Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particle...Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particles of fine(0.2 to 1.0 mm),medium(1.0 to 2.5 mm),and coarse(2.5 to 12.0 mm)sizes,derived from the bark of Leucaena leucocephala,were hot-pressed using a heating plate at 175℃for 7 min to create single-layer particleboards measuring 320 mm×320 mm×10 mm,targeting a density of 700 kg/m^(3).Subsequently,the samples were trimmed and conditioned at 20℃and 65%relative humidity.In this study,we compared bark particleboard bonded with urea formaldehyde(UF)adhesive to fine-sized particleboard bonded with demethylated lignin adhesive.The results indicated that bark particleboards utilizing demethylated lignin and UF adhesives exhibited similar qualities.Coarse particleboard showed differences in modulus of elasticity(MOE)and modulus of rupture(MOR),while medium-sized particles exhibited significant variations in moisture content(MC)and water absorption(WA).Furthermore,the thickness swelling of coarse and medium-sized particles under wet and oven-dried conditions exhibited notable distinctions.Overall,the demethylated lignin adhesive extracted from L.leucocephala bark demonstrated similar quality to UF adhesive,with particle size correlating inversely to the strength of the bark particleboard.展开更多
Lignin,lignosulfonate,and synthesized phosphorylated lignosulfonate were introduced as greenfillers in citric acid-sucrose adhesives for bonding particleboard fabricated from areca leaf sheath(ALS).The characteristics ...Lignin,lignosulfonate,and synthesized phosphorylated lignosulfonate were introduced as greenfillers in citric acid-sucrose adhesives for bonding particleboard fabricated from areca leaf sheath(ALS).The characteristics of particleboards were compared to that of ultralow emitting formaldehyde(ULEF-UF).Thefillers derived from Eucalyptus spp.kraft-lignin were added forflame retardancy enhancement.10%of each lignin and modified lig-nin was added into the ULEF-UF and citric acid-sucrose bonded particleboards.Analyses applied to particle-boards included thermal characteristics,X-ray diffraction analysis(XRD),morphological properties,Fourier transform infrared spectroscopy(FTIR),as well as physical,mechanical,andfire resistance characteristics of the laboratory-fabricated particleboards.Lignin and modified lignin resulted in improved thermal stability of the composites bonded with ULEF-UF while the improvement in the particleboard bonded with citric acid-sucrose was not significant.The introduction offiller exerted a higher influence on the UF-bonded particleboards compared to composites fabricated with citric acid-sucrose.Generally,the presence of lignin,lignosulfonate,and phosphorylated lignosulfonate enhanced the mechanical strength of the ULEF-bonded particleboards,although their dimensional stability has deteriorated.Markedly,the use of lignin and lignosulfonate enhanced thefire resis-tance of the particleboards produced with lower observed weight loss.All laboratory particleboards exhibited satisfactoryfire resistance,attaining a V-0 rating in according to the UL-94 standard.展开更多
The poor bonding performance between aqueous adhesives represented by melamine-urea formaldehyde(MUF)resins and reed straw hinders their applications in the field of non-wood-based panels.Multi-hydroxyl polymers are h...The poor bonding performance between aqueous adhesives represented by melamine-urea formaldehyde(MUF)resins and reed straw hinders their applications in the field of non-wood-based panels.Multi-hydroxyl polymers are highly reactive and are often used as crosslinkers.This study fabricated a resin with a strengthened crosslinked structure by combining a multi-hydroxyl polymer and MUF resin prepolymer.The reed particleboard was prepared by using this resin as an adhesive and reed stalk as the matrix.The results show that neighboring molecules combined to form C–O–C bonds that strengthened the cross-linked structure of the resin.In addition,the viscosity of the resin was increased,and a continuous adhesive layer on the surface of reed particles was formed,which slowed the penetration of reed particles.The adhesive layer significantly improved the mechanical properties of the reed particleboard.The maximum modulus of rupture(MOR),modulus of elasticity(MOE),and internal bonding strength(IB)of the reed particleboard were 33.53,4126,and 0.79 MPa,respectively.The IB of the board was 3.3 times higher than that of the reed particleboard prepared with a conventional MUF resin.Reed straw is a non-wood biomass material that has the advantage of sustainable development and may replace woodbased materials to produce particleboard.This resin-prepared reed particleboard is expected to be used in areas such as custom furniture and engineering materials.展开更多
Aminated tannins were prepared by reacting mimosa condensed tannin extract with ammonia yielding the substitution of many,if not all of the tannin hydroxyl groups with–NH_(2)groups.A tannin-aminated tannin(ATT)partic...Aminated tannins were prepared by reacting mimosa condensed tannin extract with ammonia yielding the substitution of many,if not all of the tannin hydroxyl groups with–NH_(2)groups.A tannin-aminated tannin(ATT)particleboard coating was then prepared by reacting raw tannin extract with aminated tannin extract and thus cross-linking the two by substituting tannin’s hydroxyl groups with the–NH_(2)groups on the aminated tannin to form–NH-bridges between the two.The resulting particleboard coating gave encouraging results when pressed at 180℃for 3 min.Conversely,the system in which tannin was reacted/cross-liked with urea(ATU)by a similar amination reaction did not perform as well as the ATT system,and this even when a higher curing temperature and longer hot press time were used.In particular its water repellence was worse probably due to the presence of urea and such a system with lower reactivity.Nonetheless,substituting the tannin–OHs with the urea–NH_(2)groups appeared to also take place.ATT gave better results than ATU as regards water repellence and mechanical resistance as shown by the cross cut test.The ATT system was shown to be between 95%and 98%biosourced.The difference appeared to be due,by TMA analysis,to the much faster formation of the ATT hardened network leading to a better cross-linked polymer coating.The chemical species formed for both the ATT and ATU system were studied by MALDI ToF and CP MAS^(13)C NMR.展开更多
基金the financial support provided by UMS Great(GUG0217-1/2018),which played a crucial role in the completion of this study.
文摘Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particles of fine(0.2 to 1.0 mm),medium(1.0 to 2.5 mm),and coarse(2.5 to 12.0 mm)sizes,derived from the bark of Leucaena leucocephala,were hot-pressed using a heating plate at 175℃for 7 min to create single-layer particleboards measuring 320 mm×320 mm×10 mm,targeting a density of 700 kg/m^(3).Subsequently,the samples were trimmed and conditioned at 20℃and 65%relative humidity.In this study,we compared bark particleboard bonded with urea formaldehyde(UF)adhesive to fine-sized particleboard bonded with demethylated lignin adhesive.The results indicated that bark particleboards utilizing demethylated lignin and UF adhesives exhibited similar qualities.Coarse particleboard showed differences in modulus of elasticity(MOE)and modulus of rupture(MOR),while medium-sized particles exhibited significant variations in moisture content(MC)and water absorption(WA).Furthermore,the thickness swelling of coarse and medium-sized particles under wet and oven-dried conditions exhibited notable distinctions.Overall,the demethylated lignin adhesive extracted from L.leucocephala bark demonstrated similar quality to UF adhesive,with particle size correlating inversely to the strength of the bark particleboard.
基金funded by the Equity Project Universitas Sumatera Utara(Number:10/UN5.2.3.1/PPM/KPEP/2023),which is entitled Pengembangan Papan Partikel Tahan Api Rendah Emisi Berbahan Limbah Tanaman Mangrove dan Limbah Tanaman Pertanian Melalui Penambahan Lignin Terfosforilasi Sebagai Filler.PT Greenei Alam Indonesia(PT GAI)contributed to providing the areca leaf sheath through the implementation of a collaboration agreement with the Research Center for Biomass and Bioproducts BRIN FY 2023-2025.
文摘Lignin,lignosulfonate,and synthesized phosphorylated lignosulfonate were introduced as greenfillers in citric acid-sucrose adhesives for bonding particleboard fabricated from areca leaf sheath(ALS).The characteristics of particleboards were compared to that of ultralow emitting formaldehyde(ULEF-UF).Thefillers derived from Eucalyptus spp.kraft-lignin were added forflame retardancy enhancement.10%of each lignin and modified lig-nin was added into the ULEF-UF and citric acid-sucrose bonded particleboards.Analyses applied to particle-boards included thermal characteristics,X-ray diffraction analysis(XRD),morphological properties,Fourier transform infrared spectroscopy(FTIR),as well as physical,mechanical,andfire resistance characteristics of the laboratory-fabricated particleboards.Lignin and modified lignin resulted in improved thermal stability of the composites bonded with ULEF-UF while the improvement in the particleboard bonded with citric acid-sucrose was not significant.The introduction offiller exerted a higher influence on the UF-bonded particleboards compared to composites fabricated with citric acid-sucrose.Generally,the presence of lignin,lignosulfonate,and phosphorylated lignosulfonate enhanced the mechanical strength of the ULEF-bonded particleboards,although their dimensional stability has deteriorated.Markedly,the use of lignin and lignosulfonate enhanced thefire resis-tance of the particleboards produced with lower observed weight loss.All laboratory particleboards exhibited satisfactoryfire resistance,attaining a V-0 rating in according to the UL-94 standard.
基金supported by the Hunan Province Science and Technology Major Project[2021NK1050]Strategic Research and Consulting Project of the Chinese Academy of Engineering:Research on Green and Low-Carbon Technology Innovation Strategy of Wood-Based Panel Industry[2022-XY-62]+1 种基金Changsha Science and Technology Project[kq2004096]Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology[2016TP1013].
文摘The poor bonding performance between aqueous adhesives represented by melamine-urea formaldehyde(MUF)resins and reed straw hinders their applications in the field of non-wood-based panels.Multi-hydroxyl polymers are highly reactive and are often used as crosslinkers.This study fabricated a resin with a strengthened crosslinked structure by combining a multi-hydroxyl polymer and MUF resin prepolymer.The reed particleboard was prepared by using this resin as an adhesive and reed stalk as the matrix.The results show that neighboring molecules combined to form C–O–C bonds that strengthened the cross-linked structure of the resin.In addition,the viscosity of the resin was increased,and a continuous adhesive layer on the surface of reed particles was formed,which slowed the penetration of reed particles.The adhesive layer significantly improved the mechanical properties of the reed particleboard.The maximum modulus of rupture(MOR),modulus of elasticity(MOE),and internal bonding strength(IB)of the reed particleboard were 33.53,4126,and 0.79 MPa,respectively.The IB of the board was 3.3 times higher than that of the reed particleboard prepared with a conventional MUF resin.Reed straw is a non-wood biomass material that has the advantage of sustainable development and may replace woodbased materials to produce particleboard.This resin-prepared reed particleboard is expected to be used in areas such as custom furniture and engineering materials.
基金supported by a grant of the French Agence Nationale de la Recherche(ANR)in the Ambit of the Laboratory of Excellence(Labex)ARBRE.This work was also supported by“The 111 Project(D21027)”.
文摘Aminated tannins were prepared by reacting mimosa condensed tannin extract with ammonia yielding the substitution of many,if not all of the tannin hydroxyl groups with–NH_(2)groups.A tannin-aminated tannin(ATT)particleboard coating was then prepared by reacting raw tannin extract with aminated tannin extract and thus cross-linking the two by substituting tannin’s hydroxyl groups with the–NH_(2)groups on the aminated tannin to form–NH-bridges between the two.The resulting particleboard coating gave encouraging results when pressed at 180℃for 3 min.Conversely,the system in which tannin was reacted/cross-liked with urea(ATU)by a similar amination reaction did not perform as well as the ATT system,and this even when a higher curing temperature and longer hot press time were used.In particular its water repellence was worse probably due to the presence of urea and such a system with lower reactivity.Nonetheless,substituting the tannin–OHs with the urea–NH_(2)groups appeared to also take place.ATT gave better results than ATU as regards water repellence and mechanical resistance as shown by the cross cut test.The ATT system was shown to be between 95%and 98%biosourced.The difference appeared to be due,by TMA analysis,to the much faster formation of the ATT hardened network leading to a better cross-linked polymer coating.The chemical species formed for both the ATT and ATU system were studied by MALDI ToF and CP MAS^(13)C NMR.
