Characteristics and uses of PE, PP, PVC, PC, PET
1. Plastic PE (Polyethylene):
– Throughout, slightly dim light, polished surfaces and soft.
– Waterproof and good water vapor.
– Waterproofing of O2, CO2, N2 and grease are poor.
– Withstands high temperature (230o C below) in a short time.
– Have swollen and damaged when exposed to aromatic oils or cleaning agents such as alcool, acetone, H2O2 …
– It is possible for gas, aroma penetrates through, so PE can also absorb odor of the packaging itself, and this smell can also be absorbed by the food contained, causing the value of feelings of the product concerned.
– Making all kinds of bags, barrels (can) have the volume from 1 to 20 liters with different thicknesses.
– Production of bottle caps. Due to smell the bottle cap should be absorbed food containers covered with PE lid must be stored in an environment free from odors.
2. PP (Polypropylene)
– High mechanical durability (tear and tensile strength), rather rigid, not flexible as PE, no stretching so long made into yarn. Special abilities easily torn when there is a cut or a small puncture wound.
– Throughout, high-gloss surface for enhanced printing capabilities, in clear strokes.
– Resistant to temperatures higher than 100 ° C but the temperature solder paste eyelid (body), PP (140 °) – higher than PE – flow can cause structural damage to the membrane transplantation outside, so are less likely to use PP made in the same class.
– There O2 waterproofing properties, steam, oil and other gases.
– Use as packing a layer containing food preservatives, antioxidants do not require a rigorous way.
– Create a yarn, woven into food containers, bulk grain.
– PP also produce coatings for membranes laminated to increase membrane permeability gas, steam, enabling higher printing, and easy to tear open the packaging (made available due to a cut) and create high gloss for packaging.
3. PVC (Polyvinylchloride):
– Products PVC ago (1920 onwards) used huge quantities, but today has been overcome PE. Currently, the majority of users covered PVC power cables, making drainage pipes, rain coats, household plastic film …
– In vinylchoride quality PVC, commonly known as VCM is capable of causing cancer (discovered 1970)
PVC packaging defects as follows:
– Density: 1,4g / cm2 PE and PP higher should have to spend a large salary to get a PVC membrane area and thickness compared to PE and PP.
– Waterproofing of breath, poor water than other types of PE, PP.
– Taking into brittle, not flexible as PE or PP. to manufacture flexible PVC packing must be used to add additives.
– Type of plasticised PVC was dressed by denaturing additive will be hard brittle after a period of time.
– Although controlled by residual VCM is a level lower than 1ppm safety allows, but in Europe, PVC has not been used as food packaging though cheaper other plastic packaging.
– Used as heat-shrink labels for bottles and cans, plastic or shrink wrap preserved foods, circulating in a short time such as raw meat, fresh vegetables ….
– In addition, PVC is used to make many household items as well as the types of products in other sectors.
4. Plastic PC (Polycarbonates):
– As of waterproof and gas, slightly higher than other types of PE, PVC, but lower than PP, PET.
– Throughout, durable engines and features very high rigidity, abrasion resistance and is not affected by the composition of the food.
– Refractory (over 100 ° C).
– With the ability to withstand high temperatures should be used as PC bottle, bottles, lids containing sterilized food needs.
– PC Membrane impermeability gas, slightly less, costs three times PC PP, PET, PP should be rarely used.
5. Plastic PET (Polyethylene Terephthalate):
PET is an important food packaging have manufactured film or shaped bottles because of the nature:
– High mechanical strength, able to withstand the force of impact force and tear, withstand high abrasion, with high rigidity.
– Accommodation in the food environment.
– Waterproofing of O2, CO2 and other resins better.
– Heated to 200 ° C when cooling at – 90oC, the chemical structure of PET circuit remain unchanged, gas vapor permeability remains unchanged when the temperature is about 100 ° C
Due to the very high waterproofing should be used as PET bottles, jugs of purified water, carbonated soft drinks ….