Cationized pulp fibers （CPF） were prepared by the adsorption of a novel biodegradable cationic ester quaternary ammonium salt （31441） on bleached softwood kraft pulp fibers. The optimized conditions for the CPF pr...Cationized pulp fibers （CPF） were prepared by the adsorption of a novel biodegradable cationic ester quaternary ammonium salt （31441） on bleached softwood kraft pulp fibers. The optimized conditions for the CPF preparation were： 4% of 31441 （based on oven-dry pulp）, 80℃ and 30 rain. The CPF was characterized by FT-IR, SEM and XPS. Experimental results showed that the CPF improved the retention of precipitated calcium carbonate （PCC） filler significantly. With 0.9% CPF （based on oven-dry pulp）, the retention of PCC increased from 57.53% to 72.21%. The physical properties of paper were also slightly improved. The tensile strength and burst strength of the paper with CPF were higher than those with CPAM. CPF addition had no effect on the stock drainage.展开更多
In order to investigate the effect of the relative motion of nano CaCO_(3)reinforced bamboo pulp fiber(BPF)/HDPE composite components on the mechanical performance,a comparative study was performed.BPF was treated by ...In order to investigate the effect of the relative motion of nano CaCO_(3)reinforced bamboo pulp fiber(BPF)/HDPE composite components on the mechanical performance,a comparative study was performed.BPF was treated by nano CaCO_(3)blending(BM)and impregnation modification(IM)technology.The composites were produced using hot press(HPMP),extrusion(EMP)and injection molding process(IMP).The physical morphology of BPF was similar at different manufacturing processes.Compared to the samples manufactured by HPMP,a decrease in the(specific)flexural strength of BPF/HDPE composites and an increase in those of composites treated by nano CaCO_(3)manufactured by EMP and IMP were observed.The injection molded composites exhibited the best values in the(specific)impact strength,(specific)tensile properties.IM had a greater effect on the rheological behavior of the composites than BM,and nano CaCO_(3)treatment most effectively affected the performance of the extrusion molded composites.展开更多
The flow of pulp fiber suspensions with a consistency below 5% through a pump falls into the turbulent region. The 2-phase 3D turbulent flow of the mixture is simulated in the hydraulic components composed by suction ...The flow of pulp fiber suspensions with a consistency below 5% through a pump falls into the turbulent region. The 2-phase 3D turbulent flow of the mixture is simulated in the hydraulic components composed by suction chamber, front board, semi-impeller and volute casing for the first time. The pseudo-fluid model and the k-ε turbulent model are modified. Phase coupled SIMPLE algorithm is applied to make pressure-velocity correction equation. Based on the results of the numerical simulation, the distribution of velocity, pressure and density of liquid and particle phase are compared and analyzed. The flow analysis in the tip between front board and impeller is emphasized, which reflects the advantage of semi-open impeller when it transports 2-phase medium. This calculation result will be helpful for the design of pump impeller and the establishment of design method of centrifugal stock pump.展开更多
The fiber processed from bamboo can be divided into natural bamboo fiber (bamboo fiber) and chemical bamboo fiber (including bamboo pulp fiber and bamboo charcoal fiber). Compared with the antibacterial, antibacterial...The fiber processed from bamboo can be divided into natural bamboo fiber (bamboo fiber) and chemical bamboo fiber (including bamboo pulp fiber and bamboo charcoal fiber). Compared with the antibacterial, antibacterial, deodorizing and anti-ultraviolet properties of bamboo fiber, the natural properties of bamboo fiber are destroyed in the process of processing, and the deodorizing, antibacterial and anti-ultraviolet functions of bamboo fiber are reduced. In recent years, there are more and more reports and researches on bamboo fiber and its fabric. However, the nomenclature of bamboo fiber, bamboo fiber and bamboo pulp fiber is confused in different literatures. Bamboo fiber is called bamboo fiber, and some bamboo fiber is called bamboo fiber. In this paper, the identification and performance test of bamboo pulp fiber and viscose fiber are studied and analyzed for reference.展开更多
The oxidized bamboo pulp fiber yarns were prepared by the HNO3?/H3PO4-NaNO2 oxidation system. The effects of the oxidation concentration and reaction time on the weight loss, the carboxyl content and the breaking stre...The oxidized bamboo pulp fiber yarns were prepared by the HNO3?/H3PO4-NaNO2 oxidation system. The effects of the oxidation concentration and reaction time on the weight loss, the carboxyl content and the breaking strength of the bamboo pulp fiber yarns were studied and the aggregation structure was investigated by Fourier transform infrared, X-ray and scanning electron microscopy. The results revealed an increase in carboxyl content and a decrease in breaking strength of oxidized bamboo pulp fiber yarns with increasing concentration of oxidant and reaction time. The breaking strength of oxidized bamboo fiber yarns was damaged seriously once the reaction time was more than 120 min or the concentration of oxidant was greater than 1.0%. The crystallinity of bamboo pulp fibers increased slightly under low oxidation degree but decreased with higher oxidation degree.展开更多
Native corn starch and hydroxypropyl starch (HPS) based plastic films were prepared using the short pulp fiber as reinforcement and the glycerol as the plasticizer. The results of tensile test showed that the tensile ...Native corn starch and hydroxypropyl starch (HPS) based plastic films were prepared using the short pulp fiber as reinforcement and the glycerol as the plasticizer. The results of tensile test showed that the tensile strength and the elongation at break increased with the pulp contents. With the glycerol contents, the elongation at break increased considerably, but the tensile strength decreased. The water uptake of the films decreased with the pulp contents and hydroxypropylation, but increased with the glycerol contents. So it is concluded that the films was reinforced by pulp fiber and hydroxypropylation.展开更多
The food packaging industry generally uses papers and paperboards (PPBs) especially for disposable products. According to the Framework Regulation (EC) No. 1935/2004 of the European Union, no transfer of contamination...The food packaging industry generally uses papers and paperboards (PPBs) especially for disposable products. According to the Framework Regulation (EC) No. 1935/2004 of the European Union, no transfer of contamination should occur from food packaging material to the food items. The aim of this study was to determine the presence, numbers, source and different kinds of bacteria present in food packaging PPBs with various contents of pulp fiber. The samples were randomly collected from popular confectioners and fast food restaurants in Saharanpur, India. The results indicated the presence of bacteria in all the samples, ranging from 1.3 × 102 to 6.1 × 103 cfu/g. Most of the samples contained bacteria in more than the permitted concentration of 2.5 × 102 cfu/g as set by Food and Drug Administration (FDA). The detected bacteria were from genera Bacillacea, Staphylococcus and Pseudomonas. According to the FDA declaration, pathogenic bacteria such as B. cereus and S. aureus have been associated with food borne diseases (FBD). Some contaminants in food packaging PPBs were found to be B. subtilis and P. aeroginosa, which produce enzymes like peroxidases and lipoxygenases that are odor generating enzymes.展开更多
Solar evaporation has emerged as an attractive technology to produce freshwater by utilizing renewable solar energy.However,it remains a huge challenge to develop efficient solar steam generators with good flexibility...Solar evaporation has emerged as an attractive technology to produce freshwater by utilizing renewable solar energy.However,it remains a huge challenge to develop efficient solar steam generators with good flexibility,low cost and remarkable salt resistance.Herein,we prepare flexible,robust solar membranes by filtration of porous carbon and commercial paper pulp fiber.The porous carbon with well-defined structures is prepared through controlled carbonization of biomass/waste plastics by eutectic salts.We prove the synergistic effect of porous carbon and paper pulp fiber in boosting solar evaporation performance.Firstly,the porous carbon displays a high light absorption,while the paper pulp fiber with good hydrophilicity effectively promotes the transport of water.Secondly,the combination between porous carbon and paper pulp fiber reduces the water vaporization enthalpy by 20%,which is important to significantly improve the evaporation performance.As a proof of concept,the porous carbon/paper pulp fiber membrane possesses a high evaporation rate of 1.8 kg m^(-2)h^(-1)under 1 kW m^(-2)irradiation.Thirdly,the good flexibility and mechanical property of paper pulp fiber enable the solar membrane to work well under extreme conditions(e.g.,after 20 cycles of folding/stretching/recovery).Lastly,due to the super-hydrophilicity and superwetting,the hybrid membrane exhibits the exceptional salt resistance and long-term stability in continuous seawater desalination,e.g.,for 50 h.Importantly,a large-scale solar desalination device for outdoor experiments is developed to produce freshwater.Consequently,this work provides a new insight into developing advanced flexible solar evaporators with superb performance in seawater desalination.展开更多
Basalt Fiber Reinforced Polymer(BFRP)composites have huge potential application respects for some civil fields due to enough strength/modulus to weight and low cost by replacing carbon fiber composites.Aiming at the i...Basalt Fiber Reinforced Polymer(BFRP)composites have huge potential application respects for some civil fields due to enough strength/modulus to weight and low cost by replacing carbon fiber composites.Aiming at the issues in the Resin-Rich Region(RRR)and Interfacial Transition Region(ITR)of fiber reinforced polymer composites,the characteristic Aramid Pulp(AP)fibers with micro-fiber trunk and nano-fiber branches were manufactured into multiple non-woven ultra-thin interleaving at the interlayers of BFRP composites via compression molding to reinforce the flexural strengths and elastic moduli.AP fibers were introduced into RRR to form interleaving at the interlayer,the brittle epoxy adhesive layer was improved and enabled to avoid cracking under a low external load.Free fiber branches of AP were also embedded into BF layer to construct quasi-vertical fiber bridging behaviors in ITR,stronger mechanical interlocking was created to prevent crack propagation along the bonding interface of BF/epoxy.Three-point bending testing results showed the interleaving film with 4 g/m^(2)AP exhibited the best effect among various areal densities and yielded average 315.75 MPa in flexural strength and 21.38 GPa in elastic modulus,having a 63.4%increment and a 47.1%increment respectively compared with the bases.Overall,the simple and low-cost AP interleaving is confirmed as an effective method in improving interlayer structure and flexural performance of BFRP composites,which may be considered to manufacture high-performance laminated fiber reinforced polymer composites in civil aviation industry.展开更多
The fiber morphology and pulping properties of triploid of populus tomentosa from plantation at different ages were investigated in the paper,also the main chemical compositions were determined. The results showed tha...The fiber morphology and pulping properties of triploid of populus tomentosa from plantation at different ages were investigated in the paper,also the main chemical compositions were determined. The results showed that the difference of chemical compositions is not significant, and the extractive contents become bigger in some sort with age, the difference of length weighted mean length of fiber also is not significant, and coarseness of fiber has trend of augment by degree, while the fines content increases obviously with age. That difference of pulping properties between chemical pulping (KP process and Soda-AQ process) and chemimechanical pulping (SCMP process and APMP process) is not significant, which is consistent with the analysis of chemical composition and fiber morphology. Considering comprehensively, the tree age of 5 years is better for paper making industry, also the mixed pulping with different ages of the triploid of populus tomentosa is feasible with steady pulp quality.展开更多
A bentonite & PAM particle flocculation system was employed in recycled fiber pulp wastewater treatment in this paper. The optimum conditions of the adsorption & coagulation treatment was explored and optimize...A bentonite & PAM particle flocculation system was employed in recycled fiber pulp wastewater treatment in this paper. The optimum conditions of the adsorption & coagulation treatment was explored and optimized and effects of the treatment were focused on, especially stickies substances removal. Under the optimal conditions, the removal of MTBE extract and cationic demand reached 91.26% and 86.93%, and the average particle size in the treated wastewater pollutants is reduced from 40.95μm to 0.5μm. In this treatment the removal of CODcr, turbidity, SS and color were 89.67%, 99.56%, 95.58% and 93.08%, respectively. The results showed that the particle flocculation system was effective for the treatment of recycled fiber pulp wastewater, especially for controlling the stickies.展开更多
The refining performances of mixed poplar and eucalyptwoodchips(mixture ratio 6:4)were investigated at medium and highpulp consistency via chemi-mechanical pulping(CMP).The specificrefining energy consumption(SEC),fib...The refining performances of mixed poplar and eucalyptwoodchips(mixture ratio 6:4)were investigated at medium and highpulp consistency via chemi-mechanical pulping(CMP).The specificrefining energy consumption(SEC),fiber fraction proportion,andCanadian standard freeness(CSF)were determined to evaluate the effectsof pulp consistency and NaOH dosage on the refining performancesof mixed poplar and eucalypt woodchips.While the dosage of NaOHfor impregnation was maintained constant,the SEC and shive contentincreased with increasing pulp consistency.Different fractions obtainedfrom the Bauer-McNett classifier showed that higher pulp consistencycould be expected to yield more long fibers and shive in the stock.Upon increasing the NaOH dosage,the shive content and SEC reducedsignificantly.When the NaOH dosage was increased to 6%,the resultsindicated that it was difficult to reduce the shive content to less than 1%athigh pulp consistencies(25%~35%),whereas 0.18%shive fraction couldbe achieved at a medium pulp consistency(15%).展开更多
The paper deals with the fluid field of web forming in wet-laid non-woven production.The influence of the turbulent flow on blending fiber and occluded fluid produced in pulp flow has been discussed in theory and prac...The paper deals with the fluid field of web forming in wet-laid non-woven production.The influence of the turbulent flow on blending fiber and occluded fluid produced in pulp flow has been discussed in theory and practice.The suitable use of the imported velocity of pulp is very important in producing wet-laid products of good quality.展开更多
基金the Key Scientific and Technological Project of Heilongjiang Province (GB06B501-1)
文摘Cationized pulp fibers （CPF） were prepared by the adsorption of a novel biodegradable cationic ester quaternary ammonium salt （31441） on bleached softwood kraft pulp fibers. The optimized conditions for the CPF preparation were： 4% of 31441 （based on oven-dry pulp）, 80℃ and 30 rain. The CPF was characterized by FT-IR, SEM and XPS. Experimental results showed that the CPF improved the retention of precipitated calcium carbonate （PCC） filler significantly. With 0.9% CPF （based on oven-dry pulp）, the retention of PCC increased from 57.53% to 72.21%. The physical properties of paper were also slightly improved. The tensile strength and burst strength of the paper with CPF were higher than those with CPAM. CPF addition had no effect on the stock drainage.
基金This study is financially supported by the Basic Research Operating Expenses Program of International Centre for Bamboo and Rattan(1632021002).
文摘In order to investigate the effect of the relative motion of nano CaCO_(3)reinforced bamboo pulp fiber(BPF)/HDPE composite components on the mechanical performance,a comparative study was performed.BPF was treated by nano CaCO_(3)blending(BM)and impregnation modification(IM)technology.The composites were produced using hot press(HPMP),extrusion(EMP)and injection molding process(IMP).The physical morphology of BPF was similar at different manufacturing processes.Compared to the samples manufactured by HPMP,a decrease in the(specific)flexural strength of BPF/HDPE composites and an increase in those of composites treated by nano CaCO_(3)manufactured by EMP and IMP were observed.The injection molded composites exhibited the best values in the(specific)impact strength,(specific)tensile properties.IM had a greater effect on the rheological behavior of the composites than BM,and nano CaCO_(3)treatment most effectively affected the performance of the extrusion molded composites.
基金This project is supported by Provincial Natural Science Foundation of Education Department of Jiangsu(No.02kjd470001).
文摘The flow of pulp fiber suspensions with a consistency below 5% through a pump falls into the turbulent region. The 2-phase 3D turbulent flow of the mixture is simulated in the hydraulic components composed by suction chamber, front board, semi-impeller and volute casing for the first time. The pseudo-fluid model and the k-ε turbulent model are modified. Phase coupled SIMPLE algorithm is applied to make pressure-velocity correction equation. Based on the results of the numerical simulation, the distribution of velocity, pressure and density of liquid and particle phase are compared and analyzed. The flow analysis in the tip between front board and impeller is emphasized, which reflects the advantage of semi-open impeller when it transports 2-phase medium. This calculation result will be helpful for the design of pump impeller and the establishment of design method of centrifugal stock pump.
文摘The fiber processed from bamboo can be divided into natural bamboo fiber (bamboo fiber) and chemical bamboo fiber (including bamboo pulp fiber and bamboo charcoal fiber). Compared with the antibacterial, antibacterial, deodorizing and anti-ultraviolet properties of bamboo fiber, the natural properties of bamboo fiber are destroyed in the process of processing, and the deodorizing, antibacterial and anti-ultraviolet functions of bamboo fiber are reduced. In recent years, there are more and more reports and researches on bamboo fiber and its fabric. However, the nomenclature of bamboo fiber, bamboo fiber and bamboo pulp fiber is confused in different literatures. Bamboo fiber is called bamboo fiber, and some bamboo fiber is called bamboo fiber. In this paper, the identification and performance test of bamboo pulp fiber and viscose fiber are studied and analyzed for reference.
文摘The oxidized bamboo pulp fiber yarns were prepared by the HNO3?/H3PO4-NaNO2 oxidation system. The effects of the oxidation concentration and reaction time on the weight loss, the carboxyl content and the breaking strength of the bamboo pulp fiber yarns were studied and the aggregation structure was investigated by Fourier transform infrared, X-ray and scanning electron microscopy. The results revealed an increase in carboxyl content and a decrease in breaking strength of oxidized bamboo pulp fiber yarns with increasing concentration of oxidant and reaction time. The breaking strength of oxidized bamboo fiber yarns was damaged seriously once the reaction time was more than 120 min or the concentration of oxidant was greater than 1.0%. The crystallinity of bamboo pulp fibers increased slightly under low oxidation degree but decreased with higher oxidation degree.
文摘Native corn starch and hydroxypropyl starch (HPS) based plastic films were prepared using the short pulp fiber as reinforcement and the glycerol as the plasticizer. The results of tensile test showed that the tensile strength and the elongation at break increased with the pulp contents. With the glycerol contents, the elongation at break increased considerably, but the tensile strength decreased. The water uptake of the films decreased with the pulp contents and hydroxypropylation, but increased with the glycerol contents. So it is concluded that the films was reinforced by pulp fiber and hydroxypropylation.
文摘The food packaging industry generally uses papers and paperboards (PPBs) especially for disposable products. According to the Framework Regulation (EC) No. 1935/2004 of the European Union, no transfer of contamination should occur from food packaging material to the food items. The aim of this study was to determine the presence, numbers, source and different kinds of bacteria present in food packaging PPBs with various contents of pulp fiber. The samples were randomly collected from popular confectioners and fast food restaurants in Saharanpur, India. The results indicated the presence of bacteria in all the samples, ranging from 1.3 × 102 to 6.1 × 103 cfu/g. Most of the samples contained bacteria in more than the permitted concentration of 2.5 × 102 cfu/g as set by Food and Drug Administration (FDA). The detected bacteria were from genera Bacillacea, Staphylococcus and Pseudomonas. According to the FDA declaration, pathogenic bacteria such as B. cereus and S. aureus have been associated with food borne diseases (FBD). Some contaminants in food packaging PPBs were found to be B. subtilis and P. aeroginosa, which produce enzymes like peroxidases and lipoxygenases that are odor generating enzymes.
基金financially supported by the National Natural Science Foundation of China(51903099 and 51991353)Huazhong University of Science and Technology(3004013134 and 2021XXJS036)+1 种基金the 100 Talents Program of the Hubei Provincial Governmentthe Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003).
文摘Solar evaporation has emerged as an attractive technology to produce freshwater by utilizing renewable solar energy.However,it remains a huge challenge to develop efficient solar steam generators with good flexibility,low cost and remarkable salt resistance.Herein,we prepare flexible,robust solar membranes by filtration of porous carbon and commercial paper pulp fiber.The porous carbon with well-defined structures is prepared through controlled carbonization of biomass/waste plastics by eutectic salts.We prove the synergistic effect of porous carbon and paper pulp fiber in boosting solar evaporation performance.Firstly,the porous carbon displays a high light absorption,while the paper pulp fiber with good hydrophilicity effectively promotes the transport of water.Secondly,the combination between porous carbon and paper pulp fiber reduces the water vaporization enthalpy by 20%,which is important to significantly improve the evaporation performance.As a proof of concept,the porous carbon/paper pulp fiber membrane possesses a high evaporation rate of 1.8 kg m^(-2)h^(-1)under 1 kW m^(-2)irradiation.Thirdly,the good flexibility and mechanical property of paper pulp fiber enable the solar membrane to work well under extreme conditions(e.g.,after 20 cycles of folding/stretching/recovery).Lastly,due to the super-hydrophilicity and superwetting,the hybrid membrane exhibits the exceptional salt resistance and long-term stability in continuous seawater desalination,e.g.,for 50 h.Importantly,a large-scale solar desalination device for outdoor experiments is developed to produce freshwater.Consequently,this work provides a new insight into developing advanced flexible solar evaporators with superb performance in seawater desalination.
基金supported financially by the National Natural Science Foundations of China(No.52102115)the Overseas High-End Talent Introduction Project of Sichuan Province,China(No.2023JDGD0013)the Natural Science Foundations of Sichuan Province,China(No.2023NSFSC0961)。
文摘Basalt Fiber Reinforced Polymer(BFRP)composites have huge potential application respects for some civil fields due to enough strength/modulus to weight and low cost by replacing carbon fiber composites.Aiming at the issues in the Resin-Rich Region(RRR)and Interfacial Transition Region(ITR)of fiber reinforced polymer composites,the characteristic Aramid Pulp(AP)fibers with micro-fiber trunk and nano-fiber branches were manufactured into multiple non-woven ultra-thin interleaving at the interlayers of BFRP composites via compression molding to reinforce the flexural strengths and elastic moduli.AP fibers were introduced into RRR to form interleaving at the interlayer,the brittle epoxy adhesive layer was improved and enabled to avoid cracking under a low external load.Free fiber branches of AP were also embedded into BF layer to construct quasi-vertical fiber bridging behaviors in ITR,stronger mechanical interlocking was created to prevent crack propagation along the bonding interface of BF/epoxy.Three-point bending testing results showed the interleaving film with 4 g/m^(2)AP exhibited the best effect among various areal densities and yielded average 315.75 MPa in flexural strength and 21.38 GPa in elastic modulus,having a 63.4%increment and a 47.1%increment respectively compared with the bases.Overall,the simple and low-cost AP interleaving is confirmed as an effective method in improving interlayer structure and flexural performance of BFRP composites,which may be considered to manufacture high-performance laminated fiber reinforced polymer composites in civil aviation industry.
文摘The fiber morphology and pulping properties of triploid of populus tomentosa from plantation at different ages were investigated in the paper,also the main chemical compositions were determined. The results showed that the difference of chemical compositions is not significant, and the extractive contents become bigger in some sort with age, the difference of length weighted mean length of fiber also is not significant, and coarseness of fiber has trend of augment by degree, while the fines content increases obviously with age. That difference of pulping properties between chemical pulping (KP process and Soda-AQ process) and chemimechanical pulping (SCMP process and APMP process) is not significant, which is consistent with the analysis of chemical composition and fiber morphology. Considering comprehensively, the tree age of 5 years is better for paper making industry, also the mixed pulping with different ages of the triploid of populus tomentosa is feasible with steady pulp quality.
文摘A bentonite & PAM particle flocculation system was employed in recycled fiber pulp wastewater treatment in this paper. The optimum conditions of the adsorption & coagulation treatment was explored and optimized and effects of the treatment were focused on, especially stickies substances removal. Under the optimal conditions, the removal of MTBE extract and cationic demand reached 91.26% and 86.93%, and the average particle size in the treated wastewater pollutants is reduced from 40.95μm to 0.5μm. In this treatment the removal of CODcr, turbidity, SS and color were 89.67%, 99.56%, 95.58% and 93.08%, respectively. The results showed that the particle flocculation system was effective for the treatment of recycled fiber pulp wastewater, especially for controlling the stickies.
文摘The refining performances of mixed poplar and eucalyptwoodchips(mixture ratio 6:4)were investigated at medium and highpulp consistency via chemi-mechanical pulping(CMP).The specificrefining energy consumption(SEC),fiber fraction proportion,andCanadian standard freeness(CSF)were determined to evaluate the effectsof pulp consistency and NaOH dosage on the refining performancesof mixed poplar and eucalypt woodchips.While the dosage of NaOHfor impregnation was maintained constant,the SEC and shive contentincreased with increasing pulp consistency.Different fractions obtainedfrom the Bauer-McNett classifier showed that higher pulp consistencycould be expected to yield more long fibers and shive in the stock.Upon increasing the NaOH dosage,the shive content and SEC reducedsignificantly.When the NaOH dosage was increased to 6%,the resultsindicated that it was difficult to reduce the shive content to less than 1%athigh pulp consistencies(25%~35%),whereas 0.18%shive fraction couldbe achieved at a medium pulp consistency(15%).
文摘The paper deals with the fluid field of web forming in wet-laid non-woven production.The influence of the turbulent flow on blending fiber and occluded fluid produced in pulp flow has been discussed in theory and practice.The suitable use of the imported velocity of pulp is very important in producing wet-laid products of good quality.
