نتایج جستجو برای: three types of resins including industrial urea formaldehyde

تعداد نتایج: 21241852  

2014
Tapan K. Das

Cardanol(Cashew phenol) is subjected to diazotisation with Aniline and m-Toluidine to get monomers like Cardanol based dye from Aniline (CBDFA) and Cardanol based dye from m-Toludine (CBDFT). Such monomers have been condensed with formaldehyde in presence of acid catalyst to form resins. The resins have been characterized by FTIR spectra and their thermal behaviour have been studied.

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سمنان 1392

in the area of vocabulary teaching and learning although much research has been done, only some of it has led to effective techniques of vocabulary teaching and many language learners still have problem learning vocabulary. the urge behind this study was to investigate three methods of teaching words. the first one was teaching words in context based on a traditional method of teaching that is,...

Journal: :Contact dermatitis 2010
Anton C de Groot Ian R White Mari-Ann Flyvholm Gerda Lensen Pieter-Jan Coenraads

In this part of a series of review articles on formaldehyde-releasers and their relationship to formaldehyde contact allergy, formaldehyde-releasers in cosmetics are discussed. In this first part of the article, key data are presented including frequency of sensitization and of their use in cosmetics. In Europe, low frequencies of sensitization have been observed to all releasers: 2-bromo-2-nit...

this thesis attempts to investigate the effects of prelistening activities on enhancing iranian efl learners` listening comprehension. the present study investigated ways in which learners` background knowledge could be activated in order to enhance their l2 listening comprehension by limiting the number of possible text interpretations prior to listening. the experiments conducted in this study examined the effect of prior knowledge and vocabulary teaching on iranian efl learners listening comprehension. the current study has two purposes: one is to investigate the effect of background knowledge on the second language listening comprehension of iranian intermediates and the other is to determine whether second language is facilitated by the introduction of unknown vocabularies in the form of prelistening activities. to conduct the study different instruments such as listening proficiency test and four listening tests such as pre and posttests were used and various statistical processes and techniques including paired-sample t-test, and analysis of variance (anova) were used. the findings of this study supported all three hypotheses tested. differences were found between the means of preteaching vocabulary variable, the background knowledge activation variable, and mean difference between these two strategies variable. subjects scored higher when the unknown words were taught in advance. likewise, subjects scored higher when they were asked some relevant questions about the topic than on those without them. there was, in addition, a significant difference between the means of preteaching vocabulary strategy and background knowledge activation strategy. in fact, preteaching vocabulary had a better effect in enhancing the students’ listening comprehension, in comparison to background knowledge activation strategy.

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده زبانهای خارجی 1390

this thesis attempts to investigate the effects of prelistening activities on enhancing iranian efl learners` listening comprehension. the present study investigated ways in which learners` background knowledge could be activated in order to enhance their l2 listening comprehension by limiting the number of possible text interpretations prior to listening. the experiments conducted in this stud...

2015
K. Narayanankutty

This study reports the results of a study aimed at reducing the free formaldehyde content of Phenolformaldehyde resin by using Urea as means for forming a reversible adduct with formaldehyde. The highly volatile formaldehyde has an unpleasant odour and irritates the eyes and nasal passages. The free formaldehyde content (FFC) of the modified resol resin was determined by titration method. With ...

Journal: :Environment international 2009
Xiaojiang Tang Yang Bai Anh Duong Martyn T Smith Laiyu Li Luoping Zhang

Formaldehyde, an economically important chemical, is classified as a human carcinogen that causes nasopharyngeal cancer and probably leukemia. As China is the largest producer and consumer of formaldehyde in the world, the Chinese population is potentially at increased risk for cancer and other associated health effects. In this paper we review formaldehyde production, consumption, exposure, an...

2004
Tohru Mitsunaga Anthony H. Conner Charles G. Hill

Phenolic resins are important adhesives used by the forest products industry. The phenolic compounds in these resins are derived primarily from petrochemical sources. Alternate sources of phenolic compounds include tannins, lignins, biomass pyrolysis products, and coal gasification products. Because of variations in their chemical structures, the reactivities of these phenolic compounds with fo...

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