used to obtain a homogeneous mixture of Diphenylmethane Diisocyanate (Part A) and carbon nanofibers (CNF). The CNF were infused into the Part A of the polyurethane foam through sonic cavitation. The modified foams containing nanoparticles were mixed with Part B (Polyol) using a high-speed mechanical agitator. The mixture was then cast into pre-heated rectangular aluminum molds to form the nano-phased foam panels. Flexure, static and high strain rate compression, and dynamic mechanical analysis (DMA) were performed on neat, 0.2 wt%, 0.4 wt% and 0.6 wt% CNF filled polyurethane foam to identify the effect of adding CNF on the thermal and mechanical properties. The highest improvement on thermal and mechanical properties was obtained with 0.2 wt% loading of CNF. Morphology of the samples was studied through X-ray diffraction.

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