Effect of walnut shells and silanized walnut shells on the mechanical and thermal properties of rigid polyurethane foams

Członka, Sylwia; Strąkowska, Anna; Kairytė, Agnė

doi:10.1016/j.polymertesting.2020.106534

Cited by 95 publications

(73 citation statements)

References 71 publications

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“…One of the methods of modification of rigid PUR foams is the use of bio-fillers which affect their environmentally friendly character. In recent years, there has been a growing interest in the application as natural fillers of raw materials being waste biomass from food processing, including walnut [ 13 ] or hazelnut [ 14 ] shells and cinnamon [ 15 ], coffee, or cocoa [ 16 ] extracts. The applied bio-fillers can improve the compressive strength, dimensional stability in critical conditions [ 17 ], and thermal insulation capabilities [ 18 ] of modified products.…”

Section: Introductionmentioning

confidence: 99%

Polyurethane Hybrid Composites Reinforced with Lavender Residue Functionalized with Kaolinite and Hydroxyapatite

et al. 2021

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Polyurethane (PUR) composites were modified with 2 wt.% of lavender fillers functionalized with kaolinite (K) and hydroxyapatite (HA). The impact of lavender fillers on selected properties of PUR composites, such as rheological properties (dynamic viscosity, foaming behavior), mechanical properties (compressive strength, flexural strength, impact strength), insulation properties (thermal conductivity), thermal characteristic (temperature of thermal decomposition stages), flame retardancy (e.g., ignition time, limiting oxygen index, heat peak release) and performance properties (water uptake, contact angle) was investigated. Among all modified types of PUR composites, the greatest improvement was observed for PUR composites filled with lavender fillers functionalized with kaolinite and hydroxyapatite. For example, on the addition of functionalized lavender fillers, the compressive strength was enhanced by ~16–18%, flexural strength by ~9–12%, and impact strength by ~7%. Due to the functionalization of lavender filler with thermally stable flame retardant compounds, such modified PUR composites were characterized by higher temperatures of thermal decomposition. Most importantly, PUR composites filled with flame retardant compounds exhibited improved flame resistance characteristics—in both cases, the value of peak heat release was reduced by ~50%, while the value of total smoke release was reduced by ~30%.

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Section: Introductionmentioning

confidence: 99%

Polyurethane Hybrid Composites Reinforced with Lavender Residue Functionalized with Kaolinite and Hydroxyapatite

et al. 2021

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“…It was observed that the chemical treatment did not enhance the mechanical performance and on the contrary, it reduced the cross-link ability between the filler and polymer matrix. The authors of Reference [ 10 ] showed that the silanisation of walnut shells produced PUR biocomposite foams with improved physical and mechanical properties such as compressive and flexural strength, as well as thermal conductivity. Alkaline treatment was shown to be successful for hemp fibres, an 8% concentration showed an improvement in interfacial adhesion between the hemp fibre and the PUR matrix [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Research of Wood Waste as a Potential Filler for Loose-Fill Building Insulation: Appropriate Selection and Incorporation into Polyurethane Biocomposite Foams

et al. 2020

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Currently, the recycling potential of wood waste (WW) is still limited, and in a resource efficiency approach, recycling WW in insulation materials, such as polyurethane (PUR), appears as an appropriate solution. It is known that the quality of WW is the main aspect which influences the stability of the final products. Therefore, the current study analyses different WW-based fillers as possible modifiers for polyurethane biocomposite foams for the application as loose-fill materials in building envelopes. During the study of WW-based fillers, it was determined that the most promising filler is wood scobs (WS) with a thermal conductivity of 0.0496 W/m·K, short-term water absorption by partial immersion—12.5 kg/m2, water vapour resistance—0.34 m2·h·Pa/mg and water vapour diffusion resistance factor—2.4. In order to evaluate the WS performance as a filler in PUR biocomposite foams, different ratios of PUR binder and WS filler (PURb/WS) were selected. It was found that a 0.40 PURb/WS ratio is insufficient for the appropriate wetting of WS filler while a 0.70 PURb/WS ratio produced PUR biocomposite foams with the most suitable performance: thermal conductivity reduced from 0.0523 to 0.0476 W/m·K, water absorption—from 5.6 to 1.3 kg/m2, while the compressive strength increased from 142 to 272 kPa and the tensile strength increased from 44 to 272 kPa.

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“…As discussed previously, PUR foams containing acetylated and silanized WS have a more uniform structure, with a greater number of closed-cells (see Figure 5 ). Moreover, after the silanization and acetylation treatment, the possible chemical reaction may occur between the hydroxyl groups of WS and acetic acid or silane coupling agent, creating chemical covalent linkages that improve the interfacial adhesion between the filler and the polymeric matrix [ 66 , 67 ]. Ciobanu et al [ 68 ] reported that the incorporation of rigid, three-dimensional lignin improved the mechanical characteristics of the resulting products.…”

Section: Resultsmentioning

confidence: 99%

Rigid Polyurethane Foams Based on Bio-Polyol and Additionally Reinforced with Silanized and Acetylated Walnut Shells for the Synthesis of Environmentally Friendly Insulating Materials

Członka

Strąkowska

2020

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Rigid polyurethane (PUR) foams produced from walnut shells-derived polyol (20 wt.%) were successfully reinforced with 2 wt.% of non-treated, acetylated, and silanized walnut shells (WS). The impact of non-treated and chemically-treated WS on the morphology, mechanical, and thermal characteristics of PUR composites was determined. The morphological analysis confirmed that the addition of WS fillers promoted a reduction in cell size, compared to pure PUR foams. Among all the modified PUR foams, the greatest improvement of mechanical characteristics was observed for PUR foams with the addition of silanized WS—the compressive, flexural, and impact strength were enhanced by 21, 16, and 13%, respectively. The addition of non-treated and chemically-treated WS improved the thermomechanical stability of PUR foams. The results of the dynamic mechanical analysis confirmed an increase in glass transition temperature and storage modulus of PUR foams after the incorporation of chemically-treated WS. The addition of non-treated and chemically-treated WS did not affect the insulating properties of PUR foams, and the thermal conductivity value did not show any significant improvement and deterioration due to the addition of WS fillers.

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Effect of walnut shells and silanized walnut shells on the mechanical and thermal properties of rigid polyurethane foams

Cited by 95 publications

References 71 publications

Polyurethane Hybrid Composites Reinforced with Lavender Residue Functionalized with Kaolinite and Hydroxyapatite

Polyurethane Hybrid Composites Reinforced with Lavender Residue Functionalized with Kaolinite and Hydroxyapatite

Research of Wood Waste as a Potential Filler for Loose-Fill Building Insulation: Appropriate Selection and Incorporation into Polyurethane Biocomposite Foams

Rigid Polyurethane Foams Based on Bio-Polyol and Additionally Reinforced with Silanized and Acetylated Walnut Shells for the Synthesis of Environmentally Friendly Insulating Materials

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