MEMS 1 Lesson 1 - Plastics PDF

Baliuag University - Tumana Campus College of Environmental Design and Engineering Second Trimester A.Y. 2024-2025 Ecat, John Rovic T. (BSME3) THERMOPLASTIC:...

Baliuag University - Tumana Campus College of Environmental Design and Engineering Second Trimester A.Y. 2024-2025 Ecat, John Rovic T. (BSME3) THERMOPLASTIC: Plastics that can be deformed easily upon heating and can be bent easily. Linear TOPICS: polymers and a combination of linear and 1. What is Plastic? cross-linked polymers come under 2. Types of Plastic thermoplastics. Example: PVC, nylon, a. Thermoplastic polythene, etc. b. Thermosetting 3. Recycling of Plastic THERMOSETTING: 4. Properties of Plastic 5. Seven Types of Plastic Plastics that cannot be softened again by heating once they are moulded. Heavily PLASTICS: cross-linked polymers come under the category of thermosetting plastics. The word, plastic, was derived from the Example: Bakelite, melamine, etc. Bakelite word ‘Plastikos’ meaning ‘to mould’ in is used for making electrical switches Greek. whereas melamine is used for floor tiles. Plastic is defined as a material that contains an essential ingredient an RECYCLING OF PLASTIC: organic substance of large molecular weight. It is also defined as polymers of Recycling of plastic is very important. If long carbon chains. they are not recycled at the proper time, Plastic was discovered by famous German then they get mixed with other chemicals chemist Christian Schonbein in 1846. or materials and hence become more Plastics were actually discovered difficult to recycle and become a source accidentally. Christian was experimenting of pollution. in his kitchen and by accident, he spilt a They are non-biodegradable, and they do mixture of nitric acid and sulphuric acid. not get decomposed by the microbial To mop that solution (a mixture of nitric action. and sulphuric acid) he took a cloth and To avoid this, it is important to use after moping he kept it over the stove. biopolymers or biodegradable polymers. After some time, the cloth disappeared and from their plastic got its name. PROPERTIES OF PLASTIC: Strong and ductile. TYPES OF PLASTICS: Poor conductors of heat and electricity. Depending on physical properties, plastics Easily moulded into different shapes and are divided into two types: size. Thermoplastic Resist corrosion and are resistant to many Thermosetting chemicals. SEVEN TYPES OF PLASTICS: It is also harder and more opaque and can withstand somewhat higher 1. Polyethylene Terephthalate (PET or PETE) temperatures: 120 °C for short periods, 110 2. High-Density Polyethylene (HDPE) °C continuously. 3. Polyvinyl Chloride (PVC) Not only recyclable, but HDPE is also 4. Low-Density Polyethylene (LDPE) relatively more stable than PET. It is 5. Polypropylene (PP) considered a safer option for food and 6. Polystyrene (PS) drink use, although some studies have 7. Other Plastic Materials shown that it can leach estrogen- mimicking additive chemicals that could POLYETHYLENE TEREPHTHALATE (PET OR PETE) disrupt the human’s hormonal system when exposed to ultraviolet light. This type of plastic polymer is mostly used for food & drink packaging purposes, due to its strong ability to prevent oxygen from getting in & spoiling the product inside. It also helps to keep the carbon dioxide in carbonated drinks from getting out. Although PET is most likely to be picked up by recycling programs, this type of plastic contains antimony trioxide—a matter that is considered as a carcinogen—capable of causing cancer in a living tissue. The longer a liquid is left in a PET container the greater the potential for the release of the antimony. Warm temperatures inside cars, garages, and enclosed storage POLYVINYL CHLORIDE (PVC) could also increase the release of hazardous matter. This plastic type used to be the second most widely used plastic resin in the world (after polyethylene), before the manufacture and disposal process of PVC has been declared as the cause of serious health risks and environmental pollution issues. In the term of toxicity, PVC is considered the most hazardous plastic. The use of it may leach a variety of toxic chemicals such as bisphenol A (BPA), phthalates, HIGH-DENSITY POLYETHYLENE (HDPE) lead, dioxins, mercury, and cadmium. Several of the chemicals mentioned may HPDE is made from petroleum. it has a cause cancer; it could also cause allergic stronger intermolecular force and tensile symptoms in children and disrupt the strength than low density polyethylene human’s hormonal system. (LDPE).  Polyvinyl Chloride is typically used in toys, blister wrap, cling wrap, detergent bottles, loose-leaf binders, blood bags, and medical tubing. POLYPROPYLENE (PP) PP is often used for food packaging. It’s not as tough as HDPE, but it is less brittle. PP is less flexible than LDPE, somewhat stiffer than other plastics, reasonably economical, and can be translucent, opaque, or of any color. PP has very good resistance to fatigue. PP has a melting point of 320 °F (160 °C). Food containers will not melt in the dishwasher nor during industrial hot filling processes. Common uses: bottle caps, drinking LOW-DENSITY POLYETHYLENE (LDPE) straws, hinged containers, battery cases, dairy tubs (e.g. sour cream, cottage LDPE is made from oil. Its tensile strength cheese), cereal box liners. and density is lower, but its resilience is higher than high-density polyethylene (HDPE). It can withstand temperatures of 80 °C continuously and 95 °C for a short time. It can be translucent or opaque, is flexible, tough, and almost unbreakable. Although some studies have shown that LDPE could also cause unhealthy hormonal effects in humans, LDPE is considered a safer plastic option for food and drink use. Unfortunately, this type of plastic is quite difficult to be recycled. POLYSTYRENE (PS) LDPE is mostly used for bags (grocery, dry cleaning, bread, frozen food bags, PS is made from petroleum. Pure solid newspapers, garbage), plastic wraps; polystyrene is a colorless, hard plastic with coatings for paper milk cartons and hot & limited flexibility. It can be cast into molds cold beverage cups; some squeezable with fine detail. Polystyrene can be bottles (honey, mustard), food storage transparent or can be made to take on containers, container lids. They are also various colors. used for wire and cable covering.  Polystyrene (PS) is the styrofoam we all commonly used for food containers, egg cartons, disposable cups and bowls, packaging, and also bike helmet. When exposed to hot and oily food, PS could leach styrene is considered as brain and nervous system toxicant. It could also affect genes, the lungs, the liver, and the immune system. On top of all of those risks, PS has a low recycling rate. OTHER PLASTIC MATERIALS This is the catch all category of all other plastics. Many biodegradable, photo- sensitive, and plant-based plastics fit in this category. Basically any plastic that is not HDPE, LDPE, PET, PVC, PS or PP are put into this category. Additionally, any plastic resin type that has been developed since the original 6 resin types were established in 1988, are marked with the 7 or Other resin identification code. As such, listing common uses for these kinds of plastics is nearly impossible since their applications and characteristics are so diverse.