In this review, reports, patents and recently published papers and documents on polyurethane recycling, especially chemical recycling methods, are investigated in order to find an adequate method for waste reduction, protecting the environment and preventing waste land filling. The recycling of polyurethane has always posed unique challenges due to its wide variety of applications, from the industry to bio-based materials, namely, artificial organs. Mechanical regrinding is the oldest method in polyurethane waste recycling and the use of the regrind wastes as filler in the new formulations. Chemical recycling of polyurethanes by hydrolysis, aminolysis and glycolysis is for the most part considered economically uncompetitive compared to formulating with virgin raw materials. Also some thermochemical processes are utilized for PU recycling. Recycling has opened an effective and economic route for polyurethane waste treatment. Nonetheless, more research efforts are required in order to scale up the recycling methods.

This study tries to demonstrate that attenuated total reflectance-fourier transform infrared (ATR-FTIR) microspectroscopy in combination with chemometric methods can reliably distinguish malignant colon tissues from healthy ones. It is important to explore a noninvasive and rapid method for detection of colon cancer biopsies. Initially, principal component analysis was applied to examine the degree of separation between tissue samples. Soft independent modeling of class analogy (SIMCA) was also employed to evaluate the prediction accuracy of ATR-FTIR microspectroscopy for the diagnosis of colon cancer. There were significant differences in the fourier transform infrared spectra of normal and cancerous colon biopsies in the 1,800-900 cm(-1) spectral region. The SIMCA results demonstrated that the accuracy, specificity, and sensitivity of the proposed diagnostic method were 93.3, 100, and 88.2%, respectively, which could help satisfy clinical diagnostic requirements.

Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) microspectroscopy was applied for detection of colon cancer according to the spectral features of colon tissues. Supervised classification models can be trained to identify the tissue type based on the spectroscopic fingerprint. A total of 78 colon tissues were used in spectroscopy studies. Major spectral differences were observed in 1,740-900 cm(-1) spectral region. Several chemometric methods such as analysis of variance (ANOVA), cluster analysis (CA) and linear discriminate analysis (LDA) were applied for classification of IR spectra. Utilizing the chemometric techniques, clear and reproducible differences were observed between the spectra of normal and cancer cases, suggesting that infrared microspectroscopy in conjunction with spectral data processing would be useful for diagnostic classification. Using LDA technique, the spectra were classified into cancer and normal tissue classes with an accuracy of 95.8%. The sensitivity and specificity was 100 and 93.1%, respectively.

FTIR spectroscopy is a common technique for cancer diagnosis. Applied tissue samples are heterogeneous and may be damaged in preparation procedures. Easier sampling, more available samples and also easier process with assured results would be interesting. Whole blood samples include all of these qualifications and our hypothesis was the bio-molecular changes in blood which manifest themselves in different optical signatures, detectable by FTIR spectroscopy. Noncancerous blood samples were differentiated from cancerous ones using ATR-FTIR spectroscopy and LDA classification method. Procedure was 100 percent and 90 percent accurate in prediction of cancerous or noncancerous situation for 33 known and 10 unknown samples, respectively.