Jul 29 2015
I-Minerals Inc. is pleased to announce that it has received a report from a leading academic halloysite researcher that covers the results of comparative testing of I-Minerals' HalloPure halloysite with commercially available halloysite from NZ, China and Turkey as well as another development stage US halloysite.
Specific testing addressed the potential applications that rely on a stable release of chemical solutions that are important in cosmetic, pharmaceutical, agricultural and paint products. Most of the comparative analysis focused on I-Minerals and the other development stage US halloysite. Overall the analysis concluded that I-Minerals' halloysite has better tubule shapes than commercial NZ and Turkish halloysite. The Chinese halloysite from Hunan Province proved to be a quality product, but it is only available in small amounts (kg). As compared with the other development stage US halloysite, I-Minerals' HalloPure halloysite demonstrated materially longer nanotubes, which may provide better strength in polymeric composites. Loading and release characteristics compare well, showing some potential for better loading efficiency and potential for longer release times.
Scanning Electron Microscope ("SEM") work indicated that I-Minerals halloysite nanotubes ("HNTs") are much longer than any of the other HNTs tested. Most of I-Minerals HNTs measured had a length range of 1.1-2.0μm (75 %). 20 % of the tubes have length of 3.0-5.0μm. The remaining shorter HNTs were considered to be broken pieces off longer tubes. In comparison, the HNTs of the other development stage US producer measured only 0.5 ± 0.2µm, but this halloysite did demonstrate a more uniform HNT size distribution. I-Minerals' much longer HNTs are believed better for stronger polymeric composites. The diameter of I-Minerals HNTs was twice that of the other US halloysite providing improved HNT loading capacity.
A release study was also undertaken wherein I-Minerals' HalloPure HNTs and the other US producer's HNTs were loaded with different solutions and the release time measured. In the first test benzotriazole ("BTA") was loaded into both HNTs simultaneously at the same conditions. A release study in water was also performed simultaneously and the release was measured (260 nm) using a UV-Visible spectrophotometer. Initial burst release in both the cases was close to 70%. However, subsequent release of BTA was slow and sustained with I-Minerals' halloysite. The experiments were repeated at least 3 times to check the consistency of the results, which confirmed the release from I-Minerals' HNTs is longer.
In a second test, Hydroxyquinoline ("HQ" an important antioxidant and anticorrosion inhibitor) was loaded into I-Minerals' HalloPure HNTs and the other US producer's HNTs simultaneously under the same conditions. A release study in water was also performed simultaneously and the release was measured (240 nm) using a UV-Vis spectrophotometer. Initial burst release was lower in the case of I-Minerals' HalloPure HNTs (33 wt %) when compared to the other US producer's HNTs (43%). The overall release profile was similar, but release from I-Minerals' HNTs was slower. HQ release extended up to 3 hours in both cases.
Zeta potential is a key indicator of the stability of colloidal suspensions. When the like ionic charge surrounding the tubes is high such that the particles strongly repel, there is a low tendency to recombine, form aggregates and settle out. Untreated HNTs from I-Minerals were measured at -44±2 mV and when treated with Polystyrene sulfonate (PSS) the zeta potential was modified to -55 mV. Zeta potentials from 40 to 60 mV indicate good stability of colloidal dispersions and above 61 mV are considered excellent. These results indicate I-Minerals HalloPure halloysite is well suited for all sorts of cosmetic, pharmaceutical, agriculture, polymers and paint products.
"These test results support our belief that we have one of the best halloysite products that can be readily produced in commercial quantities and supports much of the research we have undertaken in Germany and elsewhere," states Thomas Conway, President and CEO of I-Minerals Inc. "We knew we had one of the highest aspect ratio halloysites available that contained no cristobalite and limited other deleterious heavy metals and now these results demonstrate our Ultra HalloPure is probably the best halloysite available."