Pertti Nousiainen

Modification of hardwood dissolving pulp with purifiedTrichoderma reesei cellulases

Hardwood dissolving pulp was treated with purifiedTrichoderma reeseiendoglucanases and cellobiohydrolases. Endoglucanases were more efficient in hydrolysing pulp carbohydrates than were the cellobiohydrolases at the same protein dosage. Endoglucanases also lowered the viscosity and improved the alkaline solubility more dramatically. There was a clear correlation between the alkaline solubility and viscosity, and therefore the solubility could only be improved by lowering the viscosity of the pulp. At the same degree of cellulose degradation, endoglucanase II was found to be most effective in reducing the viscosity and thus improving the solubility. Cellobiohydrolases had a less pronounced effect on the viscosity or solubility.

Action of purified Trichoderma reesei cellulases on cotton fibers and yarn

In this work the possibility and potential of treating cotton fibers and yarns instead of fabrics with monocomponent cellulases was investigated. Different pretreatments on fibers were performed and tested in order to improve the accessibility of cotton to enzymatic modification. The enzymatic treatments were evaluated microscopically and by analysing the effects of treated fibers on spinnability, yarn evenness, tenacity and pilling. The accessibility of the cotton fibers for cellulases could be increased by different pretreatments. Steaming of fibers prior to enzymatic treatment was found to be an efficient way to increase hydrolysis levels. Cellulase treatments of carded yarns resulted in modification of yarn properties. Decrease in yarn hairiness was observed and the knitted fabric made of the treated yarn showed a lowered tendency towards pilling. In all cases endoglucanase activity rather than cellobiohydrolase activity was responsible for these modifications.

Treatment of cotton fabrics with purified Trichoderma reesei cellulases

Two different types of cotton fabrics, i. e. cotton twill and cotton poplin, were treated with purified Trichoderma reesei cellulases. Methods used to evaluate the enzyme effects included weight loss, tear strength, bending hysteresis, wrinkle recovery and pilling tendencies. When the different fabric properties at the same weight loss level were compared, it was apparent that cellobiohydrolase I (CBH I) and endoglucanases had different effects on cotton fabrics. Endoglucanases caused more strength loss than CBH I but had also positive effects on the bending behaviour and pilling properties. The two endoglucanases tested differed in their action. At low hydrolysis levels practically no strength loss was obtained with these endoglucanases whereas at higher dosages EG II caused significantly higher strength losses as compared to EG I. A positive result in the pilling was, however, also obtained with these low enzyme levels, indicating practically no strength loss.

CELSOL – Biotransformation of cellulose for fibre spinning

The well-known ability of various cellulase enzymes to degrade cellulose has already been applied in order to improve the conventional cellulose xanthate process. The aim of the present CELSOL-research is to develop a method for making cellulose directly soluble in aqueous sodium hydroxide, without chemical substitution of the cellulose. The method is based on a combination of mechanical and biochemical treatments though efficient dissolution of hardwood pulps requires an additional chemical pretreatment. The effect of combined treatments on the supermolecular structure of common pulps was measured by the change in the degree of polymerisation and by the solubility of the cellulose in 9wt% aqueous sodium hydroxide. The celluloses treated by above methods are characterized to be highly soluble and the alkaline solution, containing 3-7 w/w% cellulose, can be regenerated to films and fibres.

Direct soluble cellulose of Celsol: properties and behaviour

ABSTRACT Biotransformation of cellulose pulps creates a new modern cellulosic raw material suitable for direct dissolution in aqueous sodium hydroxide. A new method of cellulosic fibre and film manufacture, alternative to the viscose technology, was studied. Some properties of Celsol direct soluble cellulose, including its super-molecular parameters as well as useful behaviour such as solubility or spinnability, are presented.

Functional hybrid fibers of cellulose/microcrystalline chitosan. I. Manufacture of viscose/microcrystalline chitosan fibers

Blends of microcrystalline chitosan (MCCh) with cellulose xhanthate alkaline solutions were prepared to investigate the effects of aqueous MCCh gel concentration and additives on the spinnability of hybrid cellulose/chitosan fibers and their properties. The properties of the spinning solution were mainly dependent on the concentration of MCCh in the aqueous gel-like dispersion and the amount mixed into the cellulose xhanthate solution. Sodium alginate chemically close to cellulose and chitosan was used as an additive to improve the miscibility of chitosan due to the ionic bonds formed with chitosan 2-amino groups. Using an optimized ratio of 2 : 1 of MCCh to the sodium alginate, a maximum of 6% of MCCh calculated from alpha-cellulose content could be introduced into the sodium xhanthate solution containing originally 9% of alpha-cellulose. The yield of MCCh in the resulting fibers was dependent on the molecular mass, and varied between 73–82%. The strength, elongation, and color of the resulting hybrid fibers were only slightly changed and the WRV remarkably increased compared to standard fibers.

CELSOL - MODIFICATION OF PINE SULPHATE PAPER GRADE PULP WITH TRICHODERMA REESEI CELLULASES FOR FIBRE SPINNING

ABSTRACT Never-dried pine sulphate paper grade pulp was treated with specific enzyme mixture from Trichoderma reesei , which increased the alkaline solubility of pulp from 20% to 69% and decreased the DP W from 1124 to 622. The effect of different viscose process additives and zinc oxide on solubility was studied. The best combination for producing a good spinning dope was chosen. The fibres were spun using a wet spinning machine and titre, tenacity and elongation of the fibres were determined. The strongest fibres obtained have tenacity of 1.2 cN/dtex and elongation of 12-13%, which are comparable to the properties of cotton.

3D mosquito screens to create window double screen traps for mosquito control

BackgroundMosquitoes are vectors for many diseases such as malaria. Insecticide-treated bed nets and indoor residual spraying of insecticides are the principal malaria vector control tools used to prevent malaria in the tropics. Other interventions aim at reducing man-vector contact. For example, house screening provides additive or synergistic effects to other implemented measures. We used commercial screen materials made of polyester, polyethylene or polypropylene to design novel mosquito screens that provide remarkable additional benefits to those commonly used in house screening. The novel design is based on a double screen setup made of a screen with 3D geometric structures parallel to a commercial mosquito screen creating a trap between the two screens. Owing to the design of the 3D screen, mosquitoes can penetrate the 3D screen from one side but cannot return through the other side, making it a unidirectional mosquito screen. Therefore, the mosquitoes are trapped inside the double screen system. The permissiveness of both sides of the 3D screens for mosquitoes to pass through was tested in a wind tunnel using the insectary strain of Anopheles stephensi.ResultsAmong twenty-five tested 3D screen designs, three designs from the cone, prism, or cylinder design groups were the most efficient in acting as unidirectional mosquito screens. The three cone-, prism-, and cylinder-based screens allowed, on average, 92, 75 and 64% of Anopheles stephensi mosquitoes released into the wind tunnel to penetrate the permissive side and 0, 0 and 6% of mosquitoes to escape through the non-permissive side, respectively.ConclusionsA cone-based 3D screen fulfilled the study objective. It allowed capturing 92% of mosquitoes within the double screen setup inside the wind tunnel and blocked 100% from escaping. Thus, the cone-based screen effectively acted as a unidirectional mosquito screen. This 3D screen-based trap design could therefore be used in house screening as a means of avoiding infective bites and reducing mosquito population size.

Characterization of activated carbon fibers with high surface area

Abstract Viscose fibre based materials were carbonized and activated using CO 2 as an activation agent. Materials were pretreated with fire retardants and activated at 900°C. Degree of activation varied from 5 to 75%. Sample size was from 100 mg to 8000 g. Optimization of a pilot scale activation process was done with a number of laboratory scale experiments. The samples produced were characterized by nitrogen adsorption techniques. The results were used for surface area and pore volume determinations. In addition the samples were characterized by adsorption of different organic adsorbates from vapour phase. Vapour phase adsorption determinations were carried out by measuring adsorption capacities at saturated vapour (single point) pressure at constant temperature.

Application of air bladders for medical compression hosieries

The research work presents a new design of compression hosiery where compression around a human limb is generated using special air bladders. The pressure inside the air bladders is adjustable. The objective of the research was to study graduated compression and its control on the limb using the prototype with air bladders and two commercial compression products. The compression forces were measured around the limb under a knee in three sectors: a foot, a middle part and an upper part of the leg. Measurements were mainly done in vivo using the limb of a test person – although some pre-trials were done in vitro. During the tests it was concluded that the exact control of the compression was very difficult to achieve due to, for example, the shape and the composition of the limb. Based on the results, the compression values were unstable under the sectors and the graduated compression was nonlinear in the vertical direction for every tested hosiery. There is some analogy concerning the pressure distribution reported about standard mechanical compression hosiery. The results prove that our prototype enables one to achieve very high compression values in seconds, and to manage and to adjust instantly the compression rate in each sector. Efficient controllability and comfort are important matters in the medical treatment, where a patient wears the hosieries for prolonged times.