Study

Properties of paper Physical Properties

Basis Weight or Grammage The basis weight, substance or grammage is obviously most fundamental property of paper and paperboard. The Basis weight of paper is the weight per unit area. This can be expressed as the weight in grams per square meter (GSM or g/M2), pounds per 1000 sq. ft. or weight in Kgs or pounds per ream (500 sheets) of a specific size. Paper is sold by weight but the buyer is interested in area of paper. The basis weight is what determines, how much area the buyer gets for a given weight. e.g. if basis weight is 50 g/m2, for every 1 kg weight, the buyer gets 20 m2. When the basis weight is expressed as ream weight, it tells the buyers how many reams he/she getting for a given weight. For papermaker basis weight is important from point of view of production rate. For a given machine deckle and machine speed, the production rate per day in MT will be = Machine Deckle (m) * Machine Speed (m/min) * Basis Weight (g/M2) * 1440/1000000. Papermaker always strive to get all desired properties of paper with minimum possible basis weight. All paper machines are designed to manufacture paper in a given basis weight range. Tighter the range, more efficient will be the machine operation. The standard procedure of measuring basis weight is laid out in TAPPI T 410, SCAN P6, DIN53104 & ISO: BSENISO536

Typical Grammage Values | Grade | g/m2 | Newsprint | 40 - 50 | Cigarette Tissue | 22 - 25 | Bond | 60 -90 | Paperboard | 120 - 300 | Accepted trade tolerance +/- 5% |
Bulk and Density Bulk is another very important parameter of paper particularly for printers. Bulk is a term used to indicate volume or thickness in relation to weight. It is the reciprocal of density (weight per unit volume). It is calculated from caliper and basis weight. Bulk (cubic centimeter/g) = Thickness (mm)* 1000/ Basis Weight (g/m2). Sheet bulk relates to many other sheet properties. Decrease in bulk or in

References: * 7 External links | ------------------------------------------------- Overview[edit] Roots Often called pandanus palms, these plants are not closely related to palm trees. The species vary in size from small shrubs less than 1 metre (3.3 ft) tall, to medium-sized trees 20 metres (66 ft) tall, typically with a broad canopy, heavy fruit, and moderate growth rate.[4] The trunk is stout, wide-branching, and ringed with many leaf scars. They commonly have many thick prop roots near the base, which provide support as the tree grows top-heavy with leaves, fruit, and branches. The leaves are strap-shaped, varying between species from 30 centimetres (12 in) to 2 metres (6.6 ft) or longer, and from 1.5 centimetres (0.59 in) up to 10 centimetres (3.9 in) broad. They are dioecious, with male and female flowers produced on different plants. The flowers of the male tree are 2–3 centimetres (0.79–1.2 in) long and fragrant, surrounded by narrow, white bracts. The female tree produces flowers with round fruits that are also bract-surrounded. The fruits are globose, 10–20 centimetres (3.9–7.9 in) in diameter, and have many prism-like sections, resembling the fruit of the pineapple. Typically, the fruit changes from green to bright orange or red as it matures. The fruit of some species are edible. Pandanus fruit are eaten by animals including bats, rats, crabs,elephants and monitor lizards, but the vast majority of species are dispersed primarily by water.[5] They are numerous, palm-like, dioecious trees and shrubs of the Old World tropic growing from sea level to 3,300 m. The adventitious roots are large and often branched; the tops have a crown of narrow spiny leaves.[2][3] They are large shrubs or small trees of cultural, health, and economic importance in the Pacific, second only to coconut on atolls.[6][7] They grow wild mainly in seminatural vegetation in littoral habitats throughout the tropical and subtropical Pacific, where they can withstand drought, strong winds, and salt spray. They propagate readily from seed, but also are widely propagated from branch cuttings by local people.[2] It grows fairly and quickly.[6][8] The genus is native to most of the tropical islands.[9] Three species of screwpine are commonly found in Maldives. Species with large and medium fruit are edible. Pandanus is one of the iconic tree genera of the New South Walesnorth coast.[10] Species growing on exposed coastal headlands and along beaches have thick 'prop roots ' as anchors in the loose sand.[2][11] Those prop roots emerge from the stem, usually close to but above the ground, which helps to keep the plants upright and secure them to the ground.[12] Some species ofPandanus trees can grow up to 6 m high. They have long, thin, light-green leaves, which grow in spirals on the plants ' stems. As the plants grow, the leaves drop off, leaving 'scars ' on the stems.[9] In some species of Pandanus, the fruits look a bit like a woody pineapple. They hang from the branches, and can stay on the tree for more than 12 months. The genus normally does not have branches, but very old specimens can have branches.[9] Its strange appearance impacts all travelers who find them. The trunk is covered with smooth, mottled bark. The roots forms a pyramidal tract to hold the trunk.[5] While all pandanus palms are distributed in the tropical Pacific islands, they are most numerous on the low islands and barren atolls of Polynesia and Micronesia.[1][13][14][15] The tree is grown and propagated from shoots that form spontaneously in the axils of lower leaves. Its fruit can float and spread to other islands without help from man. Other species are adapted to mountain habitats and riverine forests.[16] The fruit is a drupe.