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									ผลของความเร็วของเกลียวหมุน ตอคุณสมบัติของพอลิเมอรนาโนคอมโพสิทซึ่งผสมระหวาง
พอลิแล็คติค เอซิทกับออรกาโนเคลย โดยใชเครื่องอัดรีดแบบเกลียวคู
Effect of Screw Rotating Speed on the Properties of Poly lactic
acid(PLA)/Organoclay Nanocomposites Prepared by a Twin Screw Extruder

อนิวรรต หาสุข1, Hiroki Muramatsu2, Shuichi Tanoue2, Yoshiyuki Iemoto2 and Tsunemune
Aniwat Hasook 1, Hiroki Muramatsu2, Shuichi Tanoue2, Yoshiyuki Iemoto2 and
Tsunemune Unryu3
  Department of Industrials Engineering, Rajamangala University of Technology isan,
Nakorn Ratchasima, Thailand, E-mail address: aniwat05@gmail.com
  Department of Materials Science and Engineering, University of Fukui, Japan
  Industrial Technology Center of Fukui Prefecture, Japan

โน คอมโพสิท ซึ่งหลอมผสมระหวางพอลิเเล็คติค แอซีทกับออรกาโนเคลย โดยใชพอลิอะไมด 12 เปน
สารชวยใหเขากันหรือตัวประสาน        ในงานวิจัยนี้ไดใชความเร็วของเกลียวหมุนของเครื่องอัดรีดแบบ
เกลียวคู เปน 2 ชวง ดวย กัน คือ 65 และ 150 รอบตอนาที จากการทดสอบคุณสมบัติเชิงกลพบวา
คุณสมบัติการทนตอแรงดึงของพอลิเมอรมีคุณสมบัติเพิมขึ้นที่ความเร็วรอบที่ 150 รอบตอนาที ระยะหาง
ระหวาง ออรกาโนเคลยเพิมมาก ขึ้นแตไมขึ้นอยูกับการผสมตัวประสาน จากภาพถายพบวา ขนาดกอน
ของออรกาโนเคลยในพอลิเมอร คอมโพสิทที่ผสมกับพอลิอะไมด 12 มีขนาดเล็กกวา พอลิเมอรที่ผสมกับ
ออรกาโนเคลยอยางเดียว ในกรณีศกษา การหลอมผสมที่ความเร็วสูงของเครื่องอัด รีดแบบ เกลียวคู
สามารถเพิ่มคุณสมบัติของวัสดุ ไดดกวาความเร็วต่ํา และการผสมตัวประสานก็พบ วาสามารถเพิ่ม
คุณสมบัติในการทนตอแรงดึง และ เสถียรภาพในการทนตอความรอน

Abstract: This study analyzes the effect of different screw rotating speeds on the
properties of nanocomposites prepared by melt compounding PLA with an organoclay in a
co-rotating twin-screw extruder. Polyamide 12 was used as an additive. Two different
screw rotating speeds, 65 rpm and 150 rpm, were used in this study. According to the
tensile strength data, the Young’s modulus and tensile strengths of the PLA/clay
nanocomposites showed improvement at a screw rotating speed of 150 rpm. The d-spacing
of PLA/PA12/Clay nanocomposites was independent of adding PA12. The size of the clay
aggregates in the PLA/PA12/Clay nanocomposites is smaller than that of PLA/Clay. On
the whole, the higher screw rotating speed (150 rpm) resulted in materials with better
performance than the lower screw rotating speed (65 rpm) in a twin-screw extruder and the
addition of PA12 showed the most improvement in the tensile strength and thermal

Recently polymer/clay nanocomposites have attracted considerable attention because a
very small amount of clay can significantly improve mechanical and physical properties of
the polymers, such as strength, stiffness, moldability, thermal stability, dimensional
stability and flame retardancy [1-4]. Polymer/clay nanocomposites consist of inorganic
layered clay interaction in a polymeric matrix. It is important that clay is intercalated and
exfoliated by melt compounding. Both Poly lactic acid (PLA) and Polyamide(PA12) are
noteworthy materials. PLA is particularly noteworthy because it is produced from
biodegradable polymers from renewable resources [5]. In this study, first we describe the
preparation of PLA/organoclay nanocomposites by using different screw rotating speed in
a twin-screw extruder (TSE). Second, we investigated the effect of screw rotating speed
and the effect of adding PA12 to PLA/organoclay nanocomposites on the dispersibility of
organoclay and mechanical properties.

                                               Table 1 : Materials compounding ratio
PLA (LACEA H-100) was kindly
supplied by Mitsui Chemicals Co.,
LTD., Japan. The organoclay (S-
Ben W, called as Clay in this
study) was kindly supplied by
Hojun Co., LTD., Japan. The Clay
is intercalated by dimethyl
distearyl ammonium ion between
the clay platelets. Polyamide 12
obtained from Sigma-Aldrich Co.,
LTD. was used in this study. Ten
cases of PLA/Clay nanocomposites
were prepared in a TSE (see Table1). Compounding was carried out at a constant barrel
temperature of 180 ºC, different screw rotating speeds of 65 and 150 rpm, and a feed rate
of 0.5 kg/h for all extrusion cases. The product was characterized by tensile test, X-ray
diffraction and TEM photographs. The decomposition temperature, glass transition
temperature Tg and the melting temperatures Tm were measured by thermo-gravimetric
analysis (TGA) and differential scanning calorimetry (DSC).

Results and Discussion
The mechanical properties for the PLA/Clay nanocomposites are shown in Figure 1. The
Young’s modulus increases with addition of Clay to PLA matrix. The tensile strengths and
elongations at break become small when Clay is added to the mixture. Conversely, the
tensile strengths of PLA/Clay nanocomposites become large with addition of PA12.

 Figure 1: Tensile testing results of various PLA           Figure 2:X-ray diffraction results
 mixtures and neat PLA. (a) Young’s modulus and             of PLA/Clay nanocomposites and
 (b) Tensile strength.                                      neat Clay.
According to the XRD results, the d-spacing of
each PLA/Clay and each PLA/PA12/Clay
nanocomposite was larger than that of neat Clay.
While, the d-spacing of PLA/PA12/Clay
nanocomposite is independent of the PA12
added. Figure 3 shows the TEM photographs,
the size of the clay aggregates in the
PLA/PA12/Clay nanocomposites is smaller than
that of PLA/Clay ones and nearly exfoliated.
The number of clay platelets in clay stacks of
the PLA/Clay nanocomposites at screw rotating
speed of 150 rpm is smaller than that at screw
rotating speed of 65 rpm.                          Figure 3: Typical TEM photographs of
   From TG and DSC analyses, the thermal PLA/Clay (Case 3) and PLA/PA12
properties of the PLA/Clay nanocomposites /Clay nanocomposites (Case 7)
were increases in melting temperature Tm with
addition of PA12 and slightly different in the glass transition temperatures Tg and the
enthalpies of melting ΔHm for all cases of the PLA/Clay nanocomposites.

PLA/organoclay nanocomposites were prepared by melt compounding using a twin-screw
extruder at different screw rotating speed and the addition of PA12. On the whole,
according to the mechanical properties, XRD results, TEM photomicrographs and thermal
stabilities, in the cases studied, the higher screw rotating speed (150 rpm) resulted in
materials with better performance than the lower screw rotating speed (65 rpm) in a twin-
screw extruder (TSE) and the addition of PA12 showed the most improvement in the
tensile strength and thermal stabilities.
The authors would like to express their thanks to Mitsui Chemicals Co. Ltd., Japan for
supplying the Poly lactic acid (PLA) resin, Hojun Co. Ltd., Japan for supplying the
organoclay, and Plastic Technical Center, Sumitomo Chemicals Co. Ltd., Japan for
preparing the specimens and taking the TEM photographs.

1. L. A. Utracki, Clay-Containing Polymeric Nanocomposites, RAPRA, Shawbury,
   Shewsbury, Shropshire UK (2004).
2. L. A. Utracki and M. R. Kamal, Arabian J. Sci. Eng., 27, 43 (2002).
3. G. Chen, Y. Ma and Z. Qi, Scrita Mater., 44, 125 (2001).
4. M. Alexandre and P. Dubois, Mater. Sci. Eng., 28, 1 (2000).
5. R. E. Drumright, P. R. Gruber and D. E. Henton, Adv. Mater., 12, 1841 (2000).

Keywords: Nanocomposite, Poly lactic acid, Polyamide 12, Organoclay, Melt
          compounding, Twin-screw extruder

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