مقایسه روش اصلاح حرارتی با هوا و روغن بر ویژگی‌های فیزیکی و مکانیکی چوب پالونیا

نوع مقاله : مقاله کامل علمی پژوهشی

نویسندگان

1 عضو هیئت علمی (استادیار) دانشکده مهندسی چوب و کاغذ، گروه آموزشی علوم و مهندسی کاغذ

2 استادیار، گروه تکنولوژی و مهندسی چوب- دانشکده مهندسی چوب و کاغذ- دانشگاه علوم کشاورزی و منابع طبیعی گرگان

چکیده

سابقه و هدف: با توجه به کمبود منابع جنگلی و افزایش تقاضا برای چوب و فرآورده‌های آن، یکی از راه‌های تأمین ماده اولیه چوبی، کاشت گونه‌های سریع‌الرشد می‌باشد. یکی از این گونه‌های کشت‌شده در کشور ما، گونه پالونیا فورتونی(Paulownia fortune) بوده که دارای ویژگی‌های منحصر به فردی می باشد. با توجه به اهمیت استفاده بهینه از چوب‌ها در کاربردهای مختلف، امروزه این مواد با ارزش را با روش‌های مختلفی اصلاح می‌کنند. اصلاح حرارتی به‌عنوان روش کارآمد و دوستدار محیط زیست، گزینه مناسبی برای بهبود ویژگی‌های گونه‌های چوبی سریع‌الرشد می‌باشد. لذا در این مطالعه تأثیر روش اصلاح حرارتی در هوا و روغن بر برخی از ویژگی‌های فیزیکی و مکانیکی چوب پالونیا فورتونی مورد بررسی قرار گرفت.
مواد و روش‌ها: چوب مورد استفاده در این پژوهش سه اصله درخت پالونیا ( fortunei Paulownia) از جنگل شصت کلاته دانشگاه علوم کشاورزی و منابع طبیعی گرگان تهیه شد. گرده بینه های پالونیا فورتونی پس از تبدیل به تخته در هوای آزاد خشک شدند. سپس نمونه‌های چوبی با الیاف مستقیم و بی‌عیب از نظر ظاهری از آنها تهیه شد. نمونه‌ها با دو روش اصلاح حرارتی در هوا و روغن، اصلاح گردیدند. اصلاح حرارتی در هوا مطابق روش ترمووود نوع D ( دمای 212 درجه سانتی‌گراد و در مدت زمان 2ساعت ) انجام شد. همچنین اصلاح حرارتی با روغن کلزا نیز با شرایط دمایی مشابه روش اصلاح حرارتی در هوا برای تیمار نمونه‌ها استفاده شد. سپس آزمون‌های رنگ سنجی، مقاومت خمشی، سختی، ضربه، جذب آب و واکشیدگی ضخامت بر روی نمونه ها انجام شد.
یافته‌ها: نتایج به‌دست‌آمده نشان داد که تیمار حرارتی با هر دو روش بر دانسیته، واکشیدگی حجمی و جذب آب، رنگ‌سنجی، مقاومت به ضربه، مقاومت به سختی، مدول گسیختگی و مدول الاستیسیته به‌طور معنی‌داری تأثیر داشته است. به‌طور کلی تیمار حرارتی با هر دو روش موجب کاهش دانسیته، جذب آب و واکشیدگی، شاخص روشنایی، مقاومت به ضربه، سختی، مدول گسیختگی و مدول الاستیسیته شد. دانسیته، جذب آب و واکشیدگی حجمی نمونه‌های تیمارشده در روغن در مقایسه با نمونه‌های تیمار شده در هوا بیشتر بود. مقاومت به ضربه، مقاومت به سختی، مدول گسیختگی و مدول الاستیسیته نمونه‌های تیمارشده در روغن در مقایسه با نمونه‌های تیمارشده در هوا به-طور معنی‌داری بیشتر بود.
نتیجه‌گیری: به‌طور کلی پالونیا تیمار شده در روغن در مقایسه با تیمارشده در هوا خواص فیزیکی و مکانیکی نسبتاً بهتری نشان داد. لذا تیمار حرارتی در روغن در مقایسه با تیمار حرارتی در هوا، روش مؤثرتری برای بهبود خواص فیزیکی و مکانیکی چوب پالونیا می‌باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Comparison of thermal modification method with air and oil on physical and mechanical properties of Paulownia wood

نویسندگان [English]

  • Mozhdeh Mashkour 1
  • Davood Rasouli 2
1 Assistant professor of Department of Paper Science and Engineering, Faculty of Wood and Paper Engineering
2 Assistant Prof, Department of Wood Engineering and Technology, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources
چکیده [English]

Background and objective: One of the ways to supply wood raw material is to plant fast-growing species, with regards to the lack of forest resources and the increase in demand for wood and its products. One of the fast-growing species cultivated in our country is Paulownia fortune, which has unique characteristics. Nowadays these valuable materials are modified in various ways, due to the importance of optimal use of wood in various applications.. Thermal modification, as an efficient and environmentally friendly method, is a suitable option for improving the characteristics of fast-growing wood species. Therefore, in this study, the effect of thermal treatment in air and oil on some physical and mechanical properties of Paulownia fortunei wood was investigated.
Materials and methods: The wood used in this research was three trunks of Paulownia tree (Paulownia fortune) from Shasat Kalate forest of Gorgan University of Agricultural Sciences and Natural Resources. The wood was dried in the open air after turning into boards. Then wooden samples with straight fibers and flawless appearance were prepared from them. The samples were modified by two thermal modification methods in air and oil. Thermal modification in air was done according to Thermo-D process (at 212 ± 3 ◦C and 2 hours). Also, thermal modification with rapeseed oil was used for the treatment of samples with the same temperature conditions as the method of thermal modification in air. Then colorimetric test, bending strength, hardness, impact resistance, water absorption and thickness shrinkage tests were performed on the samples.
Findings: Results revealed that heat treatment with both methods had a significant effect on density, volumetric shrinkage and water absorption, colorimetry, impact resistance, hardness resistance, modulus of rupture and modulus of elasticity. In general, heat treatment with both methods caused a decrease in density, water absorption and elongation, brightness index, impact resistance, hardness, modulus of rupture and modulus of elasticity. The density, water absorption and volumetric shrinkage of the samples treated in oil were higher compared to the samples treated in air. The impact resistance, hardness resistance, modulus of rupture and modulus of elasticity of the samples treated in oil were significantly higher compared to the samples treated in air.
Conclusion: In general, Paulownia fortune treated in oil showed relatively better physical and mechanical properties compared to the one treated in air. Therefore, heat treatment in oil is a more effective method to improve the physical and mechanical properties of Paulownia fortune wood compared to heat treatment in air.

کلیدواژه‌ها [English]

  • Thermal modification
  • Rapeseed oil
  • Paulownia fortune wood
  • Thermowood
  • physical and mechanical properties
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