پارسی فایل

عنوان تحقیق : طبقه بندی صابون ها و مواد مغذی

تعداد صفحات : 68

زبان : انگلیسی

فرمت فایل : word

بخش هایی از متن تحقیق :

INTRODUCTION

Historical Background

Firstsynthetic detergents were produced in Germany in World War–I when animal fats were diverted to other wartime uses and were unavailable for soap manufacture. The first synthetics were short chain alkyl naphthalene sulphonates. They were only fair as detergents but are good wetting agents and are still used as textile auxiliaries .

In the late 1920 and early 1930s long chain alcohol sulphate were sold as the sodium salts together with sodium sulphate extender as the only other constituent . In the 1930s long chain a lkylaryl sulphonates were also introduced and by the end of World War-II in 1945 had largely supplanted alcohol sulphates as detergents from 1950 to 1965 detergent made by reacting propylene tetramer with benzene and sulphonating the product were predominant and had the major portion of the market the world over . Also in 1950 to 1955 the art of detergent formulation advanced and explosive growth occurred in the use of phosphate builders .

Starting in the early 1960s a wave of ecological consciousness spread and this resulted in four major changes in detergent compositions :

1) Tetrapropylene , a branched chain material was replaced with linear chains attached to the benzene mucleus . Also long chain alcohols regained popularity but the key point was that the long chain had to liner and hence degradable . This change is complete in most developed countries where pollution control lows are highly developed , although some under developed countries still use non-degradable materials .

2) Algae growth and eutrophication in lakes caused figures to be pointed at phosphates as the culprits . The influence of phosphates has been disputcd but , in any event , searches for non-phosphate builder materials have gone on and are still going on . NTA ( Nitrilotriacetic acid ) was once hailed as the perfect replacement for phosphates but health hazard fears have stunted its growth altogether . polycarboxylic acids and similar materials have found the most favour as phosphate replacements in building detergents .

3) A third major change in detergents formulations was in the introduction of enzyme additives to such formulations . These materials serve as catalysts to break down protein materials which may stain clothes . They are often used in a prewashing step to break down materials which are then loosened and removed in the washing cycle . These materials were first introduced in Europe and found wide acceptance there but only entered the U.S. market in the late 1960s , where these are now widely used .

Substance or products which are capable of dislodging , removing and dispersing solid and liquid soils from a surface being cleaned are known as detergents . In the broadest sense all materials used in cleaning-i.e. water and other solvents , alkalis and alkaline salts , acids and acid salts , abrasives , oxidizing and reducing agents may be called as detergents . Soaps are also in a way , a special class of detergents . The soapless detergents are commonly known as synthetic detergents . Broadly speaking detergents can be classified into two main divisions :

1. Natural detergents saponins , ox-bile , fuller’s earth , and water in a sense , is also included in this part .
2. Synthetic detergents , those prepared chemically . But usually the word ‘ Detergent ’ stands for synthetic detergent unless specified otherwise .