Investigation of Particleboard Production from Durian Husk and Bamboo Waste

Abstract

Agricultural residues offer promising opportunities for the development of biocomposites. Durian husk, a lignocellulosic by-product abundantly available in Southeast Asia, and bamboo waste, an underutilized biomass resource, present considerable potential for sustainable particleboard production. This study focuses on developing single-layer bio-based particleboards using varying proportions of durian husk and bamboo waste bonded with urea formaldehyde resin. The fabricated boards were evaluated for thickness swelling, modulus of rupture, and internal bond strength according to relevant European standards. Results indicated that all particleboards met the Type P1 requirements for general-purpose use under dry conditions, as specified in BS EN 312:2010. The findings demonstrate the feasibility of converting agricultural waste into value-added, eco-friendly materials, supporting waste valorization, promoting circular economy practices, and contributing to the development of bio-based materials.

1. Introduction

The development of particleboards using agricultural residues has become a key strategy in advancing sustainable materials, providing a means to reduce reliance on virgin wood while valorizing biomass waste [1]. In response to the growing demand for environmentally responsible alternatives, numerous studies have been conducted, and ongoing research continues to focus on the utilization of lignocellulosic crop by-products as sustainable raw materials for composite manufacturing [2,3,4,5]. Concurrently, heightened attention to environmentally friendly bonding methods has stimulated significant efforts toward the development of binderless boards and bio-based adhesives [6,7].

Bamboo is widely recognized for its rapid growth and high annual regrowth following harvesting, making it a highly renewable and sustainable resource [8,9,10]. Its versatility enables its application across various sectors, including construction, furniture manufacturing, handicrafts, engineered bamboo products, and bamboo-based boards [11]. Processing bamboo into strips results in an average material recovery rate of approximately 34.4% [12], leaving a considerable proportion of bamboo residues. This residual biomass offers potential for sustainable resource utilization through value-added processes such as particleboard manufacturing. Utilizing biomass by-products from the bamboo processing industry further supports environmental sustainability [13].

Durian, regarded as a highly valuable crop and one of the most extensively produced fruits in Southeast Asia, has seen remarkable growth in its global export market over the past twenty years [14]. In 2023, durian production reached approximately 1.85 million tonnes in Indonesia [15], 1.19 million tonnes in Vietnam [16], and significant volumes in Thailand, Malaysia, and the Philippines [17,18,19]. Vietnam, in particular, has emerged as a dominant exporter, with approximately 600,000 tonnes of durians exported in 2023 and total production reaching 1.5 million tonnes in 2024 [20,21]. The global durian market is projected to expand at a compound annual growth rate of 4.04% through 2035, further amplifying the need for effective utilization of durian by-products [22]. Given that the husk accounts for approximately 60% of the fruit’s mass [23], durian processing in key durian-producing countries generated an estimated 2.7 million tonnes of durian husk in just 2023. As a result, durian husk has become an abundant agricultural by-product that contributes significantly to waste generation when improperly managed through landfilling or open burning, as its substantial volume and bulk increasingly strain landfill capacity and contribute to serious environmental pollution [24,25,26,27]. In response to these challenges, there is an urgent need to explore innovative strategies for recycling durian husk as a means to reduce environmental impacts, alleviate pressure on landfill capacity, and support the utilization of agricultural residues.

Given the substantial generation of bamboo waste and durian husk, several studies have demonstrated their feasibility as raw materials for composite manufacturing, including particleboards produced from cocoa pod husk and bamboo waste [28,29], bamboo waste with maltodextrin-based adhesive [30], durian husk [31], and durian husk combined with rubberwood [32], as well as insulator boards fabricated from durian husk fibers [33]. However, despite the growing interest in utilizing agricultural residues for composite applications, research specifically investigating the combined use of durian husk and bamboo waste remains limited. This study addresses this gap by examining the fabrication of particleboards from these two residues and evaluating their physical and mechanical properties, thereby contributing to the advancement of sustainable lignocellulosic composites.

2. Materials and Methods

2.1. Materials

Durian husks were obtained from fruit processing centers in the Mekong Delta, Vietnam, while bamboo waste was collected from a bamboo furniture factory in Binh Duong Province, Vietnam. Both raw materials were processed into chips of relatively uniform sizes within their designated size classifications. The chipping process comprised two sequential steps. First, the materials were coarsely chipped; the resulting chips were then further processed through a chipper equipped with a fine perforated screen to yield finer particles. Following chipping, the durian husk and bamboo chips were dried in a Memmert UN260 (Memmert GmbH, Büchenbach, Germany) oven at 105 °C until their moisture content reached approximately 4–6%. The dried chips were subsequently screened to remove fine dust and classified into two particle size fractions using mesh screens: 0.5–2 mm and 2–4 mm. For each experimental formulation of the bio-based particleboard, the classified particles were proportionally blended according to the designated mixing ratios.

The adhesive used for particleboard production was urea formaldehyde (UF) resin, supplied by an industrial adhesive manufacturer (Better Resin Co., Ltd., Di An City, Binh Duong Province, Vietnam). The UF resin exhibited a solids content of 60%, a viscosity of 0.5 Pa·s at 20 °C, a pH value ranging from 7.5 to 8.5, and a gel time of 40–60 s at 100 °C, with a 40% solids ammonium nitrate solution employed as the hardener.

2.2. Response Surface Methodology and Central Composite Design

This study employed the central composite design (CCD) within the framework of response surface methodology (RSM) to evaluate the effects of durian husk ratio (DHR) and UF resin ratio (UFR) on the thickness swelling (TS), modulus of rupture (MOR), and internal bond strength (IB) of bio-based particleboards. A nine-run experimental design, incorporating cube, center, and axial points, was conducted using Minitab version 21.2. The factor ranges are outlined in

Table 1. Factors and their values as applied in central composite design.

Factors	Ranges of Actual and Coded Values
	−α	−1	0	+1	+α
Durian husk ratio (DHR, %)	4	10	25	40	46
UF resin ratio (UFR, %)	7	8	11.5	15	16

The coded values are defined as follows: −α indicates the lower axial point, −1 the lower cube point, 0 the center point, +1 the upper cube point, and +α the upper axial point.

, with DHR varying from 4% to 46% and UFR ranging from 7% to 16%.

2.3. Particleboard Manufacturing

Single-layer particleboards were manufactured with a density of 0.65 g/cm³ using a mixture of bamboo and durian husk particles bonded with UF resin. The ratios of durian husk particles and UF resin were varied according to CCD, as shown in Table 1. Mats measuring 360 × 360 mm were initially formed, cold-prepressed, and subsequently hot-pressed at 140 °C under a pressure of 2.5 MPa for 10 min. Each experimental condition was replicated three times, resulting in a total of 27 particleboards. Following the pressing process, the boards were left to equilibrate at room temperature for 24 h. Prior to testing, all boards were trimmed to remove edge irregularities and sanded on both faces using a wide belt sander to ensure uniform surface quality.

2.4. Chemical Analysis of Durian Husks

The lignocellulosic composition of durian husk was quantified using standardized procedures established by the Technical Association of the Pulp and Paper Industry (TAPPI), which require the prior removal of extractives to ensure accurate determination. To this end, extractive-free samples were prepared through a multi-step solvent extraction process using an ethanol–benzene mixture (1:2, v/v), followed by 95% ethanol and hot distilled water, in accordance with TAPPI T 264 cm-22 [34]. Holocellulose and lignin contents were subsequently determined from these extractive-free samples. Holocellulose, comprising cellulose and hemicelluloses, was determined using the acid chlorite method [35], while lignin content was measured following TAPPI T 222 om-21 [36], which specifies the determination of acid-insoluble lignin in wood and pulp. All analyses were performed on three replicate samples for each component.

2.5. Testing of Bio-Based Particleboards

Physical and mechanical properties of the investigated bio-based particleboards, including TS, MOR, and IB, were evaluated in accordance with BS EN 317:1993 [37], BS EN 310:1993 [38], and BS EN 319:1993 [39], respectively. For each experimental condition, three replicate boards were tested. From each board, five specimens measuring 50 × 50 mm were prepared for TS, another five of the same dimensions for IB, and five specimens measuring 290 × 50 mm for MOR. All specimens were conditioned to a constant mass in a Memmert HPP260eco (Memmert GmbH, Büchenbach, Germany) climate chamber maintained at 65% relative humidity and 20 °C. Constant mass was defined as the point at which the difference between two successive weight measurements, taken 24 h apart, did not exceed 0.1% of the specimen’s mass. For each board, the average value of the five specimens was first calculated, and the final result for each test under a given condition was obtained by averaging the three board-level means. The results were then evaluated against the specifications outlined for Type P1 particleboards intended for dry environments, as defined in BS EN 312:2010 [40], which require MOR ≥ 10.5 N/mm² and IB ≥ 0.28 N/mm² (1 N/mm² = 1 MPa).

The resulting data were subsequently subjected to statistical analysis using Minitab 21.2 (Minitab LLC, State College, PA, USA). The significance of individual factors and their interactions was evaluated using standardized effect estimates, visualized in a Pareto chart, with a 95% confidence level (p-value < 0.05). Model performance was assessed using the coefficient of determination (R²), along with the adjusted R² value. The Ryan–Joiner normality test was used to verify the normal distribution of residuals for all response variables. Final predictive models were developed for TS, MOR, and IB. All graphs and three-dimensional response surface plots were generated using OriginPro 2024 (OriginLab Corporation, Northampton, MA, USA).

3. Results and Discussion

3.1. Chemical Analysis Result of Durian Husks

The lignocellulosic composition of durian husk is presented in

Table 2. Lignocellulosic composition of durian husk compared with bamboo (%, w/w, oven dried).

Component	Durian Husk in This Study	Durian Husk [41,42]	Bamboo [43,44]
Holocellulose	72.84 (0.89)	65.3–73.54	62.5–79.9
Lignin	15.92 (0.56)	15.45–18.7	20.5–32.2

Values in parentheses represent the standard deviations based on three replicates.

. The results obtained in this study exhibit minor variations from the findings of Khedari et al. [41] and Jha et al. [42]. Durian husk demonstrates a holocellulose content comparable to that of bamboo but with moderately lower lignin levels. Consequently, the composition of durian husk is considered suitable for application in particleboard production.

3.2. Physical and Mechanical Properties of Investigated Bio-Based Particleboard

The test results on TS, MOR, and IB of the bio-based particleboards are presented in Figure 1 and Figure 2. The highest TS was observed at a formulation containing 25% DHR and 7% UFR, whereas the lowest TS was recorded at 25% DHR and 16% UFR. In terms of bending strength, the maximum MOR was achieved at 40% DHR and 15% UFR, while the minimum value was obtained at 10% DHR and 8% UFR. For IB, the highest strength was yielded at 25% DHR and 16% UFR, whereas the lowest was found at 25% DHR and 7% UFR. All recorded MOR and IB values conformed to the performance standards specified in BS EN 312:2010 [40] for Type P1 particleboards intended for applications in dry-service environments.

3.3. Effects of DHR and UFR on TS, MOR, and IB of Bio-Based Particleboard

3.3.1. Effect of DHR and UFR on TS of Bio-Based Particleboard

The ratios of durian husk and UF resin significantly affected the TS of the bio-based particleboards, as both factors exceeded the 95% confidence level in the Pareto chart (Figure 3). Among these factors, UFR exhibited a more dominant influence. Increasing UFR and decreasing DHR led to lower TS values. This trend may be attributed to the higher adhesive content provided by increased UF resin levels, as well as the greater lignin content present in particleboards with lower DHR, given that durian husk contains less lignin than bamboo (Table 2). Both lignin and UF resin are known to contribute to improved water resistance and dimensional stability [3,45,46,47]. These findings are consistent with previous studies on bio-based particleboards manufactured from lignocellulosic residues [5,7,32,48,49,50].

3.3.2. Effects of DHR and UFR on MOR and IB of Bio-Based Particleboard

The proportions of durian husk and UF resin significantly influenced the MOR and IB of the bio-based particleboards, as both factors surpassed the 95% confidence threshold in the Pareto chart (Figure 4). Among these, UFR had the most pronounced effect. Higher MOR values were associated with increasing levels of both UF resin and durian husk, whereas IB improved with increasing UFR and reducing DHR (Figure 5). These trends align with previous findings indicating that both UF resin and lignin enhance inter-fiber bonding and structural rigidity, thereby contributing to improved mechanical performance in particleboards with higher resin and lignin contents [45,46,47,49,51,52]. Additionally, the elevated cellulose content resulting from a higher durian husk ratio may further enhance mechanical properties, as cellulose is a key structural component in lignocellulosic composites [7,48]. These findings are in line with earlier studies on particleboards manufactured from various lignocellulosic residues [3,4,32,47,50,53].

3.4. Regression Analysis and Model Adequacy

Model adequacy was evaluated using R², a statistical measure that quantifies the goodness of fit between the predicted and observed values. The R² values for TS, MOR, and IB were found to be 98.52%, 97.52%, and 98.72%, respectively, demonstrating a strong correlation with the experimental data. These results indicate that the model provides a reliable representation of the variability within the dataset, leaving less than 2% residual variability for these factors.

To further assess the reliability of the model, the adjusted R² values were computed, yielding 96.05% for TS, 93.38% for MOR, and 96.58% for IB. These values reaffirm the model’s robustness and its applicability in practical field conditions, suggesting a high level of predictive accuracy.

Following model fitting, the Ryan–Joiner normality test was employed to evaluate the normality of residuals, particularly suitable for small sample sizes (<50). Based on the test criteria, residuals are considered normally distributed when the p-value exceeds 0.05, while values below this threshold imply a statistically significant departure from normality. In this study, the Ryan–Joiner test produced non-significant results (p-value > 0.1), confirming that the residuals closely followed a normal distribution. This conclusion was further supported by the normal probability plot, where data points aligned closely with the reference line, validating the reliability of the model’s predictions (Figure 6).

The final predictive mathematical models were developed based on significant actual factors influencing the properties of bio-based particleboards made from durian husk and bamboo waste. These models describe the relationships between key parameters and material performance indicators, specifically TS (%), MOR (MPa), and IB (MPa), under varying process conditions, as presented in Equations (1)–(3).

$$\mathrm{TS}=26.465+0.03569\mathrm{DHR}-0.5296\mathrm{UFR}$$

(1)

$$\mathrm{MOR}=7.47+0.1706\mathrm{DHR}+0.567\mathrm{UFR}-0.00952\mathrm{DHR}\times \mathrm{UFR}$$

(2)

$$\mathrm{IB}=0.24497-0.000606\mathrm{DHR}+0.011899\mathrm{UFR}$$

(3)

4. Conclusions

This study successfully developed single-layer bio-based particleboards from agricultural residues, specifically durian husk and bamboo waste. All produced boards met the Type P1 standard specified in BS EN 312:2010, indicating their suitability for general-purpose use in dry conditions. The findings clearly demonstrated that raw material composition significantly influenced key performance parameters, including thickness swelling, modulus of rupture, and internal bond strength. These results underscore the potential of underutilized biomass resources in creating sustainable, value-added composite materials, thereby contributing to waste valorization and advancing circular economy practices in material and construction industries.

Among the nine formulations tested, the board composed of 25% durian husk and 16% urea formaldehyde resin showed the most favorable overall performance, achieving superior dimensional stability and internal bonding while maintaining acceptable bending strength. However, the high resin content may pose challenges in terms of cost-effectiveness and environmental sustainability. In comparison, the formulation with 25% durian husk and 11.5% urea formaldehyde resin offered a more resource-efficient alternative, delivering satisfactory mechanical properties with reduced adhesive input. This composition is therefore recommended for further investigation, particularly in relation to pilot-scale production and industrial-scale implementation.