At the end of this module, you will be able to:
- Differentiate between "earlywood" and "latewood" fibers with regards to pulp properties
- Differentiate between "heartwood" and "sapwood," including the impact on the pulping process
- Differentiate between hardwood and softwood in regards to wood composition, pulping, and pulp properties
- Identify and describe key chip quality parameters, associated testing, and the impact on the pulping process
- Identify and describe woodyard safety hazards and guidelines
The following key questions are answered in this module:
How do tree growing conditions affect chip properties?
Trees in temperate climates grow slow during cold or dry periods and grow rapidly during wet and warm times. Fibers that grow fast are thinner and more flexible. Trees that grow in tropical climates where it is warm and wet all year, tend to have more uniform fibers.
What are some important chip quality parameters?
Wood species, chip size distribution, moisture content, contamination level, and chip age are all important wood chip quality parameters.
What are some properties of softwood fibers?
Softwood fibers are long and bulky. They provide strength to paper.
What are some properties of hardwood fibers?
Hardwood fibers are short, thin, flexible fibers that provide smoothness and opacity to paper.
What are the different chip size categories?
Chips can be grouped into overs, accepts, pins, and fines.
Below is a transcript of the video sample provided for this module:
Wood is the main source of the fibers used in the large scale industrial production of paper-based products. Paper can be made from other plant fibers such as papyrus, cotton, and flax but wood has much greater availability. Wood fibers come from many different regions and have unique characteristics based on the tree species and the climate they grow in. The various characteristics help developed the properties of different paper products. For example, tissue paper utilizes the soft feeling from thin, flexible eucalyptus fibers, while cardboard boxes are made of strong, bulky stiff fibers like Douglas fir. Pulping breaks down wood chips into individual fibers. The Kraft pulping process uses digestors to process wood chips at high temperature and pressure with a strong acolyte.
Use the additional resources and links below to learn more about this topic: