Chemical modification of lignins: Towards biobased polymers

The majority of commodity plastics and materials are derived from petroleum-based chemicals, illustrating the strong dependence on products derived from non-renewable energy sources. As the most accessible, renewable form of carbon (in comparison to CO2), lignocellulosic biomass (defined as organic matter available on a renewable basis) has been acknowledged as the most logical carbon-based feedstock for a variety of materials such as biofuels and chemicals. This Review focuses on methods developed to synthesize polymers derived from lignin, monolignols, and lignin-derived chemicals. Major topics include the structure and processing of lignocellulosic biomass to lignin, polymers utilizing lignin as a macromonomer, synthesis of monomers and polymers from monolignols, and polymers from lignin-derived chemicals, such as vanillin.

Strategies for the Conversion of Lignin to High-Value Polymeric Materials: Review and Perspective

Isolation of nanocellulose from waste sugarcane bagasse (SCB) and its characterization

Characterization of Habits and Crystalline Modification of Solids and Their Pharmaceutical Applications

Extraction and characterization of cellulose nanocrystals from agro-industrial residue – Soy hulls

Thermal analysis has recently become prominent, particularly in applications to fibers, plastics, and other synthetic polymeric materials. Thermal analysis may be defined as a set of techniques used to describe the physical or chemical changes associated with substances as a function of temperature [1]. Thermograms have been used to determine thermodynamic and kinetic parameters associated with the chemical changes which occur upon heating, the heat capacity of a substance, first- and second-order transition temperatures, latent heats of transformation, and effects of radiation or additives on natural and synthetic polymers. Particularly successful appears to be the simultaneous use of two or more thermal analytical techniques or the combination of thermal analytical and spectroscopic techniques (for example, infrared, electronic, and nuclear magnetic resonance analysis). The increasing commercial importance of polymers and the commercial manufacture of thermal analytical instruments have resulte...

Thermal Analysis of Lignocellulosic Materials

Samples of ordinary “ash-free” cellulose papers and similar samples decrystallized by swelling in liquid ammonia were pyrolyzed in vacuo to a weight loss ranging from <0.1% to nearly 20%. The samples were then nitrated and their molecular weight distributions determined by gel permeation chromatography. When weight loss reached 1%, both the ordinary and the ammonia-swelled celluloses showed a large drop in average degree of polymerization (D.P.). However, the ordinary cellulose showed this sharp drop long before there was any measurable weight loss; the ammonia-swelled cellulose changed D.P. only gradually in the early stages. Further, x-ray diffraction measurements showed that by the time the D.P. of the ammonia-swelled cellulose had dropped appreciably, the material had developed a significant crystalline pattern. These results support the suggestion that initial rupture of the cellulose molecule occurs at strain points at the crystalline–amorphous boundaries.

https://www.fs.fed.us/psw/publications/broido/psw_1973_broido002.pdf

Molecular weight decrease in the early pyrolysis of crystalline and amorphous cellulose

Thermal analysis is a group of techniques in which a physical property of a substance is measured as a function of temperature while the substance is subjected to a controlled temperature program. The output of thermal analysis represents data predominantly in the form of curves characteristic for a particular chemical substance or a mixture of substances. Changes in latent heat in a chemical substance are detectable by differential thermal analysis (DTA) or by differential scanning calorimetry (DSC). Progressive weight loss is detectable by thermogravimetry (TG) or differential thermogravimetry (DTG). Progressive changes in certain mechanical properties are detectable by thermomechanical analysis (TMA). Many other thermoanalytical techniques are available, but are used appreciably less often.

Edward M. Barrall

Papers

Thermal Analysis of Lignocellulosic Materials

Molecular weight decrease in the early pyrolysis of crystalline and amorphous cellulose

Thermal Analysis of Lignocellulosic Materials. Part II. Modified Materials

Precision of purity determinations by differential scanning calorimetry

Precise determination of melting and boiling points by differential thermal analysis and differential scanning calorimetry