Polymer Processing

Chapter 3. Polymer Processing Polymer Process Techniques Fig. 3. 1. Procedure for casting sheets of polymer. Polymer Materials Page ? 2 Polymer Process Techniques HEMA = hydroxyethyl methacrylate EGDMA = ethylene glycol dimethacrylate Fig. 3. 2. Centrifugal mold for poly(hydroxyethyl methacrylate) contact lenses Solvent casting of films Fig. 3. 3. Laboratory spreading device for the solution casting of films. Polymer Materials Page ? 3 Polymer Process Techniques Roll casting Fig. 3. 4. Knife coating of a polymer onto a film. Polymer Materials Page ? 4 Polymer Process TechniquesFig. 3. 5. Polymer casting bench. Polymer Materials Page ? 5 Polymer Process Techniques Fig. 3. 6. Solution casting of films on an industrial scale with the use of rotating metal drums. Polymer Materials Page ? 6 Polymer Process Techniques Fig. 3. 7. Use of a moving-belt system for the continuous solution casting of polymer films. Polymer Materials Page ? 7 Polymer Process Techniques Fig. 3. 8. ‘Bubbleâ⠂¬â„¢ blowing of films. Polymer Materials Page ? 8 Polymer Process Techniques Fig. 3. 9. Film manufacture by calendering. Polymer Materials Page ? 9 Polymer Process TechniquesMethods for melt processing of films Fig. 3. 10. Hydraulic press for the melt pressing of polymer films. Polymer Materials Page ? 10 Polymer Process Techniques Fig. 3. 11. Sequence of operations for the melt extrusion of polymer films. Polymer Materials Page ? 11 Polymer Process Techniques Fig. 3. 12. Diagram of a plastics extruder. Polymer Materials Page ? 12 Polymer Process Techniques Fig. 3. 13. Diagram of a compression-molding press and mold. Polymer Materials Page ? 13 Polymer Process Techniques Melt process Fig. 3. 14. Diagram of an injection-molding machine. Polymer MaterialsPage ? 14 Polymer Process Techniques Fig. 3. 15. Thermoforming of polymer sheets. Polymer Materials Page ? 15 Polymer Process Techniques Fig. 3. 16. ‘Plug flow reactor’ to manufacture radiation crosslinked tubings or bel ts. Polymer Materials Page ? 16 Polymer Process Techniques Reaction Injection Molding (RIM) Advantages: ? Large parts ? Low viscosity ? Inexpensive Materials : ? Urethanes ? Polyureas ? Nylon ? Polyolefins Fig. 3. 17. Reaction injection molding (RIM) device to produce reinforced polyurethanes. ? Cylinder charged with diol and triol plus dibutyltin dilaurate ?Cylinder charged with molten diisocyanate ? Half of split mold ? Half of split mold ? Cavity to be filled with reinforcing fiber, then with mixed liquid from nozzle ? Nozzle for mixing streams from ? and ? Polymer Materials Page ? 17 Polymer Process Techniques Fig. 3. 18. Apparatus for the laboratory wet spinning of fibers. Polymer Materials Page ? 18 Polymer Process Techniques Fig. 3. 19. Use of a motor-driven syringe pump for the laboratory preparation of wet-spun fibers. Polymer Materials Page ? 19 Polymer Process Techniques Fig. 3. 20. Laboratory assembly for the ry spinning of fibers. Polymer Materials Page ? 20 Polymer Pro cess Techniques Fig. 3. 21. Industrial wet spinning. Polymer Materials Page ? 21 Polymer Process Techniques Fig. 3. 22. Laboratory or pilot-plant equipment for the melt extrusion of fibers. Polymer Materials Page ? 22 Polymer Process Techniques Fig. 3. 23. Manufacturing equipment for the dry spinning of fibers. Polymer Materials Page ? 23 Polymer Process Techniques Fig. 3. 24. Equipment for the melt spinning of fibers on an industrial scale. Polymer Materials Page ? 24 Polymer Process Techniques Fig. 3. 25.Three methods for the continuous orientation of synthetic fibers. (a) The fiber passes round a ‘peg’ which stabilizes the stretch orientation being induced by the faster-turning set of rollers. (b) The faster-turning drum stretches the polymer in the orientation zone. With this technique some difficulty may be experienced with stabilization of this zone. (c) The two drums turn at the same speed. But the fiber is stretched because of the greater circumference of the se cond drum. Polymer Materials Page ? 25 Polymer Process Techniques Processing of Elastomers (Vulcanizable) Fig. 3. 26.Reactor to manufacture four-ply valcanized rubber belts. Polymer Materials Page ? 26 Polymer Process Techniques Fig. 3. 27. Tire molding process Polymer Materials Page ? 27 Polymer Process Techniques Composite & Laminate Processing Fig. 3. 28. Plug-flow reactor to form epoxy resin preimpregnated sheet. Polymer Materials Page ? 28 Polymer Process Techniques Fig. 3. 29. ‘Batch reactor’ to manufacture glass-fiber reinforced polyesters. Polymer Materials Page ? 29 Polymer Process Techniques Fig. 3. 30. Procedure used to manufacture fiber reinforced epoxy resins. Polymer Materials Page ? 30

Literature Review Essay Example | Topics and Well Written Essays - 1000 words

Literature Review - Essay Example History is replete with such instances including the Arab-Israeli war of 1948-1949 and the Balkan Crisis which ended in the breaking up of former Yugoslavia into Croat, Serb, and Bosnian states. The problem with the brokered peace in such wars is that multi-lateral agreements stem from frivolous motives. The author argues that the UN would be better off assisting the strong overcome the weak for lasting peace. Instead the peace making efforts only add to the continuity of the war by encouraging the weaker forces to remain as refugees and make for potential outbreaks of hostility, as is seen in Rwanda. The UN peace keeping forces are usually ineffective in ensuring a lasting peace through the proper use of force and the usual outcome of UN and non-governmental organizations (NGOs) peace keeping efforts is the creation of refugee nations, as is the case with Palestinians living in scattered refugee camps in the Middle-East. It is in these refugee camps that resentment of their plight and the respite provided by the peace keeping efforts that lengthens the conflict. There should be the political will not to unnecessarily intervene in wars. Powerful nations like the United States of America should discourage multi-lateral efforts to bring about peace. New rules should be created to ensure that refugee relief by the UN does not allow the creation of refugee camps, but instead repatriation, local absorption, and emigration should be encouraged to prevent any permanency of the refugee camps. These measures may seem perverse but in keeping with the paradoxical logic that wars bring peace. The strength of this article lies in its highlighting of the ineffectiveness of the peace making efforts by the UN and international bodies, whereby there is hardly any resolution the war remain, but instead it creates permanency to the presence of conflict in a

Managing Organizational Culture for Improved Performance Essay

Managing Organizational Culture for Improved Performance - Essay Example 93) indicates that organisational culture has been described as a set of norms, beliefs, principles and ways of behaving that gives organisations a distinctive character. This is the same definition that many writers have used and so there is a general understanding of what it means. Norms are established patterns of behaviour which most writers agree to. 1.3 Culture Management Culture management refers to the refreshment of the existing culture within an organisation or the change of a culture that has become obsolete (Grigoruta et al 2005). 2.0 Culture and organisational performance According to Deal and Kennedy (2000) every business has a culture.’ However, sometimes it is reduced to bits and pieces and is therefore difficult to read from the outside. Some employees are loyal to their bosses while some are loyal to the union and still there are others who only care about their fellow employees. Even though there are those who only work because they need money there are time s when the culture of an organisation is strong and cohesive with everyone having knowledge of the goals and therefore working towards it. Deal and Kennedy (2000) further points out that culture has a very powerful influence whether it is weak or strong. It affects almost everything including who gets promoted, how employees dress and the spots they play. This impact suggests that ‘culture has a major impact on the success of the business.’ Deal and Kennedy (2000) provides examples of early leaders of American businesses including Harley Procter of Procter & Gamble and Thomas Watson of IBM who believed that strong culture played a role in the success of their organisations. These leaders believed that the organisation in which persons were employed helped to shape their lives and productivity. They saw their role as creating an environment which was effectively a culture within their organisations; one in which employees felt secure and thereby carry out the work necess ary to make the organisation successful. They had no magical formula but through trial and error. The cultures that these leaders built and nourished have helped to sustain their organisations through very difficult times. The organisations that they led continue to be successful as they still have strong cultures and still continue to be leaders in their industry. What Deal and Kennedy (2000) suggests is that there is no formula – they just did it by trial and error which is much like trying something until it works. This cannot be a prescription for organisations that want to improve their performance and is far from the truth. It is clear that these leaders of whom Deal and Kennedy (2000) spoke used various means which resulted in highly motivated employees who were willing to go the extra mile to ensure that these organisations achieved there goals. Motivating people and letting them feel as if they are a very important part of the organisation is an important aspect of l eadership. It is the things that are done to motivate employees that have led to successful companies. Deal and Kennedy

Critically Assess and evaluate total reward packages as a contributory Essay

Critically Assess and evaluate total reward packages as a contributory factor in employee retention A case study based on Marks & Spencers(the orderno - Essay Example This research focuses on a particular case study within Marks and Spencer, a major UK superstore to understand the impact of rewards, incentives and performance appraisal on employee motivation and performance. Marks and Spencer is a leading name in retailing within the UK. The company maintains that the rewards package given to its employees is flexible, competitive, focused on superior results and is aimed to support personal choices of personal lifestyles. The elements of the reward packages of the company include fixed and competitive pay rates, variable performance related pay and a wide range of other benefits (marksandspencer.com, 2006). In this study we prepare a detailed questionnaire to understand the impact of these benefits, payment and reward systems on employees and we also determine whether these rewards actually help in improving motivation and how this would relate to improved company performance. Marks and Spencer has boasted of 73% employee retention over 2004-2005 and retention may be considered as an important indicator of employee satisfaction and motivation (MarksandSpencer.com, 2006). Questionnaires are distributed to employees of Marks and Spencer to determine whether rewards systems given to them have a positive impact on their motivation and performance levels and aid them in heir decision to work for one company for a long period of time. The participants are employees of Marks and Spencer working in customer service divisions and 100 completed questionnaires are obtained and the data compiled are analysed for employee motivation and satisfaction levels that provide an indication of the employee retention level within a company. Marks and Spencer claims a high percentage of employee retention. The questionnaires are aimed to determine employee expectations, rewards given, job satisfaction, employee motivation, years of service and performance levels. Literature Review Companies use different means of rewarding employees and Brody et al (2001) discuss merit pay plans used by companies to motivate and reward employees. The theory of motivation would highlight that rewards and reinforcement for individual accomplishments should produce positive results although there may also be negative outcomes (Brody et al, 2001). Brody et al suggest in their study that when individuals are involved in hiring and merit allocation for employees, their prior commitments have significant effects on rewards allocated to the employees. This shows that a manager's personal involvement with employees can lead to increased merit allocation and rewards. This study highlights the factors that determine merit allocation and rewards which may not be completely dependent on employee performance and also large depends on interpersonal relationships within the workplace. Rewards could be largely based on performance ratings and it would be important to understand how employees perceive these ratings of their performance. Smith and Rupp (2004) state that a major purpose of having performance appraisals of employees is to determine individual merit which in turn help in determining whether merit pay or benefits would be given to

Shaping a Life Essay Example | Topics and Well Written Essays - 250 words

Shaping a Life - Essay Example The realization came to me that I have lost a lot of time and that I was not getting any younger. I felt the need for a purpose for living so I decided to make things better by being focused of what I want to achieve in life. Things begun to change as I gathered myself up with my social life improving by the day, recuperating the self-esteem I have lost when I was walking without direction. Hard times pushed me to find comfort in relationships but the contentment I have been looking for was never satisfied so that finding the man who later became my husband gave me a fresh hope on love and life. I finally learned to trust a man on a deeper level where I know my respect to a person is equally reciprocated, making my marriage to my husband another big event in my life that has left an indelible impact. November 17, 2005 is a day to cherish for me and my husband exchanged vows on this wonderful day and wonderful things just kept coming. As we expressed our love to each other, our greate st blessings have been showered upon us in the coming years. My husband and I now have two beautiful children whom we cherish. As for me, their birth has been life changing. It made me feel a greater sense of value, leading me to reset my priorities. I can now say I am a mother full of love that I could shower upon my children and husband, making sure they will always be assured of the support and love expected from me.

Compare and Contrast Essay Example | Topics and Well Written Essays - 500 words - 10

Compare and Contrast - Essay Example This symbolizes that he is still innocent and yet to be corrupted by the world. She pleads with him not to leave, but he is determined to leave. The fact that it is sunset as he begins his journey is also symbolic. The evening gets darker until the scene reaches climax. This symbolizes God’s light that slowly fades from Goodman’s heart (Bloom 64). Brown wanders into the woods with tangled ways, poor visibility, and dark. This symbolizes the confusion and loneliness of a life that is Godless. Goodman meets the devil who is described as being similar to him. This symbolizes the presence of the devil in the world according to the Christian domain. At this point, Brown makes at attempt to move away from the devil and go back to faith. He however does not achieve this and moves further into the forest where he meets several people, with the devil disappearing. When he is left alone, he tries to pray but he is distracted by a black cloud. This symbolizes how sin prevents people’s eyes from seeing the heavens (Ullen 371). Generally, symbolism within Young Goodman Brown is spiritual. Brown loses faith by following a path that is evil. The devil and Tom Walker is another symbolic story that is written by Washington Irving. The main character of the story is Tom Walker, who is wretched and leads an unhappy life. His wife is his primary source of misery. Their house is located in a dreary and desolate place. The house seemed like it was haunted and lifeless with a gloomy sensation. The house has been used symbolically to represent how Tom and his wife lived in misery (Buchanam 67). The setting has further been portrayed symbolically to portray misery, worries, and sins. Greed has been represented symbolically throughout the story. Native Americans, for instance, suffered greatly from the land owners and colonialists as a result of greed. The devil uses trees for firewood to symbolize his collection of men’s souls to

Diabetes and Evidence-based Nursing Research Paper

Diabetes and Evidence-based Nursing - Research Paper Example The day following his admission, his blood sugar level was more than 999. As a patient advocate, I was concerned for the patient’s treatment and I approached the patient and his wife about seeking a second opinion from an Endocrinologist. I recommended this with the hope of ensuring that they would gain the best possible care for the patient’s condition. The couple agreed and several weeks later returned to thank me for making the recommendation. The patient was diagnosed by the Endocrinologist with Flatbush Diabetes which is a rare form of diabetes presenting among African-American males. It calls for insulin administration for a short period of time and later to be shifted to oral diabetic medications. When untreated, it can lead to diabetic ketoacidosis. The nursing situation in this case is based on the appropriate care of the diabetic patient, on the assistance given in the administration of the patient medications, and on the monitoring of the patient’s vit al signs, diet, blood sugar levels, and blood pressure. Since the patient’s blood sugar levels were not sufficiently being lowered by the oral medications, the nursing role extends to patient advocacy – helping protect the rights of patients and ensuring that they receive the best possible care. ... B. Description of Medical/health Condition Insulin is the hormone which regulates the uptake of glucose from the blood into the cells of the body (Medical News 2011). Deficient insulin or issues with its receptors therefore play a crucial role in the manifestation and development of diabetes mellitus. Most carbohydrates in food are broken down into monosaccharide glucose, which is the main carbohydrate which is found in the blood and used as fuel by the body (Medical News, 2011). When blood glucose levels in the body are high, insulin is released in the blood by the beta cells in the Islets of Langerhans in the pancreas. Insulin is then utilized by the body’s cells in order to absorb glucose from the blood and use as fuel, and later for conversion to other molecules, and for storage (Medical News, 2011). Insulin also serves as the control signal for the conversion of glucose to glycogen for internal storage in the liver and the muscle cells. Decreased glucose level leads to re duced release of insulin. This then leads to the reverse conversion of glycogen to glucose. Glucose is mostly managed by the glucagon which then acts in opposition to insulin. Glucose recovered by the liver is re-introduced into the bloodstream; the muscle cells do not have the necessary capacity for export (Medical News, 2011). Significant insulin levels highlight the anabolic processes, including cell growth and duplication, protein synthesis, and fat storage. Insulin serves as the main signal in the conversion of bidirectional processes of metabolism from the catabolic to the anabolic direction, and vice versa (Medical News, 2011). In effect, low insulin levels trigger the onset of