Evaluation of pulp and paper making characteristics of certain fast growing plants

Summary Four species of fast growing annual plant viz.Hibiscus sabdariffa, Crotalaria juncea, Tephrosia candida andHibiscus cannabinus and a variety of reed, Neyraudia reynaudiana were evaluated in the laboratory for their pulp and paper making properties. Data on proximate chemical analysis of raw materials, unbleached and bleached pulp properties, morphological properties of fibres and physical strength properties of paper sheets were evaluated. The unbleached pulp yields were 44.90–53.20% with all the five plant materials, while bleached pulp yields varied from 39.80–50.60%. The average fibre lengths and diameters of the unbleached pulp obtained from the five plant species were within the range of 0.75 mm–2.15 mm and 20–22 pun respectively. Paper hand sheets, made with bleached pulps (45° SR) obtained from the five plant species, gave burst indices 2.75–3.92 kPa m²/g, tear indices 3.73–9.61 m N m²/g and tensile indices 37.27–47.81 N mg^–1, indicating adequate strength properties for writing and printing type of paper.The authors thank Director, Regional Research Laboratory (CSIR), Jorhat, India, for his kind permission to publish this paper. The authors also wish to thank B. N. Tosh, JPF for his assistance.     

Effects of permanence requirements on afforestation choices for carbon sequestration for Ontario, Canada

This study examines the economic and spatial impacts of afforestation choices for carbon sequestration in Ontario, Canada when the non-permanence of forestry carbon offsets is taken into consideration. We test six scenarios including three long-term projects with red pine, Norway spruce and hybrid poplar plantations and three shorter term hybrid poplar scenarios that produce temporary carbon emission offsets. We convert the break-even costs of sequestering carbon to a permanent carbon offset equivalent and analyze the possible geographical implications of the choices across eastern, southern and central Ontario, Canada.The most financially viable scenarios show a relatively large part of central Ontario with attractive choices at a 4% discount rate but a much smaller area at an 8% rate. The assumption about the future price evolution of temporary carbon offsets is one of the biggest factors that influence the attractiveness of these choices. At the 4% discount rate and the assumption of rising prices of permanent carbon offsets, the scenarios that store carbon for long periods appear to be the least-costly option. Hybrid poplar appears as the best choice in southern Ontario and a mix of conifer species and hybrid poplar in the central and northern parts. When future prices of temporary carbon offsets are assumed to decline, temporary hybrid poplar projects appear to be more attractive in the southern and eastern parts of the province. The variety of alternative scenario choices also depends on the discount rate and future price expectations for temporary carbon offsets. For a relatively narrow deviation of the carbon offset price (±$0.6 t^-1 CO₂), only 4% to 9.2% of the total 5.8 million ha area would have one or more potentially viable alternative scenarios at the 4% discount rate and almost zero alternatives at the 8% rate. Higher discount rates lead to fewer attractive choices, suggesting that landowners would be left with very few options when trying to maximize net returns from plantations.     

Optimal rate of paper recycling

This paper uses a dynamic land allocation model combined with the infinite rotation problem to determine theoretically, the recycling rate that maximizes the forest area and, thus, the number of trees under social management thereby integrating both positive externalities generated by the forest and social costs of not recycling. The results suggest that, when the recycling rate is low, increasing it to its optimal level will result in more land area being devoted to forestry and, thus, more trees. However, increasing it beyond its optimal level will reduce the number of trees in the long run. In addition, the recycling rate that maximizes the forest area is optimal in the sense that it also maximizes the social net benefit. An application shows that increasing the recycling rate up to its optimal level considerably increases the forest area. The increase in the social net benefit is very small.     

Two-dimensional linear viscoelasticity of paper

Summary Linear viscoelastic properties of laboratory handsheets have been investigated from the two dimensional aspect. According to the linear theory of viscoelasticity, the behavior of transverse isotropic materials such as handsheets subjected to plane stresses is fully described by the two in-plane relaxation functions G₁₁ (t) and G₁₂ (t). In the present paper, some viscoelastic characteristic functions describing responses to in-plane deformation histories are derived from G₁₁ (t) and G₁₂ (t) determined by strip biaxial stress relaxation testing. The predicted uniaxial relaxation function curve was in good agreement with the experimental one, and the viscoelastic Poisson's ratios in uniaxial stress relaxation and in uniaxial constant strain rate extension were decrease functions of time. Effects of beating on the areal dilatation and shear relaxation functions are discussed by introducing the classical concept of relaxation spectrum.     

蔬菜纸的加工技术

当前,食品加工正向着营养全面、纯天然、食用方便的方向发展。消费者对食品要求是营养均衡,并希望食品同时具有保健功能。因而,食品的加工生产无论是原料、生产工艺,还是设备都应力求使产品具有天然性、营养性和方便性。蔬菜纸是近年来新出现的一种方便食品,它以低热量、富含维     

加快纸材林基地建设拓展造纸业发展空间 --岳阳林纸集团公司林纸结合的实践

湖南省岳阳林纸集团有限责任公司(以下简称岳纸公司)地处洞庭湖与长江交汇处的城陵矶,一直是国家扶优扶强的重点企业,也是国家文化用纸的重要生产基地。1999年公司被列入国家重点支持的520户大型企业行列。目前,已发展成为集制浆造纸、碱回收、轻机制造、发电供热、科研设计、进出口贸易、原料基地开发于一体国有大型一类企业,拥有资产总值48亿元。2002年主营业务总产量26万t、完成工业增加值5.8亿元、利税2.4亿元。2003年6月,公司胶印书刊纸技改项目投产后,生产能力已达50万t。公司目前是湖南省境内最大的木材消耗企业。从上世纪80年代初开…     

对废纸再生的几点思考

结合当前纸业原料结构和我国生态保护的现状 ,分析了废纸再生的重要意义。简要介绍了国际、国内废纸再生的发展概况 ,并对我国废纸再生事业的发展提出了几点建议。     

WTO与中国的造纸工业

回顾历史,古代中国造纸术的发明比西方早了数百年;审视当今,现代中国的造纸业落后世界水平有数十年。我们有广阔的市场,也有多方面的发展潜力,面对WTO的新形势,我们如何加快造纸工业基地建设,做强我国的造纸工业呢?请您随下面的文章一同思考。     

Characterization of paper sheets from agricultural residues

Summary In this work we characterized olive tree fellings, wheat straw, sunflower stalks, vine shoots and cotton plant stalks, as well as pulp and paper sheets obtained from them. Thus, we determined the 1% NaOH solubles, alcohol-benzene extractables, ash, holocellulose, lignin, -cellulose and pentosans in the aforementioned agricultural residues and their pulps, as well as the breaking length, stretch, burst index, tear index, porosity and water absorption of the resulting paper sheets, which were also subjected to the concora medium, concora crush and rings crush tests. Wheat straw and vine shoots were found to be the most and least suitable raw material, respectively, for paper production.The authors are grateful to the DGICyT for financial support of Project PB87 0820     

高耐磨浸渍纸及其生产工艺的研究

介绍了一种新的人造板贴面用高耐磨浸渍纸及其生产工艺。该纸的制作过程中将所有起耐磨作用的组份按比例制成液体形态，使每个耐磨颗粒都被胶液包裹着，均匀地分布于胶层的各个层面中，再将上述混合胶液涂在表层纸或装饰纸上，经干燥后得到的具有高耐磨度的浸渍纸。     

Surface analysis of paper containing polymer additives by X-ray photoelectron spectroscopy I: Application to paper containing dry strength additives

The surfaces of handsheets containing polydiallyl-dimethylammonium chloride (PDADMAC) and anionic polyacrylamide (A-PAM) were analyzed using X-ray photoelectron spectroscopy (XPS). The observed N1s chemical shifts were compared with those of the strength additives. Chemical covalences on paper surfaces due to a small amount of polymer additives were clarified and determined by an XPS curve-fitting technique. Some of the problems associated with surface analysis of paper by XPS are discussed. The effects of strength additives on the fiber surface or between fibers are illustrated. This technique appears promising as a tool to analyze paper surfaces treated with small amounts of polymer additives.Part of this paper was presented at the 64th Pulp and Paper Research Conference, Tokyo, Japan, June 19–20, 1997     

发展竹浆造纸 节约木材资源

随着社会经济水平的发展,中国纸及纸板的现有产品结构已不适应纸张消费市场的变化与发展,加剧了国内市场对进口纸及纸板的依赖性。竹材纤维细长,是制浆造纸的优质原料。竹浆纸的开发有利于节约木材资源,有利于环境保护。中国竹资源丰富,发展竹浆造纸的市场前景非常广阔。因此,在造纸工业中实现以竹代木,建立林纸一体化的竹浆生产基地,将成为节约木材资源,减少纸及纸浆的进口,使制浆造纸工业得以持续发展的有利途径。     

Mechanisms of perception of laid lines in Japanese paper

Laid lines are observed frequently in Japanese paper. For restoration of historic document paper, the laid line intervals should be consistent between the restoration paper and the original paper for harmonized appearance. Considering this prerequisite, the perception mechanisms of the laid lines are discussed. Laid lines can be easily observed against backlight. However, there are several cases where laid lines are not visible against backlight, but are clearly visible with diffuse reflected light. With paper sheets formed on screens with short bamboo splint pitches, laid lines were observed only with diffuse reflected light. Within these sheets, there was no fiber mass distribution or surface roughness that correlated with the periodicity of the laid lines. On the other hand, paper sheets produced using long splint pitches exhibited light transmission unevenness, fiber mass unevenness, and surface roughness. Microscopic observations using two-way low-angle illumination revealed the following mechanism. In the flow sheet-forming method, fibers are oriented strongly in the cross-splint direction in the first layer while some fibers rotate and become aligned along the interspaces between the splints in the second layer during dehydration. Bidirectionally oriented fibers perpendicular to each other result in a contrasting reflectivity perceived as laid lines.     

Biotechnology in the pulp and paper industry

Summary Biotechnology implies the technical exploitation of biological processes. One of nature's most important biological processes is the degradation of wood and other lignocellulosic materials to carbon dioxide, water, and humic substances. Consequently, there should be possibilities to apply biotechnology to wood conversion. This article summarizes briefly the knowledge relating to the enzymic degradation of cellulose, hemicelluloses, and lignin. However, it is mainly focused upon biotechnological processes in commercial use or in various stages of development for the pulp and paper industry. Areas covered are ethanol and protein production, water purification, development of new bleaching techniques, microbial delignification (biopulping), and development of biosensors for analysis of pulp fiber surfaces.Academy lecture presented on May 18, 1989 at the Fourth International Conference on Biotechnology in the Pulp and Paper Industry. Raleigh, NC USA     

Mechano-sorptive creep in pulp fibres and paper

The factors affecting mechano-sorptive creep of wood and paper have been investigated for a long time. It has also been argued that single wood fibres do not exhibit mechano-sorptive creep and that the reasons for the accelerated creep under moisture cycling conditions instead are related to the bonds between the fibres. In order to examine the relevance of this argument, measurements on single pulp fibres of different composition were performed in tension, and the mechano-sorptive creep was compared to that of papers made from the same source of pulp fibres. All fibres tested were found to exhibit an increased creep rate during moisture cycling as compared to constant humidity conditions. Thus, pulp fibres show mechano-sorptive creep and in this sense behave similar to solid wood or paper products made thereof. A linear relation between the creep strain rate during cyclic humidity and the creep strain rate at a constant humidity was also noted for both fibres and paper. This relation was not affected by changes in hemicelluloses content or composition, neither for fibres nor for papers made of these fibres. However, in all cases, papers showed a much higher mechano-sorptive creep than the corresponding fibres they were made of.     

Socioeconomic factors influencing global paper and paperboard demand

To clarify the socioeconomic factors influencing global paper and paperboard demand, a panel data analysis was conducted covering the period 1961–2014. This study used paper and paperboard demand as the dependent variable, and a country’s economic level, Internet usage rate, plastic packaging demand, and time trend as the explanatory variables. An inverse U-shaped quadratic relationship, such as an environmental Kuznets curve, was found between economic level and paper and paperboard demand, which saturates and begins to decline as economic level increases. The economic level representing the turning point differs significantly with the use, ranging from around 37,000 US$/person for newsprint paper to around 66,000 US$/person for printing and writing paper. For both newsprint paper and printing and writing paper, demand declines owing to the spread of the Internet as the economic level rises, although this reductive effect is greater for printing and writing paper than for newsprint paper. A substitution relationship is not found between wrapping paper and corrugated cardboard on the one hand and plastic packaging on the other hand as the economic level becomes higher.     

Influence of coating properties on paper-to-paper friction of coated paper

Coated paper-to-coated paper friction properties were examined in relation to printing runnability difficulties like erroneous double feeding of paper sheets. Higher ratios of precipitated calcium carbonate (PCC) to clay in mixed pigment coatings resulted in higher static and kinetic coefficients of friction (COFs). Microroughness in the order of pigment particle size is considered to relate to COF, because cube-shaped particles of PCC resist sliding. Calendering decreased COF at larger amounts of PCC, but did not change COF of the sole clay formulation at all. Addition of ground calcium carbonate (GCC) decreased COF. The rate of decrease in kinetic COF with increasing number of sliding for the GCC-rich formulation was higher than that for the PCC-rich formulation, presumably because protruding parts, characteristic of the GCC-rich formulation, on the surface were selectively flattened. Addition of styrene-butadiene (SB)-latex up to 14pph decreased COF, but static COF had the highest value at 18pph. The antislip property (as a rubber) of SB-latex developed only in the static mode. Among lubricants formulated, the wax type decreased COF the most remarkably with more effect on kinetic COF than on static COF. Part of this report was presented at the 11th International Printing and Graphic Arts Conference, Bordeaux, France, October 2002