What is PVA?

Physical Properties of PVA
Chemical Properties of PVA
AMI Cell™ PVA Material

Physical Properties of PVA

PVA sponge is a synthetic sponge essentially composed of Polyvinyl Alcohol. It possesses a three dimensional open cell structure similar to that of natural sea sponges. All of its cells are interconnected, not independent. Major advantages of this physical structure are its high filtering efficiency, its ability to be reused after cleaning (non-medical uses only), and its impressive retention and wicking properties.

PVA sponge will absorb up to 12 times its dry weight in water. When saturated with water, it becomes flexible and soft like natural sea sponge. The wet volume is about 20% greater than the dry volume. PVA exhibits mechanical strength and abrasion resistance equal to or greater than any other synthetic sponge material. Pore size and shape can vary to meet specific applications. Wet PVA sponge will withstand temperatures to 90 degrees C without plastic deformation.

PVA in its raw state is pure white. It can be pigmented in any color and to a high degree of color-fastness.

Chemical Properties of PVA

During the manufacture of PVA sponge, a water soluble porous structure is chemically insolubilized. The material will withstand the action of dilute acids, strong alkalis and solutions of common detergents. Some detergents of the "sulfonate" category (over 5% strength) will slowly swell and weaken the sponge. Organic solvents do not, as a rule, affect the sponge unless they are water-miscible and are applied mixed with 30% - 60% water. If so, the sponge will swell and be weakened. Thorough washing in water will return the sponge to its original state. PVA is also incompatible with Nickel Sulphate solutions.

PVA sponge behaves in water as a negatively charged colloid and will strongly adsorb metallic cations such as copper or iron. In fact, it acts like an ion exchange resin in this respect. It also has strong affinity for cationically charged organic ions of the quaternary ammonium type.

Untreated, PVA sponge will neither support the growth of bacteria nor molds, nor will it destroy those organisms. Foam packaged wet may be treated chemically to inhibit bacteria or mold growth.

Rust stains may be removed in the same way; as they are from cotton using a solution of oxalic acid, or citric or tartaric acid. Sodium hypochlorite solution (domestic bleach) degrades the sponge.

AMI•Cell™ PVA Material

Advanced Meditech’s specially formulated AMI•Cell™ PVA materials have these advantages:

Ultra fine pore materials minimize adhesion
Continuous open pore structure results in superior softness and greater patient comfort
Smaller compressed sizes ease insertion and allow optimal positioning within the body
Extremely fast wicking
Highly absorbent
Cost effective
Biocompatible

Depending on the characteristics desired, Advanced Meditech International, Inc. uses both particle replacement technology and “whipped air” technology to form the pores in our PVA foam. For particle replacement PVA products, we use a starch granule which is then processed out, leaving very consistent, evenly-sized pores.

For some other uses, we use "whipped air" technology to form PVA pores. For this process, we essentially use air alone to form the pores, resulting in somewhat less even pore size. However, whipped air process has its advantages. It is possible to produce much larger pore size PVA than with particle replacement technology. The other advantage is that PVA made without particles does not require these particles to be processed out.

For medical-grade PVA made using particle replacement, final processing is very important. Any residues left on the PVA following processing can hydrolyze and otherwise interact with tissues and fluids within the body. Advanced Meditech’s final processing of the PVA material results in a an extremely low level of acetylization. This means essentially that there are fewer residues on AMI•Cell™product so the risk of pva residues interacting with body tissues and fluids is reduced.

Advanced Meditech’s production facilities are ISO certified. We are constantly looking for ways to improve our products and processes. Our efforts at continuous improvement are a reflection of Advanced Meditech’s commitment to quality and our clients.

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