An unusual balance of high modulus and ductile impact behavior is claimed for Xenoy HMD resins, recently launched by SABIC Innovative Plastics.

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A proprietary thermoplastic additive generates this nano-fibrillated thermoplastic network during compounding within the PC/polyester alloy.

New Xenoy X4820 outperforms standard unfilled PC/PBT in a wide range of properties. Most important, the new grade is stiffer while closely matching the unfilled grade in ductile toughness.

An unusual balance of high modulus and ductile impact behavior is claimed for Xenoy HMD resins, recently launched by SABIC Innovative Plastics. As we reported initially in November, these PC/PBT and PC/PET alloys achieve this combination of properties through the addition of a third thermoplastic ingredient that forms a nano-fibrillated network throughout the alloy matrix,
plus a patent-pending mineral filler of normal micron size. Six grades make up the initial Xenoy HMD slate. All are PC/PBT except for one high-heat PC/PET grade (X4870HH). One grade, IQ4840, incorporates PBT produced by chemical recycling of post-consumer PET.

Also in development is a flame-retardant version that achieves UL 94V-0 at 1.5 mm thickness and potentially down to 0.8 mm, as well as a high-flow version for thin-wall parts.

 

HOW THEY’RE DIFFERENT

In previous PC/polyester blends, mineral fillers have been used to enhance stiffness or reduce coefficient of thermal expansion (CTE), but at the expense of compromising ductility on impact, especially at low temperatures. In contrast, the ductility of an unfilled alloy is largely retained with the new HMD technology. 

Further advantages over standard Xenoy grades are said to include excellent fatigue resistance, better creep resistance, good chemical resistance, low CTE (down to 4.5 vs. the usual 8), and around 8° C/15° F higher HDT than unfilled Xenoy. Good surface appearance, improved hydrolytic stability, and good weatherability and color retention are also claimed.

HMD blends typically process in the same way as regular PC/polyester blends, but with the advantage that the same grade can be used for injection molding, extrusion/thermoforming, and in some cases even blow molding. Potential applications include power-tool housings, sports and safety equipment, and automotive energy absorbers, door handles, and fuel-tank flaps. While the company would not comment on pricing of the new grades, SABIC sources did say the enhanced performance of HMD grades allows for thinner walls, reducing the overall part cost.

In the accompanying table, the current HMD grades are compared with two standard Xenoy resins: CL100B, a general-purpose unfilled grade for unpainted automotive exterior parts, and X5410, a mineral-filled PC/PET for painted auto exterior parts.

 

NEW XENOY HMD COMPOUNDS VS. STANDARD GRADES
 
CL100B
Std. Unfilled
X4810
HMD
X4820
HMD
X4830
HMD
iQ4840
HMD
X4850
HMD
X4870HH
HMD
X5410
Std. Min. Filled
MECHANICAL
Tensile Mod., GPa
2.2
2.75
3.0
3.2
3.8
3.85
4.3
3.2
Tensile Str. @ Yield, MPa
55
55
52
60
62
58
63
55
Elong. @ Break, %
75
100
100
120
100
80
10
12
Flex. Mod., GPa
2.2
2.5
2.85
2.9
3.45
3.5
4.0
2.7
Flex. Str. @ Yield, MPa
85
87
87
90
96
94
98
93
IMPACT
Notched Izod, kJ/m2
23 C
46
50
55
45
20
20
10
7
0° C
--
20
30
15
--
11
--
--
-30 C
21
12
15
9
--
7
6
7
THERMAL
Vicat Temp., C
129
133
134
135
128
135
139
140
HDT, C
0.45 MPa
110
115
--
119
116
121
131
128
1.8 MPa
90
91
94
97
98
99
113
105
CTE, 1/10-5 °C
9
8
--
7.2
--
6.3
4.8
5.8
PHYSICAL
Density, g/cc
1.22
1.25
1.26
1.27
1.3
1.31
1.34
1.26
Mold Shrinkage, Flow Dir., %
0.7-1.0
0.7-0.9
0.5-0.9
0.7-0.9
0.7-0.9
0.7-0.9
0.5-0.7
0.7-0.8