Abstract: <SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">Surface modification for precipitated silica was made with n-octyl alcohol as the modifier.Effects of temperature,dosage of modifier,modified time on the activation degree,oil absorption value,and settlement volume of precipitated silica were discussed by orthogonal test.Through data processing and comprehensive analysis,optimized modification conditions of precipitated silica were obtained as follows:modified temperature was <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="80" UnitName="℃">80 <SPAN lang=EN-US style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman""><SPAN lang=EN-US>℃</SPAN></SPAN></st1:chmetcnv>,modified time was 50 min,modifier dosage was 40 mL per <st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="10" UnitName="g">10 g</st1:chmetcnv> SiO</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"><SUB>2</SUB>,solvent toluene was 10 mL,and p-toluenesulfonic acid catalyst was <st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="2" UnitName="g">2.0 g</st1:chmetcnv>.Under these conditions,the activation degree,oil absorption value,and settlement volume of precipitated silica product after modification were 91.0%,2.80 mL/g,and 4.10 mL/g,respectively.Compatibility of the modified silica and rubber was improved apparently.</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman"; mso-bidi-font-family: "Times New Roman"; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"></SPAN>