Essays on Polyurethane

Condoms are a method of contraception used by both males and females. It acts as a barrier. A male condom constitutes a thin sheath that is usually made of latex (Alexander, 2016). On the other hand, the female condom is made of polyurethane sheath that has a flexible ring at the two ends (Edlin & Golanty, 2016). Condoms are intended for protecting people from contracting STIs during sexual intercourse. Besides, they are used as contraceptives. Condoms are grouped as class II medical devices since they exhibit the second lowest level of risk. Various clinical studies have been conducted on various ...

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Background research Artificial limbs (arms and legs) or the prostheses are intended to perform the degree of the normal function to the amputees. The mechanical devices enable the amputees to walk or to continue using the hand(s) as normal. According to research, artificial limbs date back in 600 BC when armorers created the first prostheses using cumbersome and inflexible iron. Artificial hands intricate imitations of the real hands. Amputees themselves started making their limps after losing such parts. Research shows some amputees lost arms and legs during civil wars and accidents. Indeed, the twentieth century has seen ...

Lignin Chemistry

Lignin History Lignin is a plant-derived biopolymer with several applications. It is considered an effective alternative to chemically synthesized plastics that pose serious environmental problems during manufacture and disposal. Lignin is often obtained as a byproduct in paper and pulp manufacture. Lignin has to be dissolved to obtain cellulose from wood. In 1838, Anselme Payen discovered that wood contained cellulose, and oxidizable coatings (later called lignin) that bind the cellulose together (McCarthy and Islam, 2000). This coating material could be removed from wood after acid treatment and washing with an aqueous alkali solution (McCarthy and Islam, 2000). Later, several ...

Flat roofs are roofing systems with the slop less than 10 degrees. This construction allows to use them as living space. Flat roofs exist for centuries, and people developed different types of covering for these systems. There are several most popular decisions with own advantages and features. TPO. These are single-ply roof membranes made from thermoplastic olefin or ethylene propylene rubber. TPO membranes have “resistance to ozone, are algae-resistant, environmentally friendly and safe to install” (roofhelp.com, n. d.). The typical thickness of TPO sheets varies from 40 to 100 mils. Constructors use hot air to seal seams between sheets. ...

Polyisocyanurate or Polyiso or ISO owes its popularity to its excellent thermal insulation performance (determined by its R-value). This thermosetting polymer gets its hardened, irreversible, and thermally insulating molecular structure with the application of heat. This property of Polyisocyanurates is particularly useful for roofing insulation applications. But the advantages of these materials and their significance do not end with just one property. There is a significant amount of reasons why many constructors prefer to use these polymers over others as a viable insulation material for their roofing materials. This essay is an attempt to study the significance of Polyisocyanurate ...

Chapter 11, pg. 427: Denver Goes Alfresco

- What type of problems was the consolidated city-county government of Denver, Colorado, experiencing with documented management before instating the Alfresco ECM system?

Before the introduction of the Alfresco ECM system, the consolidated city-county government of Denver, Colorado experienced many problems with the documented management system. Before introducing the Alfresco ECM system, more than 70 of the consolidated city-county government used 14 different documented management systems, none of which could communicate or interact with each other (Laudon & Laudon, 2012).

The information Technology department had to manually supervise many stand-alone autonomous IT units with their own systems and standards. Using a decentralized system created problems, including document sharing, document security, and the ability to audit record keeping functions, especially financial records and scanned ...

1.0 Introduction Many sports played across the world that involves throwing, hitting and kicking are done so using a ball. However, many parameters such as humidity, materials of manufacture of the ball, size of the ball, etc. control the movement of the ball in air. Research on golf balls and tennis balls reveal their aerodynamic properties and the various parameters affecting their flight. The effect of seams on a baseball on the flight has been evaluated along with the relationship between rotation and lateral forces (Watts & Sawyer 1987). Similar studies have also been conducted on cricket balls, rugby balls, volleyballs ...