|
Swelling Capacity
The swelling capacity of a polymer is determined by the amount of liquid material that can be absorbed by it. This test can done by two methods: # Beaker test method # Tea bag test method Beaker test method In this method * A small amount of superabsorbent polymer A superabsorbent polymer (SAP) (also called slush powder) is a water-absorbing hydrophilic homopolymers or copolymers that can absorb and retain extremely large amounts of a liquid relative to its own mass. Water-absorbing polymers, which are cla ... material is taken (0.1g) and it is placed in the beaker. * 100 ml of deionized water is poured into the beaker. * After 20 min the swollen polymer was separated by using ilter paper* By weighing the polymer, one can find the swollen capacity of the SAP material. Tea bag test method * In this method, 0.1 g of SAP material is placed into a permeable bag, which is suspended over excess water in a beaker. * Wait 20 min. and weigh the bag and then calculate the percentag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals. The term "polymer" derives from the Greek word πολύς (''polus'', meaning "many, much") and μέρος (''meros'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beaker (glassware)
In laboratory equipment, a beaker is generally a cylindrical container with a flat bottom.Oxford English Dictionary 1989 edition Most also have a small spout (or "beak") to aid pouring, as shown in the picture. Beakers are available in a wide range of sizes, from one milliliter up to several liters. A beaker is distinguished from a flask by having straight rather than sloping sides. The exception to this definition is a slightly conical-sided beaker called a Philips beaker. The beaker shape in general drinkware is similar. Beakers are commonly made of glass (today usually borosilicate glass Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), ma ...), but can also be in metal (such as stainless steel or aluminum) or certain plastics (notably polythene, polypropylene, PTFE). A common use fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tea Bag
A tea bag, or the compound teabag, is a small, porous, sealed bag or packet, typically containing tea leaves or the leaves of other herbs, which is immersed in water to steep and make an infusion. Originally used only for tea ('' Camellia sinensis''), they are now made with other tisanes ("herbal teas") as well. Tea bags are commonly made of filter paper or food-grade plastic, or occasionally of silk cotton or silk. The tea bag performs the same function as a tea infuser. Tea bags can be used multiple times until there is no extraction left. Some tea bags have an attached piece of string with a paper label at the top that assists in removing the bag, while also displaying the brand or variety of tea. History Tea bag patents date from 1903 when Roberta Lawson and Mary Molaren, of Milwaukee, Wisconsin, were granted US patent 723287 for a Tea Leaf Holder, which they had filed for in 1901. US patent 723287 was issued on MAR. 24, 1903 to R. G.LAWSON & M. McLAREN for a 'novel t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superabsorbent Polymer
A superabsorbent polymer (SAP) (also called slush powder) is a water-absorbing hydrophilic homopolymers or copolymers that can absorb and retain extremely large amounts of a liquid relative to its own mass. Water-absorbing polymers, which are classified as hydrogels when mixed, absorb aqueous solutions through hydrogen bonding with water molecules. A SAP's ability to absorb water depends on the ionic concentration of the aqueous solution. In deionized and distilled water, a SAP may absorb 300 times its weight (from 30 to 60 times its own volume) and can become up to 99.9% liquid, and when put into a 0.9% saline solution the absorbency drops to approximately 50 times its weight. The presence of valence cations in the solution impedes the polymer's ability to bond with the water molecule. The SAP's total absorbency and swelling capacity are controlled by the type and degree of cross-linkers used to make the gel. Low-density cross-linked SAPs generally have a higher absorbent capaci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
