Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/ je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky. Tutorial: Engineering Technology Topic: Plastic II. – Dis/advantages Prepared by: Ing. Vladislav zelinka

Engineering TECHNOLOGY Plastic Dis/Advantages

Briefly: Plastics are light – they have low density = thin Plastics can be either elastic, plastic or hard. Plastics almost don´t conduct electricity, heat and partly sound – that´s why they are used as insulation. Plastics are resistant against chemicals and they are weatherproof = they don´t corrode. Surface of the plastics can be diverse decorative.

Specific weight of common plastics: 0,9 to 1,4 kg/dm3 (approximately as water 1,0 kg/dm3) e.g. Teflon = 2,2 kg/dm3

Pulling test of various plastics: Graph 1. hard (fragile) 2. elastic (elastic – they restore) 3. plastic (soft– they don´t restore) Flat specimen Breaking Tension Relative prolonging Diagram of pulling test of various plastics

Examples of most frequent usage of plastics: Electric insulation – screw handle and pliers, wrap of conductors or cabels, boxes for devices,... Lagging – refrigerator, window frame, layers of facades,... Sound insulation – cars, recording studios,... Corrosion proof – car wings and fenders,… Chemical resistance – bottles for various drinks, interior of refrigerator, … Surface decoration – tanget car parts, handles,...

Summary: Plastics are thin and that´s why light as well. Plastics do not always have to be hard but they can be also elastic and plastic. Plastics are used as insulation as well because they almost do not conduct electricity, heat and partly sound. Plastics do not corrode – they are resistant against chemicals and weatherproof.. Dekorativnost povrchu plastů může být velmi různorodá.

ACTIVITY I.: Decide and choose the best solution of the problem: 1.) Product is going to be used in salt water, it should be as light as possible and it should not be cold while holding in hand. Will you use plastic? Yes / No / It isn´t easy to determine 2.) Product is going to be used around electrical conductors, it should have rough surface and its coloring should be very expressive. Will you use plastic? Yes / No / It isn´t easy to determine

ACTIVITY II.: Decide and choose the best solution of the problem: 3.) Product is going to be used under high temperatures (+90 °C) and its usage should be in tropics where the sun is strong. Will you use plastic? Yes / No / It isn´t easy to determine 4.) Product is going to be used in chemicaly aggressive environment and it won´t be exposed to grease. Will you use plastic? Yes / No / It isn´t easy to determine

Vocabulary: usefulvýhodný lightlehký softměkký hardtvrdý elasticpružný corrossion proofkorozivzdornost chemical resistanceodolnost chemická surfacepovrch pulling testtahová zkouška waeather proofodolnost proti povětrnostním vlivům insulationizolace (elektrická, tepelná, zvuková)

Resources: * Wikipedie – internetová encyklopedie (cs.wikipedia.org) * Technická Univerzita Liberec ( * ENGEL CZ s.r.o. ( * Dillinger, J. a kol. Moderní strojírenství pro školu a praxi. Praha: EUROPA SOBOTÁLES, ISBN * Mužík, J. Management ve vzdělávání dospělých. Praha: EUROLEX BOHEMIA, ISBN * Operační program Vzdělávání pro konkurenceschopnost, ESF 2007 – * Dostupné na: k-op-vzdelavani-pro-konkurenceschopnost