scholarly journals Influence of Single/Collective Use of Curing Agents on the Curing Behavior and Bond Strength of Soy Protein-Melamine-Urea-Formaldehyde (SMUF) Resin for Plywood Assembly

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1995 ◽  
Author(s):  
Zhigang Wu ◽  
Bengang Zhang ◽  
Xiaojian Zhou ◽  
Lifen Li ◽  
Liping Yu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Water Resistance ◽  
Protein Hydrolysate ◽  
Soybean Protein ◽  
Urea Formaldehyde ◽  
Curing Temperature ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Curing Agents ◽  
Crosslinking Reactions

Soybean protein hydrolysate, melamine, urea, and concentrated formaldehyde were used to synthesize an environmentally friendly soybean protein-melamine-urea-formaldehyde (SMUF) co-condensation resin. (NH4)2SO4, (NH4)2HPO4, (NH4)2HPO4 + (NH4)2SO4, (NH4)2HPO4 + (NH4)2S2O8, and (NH4)2HPO4 + (NH4)2SO4 + (NH4)2S2O8 were employed as curing agents for SMUF resin. The curing and thermal behaviors of the SMUF resin were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results revealed the following: (1) (NH4)2SO4 alone could not cure the SMUF resin completely; thus, the final shear strength accomplished plywood with the resin was low, and its water resistance was poor, while the adhesive section was loose and porous/brittle after curing. (2) (NH4)2HPO4 could be hydrolyzed to generate H+ and promote SMUF curing, but it could also form polyphosphoric acids, resulting in crosslinking reactions with SMUF in parallel; thereby, the curing properties were improved. (3) When (NH4)2HPO4 + (NH4)2SO4 + (NH4)2S2O8 were engaged collectively as curing agent, the shear strength, water resistance, and heat resistance of SMUF attained were the best possible whereas the curing temperature was decreased and the heat released by curing was elevated substantially, which signifies maximized extent of crosslinking was achieved. Further, the adhesive section exhibited mostly a crosslinking intertexture as demonstrated by means of SEM. Accordingly, this study may serve as a guide for the curing of amino resins, with low-molar ratio of formaldehyde to amine in adhesives, which are applied to plywood production.

scholarly journals Synthesis and thermal properties of some phenolic resins

2019 ◽  
Vol 7 (1) ◽  
pp. 1-15
Author(s):  
Alshawi F M ◽  
Abdul Razzq K ◽  
Hanoosh W S
Keyword(s):  
Phenol Formaldehyde ◽  
Chemical Properties ◽  
Decomposition Temperature ◽  
Industrial Applications ◽  
Stability Study ◽  
Curing Temperature ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Phenolic Resins ◽  
Physical And Chemical

Introduction: Phenolic resins have been in use since the early twentieth century and are considered the first class of synthetic polymers to achieve commercial success, moreover phenolic resins continue to succeed and attract special interest in a large range of industrial applications such as adhesives, paints, and composites; because of their unique physical and chemical properties. Materials and Methods: Prepolymers resol resins (RR, RH, RP, and RC) were synthesized by the reaction of phenolic compounds (resorcinol, hydroquinone, phloroglucinol, and catechol) respectively, with formaldehyde at molar ratio phenol/ formaldehyde 1/1.5, using sodium hydroxide as a catalyst. These resins were characterized by FTIR. The curing reaction of these resins was evaluated using differential scanning calorimetry (DSC), while the thermal stability study was evaluated using thermogravimetric analysis (TGA). Results and Discussion:From the results showing that these prepolymers have different curing temperatures and curing energy, while the TGA study showed that the cured resins have decomposition temperature more than 300 ºC, and char residue at 650 ºC more than 60%. Conclusions: These resol resins have different gel times (8-55) min, and viscosities (435-350) mpa.s. The curing temperature of these resin obtained from DSC curves was (120, 129, 105 and 127 °C), while the thermal behavior of the cured resins obtained from TGA curves showed that these cured resin have two decomposition temperatures and the rate of decomposition in the order of RC < RR< .

Study on Urea-Formaldehyde Resin for Glass Wool Products

2013 ◽  
Vol 774-776 ◽  
pp. 1232-1236
Author(s):  
Nan Zhe Zhang
Keyword(s):  
Polyvinyl Alcohol ◽  
Water Resistance ◽  
Urea Formaldehyde ◽  
Glass Wool ◽  
Orthogonal Test ◽  
Urea Formaldehyde Resin ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
Resin Adhesive ◽  
Uf Resin

In order to prepare urea-formaldehyde (UF) resin adhesive with good performance for glass wool products, we used polyvinyl alcohol (PVA), p-toluenesulfonamide (PTSA) and methanol to modify UF resin, optimized the molar ratio of formaldehyde (F) / urea (U) and reaction components ratio by orthogonal test, reduced the content of free formaldehyde in UF resin, and enhanced the water resistance, flexibility and stability of UF resin.

Preparation of Water-Resistance Plywood with UF Resin Modified by Emulsifiable Polyisocyanate

2010 ◽  
Vol 26-28 ◽  
pp. 1056-1060
Author(s):  
Li Bin Zhu ◽  
Bo Han ◽  
Ji You Gu ◽  
Yan Hua Zhang ◽  
Hai Yan Tan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Water Resistance ◽  
Urea Formaldehyde ◽  
Great Influence ◽  
Physical And Mechanical Properties ◽  
Formaldehyde Emission ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
X Ray ◽  
Uf Resin

The purpose of the study was to manufacture water-resistance plywood with using UF resin modified by emulsifiable polyisocyanate. The emulsifiable polyisocyanate which contains plenty of hydrophilic segments and teminal isocyanate groups were synthesized by reaction between various kinds of polyether polyols and polymeric methane dipthenyl diisocyanate (pMDI). A type of composite adhesive was obtained from the mixture of emulsifiable polyisocyanate and urea formaldehyde resin. The process parameters, such as the molar ratio of –NCO and –OH, mass fraction of emulsifiable polyisocyanate in UF resin and accessory ingredient have a great influence on the composite adhesive. X-ray photoelectron spectroscopy (XPS) had been used to analyze the chemical structure of bonding interface. The results showed that the composite adhesive consisting of UF resin and emulsifiable polyisocyanate content of 7.5% and kaolin content of 1.5% was used in plywood with high physical and mechanical properties, water resistance and low formaldehyde emission.

Study on Curing Behavior of Low Molar Ratio Urea-Formaldehyde Resins with Different Curing Agents

2010 ◽  
Vol 150-151 ◽  
pp. 965-968
Author(s):  
Yao Hui Dong ◽  
Qiang Gao ◽  
Yue Zhang ◽  
Jian Zhang Li
Keyword(s):  
Thermal Analysis ◽  
Bonding Strength ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Molar Ratio ◽  
Curing Agent ◽  
Curing Time ◽  
Curing Behavior ◽  
Uf Resin ◽  
Curing Agents

In order to characterize the curing behavior of low molar ratio urea-formaldehyde (UF) resin, the curing time and thermal analysis in curing reaction of the UF resins and the bonding strength and formaldehyde emission of plywood bonded by five kinds of low molar ratio UF resins with six different curing agents were studied. The results indicated that the UF resins with the molar ratio of formaldehyde to urea more than 1.0 could get reasonable curing time. The heat enthalpy of UF resins significantly increased with the enhancing the acidity of curing agent. The plywood manufactured by the UF resins with 1.1 molar ratio showed much higher bonding strength and lower formaldehyde emission.

scholarly journals Synthesis and characterization of polyurethane and its nanocomposite adhesive derived from biobased isocyanate and polyol

2021 ◽  
Vol 4 (1) ◽  
pp. 33
Author(s):  
Swarnalata Sahoo ◽  
Smita Mohanty ◽  
Sanjay Kumar Nayak
Keyword(s):  
Shear Strength ◽  
Proton Nuclear Magnetic Resonance ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Lap Shear Strength ◽  
Shear Strength Test ◽  
Lap Shear ◽  
Atomic Force ◽  
Organically Modified

In the current research, the vegetable oil based polyurethane nanocomposite (PUNC) adhesive was prepared using transesterified castor oil (CO) based polyol, partially biobased aliphatic isocyanate (PBAI) and organically modified montmorillonite nanoclay (Closite 30B). The transesterified CO was synthesized by reacting CO with ethylene glycol, which was confirmed using proton nuclear magnetic resonance (1HNMR) analysis. Further, the prepared polyurethane (PU) and its nanocomposite adhesive with specific NCO: OH molar ratio 1.3:1 was confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. The increasing of wt% of nanoclay loading level up to 3% into PU matrix increased the lap shear strength of the adhesive systems. Subsequently, the effect of polyurethane nanocomposite adhesives on the bonding strength of wood-to-wood and aluminum-to-aluminum substrate was studied using lap shear strength test. The nanoclay was observed to effectively intercalate into the polymer matrix. Moreover, the phase separation in PU and PUNC adhesive was studied using atomic force microscope (AFM) and differential scanning calorimetry (DSC) analysis.

scholarly journals Ammonium Lignosulfonate Adhesives for Particleboards with pMDI and Furfuryl Alcohol as Crosslinkers

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1633 ◽  
Author(s):  
Venla Hemmilä ◽  
Stergios Adamopoulos ◽  
Reza Hosseinpourpia ◽  
Sheikh Ali Ahmed
Keyword(s):  
Furfuryl Alcohol ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Raw Material ◽  
Curing Temperature ◽  
Modulus Of Rupture ◽  
Scanning Calorimetry ◽  
Material Source ◽  
Sustainable Materials ◽  
Emission Limits

Tightening formaldehyde emission limits and the need for more sustainable materials have boosted research towards alternatives to urea-formaldehyde adhesives for wood-based panels. Lignin residues from biorefineries consist of a growing raw material source but lack reactivity. Two crosslinkers were tested for ammonium lignosulfonate (ALS)—bio-based furfuryl alcohol (FOH) and synthetic polymeric 4,4′-diphenylmethane diisocyanate (pMDI). The addition of mimosa tannin to ALS before crosslinking was also evaluated. The derived ALS adhesives were used for gluing 2-layered veneer samples and particleboards. Differential Scanning Calorimetry showed a reduction of curing temperature and heat for the samples with crosslinkers. Light microscopy showed that the FOH crosslinked samples had thicker bondlines and higher penetration, which occurred mainly through vessels. Tensile shear strength values of 2-layered veneer samples glued with crosslinked ALS adhesives were at the same level as the melamine reinforced urea-formaldehyde (UmF) reference. For particleboards, the FOH crosslinked samples showed a significant decrease in mechanical properties (internal bond (IB), modulus of elasticity (MOE), modulus of rupture (MOR)) and thickness swelling. For pMDI crosslinked samples, these properties increased compared to the UmF. Although the FOH crosslinked ALS samples can be classified as non-added-formaldehyde adhesives, their emissions were higher than what can be expected to be sourced from the particles.

Preparation and Performance of Bio-Adhesive Based on Acorn Starch Graft Glycidyl Methacrylate

2011 ◽  
Vol 121-126 ◽  
pp. 293-296
Author(s):  
Shi Feng Zhang ◽  
Lu Lu Zhou ◽  
Qiang Gao ◽  
Xu Xia Guo ◽  
Li Ou Chen ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Bonding Strength ◽  
Glycidyl Methacrylate ◽  
Water Resistance ◽  
National Standards ◽  
Curing Temperature ◽  
Type Ii ◽  
Scanning Calorimetry ◽  
And Performance

For improving the performance of acorn starch (AS) based bio-adhesive, AS graft glycidyl methacrylate (AS-g-GMA) adhesive was prepared in this paper. The properties of the AS-g-GMA adhesive were studied by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) measurement. The bonding strength of the plywood bonded by AS-g-GMA adhesive was measured according to Chinese National Standards methods to evaluate its water resistant. FTIR results indicated that GMA was grafted on the AS successfully. The bonding strength of the plywood bonded by AS-g-GMA adhesive showed lower curing temperature, better bonding strength, and water resistance comparing with that of control. The water resistant could reach type II grade (63°C water bath 3h) plywood requirement when the glycidyl methacrylate adding amount was 6% based on AS.

Preparation and Characterization of Self-Healing Microcapsules Containing Two-Component

2013 ◽  
Vol 734-737 ◽  
pp. 2176-2180 ◽  
Author(s):  
Xiao Mei Tong ◽  
Chang Fu Li
Keyword(s):  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Particle Surface ◽  
Average Diameter ◽  
Curing Temperature ◽  
Core Material ◽  
Gravimetric Analysis ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Two Component

Two component self-healing microcapsules were prepared by in situ polymerization with poly (melamine-urea-formaldehyde) as wall, epoxy resin and latent curing agent sebacate hydrazide as core. The ratio of two core material and the reaction process were studied. The size and distribution of particle, surface morphology, structure, thermal properties and content of core were measured and characterized by using particle size analyzer（PSA）, optical microscopy (OM), infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA). The results showed that the microcapsules have smooth and compact surfaces, and have spherical profiles. The average diameter of microcapsules is 30μm and core content of microcapsules is 70%. The heat resistance and solvent resistance of microcapsule are better. The curing temperature is 190°Cand the healing efficiency can be improved.

Study on Properties of Modified Low Molar Ratio Urea-Formaldehyde Resins (I)

2010 ◽  
Vol 113-116 ◽  
pp. 2016-2020 ◽  
Author(s):  
Shi Feng Zhang ◽  
Jian Zhang Li ◽  
Ji Zhi Zhang ◽  
Yong Hua Li ◽  
Qiang Gao
Keyword(s):  
Water Resistance ◽  
Ph Value ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
National Standards ◽  
Boiling Water ◽  
Molar Ratio ◽  
Type I ◽  
Formaldehyde Content ◽  
Uf Resin

For improving the performance of urea-formaldehyde (UF) resin, modified low molar ratio UF resins were developed to improve water resistance properties and reduce the formaldehyde emission of its bonded products. The effects of modifier feeding amount on the character of the cured resins were characterized by Fourier transform infrared spectroscopy (FTIR) measurement. The viscosity, pH value, solid content, free formaldehyde content, pot time, and curing time of the UF resins were also tested according to Chinese National Standards methods. The results show that the modified 1.00 molar ratio UF resins show lower free formaldehyde content and higher boiling-water-resistance comparing with unmodified ones. The boiling-water-resistant bonding strength of poplar plywood bonded with modified UF resin at 140 °C hot-press temperature can reach type I grade (100 °C water bath 3h) plywood requirement and the formaldehyde emission can meet the E0 grade plywood need.

scholarly journals Improvement of Water Resistance of Vegetable Proteins by the Use of Synthetic Origin Additives: Trials with Resins and Metal Ions

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 859
Author(s):  
Ilaria Santoni ◽  
Benedetto Pizzo
Keyword(s):  
Shear Strength ◽  
Metal Ions ◽  
Renewable Resources ◽  
Water Resistance ◽  
Curing Temperature ◽  
Insoluble Residue ◽  
Maturation Time ◽  
Strength Tests ◽  
Different Types ◽  
Positive Effect

The adhesives industry is increasingly interested in products coming from natural and renewable resources. The aim of the present work was to improve the water resistance of soy-based proteins by using synthetic and formaldehyde-free additives. These include polyamide-amine epichlorohydrin (PAE), different types of isocyanates, and combinations of these cross-linkers between them and with other agents, including metal ions. In addition, the effect of both curing temperature and maturation time was assessed. Performances were evaluated by means of shear strength tests, solubility tests, and spectroscopic analysis. The obtained results showed that while isocyanates reacted completely but with water instead of proteins, tests with PAE were generally successful. In fact, the insoluble residue as well as the shear strength in wet conditions dramatically increased after PAE addition. Moreover, the wet performances of protein/PAE formulations appreciably increased gluing at 60 °C instead of room temperature. Furthermore, the maturation time had a positive effect on the formulations where metal ions were added, both for solubility and wet shear strength. Actually, for the very long conditioning time of 3 months, a significant and substantial increase of wet shear strength was observed for the series protein/PAE/aluminum.

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