Ｗhat is Polyurethane Foam? And How is It Made?

What Is modified MDI?

As a derivative of the Pu Systems MDI series products,
modified MDI is currently commonly used as a technical extension of pure MDI and polymeric MDI, which could
be widely used in such sectors as slab polyols, elastomers, coatings and adhesives by providing its special
properties of usage and processing due to differences of product structure design and synthesis process.
There are various kinds of modified MDI, and several MDI manufacturers giants have also been stepping up
the research and development of modified MDI, which has enriched modified MDI types. And the products that
have been produced and used in a large scale.

The two major components of polyurethane formulations are a polyol component and an isocyanate
component. Polyols for Polyurethanes and
polyester polyols have been used as the polyol component in polyurethane formulations for many decades.
They remain the most commonly used polyols. Vast numbers of polyether polyols and polyester polyols,
optimized to provide different combinations of behavior during fabrication processes and performance
characteristics of fabricated articles, are available from many different manufacturers.

More recently, polycarbonate polyols have been gaining increasing interest and use in polyurethane
formulations, either by themselves or more often in mixtures with selected polyether polyols or polyester
polyols, because of their many attractive attributes. These attributes include performance benefits
resulting from the high-density polycarbonate backbone. Furthermore, polycarbonate polyols are based on
carbon dioxide (CO2), and sequester CO2 directly in their backbones, enhancing the sustainability of
polyurethanes.

The images shown in this post are reproduced from product literature by Novomer which is a leading
supplier of polycarbonate polyols.

The following reaction scheme shows how CO2 is sequestered in the backbone of a polycarbonate polyol by
reaction with an epoxide during synthesis. Many different “R” groups can be used, to provide a broad
range of polycarbonate polyol molecular structures.

The functionality of a polycarbonate polyol can also be chosen as desired, by using any one of many
different possible starting molecules. For example, the choices of the following three starting molecules
produce, from left to right, a diol, a triol, and a tetrol.

Rigid polyisocyanurate panel foams with better blowing efficiency (and hence smaller density when using
the same concentration of the blowing agent pentane) and smaller cell sizes were obtained, while keeping
the formulation viscosity manageable, by mixing 25% to 70% by weight of a polycarbonate polyol with a
polyester polyol.

Ｗhat is Polyurethane Foam? And How is It Made?

What is Polyurethane Foam? Consumers and
manufacturers alike may want to know the answer to this question. Are you a polyurethane foam technician, a
plant manager, or the owner of the foaming plant itself? Do you want a stronger foundational understanding
of how polyurethane flexible foaming actually works?

This article will detail the fundamental elements of polyurethane foaming, particularly as it applies
to continuous flexible foaming.

At its most basic, polyurethane foam does two things in the factory. From the liquid stage it:

• expands

• and gels

The liquid first expands as air bubbles are introduced, then a secondary reaction gels, or hardens the
material at some point in that expansion.

Let’s break down PU foaming Additives for
Polyurethane by function. One of the most important additives is the catalyst, which can affect the
basic reactions in several ways. It can speed the expansion, speed the gelling, cool the reaction (so you
have less of a fire hazard on your hands), etc. There are also curing agents, which include chain-extenders
and cross-linking agents. Chain-extenders, like their name suggests, extend polymer chains, which increases
material flexibility. Cross-linking agents promote and strengthen cross-linkages, increasing structural
integrity for more rigid foams.

Remember that CO2 gas from the reaction with water acts as a blowing agent? Well, other blowing agents
may also be used or added. The main inconvenience of water blowing in the high temperature of the reaction,
making PU foaming a fire hazard. Physical blowing agents (additives that physically encourage the expansion
of cells instead of that initial CO2, which is chemically blown) reduce that fire hazard.

A similar class of additives is fillers. They come as particles or fibers. Particulate fillers can
reduce flammability and add weight to foam (good for cushioning <a href="https://www.gvchem.com/flexible-
foams/">Flexible Foams). Fibrous fillers reinforce cell structure. All fillers function to 1) add
physical properties like tensile or compressive strength to foam, and 2) save on costs by reducing the
amount of liquid chemicals used per batch.