Content: The thermal degradation kinetics of hides before and after being tanned with formaldehyde were investigated using thermalgravimetric analysis (TGA) at four different heating rates of 5, 10, 20, 30 K/min. Such model-free methods as Flynn-Wall-Ozawa and Friedman as well as model-fitting method of Criado were employed to determine the thermal degradation active energy and degradation mechanism. Based on the Flynn-Wall-Ozawa and Friedman methods, the average active energy (Ea) of formaldehyde-tanned leather was 223.1 kJ/mol and 230.7 kJ/mol respectively. Results from general master curves showed diffusion processes in the thermal degradation of formaldehyde-tanned leather. Neither the thermal degradation activation energy nor the degradation mechanism is affected by the formaldehyde tanning. Nevertheless, the results by thermalgravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR) indicated difference in the relative amounts of evolved products. According to the 3D-FTIR analysis, the dominant components of evolved gas for both untanned and tanned hides are CO2, CH4, H2O, NH3 along with small amount of HNCO. However, after formaldehyde tanning, both the evolved NH3 by the decomposition of free –NH2 groups and peptide –NH– groups from different amino acids in collagen and CH4 by the cleavage of -CH3 and -CH2- increase. Take-Away: 1. The theraml degradtion mechanism of hides before and after formaldehyde-tanning is eatablished in our paper. 2. The main degradation pathway of hides before and after formaldehyde-tanning is discussed with the help of TG-FTIR analysis.

Le traitement thermique est basé sur la modification chimique des biopolymères par thermodégradation, en évitant l'ajout de produits chimiques. Ce traitement améliore la stabilité dimensionnelle et la durabilité fongique du bois. Ces améliorations se font au détriment des propriétés mécaniques qui ont tendance à s'affaiblir. Aujourd'hui, plusieurs types de procédés sont utilisés. Ils se distinguent entre autre par la nature du milieu dans lequelle se déroule le traitement. La durabilité de ce nouveau matériau bois est liée au degré de thermodégradation, dépendant des conditions et de l'intensité du traitement. Un pilote de traitement par conduction, travaillant sous vide ou sous azote, mesurant la masse en dynamique est utilisé afin de mieux comprendre l'influence de l'atmosphère. Les résultats obtenus montrent que l'utilisation du vide permet d'éliminer, de l'enceinte de traitement, les produits volatils formées au cours du traitement conduisant à des taux de lignine de Klason plus faibles du fait de la non recondensation des produits de dégradation. Cette limitation de recondensation des produits volatiles engendre des pertes de masse, pour une même intensité de traitement plus faibles, confirmés par des taux de polysaccharides plus élevés pour un traitement sous vide. Des études de cinétiques des réactions de thermodégradation ont confirmé la plus grande sensibilité des feuillus vis-à-vis de la thermodégradation (comparé aux résineux). De plus, ces analyses ont permis d'identifier les principaux produits de thermodégradation du bois qui varient en fonction de l'intensité du traitement et a permis de montrer une thermosensibilité plus importante de la lignine que de l'holocelluloses pour la gamme de températures utilisée. Le fruit de ces travaux est donc une progression significative des connaissances de bases sur les mécanismes de thermodégradation et leurs relations avec les paramètres de traitement / Thermal treatment is based on biopolymer chemical degradation by heat transfer, without additional chemical products impregnation. This process improves the dimensional stability and the decay resistance of wood. These improvements come at the expense of wood mechanical properties of wood which weak. Several types of heating processes exist currently differing mainly by the nature of the inert atmosphere used during treatment. The durability of this new wood material is correlated to the degree of polymers thermal degradation depending on the conditions and the treatment intensity. A conducting heat treatment pilot using nitrogen or vacuum and allowing dynamic record of mass loss is used to understand better the atmosphere influence. The results show that utilization of vacuum permit the elimination of volatile products formed during heat treatment and accumulated in oven, leading to lower extractives and Klason lignin contents due to the non recondensation of thermal degradation products. Limitation of the formation of recondensation products generates a lower mass loss for same treatment intensity and explains the lower polysaccharides degradation during a vacuum process. Fine chemical analyses and the study about thermal degradation reaction kinetics have allowed confirming the higher sensibility of hardwood than softwood to thermal degradation. In addition, these analyses have permitted the volatile thermal degradation products identification related to the treatment intensity. Subsequently, results have shown a higher thermal sensibility of lignin than holocelluloses for temperatures below 230°C. This work is a significant increase in basic knowledge about the mechanisms of wood thermal degradation and their relations with the processing parameters

Applications of Hot Melt Extrusion (HME) in pharmaceuticals have become increasingly popular over the years but nonetheless a few obstacles still remain before wide scale implementation. In many instances these improvements are related to both processing and product performance. It is observed that HME process optimisation is majorly focused on the active pharmaceutical ingredient's (API) properties. Characterising polymeric properties for their suitability in HME should be equally studied since the impact of excipients on both product and process performance is just as vital. In this work, two well-established cellulose ester derivatives: Hydroxy Propyl Methyl Cellulose Acetate Succinate (HPMCAS) and Hydroxy Propyl Methyl Cellulose Phthalate (HPMCP) are studied for their HME suitability. Their thermal, thermodynamic, rheological, thermo-chemical and degradation kinetic properties were evaluated with model plasticisers and APIs. It was found the thermal properties of HPMCP are severely compromised whereas HPMCAS is more stable in the processing zone of 150 to 200 °C. Thermodynamic properties revealed that both polymers share an important solubility parameter range (20-30 MPa P1/2P) where the majority of plasticisers and BCS class II APIs lie. Thus, greater miscibility/solubility can be expected. Further, the processability of these two polymers investigated by rheometric measurements showed HPMCAS possesses better flow properties than HPMCP because HPMCP forms a weak network of chain interactions at a molecular level. However, adding plasticisers such as PEG and TEC the flow properties of HPMCP can be tailored. The study also showed that plasticisers have a major influence on thermo-chemical and kinetic properties of polymers. For instance, PEG reduced polymer degradation with reversal in kinetic parameters whereas blends of CA produced detrimental effects and increased polymer degradation with reduction in onset degradation temperatures. Further, both polymers are observed to be chemically reactive with the APIs containing free -OH, -SOR2RN- and -NH2 groups. Finally, these properties prove that suitability of HPMCP is highly debated for HME and demands great care in use while that of HPMCAS is relatively better than HPMCP in many instances.

Applications of Hot Melt Extrusion (HME) in pharmaceuticals have become increasingly popular over the years but nonetheless a few obstacles still remain before wide scale implementation. In many instances these improvements are related to both processing and product performance. It is observed that HME process optimisation is majorly focused on the active pharmaceutical ingredient's (API) properties. Characterising polymeric properties for their suitability in HME should be equally studied since the impact of excipients on both product and process performance is just as vital. In this work, two well-established cellulose ester derivatives: Hydroxy Propyl Methyl Cellulose Acetate Succinate (HPMCAS) and Hydroxy Propyl Methyl Cellulose Phthalate (HPMCP) are studied for their HME suitability. Their thermal, thermodynamic, rheological, thermo-chemical and degradation kinetic properties were evaluated with model plasticisers and APIs. It was found the thermal properties of HPMCP are severely compromised whereas HPMCAS is more stable in the processing zone of 150 to 200 °C. Thermodynamic properties revealed that both polymers share an important solubility parameter range (20-30 MPa P1/2P) where the majority of plasticisers and BCS class II APIs lie. Thus, greater miscibility/solubility can be expected. Further, the processability of these two polymers investigated by rheometric measurements showed HPMCAS possesses better flow properties than HPMCP because HPMCP forms a weak network of chain interactions at a molecular level. However, adding plasticisers such as PEG and TEC the flow properties of HPMCP can be tailored. The study also showed that plasticisers have a major influence on thermo-chemical and kinetic properties of polymers. For instance, PEG reduced polymer degradation with reversal in kinetic parameters whereas blends of CA produced detrimental effects and increased polymer degradation with reduction in onset degradation temperatures. Further, both polymers are observed to be chemically reactive with the APIs containing free -OH, -SOR2RN- and -NH2 groups. Finally, these properties prove that suitability of HPMCP is highly debated for HME and demands great care in use while that of HPMCAS is relatively better than HPMCP in many instances.