Preliminary thermal characterization of natural resins from different botanical sources and geological environments

Abstract

The preliminary studies on thermal behavior of differently aged natural resins from Russia (Khatanga), Dominican Republic (El Valle), Colombia and Poland (Jantar) were performed. Thermal stability and behavior under elevated temperature were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC), while the differences in the structure and composition by FT-IR spectroscopy. Analyzed resins show different thermal effects during heating suggesting that possible post-reactions and structural changes occurred. TG results indicated that Dominican, Russian and Colombian resins present relatively high thermal stability under air conditions in the range of 228-300°C, whereas the mass loss of 5mass% at about 217°C was observed for Baltic amber. During DSC experiments, the analyzed resins expose thermal events which make impossible determination of glass transition temperature in a raw sample. The results indicate that both TG and DSC cannot be considered as methods for age dating of natural resins and more advanced techniques should be applied. Careful analysis of FT-IR data in the carbonyl region may provide additional information about the composition and history of the natural resin. Keywords Glass transition Á DSC Á Fossil resins Á Copal Á Fossilization Paper dedicated to 100th anniversary of Polish Geological Institute.

Amber extract as a bio‐additive to poly(lactic acid) films: Multimethod analysis of crystallinity and stability

“…Further and very importantly, there is no second chance on the subsequent cooling and heating cycles for observing it, because that inherent information is the result of millions of years of polymerization, which cannot be reproduced by equipment. This would justify the extensive glass transition temperature range for Baltic amber reported in the literature, for example, 97.5 and 113.8°C 42 ; 118°C 34,40 ; 145°C 43 ; and 154°C 8 …”

Geographical variations and correlation among some chemical and thermal properties of Almaciga (Agathis philippinensis Warb.) resins from selected commercial sites in the Philippines

“…There was also weakening of the peak due to = C–H stretch at around 3080 cm −1 , possibly arising from conjugation with a C=C or aromatic ring unit, while ring strain could shift a particular band to a higher wavenumber ( Shriner et al., 1997 ). This suggests oxidation and transformation via conjugation or ring formation with ageing, as reactive and volatile components are converted to stable species and higher molecular mass compounds ( Pagacz et al., 2019 ). The presence of strong carbonyl stretch and broad hydroxyl stretch upon ageing reveals the presence of polar groups in the chemical components of the resin.…”

“…Good tapping practices include diameter-based selection of trees, tapping without damage to the cambium, spraying the cut portion with sulfuric acid to stimulate resin flow, and periodic tapping for sustained resin production ( Ella and Tongacan, 1992 ). The soft, resinous exudate from fresh injuries on the almaciga bark hardens over time ( Gonzales and Abejo, 1978 ) as reactive and volatile components escape or combine to form stable species and higher molecular mass compounds ( Pagacz et al., 2019 ).…”

New paradigm for configurational entropy in glass-forming systems

“…The gradual transformation from the 'fragile' to 'strong' h(𝑃) or t(𝑃) evolution when increasing temperatures of tested isotherms can be found for glycerol, for instance. For paths (5) and ( 6) one can expect that h(𝑃) or t(𝑃) first increases on compressing, until the rise associated with approaching the line relate to the second vitrification mechanism appears. For path (6) one can expect that at first the 'flat' domain associated with the proximity od 𝑇 𝑔 (𝑃) curve maxim before the drop of h(𝑃) associated with moving away from 'mechanism I' glass transition curve start to dominate.…”

“…Vitrification and glass transition are common in nature [1][2][3][4][5][6] and essential for variety of applications: from food [7], pharmaceuticals [8], cosmetics [9], polymers [10], modern materials, chemical processing and cryogenic implementations [11][12][13]. It constitutes also a grand fundamental challenge for which the long-awaited cognitive breakthrough has been expected for decades.…”