Treesearch

Removal of stickie contaminants is currently a major focus of paper recycling research. Medium consistency alkaline repulping followed by pressure screening has proven to be effective for stickie removal. There is, however, an alternate method that is equally effective and more environmentally benign. This study compares the effectiveness of this alternative method, neutral enzymatic repulping, with conventional alkaline repulping for contaminant removal from a controlled office paper furnish spiked with typical pressure-sensitive adhesives. Neutral repulping on a pilot scale was performed...

Wind pressures can play an important role in the wetting of exterior walls (driving rain). In response, the rain screen concept, including compartmentalization and air spaces, has been developed to provide pressure equalization and limit water entry into the wall. However, conventional construction such as wood lap siding has not been evaluated as to its ability to function as a rain screen. As part of a two-year project assessing the performance of hardboard lap siding, we measured air pressure differences across the siding over extended periods of time in two single-story wood-frame...

Xylanases reduce kappa and release UV- and visibly absorptive materials from kraft pulps. The extents of these actions depend on the origin and processing of the pulp, access of enzymes to the substrate, and the natures of the enzymes. Hexeneuronic acid (HexA) is a component of kraft pulp xylans that accounts for a fraction of the kappa content. It absorbs strongly in the UV region (235 nm), and its release can be used to monitor xylanase activity. This report shows that HexA release correlates closely with release of xylooligo-saccharides, but not with the reduction in kappa.

The following results are preliminary, but show some basic information that will be used in an attempt to model pulp molded structures so that by measuring several basic fundamental properties of a fiber furnish and specifying process conditions, a molded structure could be designed for a particular performance need.

The steam injection schedule best suited for dimensionally stabilizing a flake mat is one in which steam treatment is initiated before the press is closed and is continued at least until the mat attains target thickness. Experiments showed that resinless mats treated with 20 sec of steam at 600 kPa had maximum thickness swelling of 205% compared to 350% for resinless mats pressed in a conventional fashion. Reductions in thickness swelling were proportional to steam duration and pressure. Mats treated with 20 sec of steam at 1.950 kPa had only one-tenth the thickness swelling measured in...

Four new species of Alboleptonia are described from Puerto Rico and new distribution records for Alboleptonia are noted for Puerto Rico and St. John, U.S. Virgin Islands. Information from examination of the type collections of Alboleptonia aripoana, A. cyathiformis, and A. hyalodepas is discussed. Clarification of conflicting reports in the literature concerning the application of A. hyalodepas is presented and a lectotype is designated. Two new combinations are also made for Entoloma minutoalbum and E. talisporum. A key to the taxa of Alboleptonia occurring in and around the Caribbean...

Recycled newsprint (ONP) and dry process aspen fiber were combined with styrene maleic anhydride (SMA) copolymers containing either 7 or 14 percent maleic anhydride. The fiber-filled SMA composites were equivalent or superior to unfilled SMA in strength, stiffness, and notched Izod impact strength. ONP performed surprisingly well as a filler. Unnotched Izod impact strengths for filled polymers were lower than for unfilled polymers. Water sorption was similar among fillers, and was small compared with solid wood.

Battarrea stevenii and Tulostoma cf. meridionale, two cosmopolitan taxa are reported as new records for Puerto Rico. Both species were collected from the same disturbed subtropical dry forested area. A partial checklist of the taxa of macromycetes collected from Boquer*on Commonwealth- and Laguna Cartagena National Wildlife Refuges is also provided.

A new method for obtaining triaxial stress versus strain data is presented. The method tests cubic specimens and can provide constitutive data along three mutually perpendicular axes. Issues of removing the effects of boundary conditions in the proposed device are discussed. Two devices were constructed and used to obtain triaxial stress versus strain data on paperboard and on redwood samples. Representative data are shown.

The USDA Forest Service is preparing a national assessment of supply and demand for wood fiber resources in the United States. Based in part on preliminary results of this assessment and partly on our 1993 Assessment, this paper outlines trends and gives an outlook for demand and trade for timber and fiber products, changes in technology, and wood fiber resource supply. We use the term wood fiber to include timber for solid wood products, pulp and paper products, and recycled paper for paper products. Demand for solid wood products and paper and paperboard products will be driven by growth...