Toughening – Elastomer E-140

Toughness Enhancement of TOPAS® COC Resins using TOPAS® COC Elastomer E-140

Introduction

TOPAS® cyclic olefin copolymers (COC) are rigid, amorphous polyolefins with glass transition temperatures (T_g’s) ranging from 65°C to 178°C. The high T_g of COC results in high modulus and heat resistance in thin films. However, sometimes an application needs to couple the high modulus and heat resistance of TOPAS® COC resins with a little more toughness. Blending in some TOPAS® Elastomer E-140 can help improve the durability of COC while maintaining the food contact and regulatory compliance for which TOPAS® COC is known. 

Materials

TOPAS® COC Elastomer E-140 is a semi-crystalline ethylene-norbornene copolymer that can be used on its own or as a blend component with rigid TOPAS® COC or other polyolefins to finely tune performance characteristics. Elastomer E-140 is distinct from other COC resins in that it has a melting temperature as a semi-crystalline polymer, and that it has a tensile modulus around 70MPa rather than above about 2000MPa for COC grades. TOPAS® COC are amorphous polyolefins with high Tg’s relative to traditional polyolefins. And because COC resins are amorphous, they do not have a melt temperature but are instead classified by their glass transition temperatures. 

Three grades of TOPAS® COC were used in this study alongside Elastomer E-140: 8007F-04, 5013F-04, and 6013M-07. The T_g, T_m data, melt flow rate for the three COC and Elastomer E-140 are given in Table 1, below.

Table 1: Melt flow rate, melt temperature, and glass transition temperature for the four TOPAS® grades used in this study. The COC resins are amorphous and do not have a melt temperature.

TOPAS® Grade	Melt Flow Rate Value	Melt Flow Rate Conditions	Melt Temperature (Tm)	Glass Transition Temperature (Tg)
Elastomer E-140	2.7g/10min	(190°C, 2.16kg)	84°C	< -90°C
COC 8007F-04	1.8g/10min	(190°C, 2.16kg)	N/A	78°C
COC 5013F-04	8g/10min	(230°C, 2.16kg)	N/A	136°C
COC 6013M-07	12g/10min	(260°C, 2.16kg)	N/A	138°C

Processing

Blends of three TOPAS® COC (8007F-04, 5013F-04, and 6013M-07) were made with 10%, 20% and 30% TOPAS® Elastomer E-140. The materials were pellet blended in the single screw extruder and subsequently extruded through a 300mm wide coat hanger die with a die gap of 0.6mm. The throughput was approximately 5kg/h and drawn down to a film of about 100µm thickness. Films with a bulk phase of 8007F-04 were extruded at 200°C and 230°C, and were quenched on a cooling roll set to 70°C. Films with a bulk phase of either 5013F-04 or 6013F-04 were extruded at 230°C and 260°C, and were quenched on a cooling roll set to 125°C. 

Evaluation Methods

All testing was completed at Polyplastics’ TSC in Fuji, Japan. Films were evaluated for Tensile Strength, Elongation, and Modulus of Elasticity using standard JIS K7127, Bending Toughness using JIS P8115, and Haze using JIS K7105. 

The reported Bending Toughness value is the count of how many times a sample can be bent to set angle before breaking. Each trip to the determined angle is a single count. For example, if the set angle was 90° then bending to 90° and returning to the starting position counts as two bendings. 

The test conditions for Bending Stiffness used in this study were: 175 counts per minute, a 1000g tension, and an angle of 135°. The test standard used was JIS P8115 and was completed on a MIT Automatic Folding Endurance Tester. A comparable method is ASTM D2176.

Results

The result of blending TOPAS® Elastomer E-140 into COC was a nearly linear reduction in modulus and significant increases in bending toughness. Results for all three COC grades tested can be found below in Tables 2, 3 and 4. 

Table 2: Physical properties of TOPAS® COC 8007F-04 blended with TOPAS® COC Elastomer E-140. 

			TOPAS® Elastomer E-140 (wt.%)
	Unit	Film Direction	0%	10%	20%	30%
Extrusion Temp.	°C	–	230	200	200	200
Tensile Strength	MPa	MD	60	54	49	43*
		TD	61	45	37*	31*
Elongation at Break	%	MD	2.8	2.9	3.1	250
		TD	2.7	3.1	110	140
Tensile Modulus	MPa	MD	2300	2000	1800	1500
		TD	1800	1400	1300	1100
Bending Toughness	# of Cycles	MD	540	2000	4400	9000
		TD	150	2100	3800	8500
Haze		–	0.4	1.2	3.1	5.4

Table 3: Physical properties of TOPAS® COC 5013F-04 blended with TOPAS® COC Elastomer E-140. 

			TOPAS® Elastomer E-140 (wt.%)
	Unit	Film Direction	0%	10%	20%	30%
Extrusion Temp.	°C	–	260	230	230	230
Tensile Strength	MPa	MD	45	45	43	40*
		TD	43	43	37*	32*
Elongation at Break	%	MD	1.7	7.4	6.1	37
		TD	1.6	3.1	32	150
Tensile Modulus	MPa	MD	2900	2600	2300	2000
		TD	2300	1900	1700	1500
Bending Toughness	# of Cycles	MD	0	160	300	440
		TD	0	230	1200	3200
Haze		–	0.2	8.4	12	17

Table 4: Physical properties of TOPAS® COC 6013M-07 blended with TOPAS® COC Elastomer E-140.

			TOPAS® Elastomer E-140 (wt.%)
	Unit	Film Direction	0%	10%	20%	30%
Extrusion Temp.	°C	–	260	260	260	260
Tensile Strength	MPa	MD	60	64	63	56
		TD	56	53	43*	36*
Elongation at Break	%	MD	2.6	2.8	3.5	3.5
		TD	2.3	4.0	59	91
Tensile Modulus	MPa	MD	2800	2500	2100	1900
		TD	2300	1900	1500	1300
Bending Toughness	# of Cycles	MD	0	11	24	920
		TD	0	338	1200	3400
Haze		–	0.1	6.7	12	17

Applications

The increased toughness that Elastomer E-140 brings to COC creates opportunities for applications that need the modulus, the high temperature resistance, and the purity of COC but need more toughness than was previously available. Commercial uses of TOPAS® COC Elastomer E-140 and rigid TOPAS® COC blends may include liquid hot-fill VFFS films with improved dimensional stability, recyclable pouches with increased drop strength, or medical packages and devices with increased toughness. 

For more information about TOPAS® resins, including Elastomer E-140, see our Packaging Brochure and Packaging Market pages, or reach out to us via the Contact Us or Find a Rep links at the top of every page on our website.