scholarly journals Highly Crosslinked Polybenzoxazines from Monobenzoxazines: The Effect of Meta-Substitution in the Phenol Ring

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 254 ◽  
Author(s):  
Alba Martos ◽  
Marc Soto ◽  
Hannes Schäfer ◽  
Katharina Koschek ◽  
Jordi Marquet ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Relative Position ◽  
Crosslink Density ◽  
Mechanical Analysis ◽  
Polymerization Temperature ◽  
Meta Position ◽  
Phenolic Ring ◽  
Crosslinked Networks ◽  
Phenol Ring ◽  
Thermal Stability Of

It is possible to control the crosslink density of polymers derived from monobenzoxazines by switching the type of substituents in the phenolic ring and their relative position with respect to the phenol group. We prepared several substituted monobenzoxazines in the para and meta positions of the phenolic ring and studied how these substituents affected the polymerization temperature of monomers and the thermal stability of the final polymers and, more extensively, how they affected the crosslink network of the final polymers. Gel content and dynamic mechanical analysis confirm that ortho- and para-orienting substituents in the meta position generate highly crosslinked materials compared to para ones. This fact can lead to the design of materials with highly crosslinked networks based on monobenzoxazines, simpler and more versatile monomers than the commercial bisbenzoxazines currently in use.

scholarly journals Effect of Compatibilizer on the Interface Bonding of Graphene Oxide/Polypropylene Composite Fibers

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1283 ◽  
Author(s):  
Miao Miao ◽  
Chunyan Wei ◽  
Ying Wang ◽  
Yongfang Qian
Keyword(s):  
Thermal Stability ◽  
Graphene Oxide ◽  
Loss Modulus ◽  
Composite Fiber ◽  
Mechanical Analysis ◽  
Interfacial Bonding ◽  
Composite Fibers ◽  
Scanning Calorimetry ◽  
Blending Method ◽  
Thermal Stability Of

To improve the interfacial bonding and thermal stability of graphene oxide (GO)/polypropylene (PP) composite fibers, a composite fiber with PP as the matrix, GO as reinforcement and maleic anhydride-grafted PP (PP-g-MAH) as a compatibilizer was prepared by a simple and efficient melt-blending method. The GO content was 0.0–5.0 wt %. According to the Fourier Transform Infrared (FT-IR) spectroscopy results, the interfacial bonding in the PP/MAH/GO composite fibers was improved. The Dynamic Mechanical Analysis (DMA) results show that the addition of GO resulted in better interfacial adhesion and higher storage modulus (E′). The loss modulus (E′′) of the PP/MAH/GO-x composite fibers increased with increasing amount of added GO, whereas the loss factor (tan δ) decreased. GO and PP-g-MAH were analyzed by Thermogravimetric Analysis (TGA). The thermal stability of the composite fibers was improved compared to PP. Differential Scanning Calorimetry (DSC) analysis showed that the addition of PP-g-MAH to the composite fiber improved the interfacial bonding of GO in the PP matrix. Thus, compatibility between the two components was obtained. Based on the Scanning Electron Microscopy (SEM) results, the PP fibers exhibited relative orientation due to the strong crystalline morphology. The rough section, PP/GO blend fiber exhibits a very clear phase separation morphology due to the incompatibility between the two and the compatibility of GO and PP in PP/MAH/GO-3 composite fiber is improved, resulting in the interface between the two has improved.

Thermal and Thermomechanical Properties of Poly(butylene succinate) Nanocomposites

2008 ◽  
Vol 8 (4) ◽  
pp. 1679-1689 ◽  
Author(s):  
Mamookho E. Makhatha ◽  
Suprakas Sinha Ray ◽  
Joseph Hato ◽  
Adriaan S. Luyt
Keyword(s):  
Thermal Stability ◽  
Tensile Modulus ◽  
Melting Behavior ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Butylene Succinate ◽  
Modulated Differential Scanning Calorimetry ◽  
Thermal Stability Of

This article describes the thermal and thermomechanical properties of poly(butylene succinate) (PBS) and its nanocomposites. PBS nanocomposites with three different weight ratios of organically modified synthetic fluorine mica (OMSFM) have been prepared by melt-mixing in a batch mixer at 140 °C. The structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD) analyses and transmission electron microscopy (TEM) observations that reveal the homogeneous dispersion of the intercalated silicate layers into the PBS matrix. The thermal properties of pure PBS and the nanocomposite samples were studied by both conventional and temperature modulated differential scanning calorimetry (DSC) analyses, which show multiple melting behavior of the PBS matrix. The investigation of the thermomechanical properties was performed by dynamic mechanical analysis. Results reveal significant improvement in the storage modulus of neat PBS upon addition of OMSFM. The tensile modulus of neat PBS is also increased substantially with the addition of OMSFM, however, the strength at yield and elongation at break of neat PBS systematically decreases with the loading of OMSFM. The thermal stability of the nanocomposites compared to that of the pure polymer sample was examined under both pyrolytic and thermooxidative environments. It is shown that the thermal stability of PBS is increased moderately in the presence of 3 wt% of OMSFM, but there is no significant effect on further silicate loading in the oxidative environment. In the nitrogen environment, however, the thermal stability systematically decreases with increasing clay loading.

Study on the thermal stability of Controlled Permeability Formwork

2011 ◽  
Vol 374-377 ◽  
pp. 1426-1429
Author(s):  
Xiao Meng Guo ◽  
Jian Qiang Li ◽  
Xian Sen Zeng ◽  
De Dao Hong
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Dynamic Mechanical Analysis ◽  
Thermo Gravimetric Analysis ◽  
Mechanical Analysis ◽  
Gravimetric Analysis ◽  
Construction Work ◽  
Thermo Gravimetric ◽  
Excellent Thermal Stability ◽  
Thermal Stability Of

In this study, the thermal properties of a kind of new geotextile materials, so called controlled permeable formwork (CPF), were studied. Thermo-gravimetric analysis showed that the weight of CPF didn’t change much between 0~350 °C. Dynamic mechanical analysis showed that the storage modulus of CPF reduced from 25 MPa to around 10 MPa when the temperature rose to above 100 °C. The strength of sample decreased slightly with the increase of the temperature. The breaking elongation changed slightly with a maximum at 80 °C. The CPF showed excellent thermal stability and was suitable for general use in construction work.

Preparation and Properties of Silane-Terminated Poly(urethane-Imide)

2013 ◽  
Vol 690-693 ◽  
pp. 1577-1580
Author(s):  
Xiao Xi Hu ◽  
Yun Wang
Keyword(s):  
Thermal Stability ◽  
Water Resistance ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Silane Coupling ◽  
Ft Ir ◽  
And Storage ◽  
Thermal Stability Of

A serious of silane-terminated poly (urethane-imide) (Si-PUI) was synthesized via prepolymer method using polycarbonatediols (PCDL), 2,4-tolylene diisocyanate (TDI), 4,4'-Oxydiphthalic Anhydride (ODPA) and silane coupling agent KH-550. The structure of the products was characterized by FT-IR. The thermal properties were measured by thermal gravimetric analysis (TGA). The thermal mechanical behavior was investigated by dynamic mechanical analysis (DMA).The mechanical characteristic was measured by tensile tests. The water absorption (Wa) was also been tested. With the imide content increasing, the thermal stability, tensile strength and storage modulus of poly (urethane-imide) improve significantly, and the glass transition temperature rises. The introduction of silanes improves the water resistance and further enhances the thermal stability of poly (urethane-imide).

Dynamic Mechanical Analysis and Thermal Stability of Neem Wood Veneer Plastic Composites

2020 ◽  
Vol 24 ◽  
pp. 2265-2273
Author(s):  
M. Nagamadhu ◽  
S. Vijay Kumar ◽  
S. Ravi Kumar ◽  
R. Suraj ◽  
G.C. Mohan Kumar
Keyword(s):  
Thermal Stability ◽  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Wood Veneer ◽  
Dynamic Mechanical ◽  
Plastic Composites ◽  
Thermal Stability Of

N-(Aminothio)imide Cure Modifiers

1976 ◽  
Vol 49 (2) ◽  
pp. 333-340 ◽  
Author(s):  
J. P. Lawrence
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Crosslink Density ◽  
Electronic Effects ◽  
Cure Rate ◽  
Cure Characteristics ◽  
Free Amine ◽  
Diene Rubbers ◽  
Thermal Stability Of

Abstract N-(Aminothio)imides have been found to influence the cure characteristics of diene rubbers accelerated by conventional vulcanization accelerators. In this respect, they generally act both as scorch inhibitors and activators to increase the cure rate and crosslink density. The ability of these compounds to act as scorch inhibitors is believed to be attributable to trapping of MBT with resultant formation of the corresponding free imide and 2-(aminodithio)benzothiazole. The latter is an active vulcanization agent and may lead directly to the formation of pendent accelerator groups and free amine, likely the source of the cure activation. As precursors to crosslink formation, the pendent accelerator groups carry an atom of sulfur derived from the cure modifier and thus lead to higher crosslink density. The relative scorch inhibiting characteristics are influenced by the basicity of the parent amine and thermal stability of the cure modifier. The compounds derived from amines of weaker basicity are better retarders and less subject to thermal degradation which would lead to nonretarding products. The relative cure activating effects are apparently influenced by both steric and electronic effects of the parent amine. Cure activation increases as the steric bulk decreases and basicity increases. As expected, the nature of the imide substituent played a relative insignificant role in influencing the cure characteristics, aside from a possible stabilization against thermal degradation.

Studies on a Miscible Polyimide Blend

1997 ◽  
Vol 9 (3) ◽  
pp. 263-279 ◽  
Author(s):  
J A Campbell ◽  
A A Goodwin ◽  
F W Mercer ◽  
V Reddy
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Physical Aging ◽  
Adhesive Bond ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Adhesive Properties ◽  
Dynamic Mechanical ◽  
Thermal Stability Of

Blends of polyimides XU-218 and PEI were investigated using differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis and adhesive bond testing. The thermal stability of the blends increased as the proportion of PEI increased while the α-relaxation of the blends occurred at a slower rate and was broader and more cooperative in some blends, compared with the pure polymers. Physical aging of the pure polymers and blends in the glass state revealed changes in relaxation rate and lost enthalpy that were also consistent with blends not behaving as simple mixtures. The dynamic mechanical and physical aging behaviour was attributed to an increase in density on blending which decreased the unoccupied volume and increased the constraints on molecular mobility, as well as to the presence of concentration fluctuations. The adhesive properties of the blends were also investigated and bond strength was found to vary with blend composition and test temperature.

Performance properties of rigid polyurethane-polyisocyanurate/brewers’ spent grain foamed composites as function of isocyanate index

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 427-437 ◽  
Author(s):  
Aleksander Hejna ◽  
Józef Haponiuk ◽  
Łukasz Piszczyk ◽  
Marek Klein ◽  
Krzysztof Formela
Keyword(s):  
Thermal Stability ◽  
Compressive Strength ◽  
Fourier Transform ◽  
Glass Transition ◽  
Crosslink Density ◽  
Mechanical Analysis ◽  
Ftir Analysis ◽  
Blowing Agent ◽  
Isocyanate Index ◽  
Spent Grain

AbstractIn the presented work, rigid polyurethane-polyisocyanurate (PUR-PIR) foams filled with brewers’ spent grain (BSG) were prepared. The influence of the isocyanate index (II) on its performance was investigated. Foams obtained with higher isocyanate index required a higher amount of hydrofluorocarbon physical blowing agent to provide the same apparent density of material. An increase of isocyanate index resulted in a slight decrease of cell size, which was related to the increased crosslink density due to enhanced generation of allophanate and biuret groups. Deterioration of compressive strength, from 226 to 202 kPa was observed with the rise of the isocyanate index. Dynamic mechanical analysis and swelling tests confirmed the increase of crosslink density with the increasing isocyanate index. The glass transition temperature rose from 165.7°C to 193.2°C. Fourier transform infrared (FTIR) analysis indicated an increase of the isocyanurate rings’ content in composites with a higher isocyanate index, causing noticeable enhancement of thermal stability. The onset of degradation was shifted from 196°C to 211°C.

Dynamic Mechanical Properties of Epoxy Resin with Multifunctional Polyamine Curing Agent

2015 ◽  
Vol 744-746 ◽  
pp. 1374-1377
Author(s):  
Xi Wang
Keyword(s):  
Thermal Stability ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Diglycidyl Ether ◽  
Curing Agent ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Dynamic Mechanical ◽  
Glass Relaxation ◽  
Thermal Stability Of

A nonlinear multifunctional polyamine N,N,N’,N’-tetra (3-aminopropyl)-1,6-diamino-hexane (TADH), was prepared and employed as a novel hardener for diglycidyl ether of bisphenol A (DGEBA). Nonisothermal reactions of DGEBA/TADH were systematically investigated with differential scanning calorimetry (DSC). In addition, analysis of thermal stability of the cured DGEBA/TADH with thermogravimetric analysis (TGA) revealed that it possessed quite good thermal stability and increased residual char content at 600◦C in nitrogen. Furthermore, dynamic mechanical analysis (DMA) of the DGEBA/TADH network showed its relaxations were characterized by localized motions of hydroxyl ether segments and cooperative motions of whole network chains (glass relaxation) at different temperature regions.

Effect of Rubber Contents on Tribological and Thermomechanical Properties of Polybenzoxazine

2014 ◽  
Vol 576 ◽  
pp. 75-79 ◽  
Author(s):  
Chanchira Jubsilp ◽  
Sarawut Rimdusit ◽  
Tsutomu Takeichi
Keyword(s):  
Thermal Stability ◽  
Wear Resistance ◽  
Glass Transition ◽  
Mass Fraction ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Flexural Property ◽  
Test Machine ◽  
Thermal Stability Of ◽  
Ball On Disc

Bisphenol-A/aniline based polybenzoxazine (PBZ) modified with amine terminated butadiene–acrylonitrile (ATBN) were prepared. The tribological and thermomechanical properties as well as thermal stability of the PBZ/ATBN copolymers were investigated by ball-on-disc tribometer, dynamic mechanical analysis (DMA), universal test machine and thermogravimetric analysis (TGA). The inclusion of ATBN at a mass fraction of 5% was found to greatly increase friction coefficient and wear resistance of the copolymers. DMA measurements showed that the storage modulus and the glass transition temperature of the PBZ can be maintained with an addition of ATBN in the range of 1-5wt%. Moreover, flexural property measurements indicated that the flexural strength of the copolymer increased with increasing of ATBN content up to 10wt% whereas TGA results revealed that an increase of the PBZ content can help improve thermal stability of the copolymers.

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