Thickness swelling

Boards with reduced thickness swelling, e.g. for laminate flooring. 

Example 4.4 A blow moulding die has an outside diameter of 30 mm and an inside diameter of 27 mm. The parison is inflated with a pressure of 0.4 MN/m to produce a plastic bottle of diameter 50 mm. If the extrusion rate used causes a thickness swelling ratio of 2, estimate the wall thickness of the bottle. Comment on the suitability of the production conditions if melt fracture occurs at a stress of 6 MN/m. ... 

For the resultant 8 x 8 x j -in. board board density = 40.67 Ib/ft3 internal bond strength (ASTM D1037) = 133 psi thickness swell (ASTM D1037) = 18.8%. 

Press Time Density (kg/m3) Versal Tensile Strength (N/mm2) Thickness Swelling After ... 

U50 000 psi IB, minimum = 60 psi and linear expansion, maximum = 0.25. Properties of all examples given in Table II substantially surpass the comercial standard and also surpass the properties of the PF control boards with respect to linear expansion, thickness swelling, and absorption in the one-hour boil test. Internal bonds, both initial and after the one-hour boil test, and water immersion results of the HDA experimental boards were slightly inferior to results of these tests for the PF control boards. Properties of urea-formaldehyde control boards were similar to the PF control boards excepting in the one-hour boil test where complete failure of all bonding took place in about 15 minutes. 

After the boards were removed from the hot press they were conditioned at room temperature for several days before testing. Three 2 x 10-inch strips were cut from each board for determining breaking load. A 0.24-inch-per-minute loading rate and a 9-inch span were used. Thickness of each strip was measured at the point where the load was to be applied, and after the strip had been "broken each half was cut into two 2 x 2-inch samples. These samples were used to obtain data necessary for determination of oven-dry density, water absorption and thickness swelling, internal bond, and a 2-hour boiling-in-water thickness swelling test. 

Bark Extracts Density O.D. (gm/cc) Modulus of Rupture (psi) Internal Bond (psi) 24-hr Water Absorption (%) Immersion Thickness Swelling (%> 2-hr Boil Test Thickness Swelling (%> Linear Expansion (%)... 

Dost in 1971 reported on a study where redwood bark fiber was used in three-layer particleboard (44). Amount of bark in the furnish, by weight, was 0, 10, 20, and 30% hammemilled disk flakes or Pallmann flakes of redwood wood made up the remainder of the furnish. Urea formaldehyde resin was applied at three percentages. Test results showed surface smoothness and strength properties (MOR, MOE, and IB) decreased with increasing bark content in the boards. Water absorption decreased, but thickness swelling and linear expansion increased as the amount of bark increased. 

So far this year, two reports have been published on the effect of bark in medium-density fiberboard. The first by Woodson (61) covered the bark of three southern hardwoods, sweetgum, southern red oak, and mockernut hickory percentage of bark in the whole-tree furnish was 13.4, 20.0, and 18.6%, respectively. Urea-melamine formaldehyde binder was added at 8-10%, and wax at 1%. Test results showed inclusion of bark decreased tensile and bending strengths by 16-18%, MOE by 10-14%, and IB by 8%. Linear expan sion was not affected significantly by bark. Thickness swelling was improved in two of the three species. Woodson concluded good quality, medium-density fiberboard could be made from barky chips. 

Extract Code3 Extract Content PMDI Content Modulus of Rupture Internal Bond (V20) Thickness Swelling... 

In Table V, the mechanical properties of particleboard bonded with nonemulsifiable diisocyanate modified with maize starch are given. The extender content for the diisocyanate was up to 20%. However, with increasing extender content, the internal bond of the boards decreased, and the thickness swelling increased the boards had V100 quality. First tests with adhesives of diisocyanates and starch were encouraging, and more attempts in developing new glue formulations... 

Resin Temperature- Density IB Thickness Swell Dried4... 

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