Rubber and plastics

Rubber vs. Plastic

In the past, people have seen the progress of technology. From the simple usage of wood and cement to the invention of metal, mankind has really made great progress to become what they are today. Along with this progress are some changes to their lifestyle. These changes were brought about by the materials surrounding them, and two materials that revolutionized man’s life today is rubber and plastic.

It is quite easy to differentiate between the two. By simply looking at each material, one can immediately tell that a particular thing, or object, is made of rubber and not plastic, or vice versa. The only confusion between the two is when the term polymer is used. Yes, polymer as a term that greatly denotes plastics, but nonetheless, this term also describes the characteristic of rubbers. Although rubber is more of the specific elastomer (a viscous or elastic variation of polymers), it is still considered to be a polymer.

Both plastics and rubbers are classified in many different manners. In fact, for plastics alone there are more than 10,000 different types. Some are grouped according to type, quality, design or to the material(s) used to make the rubber or plastic. This is why both materials have become very diverse in terms of their usage. Plastics are used in almost every aspect, like clothing, food, beverages, construction and many others. Its major classes are the more common thermoplastics (plastics that will melt when enough heat is applied) and the thermosets (can only melt or take form once, because they remain solid after they have been solidified). Rubbers are more commonly used in vehicle tires, industrial purposes and basic to advanced warfare.

It is also important to denote that it was around the year 1976 when plastic become widely used around the world. Plastics are basically made from natural gas and petroleum. Both of these raw materials are nonrenewable. Hence, recycling plastics is the immediate solution to the growing demand for the said material. On the contrary, rubber can be either synthetic or natural. Synthetic means that the rubber is made from crude oil, which also happens to be another nonrenewable resource. Nevertheless, the other type (natural rubber) can be harnessed from trees (i.e. rubber tree), in which a substance (latex) is then extracted.

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Although both are polymers, plastic and rubber differ because:

Rubber can be considered elastomers, and that’s why when compared to plastics, they are naturally more elastic.
Synthetic rubber is derived from crude oil, whereas synthetic plastic is made of petroleum and natural gas. identification of rubber and plastics.

How to Identify Plastics Here is a preliminary guide that will help you to identify many of the basic types of plastics using simple techniques and readily available tools. Naturally, these tests should be used only for tentative identification because some complex plastic compounds require a rigorous analysis for identification. To initially determine whether a material is thermoset or thermoplastic, heat a stirring rod (to about 500° F) and press it against the sample. If the sample softens, the material is a thermoplastic; if not, it is probably thermosetting.

Next, hold the sample to the edge of a flame until it ignites. Hold the flame for about 10 seconds, if no flame is produced immediately. If the material burns, note the color of the flame, the nature of the smoke, the presence of the soot in the air and, if while burning, the sample drips. Next, extinguish the flame and cautiously smell the fumes.

In identifying odor, a known sample is most helpful for comparison. Finally, check your observations against the know characteristics of each plastic given below. Once you have made a tentative identification, it usually is desirable to make one additional test to confirm the results of the original identification.

No Flame Burns, but extinguishes on removal of flame source Continues to burn after removal of flame source Materials Odor Odor Color of Flame Drips Odor Color of flame Drips Speed of Burning Remarks Thermoplastics ABS – Acride Yellow, Blue edgese Noe Acrid Yellow, Blue edges Yes Slow Black smoke with soot in air Acetals – – – – Formaldehyde Blue, no smoke Yes Slow – Acrylics – – – – Fruity Blue, Yellow tip No (cast) Yes (molded) Slow Flame may spurt if rubber modified Cellulosics Acetate – Vinegare Yellow with sparkse Noe Vinegar Yellow Yes Slow Flame may spark Acetate Butyrate – – – – Rancid Butter Blue, Yellow tip Yes Slow Flame may spark Ethyl Cellulose – – – – Burnt Sugar Yellow, Blue edges Yes Rapid – Nitrate – – – – Camphor White No Rapid – Propionate – – – – Burnt Sugar Blue, Yellow tip Yes Rapid – Chlorinated Polyether – – Green, Yellow tip No – – – – Black smoke with soot in air No Flame Burns, but extinguishes on removal of flame source Continues to burn after removal of flame source Materials Odor Odor Color of Flame Drips Odor Color of flame Drips Speed of Burning Remarks Fluorocarbons FEP Faint odor of burnt hair – – – – – – – Deforms; no combustion but drips PTFE Faint odor of burnt hair – – – – – – – Deforms; does not drip CTFE Faint odor of acetic acid – – – – – – – Deforms; no combustion but drips PVF – – – – – – – – Deforms Nylons Type 6 – Burnt Wool Blue, Yellow Tip Yes – – – – – Type 6/6 – Burnt Wool or Hair Blue, Yellow Tip Yes – – – – More rigid than Type 6 Nylon Phenoxies – Acrid e Yellow e No e Acridd Yellowd Yesd Slowd Black smoke with soot in air Polycarbonates – Faint, Sweet Aromatic Ester Orange Yes – – – – Black smoke with soot in air Polyethylenes – – – – Paraffin (wax) Blue, Yellow Tip Yes Slow Floats in water Polyphenylene Oxides (PPO) – Phenol YellowOrange No – – – – Flame spurts; very difficult to ignite Modified Grade – Phenol YellowOrange No – – – – Flame spurts; difficult to ignite; soot in air Polymides b – – – – – – – Chars; material very rigid Polypropylene – Acride (burning rags) Yellow e No e Sweet Blue, Yellow Tip Yes Slow Float in water; more difficult to scratch than PE Polystyrene – – – – Illuminating gas Yellow Yes Rapid Dense black smoke with soot in air Polysulfones – – Orange Yes – – – – Black smoke Polyurethanes – – – – b Yellow No Slow Black smoke Vinyls Flexible – Hydrochloric Acid Yellow with green spurts No – – – – Chars, melts Rigid – Hydrochloric Acid Yellow with green spurts No – – – – Chars, melts Polyblends ABS/ Polycarbonate – – – – b Yellow, Blue edges No – Clack smoke with soot in air ABS/PVC – Acrid Yellow, Blue edges No – – – – Black smoke with soot in air PVC/Acrylic – Fruity Blue, Yellow tip No – – – – – Thermosets Alkyds – – – – – – – – – Diallyl Phthalates – – – – Phenolic Yellow No Slow Black smoke, cracks Diglycol Carbonate – – – – Acrid Yellow No Slow Black smoke with soot Epoxies – – – – Phenol Black smoke No Slow Black smoke with soot Malamines Formaldehyde and fish – – – – – – – – Phenolics Formaldehyde and phenol Phenol and wood or paper Yellow No – – – – May crack Polyesters – Hydrochloric acid Yellow No b Yellow, blue edges No Slow Cracks and breaks Silicones b – – – – – – – Deforms Ureas Formaldehyde – – – – – – – – * Flame retardant grade b Nondescript e Inorganic filler d Organic filler Credit: Materials