Thermal decomposition and combustion behavior of kevlar fiber reinforced polyester resin composites containing fire retardant additives

Hóa học & Kỹ thuật môi trường<br /> <br /> THERMAL DECOMPOSITION AND COMBUSTION BEHAVIOR<br /> OF KEVLAR FIBER REINFORCED POLYESTER RESIN<br /> COMPOSITES CONTAINING FIRE RETARDANT ADDITIVES<br /> Pham Hong Thach1*, Ha Thuc Chi Nhan2, Tang Phan Dang Khoa2,<br /> Le Van Tam1, Nguyen Thi Thom1<br /> <br /> Abstract: In this research, a number of studies had been conducted on the<br /> thermal decomposition and fire behavior of kevlar fiber reinforced polymer<br /> composites (CP-KUFR). Unsaturated polyester (UPE) was mixed with fire<br /> retardant additives including antimony trioxide (Sb2O3), aluminum hydroxide<br /> Al(OH)3, chlorinated paraffin (CPs). The composite materials burning rate (Vc) was<br /> determined according to ASTM D635-14 and UL94-HB standards. The thermal<br /> decomposition behavior of CP-KUFP was investigated by carrying out the<br /> thermogravimetry analyzed method (TGA). Results: The optimal mixing formula<br /> was determined with kevlar fiber 35 wt%, flame retardant 10 wt%, MEKP curing<br /> agent 0.55 wt% and UPE resin content 54.45 wt%. CP-KUFR material was<br /> achieved UL-94HB standard; Burning rate zero; With standing to 800oC; The low<br /> weight change process was shown from 11 %/mg to 16 %/mg.<br /> Keywords: Kevlar fiber; Flame retardant additives; Composite; Unsaturated polymer resin.<br /> <br /> 1. INTRODUCTION<br /> Composite materials are increasingly used in the world because of its<br /> outstanding properties. UPE resins have been used as a substrate in composite<br /> materials for use in military and a number of industries such as construction,<br /> aerospace, transportation... due to their lightweight properties, good corrosion<br /> resistance and performance. However, polyester is very easy to ignite, so it is<br /> necessary to research to develop fire retardant for UPE composite material. At<br /> present, the method of efficiency and convenience is to enhance the thermal<br /> decomposition and reduce the combustion capacity of the polymer by adding flame<br /> retardants to interfere with the combustion of the polymer, altering the solid state<br /> decomposition mechanism of In this study, flame retardants used include antimony<br /> trioxide, chlorinated paraffin, aluminum hydroxide. The combination of UPE resin,<br /> kevlar fiber and fire retardant additives both creates the material that meets the<br /> needs of the user, as well as the research that creates the new material, contributing<br /> to the richness of the composite material [1-4].<br /> 2. MATERIALS AND METHODS<br /> 2.1. Materials<br /> The resin composition by weight from safety data sheet is 50-60 wt% for the<br /> unsaturated polyester (Singapore), 30-50 wt% of styrene, 0.2 wt% cobalt (Co2+),<br /> and 1 wt% Methyl ethyl ketone peroxide (MEKP); MEKP is a free radical-<br /> decomposing catalyst, cobalt is a catalyst promoting the free radical<br /> decomposition of the catalyst, styrene is a compatible monomer that bridges the<br /> UPE circuit, the double bonds of styrene and UPE constitute the active centers of<br /> the suture response. The 1500D Kevlar fiber (Russia): weight 410 g/cm2, density<br /> <br /> 130 P. H. Thach, H. T. C. Nhan,…, “Thermal decomposition… retardant additives.”<br /> Nghiên cứu khoa học công nghệ<br /> <br /> 1.4 g/cm3; The main role is to enhance the mechanical properties, the secondary<br /> role is fire resistance. Antimony Trioxide Sb2O3, Aluminum Hydroxide Al(OH)3<br /> and Chlorinated Paraffin (China); They have major role in fire resistance of the<br /> CP-KUFR.<br /> 2.2. Analytical methods of composite materials<br /> - Tensile strength and modulus are determined according to ISO 527: 2012, on<br /> the INSTRON 300D1 (USA) [5].<br /> - Flexural strength and modulus are determined according to ISO 178: 2010, on<br /> the INSTRON 300D1 (USA) [6].<br /> - Impact resistance is determined according to ASTM D256-10, on ITR 2000 [7].<br /> - Compressive strength and modulus are determined according to ISO 604:<br /> 2012, on the INSTRON 300D1 (USA) with a compression speed of 2 mm/min [8].<br /> - Burning rate is determined according to ASTM D635-14, on the CEAST<br /> equipment (Italy). The test specimen is made up of 125 mm length, 13 mm width<br /> and 3 mm thickness and divided into three sections of 25-75-25 mm size [9-10].<br /> - The thermal degradation and fire behavior of composite materials are<br /> performed by thermogravimetric analysis on TA-Q500 (Canada). The TGA curve<br /> changes with the temperature axis used to determine the mass content of<br /> substances present in the sample, solvent, additives, etc. The sample is measured<br /> with a temperature range from 28-800oC, a heating rate of 20 oC/min.<br /> 2.3. Preparation of CP-KUFR materials<br /> 05 samples of CP-KUFR labeled M1-05, M2-05, M3-05, M4-05, M5-05<br /> correspond to 20 wt%, 25 wt%, 30 wt%, 35 wt% and 40 wt% kevlar fiber with 10<br /> wt% of flame retardant additives (FR) were mixed for CP preparation.<br /> Before making composite materials, cut the kevlar fiber according to the<br /> calculated size, drying at 80oC for 30 minutes combined with vacuum aspiration<br /> to remove moisture. Apply Wax 8 non-stick coating, rub all over the mold<br /> surface. First, sweep a thin layer of plastic onto the mold, then lay the<br /> reinforcement up. Use a soft-bristled brush to scrape onto the yarn to absorb the<br /> resin. Then use rolled steel rolls for the fiber to be packed and sealed with plastic<br /> until it reaches a thickness of 4 mm. Polymer CP is vacuum-dried to remove air<br /> bubbles, to cure at room temperature (25-30°C) after 24 h and dried for 3 h at<br /> 80°C. After 7 days cut the sample and determine the properties, each<br /> characteristic of minimum 5 samples.<br /> 3. RESULTS AND DISCUSSION<br /> 3.1. Preparation of reinforced composite materials from kevlar fiber based<br /> flammability retardant UPE<br /> In the study [2], we have successfully researched composite materials based<br /> UPE, MEKP, flame retardant 10 wt% with kevlar fiber content 20, 25 , 30, 35, 40<br /> and 45 wt%, corresponding: M1-05, M2-05, M3-05, M4-05 and M5-05. The CP<br /> materials were summarized in Tables 1-2 and Figures 1-2.<br /> <br /> <br /> <br /> Tạp chí Nghiên cứu KH&CN quân sự, Số Đặc san NĐMT, 09 - 2017 131<br />  Hóa học & Kỹ thuật môi trường<br /> <br /> Table 1. Effect of kevlar fiber concentration on mechanical properties of CP.<br /> <br /> Kevlar σk Ek σn En σu Eu σvđ<br /> Samples<br /> % MPa GPa MPa GPa MPa GPa KJ/m2<br /> M1-05 20 328.6 13.2 226.7 9.7 301.2 12.8 114.2<br /> M2-05 25 338.1 14.3 297.7 11.9 324.9 13.5 122.6<br /> M3-05 30 388.2 17.6 318.9 15.1 370.6 16.9 135.6<br /> M4-05 35 407.2 18.5 332.6 16.8 382.9 17.3 153.4<br /> M5-05 40 365.3 16.1 310.2 13.2 349.6 15.1 140.5<br /> <br /> <br /> <br /> <br /> Fig.1. The mechanical properties of CP-KUFR.<br /> From Table 1 and Fig.1, were found that kevlar fiber content increasing from 20<br /> wt% to 35 wt%, the mechanical properties of the composite material increased, due<br /> to the intrinsic nature of the mechanical properties [3]. As the kevlar fiber<br /> concentration by 40 wt% of the composite material's mechanical properties<br /> reduced, the UPE background was not sufficient to wet the fibers so the bonding<br /> between the layers decreased.<br /> The burning rate of CP-KUFR samples was zero. Restart the timing device when<br /> the flame front reaches the 25 mm reference mark, meets in the UL 94-HB standard<br /> (Table 2 and Fig.2). This is explained by the high fire resistance and the low thermal<br /> decomposition behavior of kevlar fiber, so composite materials had good fire<br /> resistance. Composite fire resistance was higher when kevlar fiber content was<br /> higher, but mechanical properties decrease (if the kevlar fiber concentration exceeds<br /> 40 wt%). Therefore, composite materials with good fire resistance and high<br /> mechanical properties, the kevlar fiber content should be 35 wt%.<br /> <br /> <br /> 132 P. H. Thach, H. T. C. Nhan,…, “Thermal decomposition… retardant additives.”<br /> Nghiên cứu khoa học công nghệ<br /> <br /> Table 2. Burning rates of CP-KUFR samples.<br /> Kevlar fiber Burning Vc Burned UL<br /> Sample<br /> concentratio time (mm/min length 94-HB<br /> s<br /> n (%) (minute) ) (mm)<br /> M1-05 20 1.09 0 0 Yes<br /> M2-05 25 0.00 0 0 Yes<br /> M3-05 30 0.79 0 0 Yes<br /> M4-05 35 0.00 0 0 Yes<br /> M5-05 40 0.00 0 0 Yes<br /> <br /> <br /> <br /> <br /> Fig. 2. The CP-KUFR samples after fire resistance experimental.<br /> <br /> 3.2. The thermal degradation behavior of CP-KUFR<br /> Investigated the thermal degradation behavior of composite materials in a<br /> nitrogen gas with a constant heating rate at 20 °C/min, heating range from 28°C to<br /> 800°C. CP-KUER composition: kevlar fiber 35 wt%, FR wt10%, MEKP 0.55 wt%<br /> and UPE 54.45 wt%.<br /> <br /> <br /> <br /> <br /> Fig.3. The TGA and the DTGA diagram of CP-KUFR.<br /> <br /> <br /> Tạp chí Nghiên cứu KH&CN quân sự, Số Đặc san NĐMT, 09 - 2017 133<br />  Hóa học & Kỹ thuật môi trường<br /> <br /> The TGA and the DTGA results were shown in Figure 3. The TGA data (red<br /> curve) can be noticed that the CP-KUFR decomposition was a two-stage process<br /> characterized by first step in the temperature range from 380oC to 480oC, with<br /> mass loss from 16.57 wt% to 50.93 wt%, followed by second decomposition step<br /> located the range 480oC-800oC and characterized by mass loss from 50.93 wt% to<br /> 75.15 wt%. The final residue of CP-KUFR was 24.48 wt%. The DTGA diagram<br /> (blue curve) had two peaks. The first peak showed the temperature range from<br /> 380oC to 480oC of the strongest decomposition temperature at 414.18oC with the<br /> derivative weight 16.38 %/mg. The second peak showed the temperature range<br /> from 480oC to 800oC of the strongest decomposition temperature at 638.13oC with<br /> the derivative weight 11.61 %/mg.<br /> It was explained that, in the temperature range 380oC-480oC, The chlorinated<br /> paraffin reacted with free radicals OH*, H* to prevent the cause of burning spread.<br /> The temperature range 480oC-800°C, Sb2O3 reacted with free radicals OH*, H*<br /> HCl gas, forming an ash layer combined with poor thermal and low heat<br /> conductivity of kevlar fibers to prevent heat transfer and phase transition from<br /> solid phase on composite surface to gas phase.<br /> 4. CONCLUSIONS<br /> This study had made kevlar fiber reinforced unsaturated polyester resin<br /> composite. CP-KUFR composition: Kevlar fiber 35 wt%, flame retardant 10 wt%,<br /> MEKP curing agent 0.55 wt% and UPE resin 54.45 wt%. The thermal<br /> decomposition and fire behavior of CP-KUFR were investigated. Composite test<br /> was achieved UL-94HB standard; Burning rate zero; Withstanding to 800oC; The<br /> low weight change process was shown from 11 %/mg to 16 %/mg.<br /> REFERENCE<br /> [1]. Maria R Ricciardi, Vincenza Antonucci, “Thermal decomposition and fire<br /> behavior of glass fiber reinforced polyester resin composites containing<br /> phosphate based fire-retardant additives”, Journal of fire sciences, Vol 4, No.<br /> 30 (2012), pp. 318-330.<br /> [2]. Huynh Dai Phu, Pham Hong Thach, Do Ngoc Tuong Vy, “Research of<br /> composite from kevlar fiber with polyester resin having flame retardant”,<br /> Graduate thesis of Ton Duc Thang University, 2/2017.<br /> [3]. Nguyen Dang Cuong, “Composite of Fiberglass and Applications”, Science<br /> and Technics Publishing House, 2011.<br /> [4]. Thai Hoang, Nguyen Thac Kim, Nguyen Vu Giang, Do Quang Tham,<br /> “Thermal resistance, fire–retardant and electrical properties of composite<br /> poly (vinyl clorua)/clay”, Journal Science and Technology, Vol. 45, No. 3<br /> (2007), pp. 67-73.<br /> [5]. Standard of ISO 527-4:2012, “Plastics - Determination of tensile properties -<br /> Part 4: Test conditions for isotropic and orthotropic fiber-reinforced plastic<br /> composites”.<br /> [6]. Standard of ISO 178-2010, “Plastics - Determination of flexural properties”.<br /> <br /> <br /> 134 P. H. Thach, H. T. C. Nhan,…, “Thermal decomposition… retardant additives.”<br /> Nghiên cứu khoa học công nghệ<br /> <br /> [7]. Standard of ASTM D256 – 10, “Standard Test Methods for Determining the<br /> Izod Pendulum Impact Resistance of Plastics”.<br /> [8]. Standard of ISO 604- 2010, “Plastics - Determination of compressive<br /> properties”.<br /> [9]. Standard of ASTM D635 – 12, “Standard Test Method for Rate of Burning<br /> and/or Extent and Time of Burning of Plastics in a Horizontal Position”.<br /> [10]. Standard of UL 94-HB, “Test for Flammability of Plastic materials for Parts<br /> in Devices an Appliances”.<br /> <br /> <br /> TÓM TẮT<br /> SỰ PHÂN HỦY THEO NHIỆT ĐỘ VÀ HÀNH VI CHÁY CỦA VẬT LIỆU<br /> COMPOZIT POLYESTER GIA CƯỜNG TỪ SỢI KEVLAR CÓ CHỨA<br /> PHỤ GIA CHỐNG CHÁY<br /> Trong công trình khoa học này, đã thực hiện một số nghiên cứu về sự<br /> phân hủy nhiệt và hành vi cháy của vật liệu compozit gia cường sợi kevlar<br /> chứa phụ gia chống cháy (CP-KUFR). Nhựa polyester không no (UPE) được<br /> trộn hợp với các loại phụ gia chống cháy gồm antimoni trioxide (Sb2O3),<br /> nhôm hydroxide Al(OH)3, parafin clo hóa (PCs). Khả năng chống cháy của<br /> vật liệu compozit được đánh giá theo tiêu chuẩn D635 – 14 và UL 94-HB.<br /> Thông qua phương pháp nhiệt trọng lượng (TGA) cho thấy ưu điểm của sợi<br /> kevlar đối với khả năng chống cháy của vật liệu compozit. Kết quả: xác định<br /> được công thức phối trộn tối ưu chế tạo với hàm lượng sợi kevlar chiếm<br /> 35%, hỗn hợp chất chống cháy chiếm 10%, chất đóng rắn MEKP chiếm<br /> 0,55% và lượng nhựa UPE là 54,45% khối lượng compozit. CP-KUFR đạt<br /> chuẩn UL 94-HB, tốc độ cháy bằng 0, chịu được nhiệt độ 8000C và quá trình<br /> thay đổi khối lượng diễn ra chậm từ 11 %/mg – 16 %/mg.<br /> Từ khóa: Sợi kevlar, Phụ gia chống cháy, Compozit, Nhựa polyester không no.<br /> <br /> Received: 1st Aug, 2017<br /> Completed revision: 25th Aug, 2017<br /> Accepted for publication: 8st Sep, 2017<br /> Address:<br /> 1<br /> Institute for Tropicalization and Environment, Academy of Military Science and<br /> Technology, 57A Truong Quoc Dung Street, Ward 10, Phu Nhuan District, Ho Chi Minh<br /> City, Viet Nam;<br /> 2<br /> Faculty of Materials Science, University of Science – VNUHCM,<br /> 227 Nguyen Van Cu Street, Ward 4, Dist.5, Ho Chi Minh City, Vietnam.<br /> *<br /> Email: thachvktnd@yahoo.com.<br /> <br /> <br /> <br /> <br /> Tạp chí Nghiên cứu KH&CN quân sự, Số Đặc san NĐMT, 09 - 2017 135<br />