Possible phase transformation toughening of thermoset polymers by poly(butylene terephthalate)

Mechanisms were explored by which particles of poly(butylene terephthalate) (PBT) are able to toughen a brittle epoxy. The epoxy studied was an aromatic amine-cured diglycidyl ether of bisphenol-A, which was toughened at about twice the rate with particles of poly(butylene terephthalate) as with particles of nylon 6, poly(vinylidene fluoride), or CTBN rubber. Many of the mechanisms of toughening are visible on the fracture surface of the PBT-epoxy blend, but a mechanism suggested to account for perhaps half of the increased toughness with PBT, phase transformation toughening, is not. The two types of experiment performed to detect phase transformation toughening were: (1) measurements of the rubber cavitation zone in PBT-CTBN rubber-epoxy ternary blends, which would detect an expansion of the PBT particles during fracture if it occurred, and (2) measurements of the fracture energy in PBT-epoxy blends in which the various mechanisms of toughening were selectively suppressed. Both types of experiment indicated the occurrence of phase transformation toughening in these PBT-epoxy blends.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44711/1/10853_2005_Article_BF01154110.pd

Ferrite Industry in India. Present Scenario and Future Outlook

Present Indian ferrite industry has come long way. Commercial production of ferrites started in 1960's. The production of ferrites in 1990 was about 7000 MT which has grown to about 15000 MT by 1995 indigenously. Indian ferrite industry is now posed for big jump and now getting ready to compete in the world market. The major companies are now proposing for big expansions in their production capacities with a desire to become global player. These plans have got further boost due to new economic reforms initiated by the Govt. of India and helping the industry to increase their share in world ferrite market. The new liberalised policy of Indian Govt. have also attracted many foreign companies to set up their production bases in India. The present paper deals in detail the scenario of the Indian industry, availability of main input raw materials, new Govt. policies, opportunities for new ventures etc

An in vitro scanning electron microscopic study comparing MTAD (intracanal irrigant) and various root biomodifiers on periodontally involved human teeth

Background: Smear layer removal and collagen fiber exposure may improve regeneration outcome, which can be accomplished by use of root biomodifiers. These enhance the degree of connective tissue attachment to denuded roots. The objective of this in vitro scanning electron microscopic study was to comparatively evaluate mixture of tetracycline (TTC) and acid and detergent (MTAD) and other root biomodifiers for smear layer removal on periodontally involved human teeth. Materials and Methods: Forty human teeth were collected and stored in saline. After scaling and root planning, two samples were obtained from each tooth. A total of 80 dentin blocks were randomly divided into four groups: MTAD, TTC hydrochloride (TTC HCl), citric acid (CA), and normal saline. The agents were applied for 3 min by active burnishing. Immediately following treatment, the specimens were rinsed, dehydrated, fixed and prepared for scanning electron microscope and was examined at Χ3500 magnification. Previously trained blind examiners evaluated photomicrographs using Sampaio′s index (2005). Statistical analysis was performed. Results: MTAD is most efficacious in removing smear layer and showed statistically significant dentinal tubules opening, followed by TTC HCl and CA. Conclusion: MTAD and conventional root biomodifiers used in the study alters the dentin surface by smear layer removal and exposure of dentinal tubules. Hence, MTAD as a root biomodifier may have a significant role in periodontal regeneration