Fundamental Science and Applications for Biomaterials 53
chromatography (GC), size-exclusion chromatography (SEC), gas chromatography
mass spectrometry (GC-MS), high-performance anion-exchange pulse amperometric
detection (HPAE-PAD) chromatography, 1D and 2D NMR spectrometry, and
matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS.
2.3.3 Lignin Reactivity
Many new techniques were developed to isolate lignin formulations to study [29–33].
Generally, three approaches were taken toward investigating lignin structure: degra-
dation reactions, biosynthetic work, and spectroscopy studies. In the most common
approach, lignin formulations were subjected to various degradation reactions yielding
identifiable products that gave useful structural information. Many new analytical
techniques were developed during these times that were highly useful for the lignin
chemists. In the final approach, model compounds were synthesized from postulated
lignin precursors to produce new products for study. This was a time in which much
work was applied to developing new methods to isolate lignin. In 1936, Bailey at the
University of Washington showed by microdissection that the middle lamella was
composed mainly (72%) of lignin rather than pectin. In 1935, Van Beckum and Ritter
at the US Forest Products Laboratory (USFPL) removed lignin from plant tissues with
hypochlorite followed by NaOH. The material that remained termed holocellulose
consisted of the total carbohydrate mass present in the plant tissues. In 1939, Brauns
reported that neutral solvent extraction of woody tissue and subsequent purification
created a few percent of what he named native lignin or Braun’s lignin. Presently, many
investigators view this material as a mixture of lower molecular weight lignins and/or
lignans. This work reflected the continuing search by some classical organic chemists
for a lignin that could be extracted simply by use of solvents without chemical reaction.
In 1947, Richie and Purves at McGill University oxidized wood at pH 4 with aqueous 5%
sodium periodate. The periodate lignin preparation thus obtained was 86–96% Klason
lignin, insoluble in organic solvents even at boiling temperature but completely soluble
under conditions of sulfite pulping. A periodate lignin from spruce closely duplicated
the behavior of spruce lignin in situ toward many degradative procedures.
2.4 Composite as a Unique Application for Renewable Materials
Plastic composite processors worldwide are becoming increasingly aware that
environmentally sustainable products have become mainstream, and it can no longer
be considered only a niche market that can be ignored [34–37]. Moreover, in the
light of the recent Paris climate agreement in 2015, development of environmentally
sustainable new technologies and materials is of growing importance; state and local
governments are mandating it; and now, even the largest retailers are building it into
the foundation of their marketing strategies. The development of renewable/sustainable
materials is perceived by the industry as a hedge against the prospect that traditional
plastics will be much more costly in the future due to dramatically higher petroleum
prices. The sustainability movement is further seen as a positive development for plastic
processors since it will drive further innovation and a new generation of materials
