Addition polyimides. I

Varma, I. K.; Gupta, Ashok; Sangita,; Varma, D. S.

doi:10.1002/app.1983.070280116

Cited by 65 publications

(34 citation statements)

References 7 publications

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“…In our earlier articles we have reported the synthesis and characterisation of bismaleimides and chain extentled bismaleimides [1][2][3][4][5][6][7]. Effect of structure on thermal characteristics of bismaleimides was also studied.…”

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confidence: 99%

Thermal characterization of bismaleimide blends

Varma

Tiwari

1987

Journal of Thermal Analysis

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4,4'-bismaleimidophcuyl methane (BM) and 3,3'-bismaleimidophenyl sulfone (BS)were blended in solution using weight ratios 3 : 1 (MS31), 2 : 1 (MS21), 1 : 1 (MSI 1), 1 : 2 (MSI2) and 1 : 3 (MS 13). Chain extended bismaleimide resins were also p~ax~d by treating BS/BM with 4,4'-diaminodiphenylether in molar ratios of 1:0.3 (BM-E and BS--E resins). These resins were also blended with bismaleimides and the curing characteristics were evaluated'by differential scanning calorimetry. Increase in BM content in BM : BS blends or increase in chain extended bismaleimide content in BM-E: BS or BS-E : BM blends resulted in a reduction of melting and curing temperatures. Indication about the extent of cross-linking was obtained from solubility measurements (in DMF) of isothermally cured resins (180 ~ lh and 220 ~ lh in an air oven). Thermo~avimetric analysis of samples isothermally cured at 180 ~ and 220 ~ (lh each) was carried out in nitrogen atmosphere. Improvement in thermal stability of chain extended bismaleimides was observed on blending.Bismaleimides are prime candidates as matrix resins for fibre reinforced composites and are finding increasing acceptance as engineering materials for high performance engineering applications. These resins are cured by thermally induced addition reaction giving highly crosslinked, void free network polymers having good physical properfies, thermal stability, better fire resistance and lower water absorption than currently used epoxy resins. Chain extended bismaleimides, obtained by nucleophilic addition reaction with aromatic diamine have also been used as resing for advanced fibre reinforced composites.In our earlier articles we have reported the synthesis and characterisation of bismaleimides and chain extentled bismaleimides [1-7]. Effect of structure on thermal characteristics of bismaleimides was also studied. It was observed that the presence of electron donor groups in bismaleimides reduces the melting and curing temperatures of the resins. On the other hand, presence of electron withdrawing groups results in higher melting point and curing temperature [8-9].Blending of bismaleimides containing electron withdrawing and electron donating substituents is expected to effect the melting and curing temperatures. John Wiley & Sons, Limited, ChichesterAkad~miai Kiadt, Budapest

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confidence: 99%

Thermal characterization of bismaleimide blends

Varma

Tiwari

1987

Journal of Thermal Analysis

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“…The results indicate that this is not influenced by the presence of NH2 groups in the backbone. For maleimide resins, on the other hand, Michael-type addition reactions between the electron-deficient maleimido group and the electron-rich amino group lead to a significant reduction in Texo [8] . If a maleimido group was generated during a retrograde DielsAlder reaction, then a decrease in Texo of nadimides containing -NH2 groups would be expected, but this was not observed in the present work.…”

Section: A Good Correlation Between Observed and Calculated Elementalmentioning

confidence: 99%

Phosphorus-Containing Nadimide Resins: Synthesis and Characterization

Varma

Mittal

1989

Journal of Macromolecular Science: Part A - Chemistry

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A series of phosphorus-containing nadimide-endcapped resins was prepared by reacting endo-5-norbornene-2,3-dicarboxylic acid anhydride (nadic anhydride), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, and tris(3-aminopheny1)phosphine oxide in glacial acetic acid/ dimethylformamide. Structural characterization of resins was done by elemental analysis, FTIR, and H NMR. In DSC traces of these resins, an exothermic transition associated with crosslinking was observed above 280°C. Thermogravimetric studies revealed a multistep decomposition reaction. Residual welght at 800°C in nitrogen was found to depend on the backbone structure and ranged from 42 to 6Wo.

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“…The maximum and minimum values of tensile stress were 56.6 and 23.6 MPa, with an increase of 3.5% and a decrease of 57%, respectively, respect to the values determined for neat PLA probes. The influence of the considered factors on the mechanical strength is described by the following equation σ t = 40.71 -6.98T* e -7.41T* i + 0.19S* i -2.85T* m + + 5.57P* h -5.1t* c + 0.72S* e (3) which showed that the most influential processing factors were T e , T i and t c (all of them with negative influence), and P h (with positive influence). In order to allow an easier interpretation of results, Fig.…”

Section: Manufacture and Properties Of Compositesmentioning

confidence: 99%

Assessment on the effects of the operational conditions on the manufacture of PLA-based composites using an integrated compounding–injection moulding machine

González

Campos²,

Cunha

et al. 2011

Collect. Czech. Chem. Commun.

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Cellulose fibres were employed as reinforcement agent for biodegradable composites using polylactic acid (PLA) as a polymer matrix. PLA can be obtained from renewable resources, and it is attracting much interest owing to its favourable physico-mechanical properties and biodegradability. Prior to composite compounding, two commercial PLA from different suppliers were characterized for apparent density, flow index, crystallinity, thermal properties, melt flow rheology and intrinsic viscosity for comparison. In experiments performed with an integrated compounding-injection moulding machine (ICIM), the effects of the processing conditions on the mechanical properties of composites (tensile strength, stiffness and strain at break) were analyzed using a Taguchi experimental design. Other properties of the composites, such as surface morphology and fibre length distribution, were also considered. ICIM technology provided composites with better mechanical properties and lower fibre degradation than the conventional sequential extrusion and injection moulding (SEIM) technology.

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Addition polyimides. I

Cited by 65 publications

References 7 publications

Thermal characterization of bismaleimide blends

Thermal characterization of bismaleimide blends

Phosphorus-Containing Nadimide Resins: Synthesis and Characterization

Assessment on the effects of the operational conditions on the manufacture of PLA-based composites using an integrated compounding–injection moulding machine

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