Polypropylene vs. PVC: Material Differences and Comparisons

 Polypropylene (PP) and polyvinyl chloride (PVC) are two widely used general-purpose plastics in daily life and industry. Although they seem to have overlapping applications, their raw material structures, temperature resistance, safety, and applicable scenarios are quite different. Here, we will explain the real differences between the two from a practical and easy-to-understand perspective.
I. Basic Characteristics Comparison
Polypropylene (PP) is an olefin plastic, consisting only of carbon and hydrogen, without chlorine. It has a very low density and is the lightest among common plastics. It is relatively flexible, resistant to impact and bending, and can be either semi-transparent or opaque. It hardly absorbs water.
Polyvinyl chloride (PVC) contains chlorine and is inherently hard. To make it soft, plasticizers must be added. Its density is much higher than that of PP, making it feel heavier in hand. It can be made very transparent or in various colors, and has better inherent flame resistance than PP.
II. Temperature Resistance and Usage Environment
PP has good heat resistance and can be used for a long time at around 100°C. It can be used in microwave ovens and high-temperature steam sterilization without easily deforming. However, it is sensitive to ultraviolet light and may become brittle and crack if exposed to long-term sunlight. For outdoor use, UV stabilizers need to be added.
PVC has poor heat resistance and begins to soften at around 60-70°C. At higher temperatures, it may deform or even decompose. After adding stabilizers, its weather resistance is good, making it suitable for outdoor building materials such as windows and drainage pipes. However, it is not safe at high temperatures.
III. Chemical and Mechanical Properties
Chemical Resistance: PP is stable to acids, bases, most detergents, and organic solvents, and is commonly used in chemical containers and pipes. PVC is stable to common acids and bases but is easily corroded by ketones and aromatic solvents.
Hardness and Toughness: Hard PVC has high hardness and rigidity, making it suitable for structural components, pipes, and profiles. PP has better toughness and is less likely to break when repeatedly bent. Many common "hinge" structures are made of PP. PVC becomes significantly brittle at low temperatures, while PP maintains relatively stable toughness at low temperatures.
IV. Safety and Environmental Impact
Food and Medical Safety: PP is non-toxic and does not contain BPA, making it a recognized safe material for food and medical use. It is widely used in food containers, water cups, syringes, and infusion bags.
PVC is not suitable for direct food contact. The plasticizers in soft PVC may leach out, and many children's products and food packaging have been gradually restricted. Only special plasticizer-free hard PVC can be used under specific conditions.
Recycling and Environmental Impact: The recycling symbol for PP is #5, and it is relatively easy to recycle and incinerate cleanly. The recycling symbol for PVC is #3, and it is difficult to recycle. Burning PVC releases harmful chlorine-containing gases, which is environmentally unfriendly if not properly handled.
V. Typical Application Scenarios
PP is commonly used in food storage containers, bottle caps, straws, non-woven fabrics, automotive interiors, medical devices, high-temperature chemical pipes, and turnover boxes.
PVC is commonly used in plastic-steel windows, rigid water and drainage pipes, wire and cable sheaths, flooring, waterproof membranes, packaging blisters, hoses, and artificial leather.
VI. Simple Selection Suggestions
For high-temperature resistance, food storage, medical products, and a focus on toughness and environmental friendliness → Choose PP
For low cost, high rigidity, flame resistance, and use in building materials and insulation products → Choose PVC
For any scenario involving contact with the mouth, skin, or high temperatures, avoid ordinary PVC and prefer PP for greater safety.