PVC, PP, PE & Plasticizers: The Complete Material Guide

Commodity thermoplastics are the raw material of modern manufacturing. Three families — PVC, polypropylene (PP) and the polyethylenes (PE) — cover an enormous share of everyday products, and plasticizers turn rigid PVC into flexible PVC. Knowing how the grades differ is the difference between a part that performs and one that fails.

PVC — polyvinyl chloride

PVC is uniquely versatile because it can be rigid or flexible depending on additives. Rigid PVC (uPVC), with no plasticizer, makes pipes, fittings, window and door profiles and rigid sheet. Flexible PVC, plasticised, makes cable insulation, flooring, hoses, film and synthetic leather.

Suspension vs emulsion PVC

Suspension PVC (S-PVC) is the general-purpose resin for most rigid and flexible processing. Emulsion/paste PVC (E-PVC) is used as a paste (plastisol) for coatings, dip moulding, rotational moulding and flooring.

K-value — the number that matters

K-value expresses the resin's molecular weight and tells you how it processes and performs: higher K-value means higher molecular weight, better mechanical properties but harder processing.

K-value	Character	Typical use
K57–K60	Lower MW, easy flow	Injection moulding, fittings, rigid parts
K65–K67	Balanced	Pipes, profiles, rigid sheet
K70–K71	Higher MW	Flexible cables, hoses, film

Polypropylene (PP)

PP is light, stiff and heat-resistant, with good chemical resistance. Three grades cover most needs:

Homopolymer — stiffest and most heat-resistant; rigid packaging, housewares, BOPP film, fibres.
Random copolymer — clearer and tougher; transparent containers, PPR pipe, medical.
Impact (block) copolymer — high impact strength, even in cold; automotive parts, crates, appliances.

Grades are also described by melt flow index (MFI) — high MFI flows easily for thin-wall injection moulding; low MFI suits extrusion and higher strength.

The polyethylene family (PE)

One chemistry, defined by density and branching:

Type	Character	Typical use
LDPE	Soft, flexible, clear	Films, bags, squeeze bottles, coatings
LLDPE	Tough, puncture-resistant	Stretch & cling film, heavy-duty bags, liners
HDPE	Rigid, strong, chemical-resistant	Pipe, bottles, jerry cans, crates, tanks
MDPE	Balance of the two	Gas pipe, film, fittings

Plasticizers — turning rigid into flexible

Plasticizers are what convert hard PVC resin into soft, bendable product — the difference between a rigid pipe and a flexible cable. Grades run from general-purpose DOP to non-phthalate DOTP and bio options for sensitive uses. We cover selection in depth in DOP vs DINP vs DOTP.

Choosing the right polymer

Need	Best fit
Rigid pipe / profile	uPVC or HDPE
Flexible tubing / cable	Flexible PVC
Clear rigid container	PP random copolymer
Impact-resistant part	PP impact copolymer or HDPE
Stretch / cling film	LLDPE
Chemical / water tank	HDPE
Heat-resistant part	PP homopolymer

Identifying plastics by recycling code

The resin identification codes are a quick field guide: 2 = HDPE, 3 = PVC (V), 4 = LDPE, 5 = PP. They don't tell you the exact grade, but they narrow it down fast.

Sourcing tips

Specify the polymer, grade and processing parameter (K-value for PVC, MFI for PP/PE), the application, and packaging. Ask for a technical datasheet and a COA, and confirm the grade is consistent batch to batch. Whether you need one resin or a full basket, a single reliable supplier simplifies your supply chain.

How each polymer is processed

The processing route often narrows the grade you need, because melt flow and heat behaviour differ by polymer:

Extrusion (pipe, profile, film, cable) — favours higher-molecular-weight grades: mid/high-K PVC, low-MFI PP and PE. Continuous and high-volume.
Injection moulding (fittings, caps, housewares, crates) — needs easy-flow grades: lower-K PVC, higher-MFI PP, HDPE injection grades.
Blow moulding (bottles, jerry cans, tanks) — HDPE and PP blow grades with the melt strength to hold a parison.
Calendering (flooring, flexible sheet, banners) — flexible PVC compounds.
Rotational moulding (large tanks, containers) — specific HDPE rotomoulding grades.

This is why "which PP?" is really two questions — which family (homo/random/impact) and which MFI — and why telling your supplier the process, not just the polymer, gets you the right grade first time.

Ambizent supplies PVC resin and plasticizers, and works across the polymer basket — see our PVC & plasticizers range and polyurethane chemicals. Tell us what you need and we'll quote.

Frequently asked questions

What is the difference between PP and PE?

Both are polyolefins, but polypropylene (PP) is stiffer, more heat-resistant and lighter, while polyethylene (PE) is tougher and more flexible. PP suits rigid, heat-exposed parts; PE suits films, bottles and pipe.

What does K-value mean in PVC?

K-value reflects the molecular weight of the PVC resin. Higher K-value gives better mechanical properties but is harder to process; lower K-value flows more easily. K65–K67 suits pipes and profiles; K70–K71 suits flexible products.

What is the difference between HDPE and LDPE?

HDPE is high-density — rigid, strong and chemical-resistant, used for pipe, bottles and tanks. LDPE is low-density — soft and flexible, used for films and squeeze bottles. LLDPE adds toughness for stretch film.

Which of these plastics is food-safe?

Food-grade versions exist across PP, HDPE and LDPE, and non-phthalate flexible PVC is used in food-contact film. The specific grade and additive package determine compliance, so always confirm the food-contact certification.

Can I get PVC, PP and PE from one supplier?

Yes — sourcing your polymer basket and plasticizers from a single trading partner simplifies logistics and documentation. Ambizent supplies PVC and plasticizers and works across the polymer range.

Ambizent International Trading supplies sulphur, PVC & plasticizers, polyurethane chemicals and premium quartz sand to manufacturers in 30+ countries, with a Certificate of Analysis on every shipment. Request a quote →