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A new formaldehyde-free wood adhesive from renewable materials

A new formaldehyde-free wood adhesive from renewable materials
Learning Objets
Summary
This study presents the development and evaluation of a formaldehyde-free wood adhesive composed of soy flour (SF) and a novel curing agent (CA) synthesized from epichlorohydrin (ECH) and ammonium hydroxide. The adhesive was tested on various plywood configurations (seven-ply, five-ply yellow poplar, and five-ply aspen) and assessed for water resistance using standardized soak and boil tests. The research explores the effects of reaction temperature, NaOH addition, curing agent preparation methods, and storage stability on adhesive performance. Results show that adhesives prepared at 45–60 °C with simultaneous mixing of ECH and ammonium hydroxide yield strong, water-resistant bonds suitable for interior plywood applications. The curing agent, potentially derived from renewable glycerol, offers a sustainable alternative to petrochemical-based resins, aligning with the principles of Green Chemistry.

This Learning Object is ideal for university students studying Green Chemistry, polymer science, and sustainable materials engineering, as it demonstrates the design and testing of bio-based adhesives that reduce environmental and health risks associated with formaldehyde.

Authors/Contributors:
Yonghwan Jang, Jian Huang, Kaichang Li
Department of Wood Science and Engineering, Oregon State University, Corvallis, OR, USA

Citation:
Jang, Y., Huang, J., & Li, K. (2011). A new formaldehyde-free wood adhesive from renewable materials. International Journal of Adhesion & Adhesives, 31(7), 754–759. https://doi.org/10.1016/j.ijadhadh.2011.07.003
Keyword Tags
Soy Chemistry
Materials Science
Organic Chemistry
Polymer Chemistry
Adhesives
Renewable Feedstocks
Biopolymers
Link to external
Link to journal article
Learning Goals/Student Objectives
Learning Goals
1. Understand the chemical principles behind the synthesis and function of bio-based adhesives.
2. Explore the environmental and health impacts of formaldehyde-based adhesives and the benefits of renewable alternatives.
3. Analyze experimental design and performance testing of adhesives in real-world applications.
4. Apply Green Chemistry principles to the development of safer, more sustainable industrial materials.
5. Evaluate the scalability and commercial viability of renewable chemical technologies.

Student Objectives
By the end of this module, students will be able to:
1. Describe the synthesis of curing agents from epichlorohydrin and ammonium hydroxide and their role in crosslinking soy protein.
2. Explain how molecular structure (e.g., azetidinium and chlorohydrin groups) affects adhesive performance.
3. Interpret water resistance and shear strength data to assess the effectiveness of different adhesive formulations.
4. Compare the environmental and health risks of formaldehyde-based adhesives with bio-based alternatives.
5. Design an experiment to test alternative curing agents or reaction conditions using Green Chemistry principles.
6. Discuss the implications of reaction conditions (temperature, mixing order, NaOH addition) on product performance and sustainability.
Object Type
Laboratory experiment
Case studies
Journal articles
Audience
Upper/Advanced Undergraduate
Common pedagogies covered
Blended learning
Context-based learning
Green Chemistry Principles
Waste Prevention
Less Hazardous Chemical Syntheses
Use of Renewable Feedstocks
Design for Degradation
Safer Chemistry for Accident Prevention
U.N. Sustainable Development Goals (SDGs)
Good Health and Well-Being
Industry, Innovation and Infrastructure
Responsible Consumption and Production
Climate Action
Life on Land
Safety Precautions, Hazards, and Risk Assessment
Chemical Hazards
1. Epichlorohydrin (ECH): Flammable, toxic, and potentially carcinogenic. Causes skin, eye, and respiratory irritation. Must be handled in a fume hood with gloves, goggles, and a respirator.
2. Ammonium Hydroxide: Corrosive; causes burns and respiratory irritation. Use in a fume hood with gloves and eye protection.
3. Sodium Hydroxide (NaOH): Strong base; causes severe skin and eye burns. Handle with gloves, goggles, and lab coat.

Physical Hazards
Hot-Pressing Equipment: Operates at high temperatures (up to 120 °C) and pressure (1.03 MPa). Risk of burns and crush injuries. Use heat-resistant gloves and follow all safety protocols.

Environmental Hazards
Chemical Waste: Residual ECH and curing agents must be disposed of as hazardous waste. Avoid release into drains or the environment.

Safety Precautions:
Always wear PPE: lab coat, gloves, safety goggles, and heat-resistant gloves.
Conduct all chemical reactions in a fume hood with proper ventilation.
Use cooling systems during exothermic reactions to prevent thermal runaway.
Keep spill kits and first aid supplies readily available.
Ensure proper labeling and storage of all chemicals.

Risk Assessment:
Identify all hazardous chemicals and equipment.
Evaluate exposure routes: inhalation, skin contact, ingestion, thermal injury.
Implement engineering controls: fume hoods, cooling coils, and safety interlocks.
Train personnel on emergency procedures, including chemical spill response and burn treatment.
Maintain Safety Data Sheets (SDS) for all reagents and review them before use.
NGSS Standards, if applicable
Disciplinary Core Ideas (DCIs)
HS-PS1-3: Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of interactions between particles.
The study investigates how soy protein and curing agents interact chemically to form strong adhesive bonds in plywood, with measurable performance outcomes.

HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.
Students can explore how molecular features like azetidinium and chlorohydrin groups contribute to crosslinking and adhesive strength.

HS-ETS1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs.
The research addresses the challenge of replacing formaldehyde-based adhesives with safer, renewable alternatives, balancing performance, cost, and environmental impact.

Science and Engineering Practices (SEPs)
1. Planning and Carrying Out Investigations
The study systematically varies reaction conditions, curing agent formulations, and plywood configurations to evaluate adhesive performance.

2. Analyzing and Interpreting Data
Students can analyze water resistance and shear strength data to assess the effectiveness of different adhesive formulations.

3. Constructing Explanations and Designing Solutions
The research provides a model for designing sustainable adhesives and evaluating their industrial viability.

4. Engaging in Argument from Evidence
Students can use experimental results to argue for or against the use of soy-based adhesives in commercial applications.

Crosscutting Concepts
1. Structure and Function
The relationship between the chemical structure of curing agents and their performance in bonding wood is central to the study.
2. Cause and Effect
Changes in formulation and processing conditions lead to measurable differences in plywood strength and water resistance.

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Submitted by

Kris Weigal
Published on
Moderation state
Published
Collection
Soy Chemistry Literature