Skin Rashes Caused by The Use of Latex Gloves in Hospitals Soon to Become a Thing of the Past?

A new technology is set to reduce the allergic potential of latex gloves to virtually zero, according to Dutch company Budev who patented MPXXTM technology used to wash latex during manufacture. The new process and the Cleantexx brand gloves made with it have just been launched at the recent MEDICA trade fair in Dusseldorf from 17-20 November 2010.

Cleantexx gloves are produced in Malaysia by Total Glove, a Dutch-Malaysian joint venture between Budev and the Malaysian manufacturer Latexx Partners.

CLICK HERE to read more.

Unsuitability and High Perforation Rate of Latex-Free Gloves in Arthroplasty - A Cause For Concern

Study conducted by Department of Orthopedics, Wansbeck Hospital (Northumbria Healthcare NHS Foundation Trust, Northumberland, Newcastle Upon Tyne, UK) indicated that latex-free synthetic gloves are not recommended for arthroplasty due to their inferior clinical performance compared to latex gloves i.e. gloves made form natural rubber latex.

Synthetic gloves were found to have higher incidence of perforation compared to latex gloves.

Note: Arthroplasty is joint replacement surgery.

CLICK HERE for the detailed report published in July 2010. 

How To Make PVC Latex Work For You?

Manufacturer: We're in the process of evaluating various synthetic latices (latexes) to see if they could complement our products currently made from natural rubber latex either on their own or as a blend with natural rubber latex. We've been having good results except for PVC latex which behaves quite differently from other latices. We could not get it to form a film. Could you help? How do we compound a PVC latex?

John Woon (Senior Latex and Rubber Consultant):  PVC latex or emulsion was developed as an alternative to PVC plastisol (PVC dispersed in plasticizers) because the latex version offers comparatively lower viscosity with greater versatility in compounding. Unlike elastomeric polymers (i.e. soft rubbers), PVC which is rigid does not readily form a film on drying without heat.

Temperatures up to 160ºC is required to coalesce and fuse the PVC particles together. However, this temperature could be reduced by adding a plasticizer. The PVC latex manufacturer could also modify the polymer with a second monomer during polymerization to reduce the fusing temperature to as low as the room temperature. You need to get the right grade for your purpose.

PVC latex can be compounded with colloidal stabilizers, wetting agent, thickeners, anti-foaming agents, pH modifiers, heat stabilizers (as PVC tends to discolour on heating), plasticizer, fillers, pigments, anti-blocking agent (e.g. waxes) etc.

Nitrile latex could be added to PVC latex with the former acting as the plasticizer for the latter.

University of Akron Reveals Secret Behind Adhesion of Gecko's Feet (Dry Adhesive vs Conventional Wet Latex Adhesive)

Not long after Dr. Ali Dhinojwala, chairman of The University of Akron Department of Polymer Science, unpeeled the secret (fine, clingy hairs) behind the remarkable adhesion of gecko feet, he and fellow researchers came up with a synthetic replica: carbon nanotubes. Now, five years after that initial discovery, the basis of the success of these nanotubes is published recently in an issue of the American Chemical Society's NanoLetters.

UA nano researchers Dr. Ali Dhinojwala, chairman of Department of Polymer Science, and graduate student Liehui Ge unpeel the secret to nanohair adhesion's powerful grip. 

While the story of nanotubes is one of success, not all carbon nanotubes are equal, nor is the individual adhesion performance of each strand, according to Dhinojwala. Although Dhinojwala and UA polymer science graduate student Liehui Ge determined that these 8-nanometer-diameter carbon hairs - each 2,000 times smaller than the diameter of a human hair - adhere powerfully to glass and similar substrates, they furthered their research to learn why some strands have a firmer grip than others.

Getting a grip on adhesion

Findings by the UA scientists, in collaboration with Lijie Ci and Anubha Goyal, researchers with the Department of Mechanical Engineering and Materials Science at Rice University; Rachel Shi, UA Research Experience for Undergraduates (REU) intern; and L. Mahadevan, professor of applied mathematics and professor of organismic and evolutionary biology at Harvard University, reveal that the softer the nanotube, the greater its adhesion. 

Fine hairs on the soles of gecko feet allow the lizards to climb vertical surfaces with ease. UA polymer researchers have discovered a synthetic glue (carbon nanotubes) with nearly four times the adhesion power of gecko hairs. Now the scientists reveal why the mimic version offers its remarkable staying power.

Using a combination of mechanics, electrical resistance and scanning electron microscopy (SEM) to study the contact between hairs of a large number of vertically aligned carbon nanotubes with glass or silicon substrates, the researchers found that soft nanotubes clasp and curve when pressure is applied, contributing to their adhesive strength.

"We found out that the diameter of the tubes is an important parameter for adhesion because we have to balance the adhesion and bending rigidity of the tubes," Ge says. "Also, if you apply a high pressure, the tubes bend and buckle and make a larger contact area with the surface, which is the reason for higher adhesion."

The dry adhesive, unlike liquid glue counterparts, promises successful use in extreme atmospheric and temperature conditions and in other applications that present challenges. "The carbon nanotube-based gecko adhesives are going to open up opportunities to using these materials on robots, to climb vertical walls, and could actually be used in outer space (vacuum condition) because these materials stick without any liquid glue," Dhinojwala says.

Acrylic Emulsion Sealant

Acrylic emulsion (55% solids)  40  Surfactant  1  Plasticizer  7  Mineral spirits  2  Ethylene glycol  2  Calcium carbonate (ground)  46  Miscellaneous fillers and pigments  2

PROCESSING

Once the base emulsion polymer is obtained, it is then mixed with all other liquid ingredients and additives except for the fillers. When this blend is complete, add the filler slowly, blending well between all additions. Generally, high shear mixers are sufficient to produce a heavily bodied sealant.

APPLICABLE BASE POLYMER PROPERTIES

Acrylic emulsion based sealants have taken over many of the applications where a higher movement capability is required than for polyvinyl acetate sealants. Acrylic sealants can also be used outdoors, whereas the polyvinyl acetate sealants have inferior exterior durability. Acrylic emulsion polymers are ideally suited to the formulation of medium performance sealants. There is a significant variation in the types of base polymer emulsions that are available, and these emulsions are easy to formulate. This gives the formulator a wide latitude for compounding to meet specific requirements. Sealants based on acrylic emulsions provide tough, elastic systems, with high adhesion and durability, and they are very environmentally friendly and easy to use.

RESULTING PROPERTIES

A broad product line with a wide range of properties can be developed by only varying the pigment-to-binder ratio. With high pigment-to-binder ratios, water based acrylic sealants are able to compete against the low cost polyvinyl acetate and vinyl acrylic sealants. On the other end of the formulation spectrum, low pigment-to-binder ratios provide competition to high performance sealants. In this way acrylics can compete against the polyurethane and silicone sealants meeting ASTM C 920. A typical formulation for a standard acrylic latex sealant is given above.

TIPS and TRICKS

Fillers are commonly used in water based acrylic sealants. They are used as a rheology modifier, polymer reinforcement, cost reducer, and pigment. Fillers give a formulation higher solids content, which results in less shrinkage. They can also be used to provide a mastic like consistency or even thixotropic (non-slumping) properties. The properties provided by the fillers will depend on the type, particle size, particle size distribution, and surface character of the filler. Sealants are sometimes classified by their filler to base polymer ratio (pigment to binder). Using too much filler can result in a decrease in adhesion and aging properties such as crack resistance. Lower levels of filler loading improve adhesion, but can result in excessive volume shrinkage, slump or sag, and possible crack formation.(This article was contributed by a visitor of this site)

Dynamic Mechanical Analysis in Practice: Predict & Optimize Faster Adhesive Performances

This e-Training Course will help you timely optimize your adhesives and sealants formulations and predict their performance by wisely integrating Dynamic Mechanical Analysis (DMA) in your developments.

Derek Bamborough who has more than 20 years experience in this field will guide you through advanced use of DMA to drive performance into the desired application window.

Please CLICK HERE to register.

Green Gasoline?

Prized Science Episode 2: Green Gasoline from ACS Pressroom on Vimeo.

Green chemistry is the driving force behind many eco-friendly products & could play an important role in fostering sustainability. Three scientists, Vincent Vincent D’Amico, Ph.D. (left), Emiel van Broekhoven, Ph.D. (center), and Juha Jakkula, Ph.D. (right), invented an environmentally friendly process for making a key ingredient in the production of green gasoline. The American Chemical Society selected those three scientists as the 2010 winners of its Award for Affordable Green Chemistry.