21 research outputs found
Effects of Thermal Degradation on Carbon Reinforced PEEK Composites
No full textThe application of fibre reinforced thermoplastic composites in aerospace industry has increased drastically in the last decade. Carbon fibre/Polyether-ether-ketone (C/PEEK) is one of the high-performance thermoplastic composites and is replacing metallic and thermosetting counterparts in various aircrafts components. Parts made from such composites undergo multiple heat treatment cycles, and each cycle involves processing at temperatures above melt. At these temperatures, thermal stability is a limiting factor, which results in severe thermal degradation of the polymer, especially in oxidative environments. For this project, the thermal degradation of 8-ply unidirectional C/PEEK composites is investigated. The objectives include finding the reduction in morphological properties of PEEK polymer due to degradation over four different processing temperatures (385, 405, 425, and 445°C), and times (10, 30, 60, and 90 minutes), in two processing environments (air and nitrogen), exploring the effect of oxygen and temperature on degradation, and evaluating the mechanical performance through three-point bending. Thermal analysis through Differential Scanning Calorimetry (DSC) showed that the crystallinity reduces from 32% for an untreated laminate to 28% for the lowest heat treatment condition (385°C, 10 minutes). From there, a steady reduction is observed, with 15% at 425°C, 60 minutes, and 0% at 425°C, 90 minutes and 445°C, 90 minutes. A contour plot for polymer property reduction based on crystallinity serves as a processing guideline for C/PEEK laminates. DSC analysis through the thickness of air treated laminates showed that surface plies degrade faster than the inner plies. This effect is not observed in a nitrogen environment. This showed the effect of oxygen on the surface. Though inner plies were shielded from oxygen exposure, they still showed a higher degradation than nitrogen treated laminates, showing that diffusion of oxygen through the laminates has taken place. At 425°C and 445°C, in air, the through thickness difference is higher compared to 385°C. So, in oxygen environment, polymer degrades faster at higher temperatures than at lower temperatures. In nitrogen, at 385°C, there is almost no degradation, whereas the other three temperatures show an increased degradation. The rate of degradation in different environments and at different temperatures is characterized by computation of activation energies. The air treated laminates showed an activation energy of 126 kJ/mol, whereas, nitrogen treated laminates has 193 kJ/mol. 3-point bending tests are performed to observe matrix failure. No failure was observed at 10, 30, and 60 minutes at 385°C, but from 405°C, cracks starts to appear and cracks initiates at lower stresses with increasing heat treatment conditions.Aerospace Engineering | Novel Aerospace MaterialsAerospace Engineerin
REACTION OF COWPEA GENOTYPES FOR RESISTANCE AGAINST LEGUME POD BORER, Maruca vitrata (Fabricius)
No full textAmong different pulses, cowpea is considered as most important source of nutrition to human and livestock. Several insect pests cause major constraint in cowpea production. Among the pests, the legume pod borer, Maruca vitrata (Fabricius) is a serious threat which ultimately reduces the quality and quantity of the economic produce. Management of M. vitrata using insecticides is commonly followed. But, indiscriminate use of insecticides leads to unwanted repercussions in the environment. It prompted to turn the focus on eco friendly methods to manage this pest. Among various management methods, use of tolerant and/or resistant genotypes is the first line of defence against insect pests. In the light of this consideration, 280 cowpea genotypes were screened against M. vitrata during Rabi, 2020 and Kharif, 2021 seasons at Vallampadugai Village, Cuddalore district, Tamil Nadu state, India. The per cent flower and pod infestation were noted at different days after sowing. The results revealed that, minimum flower infestation was noted on IC-202800(6.60% and 5.00%) in both rabi and kharif. Maximum infestation in rabi and kharif was noted on IC-249141(76.66%) and IC-9883 (66.66%) respectively. Minimum and maximum per cent pod infestation was noted on IC-39870 (15.00% in rabi and 10.00% in kharif) and EC-161916(100% in rabi and 93.33% in kharif) in both seasons. Based on per cent pod damage, 30 genotypes were found highly resistant, with 52 moderately resistant, 81 susceptible genotypes and 38 highly susceptible genotypes in rabi season. In kharif, 18 genotypes were highly resistant and 86 genotypes have recorded moderately resistant in contrast to 13 genotypes secured highly susceptible ratings
Role of Plant Volatiles, Pest-Resistant Varieties and Transgenics in Tri-trophic Interactions
No full textSEASONAL INCIDENCE AND REACTION OF GREENGRAM GENOTYPES AGAINST SPOTTED POD BORER, Maruca vitrata (FABRICIUS)
No full textGreengram cultivation is hampered by various insect pests, among which the spotted pod borer, Maruca vitrata (Fabricius) inflicts extensive damage. Insecticides are widely used to suppress this damage but are found to culminate in undesirable effects in the environment and humans. Exploring and exploiting host plant resistance in the gene pool of crop plants is an effective, ecofriendly alternative approach to manage such insect pests. Considering this, 333 greengram genotypes were gathered and screened under field condition to identify resistance sources against spotted pod borer during Rabi 2020 and Kharif 2021 at Sivapuri village, Chidambaram, Tamil Nadu, India. The larval population and their active webbing were accessed from flower bud initiation to end of crop growth period and per cent pod damage was worked out after harvest. The results of this study revealed that, the larval population and active webbing and per cent pod damage were the least on IC-39301-1 followed by IC-311451 and IC-39301-1 followed by IC-103207 during Rabi 2020 and Kharif 2021 respectively. In both seasons, the larval population, active webbing, and percent pod damage were higher in the genotype IC-39317, followed by IC-103981. Based on per cent pod damage 4 and 10 genotypes were found resistant, while 182 and 175 genotypes were moderately resistant, 70 and 78 genotypes were tolerant, 56 and 63 genotypes moderately susceptible and 21 and 7 genotypes were highly susceptible in Rabi 2020 and Kharif 2021 respectively. The genotypes which were grouped under resistant and tolerant category in both the seasons were selected for further evaluation to develop desirable varieties
Influence of Weather Factors on the Incidence of Major Insect Pests of Sesame (Sesamum indicum L.)
No full textPopulation dynamics of major pests viz., web worm, Antigastra catalaunalis (Duponchel), leaf hoppers Orosius albicinctus (Distant) and gallfly Asphondilia sesami (Felt) infesting sesame was studied in Coimbatore, Tamil Nadu, India during Rabi and Kharif seasons of the year 2020. Correlation between the pest population, percent damage and weather parameters was analyzed and regression equations were developed. The incidence of leaf hoppers, web worm and gallfly on sesame crop during Rabi season started on 4th, 3rd and 7th Standard meteorological week (SMW) respectively. The peak attained on 8th,11th, and 11th SMW with population of leafhoppers and damage by web worm and gallfly (2.01/plant,60.04 percent and 49.68 percent) respectively during Rabi season. In case of leafhopper and web worm, minimum temperature (r=0.031r=0.373) had non-significant positive correlation whereas mean relative humidity (r=-0.02) registered non-significant negative correlation with leaf hopper and web worm significant negative correlation Gall fly incidence showed significant positive correlation with maximum and minimum temperature. Whereas in Kharif season, incidence of leafhoppers, web worm and gallfly on sesame crop started on 33rd, 32nd and 37th SMW respectively. The peak activity and incidence was noticed during 37th, 39th and 40th SMW for leafhoppers, web worm and gallfly respectively. The correlation between weather parameters and incidence of major pests followed a similar pattern to kharif season. Regression analysis data revealed that the multiple non-linear regression equations are sufficient to predict the pest population with prevailing weather parameters
Induction of resistance in tomato against Helicoverpa armigera (Hubner) using biofertilizers
No full textBased on preliminary and confirmatory field screening of 321 tomato accessions for resistance against fruit borer, Helicoverpa armigera (Hubner), a promising accession Varushanadu Local was selected for studying induction of resistance using biofertilizers viz., Azospirillum, Phosphobacteria, Pseudomonas and K-solubilizer. In comparison, a susceptible check, I979 was also evaluated. The feeding preference of H. armigera larva was the least towards Varushanadu Local than I979 irrespective of the biofertilizer. Among the biofertilizers K-solubilizer treated plants were the least preferred than others. A trend was observed in both the free choice and confinement tests. ÂÂ
